Other
Adjunctive Therapy: LAMOTRIGINE is indicated as adjunctive therapy for the following seizure types in patients ≥2 years of age:
- partial seizures
- generalized seizures of Lennox-Gastaut syndrome
General: Fever, neck pain.
Cardiovascular: Migraine.
Digestive: Flatulence
Metabolic and Nutritional: Weight gain, edema.
Musculoskeletal: Arthralgia, myalgia.
Nervous System: Amnesia, depression, agitation, emotional lability, dyspraxia, abnormal thoughts, dream abnormality, hypoesthesia.
Respiratory: Sinusitis.
Urogenital: Urinary frequency.
Monotherapy: LAMOTRIGINE is indicated for conversion to monotherapy in adults (≥16 years of age) with partial seizures who are receiving treatment with carbamazepine, phenytoin, phenobarbital, primidone, or valproate as the single antiepileptic drug (AED).
Safety and effectiveness of LAMOTRIGINE have not been established (1) as initial monotherapy; (2) for conversion to monotherapy from AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproate; or (3) for simultaneous conversion to monotherapy from 2 or more concomitant AEDs.
Rash: There are suggestions, yet to be proven, that the risk of severe, potentially life-threatening rash may be increased by (1) coadministration of LAMOTRIGINE with valproate, (2) exceeding the recommended initial dose of LAMOTRIGINE, or (3) exceeding the recommended dose escalation for LAMOTRIGINE. However, cases have occurred in the absence of these factors [see Boxed Warning]. Therefore, it is important that the dosing recommendations be followed closely.
The risk of nonserious rash may be increased when the recommended initial dose and/or the rate of dose escalation of LAMOTRIGINE is exceeded and in patients with a history of allergy or rash to other AEDs.
LAMOTRIGINE Starter Kits provide LAMOTRIGINE at doses consistent with the recommended titration schedule for the first 5 weeks of treatment, based upon concomitant medications for patients with epilepsy (>12 years of age) and Bipolar I Disorder (≥18 years of age) and are intended to help reduce the potential for rash. The use of LAMOTRIGINE Starter Kits is recommended for appropriate patients who are starting or restarting LAMOTRIGINE [see How Supplied/Storage and Handling (16)].
It is recommended that LAMOTRIGINE not be restarted in patients who discontinued due to rash associated with prior treatment with lamotrigine, unless the potential benefits clearly outweigh the risks. If the decision is made to restart a patient who has discontinued lamotrigine, the need to restart with the initial dosing recommendations should be assessed. The greater the interval of time since the previous dose, the greater consideration should be given to restarting with the initial dosing recommendations. If a patient has discontinued lamotrigine for a period of more than 5 half-lives, it is recommended that initial dosing recommendations and guidelines be followed. The half-life of lamotrigine is affected by other concomitant medications [see Clinical Pharmacology (12.3)].
LAMOTRIGINE Added to Drugs Known to Induce or Inhibit Glucuronidation: Drugs other than those listed in the Clinical Pharmacology section [see Clinical Pharmacology (12.3)] have not been systematically evaluated in combination with lamotrigine. Because lamotrigine is metabolized predominantly by glucuronic acid conjugation, drugs that are known to induce or inhibit glucuronidation may affect the apparent clearance of lamotrigine and doses of LAMOTRIGINE may require adjustment based on clinical response.
Target Plasma Levels for Patients With Epilepsy or Bipolar Disorder: A therapeutic plasma concentration range has not been established for lamotrigine. Dosing of LAMOTRIGINE should be based on therapeutic response [see Clinical Pharmacology (12.3)].
Women Taking Estrogen-Containing Oral Contraceptives: Starting LAMOTRIGINE in Women Taking Estrogen-Containing Oral Contraceptives: Although estrogen-containing oral contraceptives have been shown to increase the clearance of lamotrigine [see Clinical Pharmacology (12.3)], no adjustments to the recommended dose-escalation guidelines for LAMOTRIGINE should be necessary solely based on the use of estrogen-containing oral contraceptives. Therefore, dose escalation should follow the recommended guidelines for initiating adjunctive therapy with LAMOTRIGINE based on the concomitant AED or other concomitant medications (see Table 1 or Table 5). See below for adjustments to maintenance doses of LAMOTRIGINE in women taking estrogen-containing oral contraceptives.
Adjustments to the Maintenance Dose of LAMOTRIGINE In Women Taking Estrogen-Containing Oral Contraceptives:
(1) Taking Estrogen-Containing Oral Contraceptives: For women not taking carbamazepine, phenytoin, phenobarbital, primidone, or rifampin, the maintenance dose of LAMOTRIGINE will in most cases need to be increased, by as much as 2-fold over the recommended target maintenance dose, in order to maintain a consistent lamotrigine plasma level [see Clinical Pharmacology (12.3)].
(2) Starting Estrogen-Containing Oral Contraceptives: In women taking a stable dose of LAMOTRIGINE and not taking carbamazepine, phenytoin, phenobarbital, primidone, or rifampin, the maintenance dose will in most cases need to be increased by as much as 2-fold in order to maintain a consistent lamotrigine plasma level. The dose increases should begin at the same time that the oral contraceptive is introduced and continue, based on clinical response, no more rapidly than 50 to 100 mg/day every week. Dose increases should not exceed the recommended rate (see Table 1 or Table 5) unless lamotrigine plasma levels or clinical response support larger increases. Gradual transient increases in lamotrigine plasma levels may occur during the week of inactive hormonal preparation ("pill-free" week), and these increases will be greater if dose increases are made in the days before or during the week of inactive hormonal preparation. Increased lamotrigine plasma levels could result in additional adverse reactions, such as dizziness, ataxia, and diplopia. If adverse reactions attributable to LAMOTRIGINE consistently occur during the "pill-free" week, dose adjustments to the overall maintenance dose may be necessary. Dose adjustments limited to the "pill-free" week are not recommended. For women taking LAMOTRIGINE in addition to carbamazepine, phenytoin, phenobarbital, primidone, or rifampin, no adjustment should be necessary to the dose of LAMOTRIGINE.
(3) Stopping Estrogen-Containing Oral Contraceptives: For women not taking carbamazepine, phenytoin, phenobarbital, primidone, or rifampin, the maintenance dose of LAMOTRIGINE will in most cases need to be decreased by as much as 50% in order to maintain a consistent lamotrigine plasma level. The decrease in dose of LAMOTRIGINE should not exceed 25% of the total daily dose per week over a 2-week period, unless clinical response or lamotrigine plasma levels indicate otherwise [see Clinical Pharmacology (12.3)]. For women taking LAMOTRIGINE in addition to carbamazepine, phenytoin, phenobarbital, primidone, or rifampin, no adjustment to the dose of LAMOTRIGINE should be necessary.
Women and Other Hormonal Contraceptive Preparations or Hormone Replacement Therapy: The effect of other hormonal contraceptive preparations or hormone replacement therapy on the pharmacokinetics of lamotrigine has not been systematically evaluated. It has been reported that ethinylestradiol, not progestogens, increased the clearance of lamotrigine up to 2-fold, and the progestin-only pills had no effect on lamotrigine plasma levels. Therefore, adjustments to the dosage of LAMOTRIGINE in the presence of progestogens alone will likely not be needed.
Patients With Hepatic Impairment: Experience in patients with hepatic impairment is limited. Based on a clinical pharmacology study in 24 patients with mild, moderate, and severe liver impairment [see Use in Specific Populations (8.6), Clinical Pharmacology (12.3)], the following general recommendations can be made. No dosage adjustment is needed in patients with mild liver impairment. Initial, escalation, and maintenance doses should generally be reduced by approximately 25% in patients with moderate and severe liver impairment without ascites and 50% in patients with severe liver impairment with ascites. Escalation and maintenance doses may be adjusted according to clinical response.
Patients With Renal Impairment: Initial doses of LAMOTRIGINE should be based on patients' concomitant medications (see Tables 1-3 or Table 5); reduced maintenance doses may be effective for patients with significant renal impairment [see Use in Specific Populations (8.7), Clinical Pharmacology (12.3)]. Few patients with severe renal impairment have been evaluated during chronic treatment with LAMOTRIGINE. Because there is inadequate experience in this population, LAMOTRIGINE should be used with caution in these patients.
Discontinuation Strategy: Epilepsy: For patients receiving LAMOTRIGINE in combination with other AEDs, a re-evaluation of all AEDs in the regimen should be considered if a change in seizure control or an appearance or worsening of adverse reactions is observed.
If a decision is made to discontinue therapy with LAMOTRIGINE, a step-wise reduction of dose over at least 2 weeks (approximately 50% per week) is recommended unless safety concerns require a more rapid withdrawal [see Warnings and Precautions (5.9)].
Discontinuing carbamazepine, phenytoin, phenobarbital, or primidone should prolong the half-life of lamotrigine; discontinuing valproate should shorten the half-life of lamotrigine.
Bipolar Disorder: In the controlled clinical trials, there was no increase in the incidence, type, or severity of adverse reactions following abrupt termination of LAMOTRIGINE. In clinical trials in patients with Bipolar Disorder, 2 patients experienced seizures shortly after abrupt withdrawal of LAMOTRIGINE. However, there were confounding factors that may have contributed to the occurrence of seizures in these bipolar patients. Discontinuation of LAMOTRIGINE should involve a step-wise reduction of dose over at least 2 weeks (approximately 50% per week) unless safety concerns require a more rapid withdrawal [see Warnings and Precautions (5.9)].
Patients Over 12 Years of Age: Recommended dosing guidelines are summarized in Table 1.
| For Patients Taking Valproate Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine [see Drug Interactions (7), Pharmacokinetics (12.3)]. | For Patients Taking AEDs Other Than Carbamazepine, Phenytoin, Phenobarbital, or Primidone These drugs induce glucuronidation and increase clearance [see Drug Interactions (7), Pharmacokinetics (12.3)]. Other drugs which have similar effects include estrogen-containing oral contraceptives and rifampin [see Drug Interactions (7), Pharmacokinetics (12.3)]. , and Not Taking Valproate | For Patients Taking Carbamazepine, Phenytoin, Phenobarbital, or Primidone | |
| Weeks 1 and 2 | 25 mg every other day | 25 mg every day | 50 mg/day |
| Weeks 3 and 4 | 25 mg every day | 50 mg/day | 100 mg/day (in 2 divided doses) |
| Weeks 5 onwards to maintenance | Increase by 25 to 50 mg/day every 1 to 2 weeks | Increase by 50 mg/day every 1 to 2 weeks | Increase by 100 mg/day every 1 to 2 weeks. |
| Usual Maintenance Dose | 100 to 200 mg/day with valproate alone 100 to 400 mg/day with valproate and other drugs that induce glucuronication (in 1 or 2 divided doses) | 225 to 375 mg/day (in 2 divided doses) | 300 to 500 mg/day (in 2 divided doses) |
Dosing recommendations for oral contraceptives can be found in General Dosing Considerations [see Dosage and Administration (2.1)]. Patients on rifampin should follow the same dosing titration/maintenance regimen used with drugs that induce glucuronidation and increase clearance.
Patients 2 to 12 Years of Age: Recommended dosing guidelines are summarized in Table 2.
Smaller starting doses and slower dose escalations than those used in clinical trials are recommended because of the suggestion that the risk of rash may be decreased by smaller starting doses and slower dose escalations. Therefore, maintenance doses will take longer to reach in clinical practice than in clinical trials. It may take several weeks to months to achieve an individualized maintenance dose. Maintenance doses in patients weighing less than 30 kg, regardless of age or concomitant AED, may need to be increased as much as 50%, based on clinical response.
| For Patients Taking Valproate Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine [see Drug Interactions (7), Pharmacokinetics (12.3)]. | For Patients Taking AEDs Other Than Carbamazepine, Phenytoin, Phenobarbital, or Primidone These drugs induce glucuronidation and increase clearance [see Drug Interactions (7), Pharmacokinetics (12.3)]. Other drugs which have similar effects include estrogen-containing oral contraceptives and rifampin [see Drug Interactions (7), Pharmacokinetics (12.3)]. , and Not Taking Valproate | For Patients Taking Carbamazepine, Phenytoin, Phenobarbital, or Primidone | |
| Note: Only whole tablets should be used for dosing. | |||
| Weeks 1 and 2 | 0.15 mg/kg/day in 1 or 2 divided doses, rounded down to the nearest whole tablet (see Table 3 for weight based dosing guide) | 0.3 mg/kg/day in 1 or 2 divided doses, rounded down to the nearest whole tablet | 0.6 mg/kg/day in 2 divided doses, rounded down to the nearest whole tablet |
| Weeks 3 and 4 | 0.3 mg/kg/day in 1 or 2 divided doses, rounded down to the nearest whole tablet (see Table 3 for weight based dosing guide) | 0.6 mg/kg/day in 2 divided doses, rounded down to the nearest whole tablet | 1.2 mg/kg/day in 2 divided doses, rounded down to the nearest whole tablet |
| Weeks 5 onwards to maintenance | The dose should be increased every 1 to 2 weeks as follows: calculate 0.3 mg/kg/day, round this amount down to the nearest whole tablet, and add this amount to the previously administered daily dose | The dose should be increased every 1 to 2 weeks as follows: calculate 0.6 mg/kg/day, round this amount down to the nearest whole tablet, and add this amount to the previously administered daily dose | The dose should be increased every 1 to 2 weeks as follows: calculate 1.2 mg/kg/day, round this amount down to the nearest whole tablet, and add this amount to the previously administered daily dose |
| Usual Maintenance Dose | 1 to 5 mg/kg/day (maximum 200 mg/day in 1 or 2 divided doses). 1 to 3 mg/kg/day with valproate alone | 4.5 to 7.5 mg/kg/day (maximum 300 mg/day in 2 divided doses) | 5 to 15 mg/kg/day (maximum 400 mg/day in 2 divided doses) |
| Maintenance dose in patients less than 30 kg | May need to be increased by as much as 50%, based on clinical response | May need to be increased by as much as 50%, based on clinical response | May need to be increased by as much as 50%, based on clinical response |
Dosing recommendations for oral contraceptives can be found in General Dosing Considerations [see Dosage and Administration (2.1)]. Patients on rifampin should follow the same dosing titration/maintenance regimen used with drugs that induce glucuronidation and increase clearance.
| If the patient's weight is | Give this daily dose, using the most appropriate combination of LAMOTRIGINE 2-mg and 5-mg tablets | ||
| Greater than | And less than | Weeks 1 and 2 | Weeks 3 and 4 |
| 6.7 kg | 14 kg | 2 mg every other day | 2 mg every day |
| 14.1 kg | 27 kg | 2 mg every day | 4 mg every day |
| 27.1 kg | 34 kg | 4 mg every day | 8 mg every day |
| 34.1 kg | 40 kg | 5 mg every day | 10 mg every day |
Usual Adjunctive Maintenance Dose for Epilepsy: The usual maintenance doses identified in Tables 1 and 2 are derived from dosing regimens employed in the placebo-controlled adjunctive studies in which the efficacy of LAMOTRIGINE was established. In patients receiving multidrug regimens employing carbamazepine, phenytoin, phenobarbital, or primidone without valproate, maintenance doses of adjunctive LAMOTRIGINE as high as 700 mg/day have been used. In patients receiving valproate alone, maintenance doses of adjunctive LAMOTRIGINE as high as 200 mg/day have been used. The advantage of using doses above those recommended in Tables 1 through 4 has not been established in controlled trials.
Conversion From Adjunctive Therapy With Carbamazepine, Phenytoin, Phenobarbital, or Primidone to Monotherapy With LAMOTRIGINE: After achieving a dose of 500 mg/day of LAMOTRIGINE according to the guidelines in Table 1, the concomitant AED should be withdrawn by 20% decrements each week over a 4-week period. The regimen for the withdrawal of the concomitant AED is based on experience gained in the controlled monotherapy clinical trial.
Conversion from Adjunctive Therapy With Valproate to Monotherapy With LAMOTRIGINE: The conversion regimen involves 4 steps outlined in Table 4.
| LAMOTRIGINE | Valproate | |
| Step 1 | Achieve a dose of 200 mg/day according to guidelines in Table 1 (if not already on200 mg/day). | Maintain previous stable dose. |
| Step 2 | Maintain at 200 mg/day. | Decrease to 500 mg/day by decrements no greater than 500 mg/day/week and then maintain the dose of 500 mg/day for 1 week. |
| Step 3 | Increase to 300 mg/day and maintain for 1 week. | Simultaneously decrease to 250 mg/day and maintain for 1 week. |
| Step 4 | Increase by 100 mg/day every week to achieve maintenance dose of 500 mg/day. | Discontinue. |
Conversion from Adjunctive Therapy With AEDs Other Than Carbamazepine, Phenytoin, Phenobarbital, Primidone, or Valproate to Monotherapy With LAMOTRIGINE: No specific dosing guidelines can be provided for conversion to monotherapy with LAMOTRIGINE with AEDs other than carbamazepine, phenobarbital, phenytoin, primidone, or valproate.
Pediatric Population: The incidence of serious rash associated with hospitalization and discontinuation of LAMOTRIGINE in a prospectively followed cohort of pediatric patients (2 to 16 years of age) with epilepsy receiving adjunctive therapy was approximately 0.8% (16 of 1,983). When 14 of these cases were reviewed by 3 expert dermatologists, there was considerable disagreement as to their proper classification. To illustrate, one dermatologist considered none of the cases to be Stevens-Johnson syndrome; another assigned 7 of the 14 to this diagnosis. There was 1 rash-related death in this 1,983-patient cohort. Additionally, there have been rare cases of toxic epidermal necrolysis with and without permanent sequelae and/or death in US and foreign postmarketing experience.
There is evidence that the inclusion of valproate in a multidrug regimen increases the risk of serious, potentially life-threatening rash in pediatric patients. In pediatric patients who used valproate concomitantly, 1.2% (6 of 482) experienced a serious rash compared with 0.6% (6 of 952) patients not taking valproate.
Adult Population: Serious rash associated with hospitalization and discontinuation of LAMOTRIGINE occurred in 0.3% (11 of 3,348) of adult patients who received LAMOTRIGINE in premarketing clinical trials of epilepsy. In the bipolar and other mood disorders clinical trials, the rate of serious rash was 0.08% (1 of 1,233) of adult patients who received LAMOTRIGINE as initial monotherapy and 0.13% (2 of 1,538) of adult patients who received LAMOTRIGINE as adjunctive therapy. No fatalities occurred among these individuals. However, in worldwide postmarketing experience, rare cases of rash-related death have been reported, but their numbers are too few to permit a precise estimate of the rate.
Among the rashes leading to hospitalization were Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema, and a rash associated with a variable number of the following systemic manifestations: fever, lymphadenopathy, facial swelling, and hematologic and hepatologic abnormalities.
There is evidence that the inclusion of valproate in a multidrug regimen increases the risk of serious, potentially life-threatening rash in adults. Specifically, of 584 patients administered LAMOTRIGINE with valproate in epilepsy clinical trials, 6 (1%) were hospitalized in association with rash; in contrast, 4 (0.16%) of 2,398 clinical trial patients and volunteers administered LAMOTRIGINE in the absence of valproate were hospitalized.
Patients With History of Allergy or Rash to Other AEDs: The risk of nonserious rash may be increased when the recommended initial dose and/or the rate of dose escalation of LAMOTRIGINE is exceeded and in patients with a history of allergy or rash to other AEDs.
Acute Treatment of Mood Episodes: Safety and effectiveness of LAMOTRIGINE in the acute treatment of mood episodes have not been established.
Children and Adolescents (less than 18 years of age): Safety and effectiveness of LAMOTRIGINE in patients below the age of 18 years with mood disorders have not been established [see Suicidal Behavior and Ideation (5.5)].
Clinical Worsening and Suicide Risk Associated With Bipolar Disorder: Patients with bipolar disorder may experience worsening of their depressive symptoms and/or the emergence of suicidal ideation and behaviors (suicidality) whether or not they are taking medications for bipolar disorder. Patients should be closely monitored for clinical worsening (including development of new symptoms) and suicidality, especially at the beginning of a course of treatment, or at the time of dose changes.
In addition, patients with a history of suicidal behavior or thoughts, those patients exhibiting a significant degree of suicidal ideation prior to commencement of treatment, and young adults are at an increased risk of suicidal thoughts or suicide attempts, and should receive careful monitoring during treatment [see Suicidal Behavior and Ideation (5.5)].
Consideration should be given to changing the therapeutic regimen, including possibly discontinuing the medication, in patients who experience clinical worsening (including development of new symptoms) and/or the emergence of suicidal ideation/behavior especially if these symptoms are severe, abrupt in onset, or were not part of the patient's presenting symptoms.
Prescriptions for LAMOTRIGINE should be written for the smallest quantity of tablets consistent with good patient management in order to reduce the risk of overdose. Overdoses have been reported for LAMOTRIGINE, some of which have been fatal [see Overdosage (10.1)].
Epilepsy: Most Common Adverse Reactions in All Clinical Studies: Adjunctive Therapy in Adults With Epilepsy: The most commonly observed (≥5% for LAMOTRIGINE and more common on drug than placebo) adverse reactions seen in association with LAMOTRIGINE during adjunctive therapy in adults and not seen at an equivalent frequency among placebo-treated patients were: dizziness, ataxia, somnolence, headache, diplopia, blurred vision, nausea, vomiting, and rash. Dizziness, diplopia, ataxia, blurred vision, nausea, and vomiting were dose-related. Dizziness, diplopia, ataxia, and blurred vision occurred more commonly in patients receiving carbamazepine with LAMOTRIGINE than in patients receiving other AEDs with LAMOTRIGINE. Clinical data suggest a higher incidence of rash, including serious rash, in patients receiving concomitant valproate than in patients not receiving valproate [see Warnings and Precautions (5.1)].
Approximately 11% of the 3,378 adult patients who received LAMOTRIGINE as adjunctive therapy in premarketing clinical trials discontinued treatment because of an adverse reaction. The adverse reactions most commonly associated with discontinuation were rash (3.0%), dizziness (2.8%), and headache (2.5%).
In a dose-response study in adults, the rate of discontinuation of LAMOTRIGINE for dizziness, ataxia, diplopia, blurred vision, nausea, and vomiting was dose-related.
Monotherapy in Adults With Epilepsy: The most commonly observed (≥5% for LAMOTRIGINE and more common on drug than placebo) adverse reactions seen in association with the use of LAMOTRIGINE during the monotherapy phase of the controlled trial in adults not seen at an equivalent rate in the control group were vomiting, coordination abnormality, dyspepsia, nausea, dizziness, rhinitis, anxiety, insomnia, infection, pain, weight decrease, chest pain, and dysmenorrhea. The most commonly observed (≥5% for LAMOTRIGINE and more common on drug than placebo) adverse reactions associated with the use of LAMOTRIGINE during the conversion to monotherapy (add-on) period, not seen at an equivalent frequency among low-dose valproate-treated patients, were dizziness, headache, nausea, asthenia, coordination abnormality, vomiting, rash, somnolence, diplopia, ataxia, accidental injury, tremor, blurred vision, insomnia, nystagmus, diarrhea, lymphadenopathy, pruritus, and sinusitis.
Approximately 10% of the 420 adult patients who received LAMOTRIGINE as monotherapy in premarketing clinical trials discontinued treatment because of an adverse reaction. The adverse reactions most commonly associated with discontinuation were rash (4.5%), headache (3.1%), and asthenia (2.4%).
Adjunctive Therapy in Pediatric Patients With Epilepsy: The most commonly observed (≥5% for LAMOTRIGINE and more common on drug than placebo) adverse reactions seen in association with the use of LAMOTRIGINE as adjunctive treatment in pediatric patients 2 to16 years of age and not seen at an equivalent rate in the control group were infection, vomiting, rash, fever, somnolence, accidental injury, dizziness, diarrhea, abdominal pain, nausea, ataxia, tremor, asthenia, bronchitis, flu syndrome, and diplopia.
In 339 patients 2 to 16 years of age with partial seizures or generalized seizures of Lennox-Gastaut syndrome, 4.2% of patients on LAMOTRIGINE and 2.9% of patients on placebo discontinued due to adverse reactions. The most commonly reported adverse reaction that led to discontinuation of LAMOTRIGINE was rash.
Approximately 11.5% of the 1,081 pediatric patients 2 to 16 years of age who received LAMOTRIGINE as adjunctive therapy in premarketing clinical trials discontinued treatment because of an adverse reaction. The adverse reactions most commonly associated with discontinuation were rash (4.4%), reaction aggravated (1.7%), and ataxia (0.6%).
Controlled Adjunctive Clinical Studies in Adults With Epilepsy: Table 8 lists treatment-emergent adverse reactions that occurred in at least 2% of adult patients with epilepsy treated with LAMOTRIGINE in placebo-controlled trials and were numerically more common in the patients treated with LAMOTRIGINE. In these studies, either LAMOTRIGINE or placebo was added to the patient's current AED therapy. Adverse reactions were usually mild to moderate in intensity.
| Body System/ Adverse Experience | Percent of Patients Receiving Adjunctive LAMOTRIGINE (n = 711) | Percent of Patients Receiving Adjunctive Placebo (n = 419) |
| Body as a whole | ||
| Headache | 29 | 19 |
| Flu syndrome | 7 | 6 |
| Fever | 6 | 4 |
| Abdominal pain | 5 | 4 |
| Neck Pain | 2 | 1 |
| Reaction aggravated (Seizure exacerbation) | 2 | 1 |
| Digestive | ||
| Nausea | 19 | 10 |
| Vomiting | 9 | 4 |
| Diarrhea | 6 | 4 |
| Dyspepsia | 5 | 2 |
| Constipation | 4 | 3 |
| Anorexia | 2 | 1 |
| Musculoskeletal | ||
| Arthralgia | 2 | 0 |
| Nervous | ||
| Dizziness | 38 | 13 |
| Ataxia | 22 | 6 |
| Somnolence | 14 | 7 |
| Incoordination | 6 | 2 |
| Insomnia | 6 | 2 |
| Tremor | 4 | 1 |
| Depression | 4 | 3 |
| Anxiety | 4 | 3 |
| Convulsion | 3 | 1 |
| Irritability | 3 | 2 |
| Speech disorder | 3 | 0 |
| Concentration disturbance | 2 | 1 |
| Respiratory | ||
| Rhinitis | 14 | 9 |
| Pharyngitis | 10 | 9 |
| Cough increased | 8 | 6 |
| Skin and appendages | ||
| Rash | 10 | 5 |
| Pruritus | 3 | 2 |
| Special senses | ||
| Diplopia | 28 | 7 |
| Blurred vision | 16 | 5 |
| Vision abnormality | 3 | 1 |
| Urogenital | ||
| Female patients only | (n = 365) | (n = 207) |
| Dysmenorrhea | 7 | 6 |
| Vaginitis | 4 | 1 |
| Amenorrhea | 2 | 1 |
In a randomized, parallel study comparing placebo and 300 and 500 mg/day of LAMOTRIGINE, some of the more common drug-related adverse reactions were dose-related (see Table 9).
| Percent of Patients Experiencing Adverse Experiences | |||
| Adverse Experience | Placebo (n = 73) | LAMOTRIGINE 300 mg (n = 71) | LAMOTRIGINE 500 mg (n = 72) |
| Ataxia | 10 | 10 | 28 Significantly greater than placebo group (p<0.05). Significantly greater than group receiving LAMOTRIGINE 300 mg (p<0.05). |
| Blurred vision | 10 | 11 | 25 |
| Diplopia | 8 | 24 | 49 |
| Dizziness | 27 | 31 | 54 |
| Nausea | 11 | 18 | 25 |
| Vomiting | 4 | 11 | 18 |
The overall adverse reaction profile for LAMOTRIGINE was similar between females and males, and was independent of age. Because the largest non-Caucasian racial subgroup was only 6% of patients exposed to LAMOTRIGINE in placebo-controlled trials, there are insufficient data to support a statement regarding the distribution of adverse reaction reports by race. Generally, females receiving either LAMOTRIGINE as adjunctive therapy or placebo were more likely to report adverse reactions than males. The only adverse reaction for which the reports on LAMOTRIGINE were greater than 10% more frequent in females than males (without a corresponding difference by gender on placebo) was dizziness (difference = 16.5%). There was little difference between females and males in the rates of discontinuation of LAMOTRIGINE for individual adverse reactions.
Controlled Monotherapy Trial in Adults With Partial Seizures: Table 10 lists treatment-emergent adverse reactions that occurred in at least 5% of patients with epilepsy treated with monotherapy with LAMOTRIGINE in a double-blind trial following discontinuation of either concomitant carbamazepine or phenytoin not seen at an equivalent frequency in the control group.
| Body System/ Adverse Experience | Percent of Patients Receiving LAMOTRIGINE as Monotherapy Up to 500 mg/day. (n = 43) | Percent of Patients Receiving Low-Dose Valproate 1,000 mg/day. Monotherapy (n = 44) |
| Body as a whole | ||
| Pain | 5 | 0 |
| Infection | 5 | 2 |
| Chest pain | 5 | 2 |
| Digestive | ||
| Vomiting | 9 | 0 |
| Dyspepsia | 7 | 2 |
| Nausea | 7 | 2 |
| Metabolic and nutritional | ||
| Weight decrease | 5 | 2 |
| Nervous | ||
| Coordination abnormality | 7 | 0 |
| Dizziness | 7 | 0 |
| Anxiety | 5 | 0 |
| Insomnia | 5 | 2 |
| Respiratory | ||
| Rhinitis | 7 | 2 |
| Urogenital (female patients only) | (n = 21) | (n = 28) |
| Dysmenorrhea | 5 | 0 |
Adverse reactions that occurred with a frequency of less than 5% and greater than 2% of patients receiving LAMOTRIGINE and numerically more frequent than placebo were:
Body as a Whole: Asthenia, fever.
Digestive: Anorexia, dry mouth, rectal hemorrhage, peptic ulcer.
Metabolic and Nutritional: Peripheral edema.
Nervous System: Amnesia, ataxia, depression, hypesthesia, libido increase, decreased reflexes, increased reflexes, nystagmus, irritability, suicidal ideation.
Respiratory: Epistaxis, bronchitis, dyspnea.
Skin and Appendages: Contact dermatitis, dry skin, sweating.
Special Senses: Vision abnormality.
Incidence in Controlled Adjunctive Trials in Pediatric Patients With Epilepsy: Table 11 lists adverse reactions that occurred in at least 2% of 339 pediatric patients with partial seizures or generalized seizures of Lennox-Gastaut syndrome, who received LAMOTRIGINE up to 15 mg/kg/day or a maximum of 750 mg/day. Reported adverse reactions were classified using COSTART terminology.
| Body System/ Adverse Experience | Percent of Patients Receiving LAMOTRIGINE (n = 168) | Percent of Patients Receiving Placebo (n = 171) |
| Body as a whole | ||
| Infection | 20 | 17 |
| Fever | 15 | 14 |
| Accidental injury | 14 | 12 |
| Abdominal pain | 10 | 5 |
| Asthenia | 8 | 4 |
| Flu syndrome | 7 | 6 |
| Pain | 5 | 4 |
| Facial edema | 2 | 1 |
| Photosensitivity | 2 | 0 |
| Cardiovascular | ||
| Hemorrhage | 2 | 1 |
| Digestive | ||
| Vomiting | 20 | 16 |
| Diarrhea | 11 | 9 |
| Nausea | 10 | 2 |
| Constipation | 4 | 2 |
| Dyspepsia | 2 | 1 |
| Hemic and lymphatic | ||
| Lymphadenopathy | 2 | 1 |
| Metabolic and nutritional | ||
| Edema | 2 | 0 |
| Nervous system | ||
| Somnolence | 17 | 15 |
| Dizziness | 14 | 4 |
| Ataxia | 11 | 3 |
| Tremor | 10 | 1 |
| Emotional lability | 4 | 2 |
| Gait abnormality | 4 | 2 |
| Thinking abnormality | 3 | 2 |
| Convulsions | 2 | 1 |
| Nervousness | 2 | 1 |
| Vertigo | 2 | 1 |
| Respiratory | ||
| Pharyngitis | 14 | 11 |
| Bronchitis | 7 | 5 |
| Increased cough | 7 | 6 |
| Sinusitis | 2 | 1 |
| Bronchospasm | 2 | 1 |
| Skin | ||
| Rash | 14 | 12 |
| Eczema | 2 | 1 |
| Pruritus | 2 | 1 |
| Special senses | ||
| Diplopia | 5 | 1 |
| Blurred vision | 4 | 1 |
| Visual abnormality | 2 | 0 |
| Urogenital | ||
| Male and female patients | ||
| Urinary tract infection | 3 | 0 |
Bipolar Disorder: The most commonly observed (≥5%) treatment-emergent adverse reactions seen in association with the use of LAMOTRIGINE as monotherapy (100 to 400 mg/day) in adult patients (≥18 years of age) with Bipolar Disorder in the 2 double-blind, placebo-controlled trials of 18 months' duration, and numerically more frequent than in placebo-treated patients are included in Table 12. Adverse reactions that occurred in at least 5% of patients and were numerically more common during the dose-escalation phase of LAMOTRIGINE in these trials (when patients may have been receiving concomitant medications) compared with the monotherapy phase were: headache (25%), rash (11%), dizziness (10%), diarrhea (8%), dream abnormality (6%), and pruritus (6%).
During the monotherapy phase of the double-blind, placebo-controlled trials of 18 months' duration, 13% of 227 patients who received LAMOTRIGINE (100 to 400 mg/day), 16% of 190 patients who received placebo, and 23% of 166 patients who received lithium discontinued therapy because of an adverse reaction. The adverse reactions which most commonly led to discontinuation of LAMOTRIGINE were rash (3%) and mania/hypomania/mixed mood adverse reactions (2%). Approximately 16% of 2,401 patients who received LAMOTRIGINE (50 to 500 mg/day) for Bipolar Disorder in premarketing trials discontinued therapy because of an adverse reaction; most commonly due to rash (5%) and mania/hypomania/mixed mood adverse reactions (2%).
The overall adverse reaction profile for LAMOTRIGINE was similar between females and males, between elderly and nonelderly patients, and among racial groups.
| Body System/ Adverse Experience | Percent of Patients Receiving LAMOTRIGINE (n = 227) | Percent of Patients Receiving Placebo (n = 190) |
| General | ||
| Back pain | 8 | 6 |
| Fatigue | 8 | 5 |
| Abdominal Pain | 6 | 3 |
| Digestive | ||
| Nausea | 14 | 11 |
| Constipation | 5 | 2 |
| Vomiting | 5 | 2 |
| Nervous System | ||
| Insomnia | 10 | 6 |
| Somnolence | 9 | 7 |
| Xerostomia (dry mouth) | 6 | 4 |
| Respiratory | ||
| Rhinitis | 7 | 4 |
| Exacerbation of cough | 5 | 3 |
| Pharyngitis | 5 | 4 |
| Skin | ||
| Rash (nonserious)† | 7 | 5 |
Patients in these studies were converted to LAMOTRIGINE (100 to 400 mg/day) or placebo monotherapy from add-on therapy with other psychotropic medications. Patients may have reported multiple adverse reactions during the study; thus, patients may be included in more than one category.
In the overall bipolar and other mood disorders clinical trials, the rate of serious rash was 0.08% (1 of 1,233) of adult patients who received LAMOTRIGINE as initial monotherapy and 0.13% (2 of 1,538) of adult patients who received LAMOTRIGINE as adjunctive therapy [see Warnings and Precautions (5.1)].
These adverse reactions were usually mild to moderate in intensity. Other reactions that occurred in 5% or more patients but equally or more frequently in the placebo group included: dizziness, mania, headache, infection, influenza, pain, accidental injury, diarrhea, and dyspepsia.
Adverse reactions that occurred with a frequency of less than 5% and greater than 1% of patients receiving LAMOTRIGINE and numerically more frequent than placebo were:
Adverse Reactions Following Abrupt Discontinuation: In the 2 maintenance trials, there was no increase in the incidence, severity or type of adverse reactions in Bipolar Disorder patients after abruptly terminating therapy with LAMOTRIGINE. In clinical trials in patients with Bipolar Disorder, 2 patients experienced seizures shortly after abrupt withdrawal of LAMOTRIGINE. However, there were confounding factors that may have contributed to the occurrence of seizures in these bipolar patients [see Warnings and Precautions (5.9)].
Mania/Hypomania/Mixed Episodes: During the double-blind, placebo-controlled clinical trials in Bipolar I Disorder in which patients were converted to monotherapy with LAMOTRIGINE (100 to 400 mg/day) from other psychotropic medications and followed for up to 18 months, the rates of manic or hypomanic or mixed mood episodes reported as adverse reactions were 5% for patients treated with LAMOTRIGINE (n = 227), 4% for patients treated with lithium (n = 166), and 7% for patients treated with placebo (n = 190). In all bipolar controlled trials combined, adverse reactions of mania (including hypomania and mixed mood episodes) were reported in 5% of patients treated with LAMOTRIGINE (n = 956), 3% of patients treated with lithium (n = 280), and 4% of patients treated with placebo (n = 803).
Pregnancy Exposure Registry:
To provide information regarding the effects of in utero exposure to LAMOTRIGINE, physicians are advised to recommend that pregnant patients taking LAMOTRIGINE enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll free number 1-888-233-2334, and must be done by patients themselves. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/.
Physicians are also encouraged to register patients in the Lamotrigine Pregnancy Registry; enrollment in this registry must be done prior to any prenatal diagnostic tests and before fetal outcome is known. Physicians can obtain information by calling the Lamotrigine Pregnancy Registry at 1-800-336-2176 (toll-free).
Effect of Lamotrigine on N-Methyl d-Aspartate-Receptor Mediated Activity: Lamotrigine did not inhibit N-methyl d-aspartate (NMDA)-induced depolarizations in rat cortical slices or NMDA-induced cyclic GMP formation in immature rat cerebellum, nor did lamotrigine displace compounds that are either competitive or noncompetitive ligands at this glutamate receptor complex (CNQX, CGS, TCHP). The IC50 for lamotrigine effects on NMDA-induced currents (in the presence of 3 μM of glycine) in cultured hippocampal neurons exceeded 100 μM.
The mechanisms by which lamotrigine exerts its therapeutic action in Bipolar Disorder have not been established.
Folate Metabolism: In vitro, lamotrigine inhibited dihydrofolate reductase, the enzyme that catalyzes the reduction of dihydrofolate to tetrahydrofolate. Inhibition of this enzyme may interfere with the biosynthesis of nucleic acids and proteins. When oral daily doses of lamotrigine were given to pregnant rats during organogenesis, fetal, placental, and maternal folate concentrations were reduced. Significantly reduced concentrations of folate are associated with teratogenesis [see Use in Specific Populations (8.1)]. Folate concentrations were also reduced in male rats given repeated oral doses of lamotrigine. Reduced concentrations were partially returned to normal when supplemented with folinic acid.
Accumulation in Kidneys: Lamotrigine accumulated in the kidney of the male rat, causing chronic progressive nephrosis, necrosis, and mineralization. These findings are attributed to α-2 microglobulin, a species- and sex-specific protein that has not been detected in humans or other animal species.
Melanin Binding: Lamotrigine binds to melanin-containing tissues, e.g., in the eye and pigmented skin. It has been found in the uveal tract up to 52 weeks after a single dose in rodents.
Cardiovascular: In dogs, lamotrigine is extensively metabolized to a 2-N-methyl metabolite. This metabolite causes dose-dependent prolongations of the PR interval, widening of the QRS complex, and, at higher doses, complete AV conduction block. Similar cardiovascular effects are not anticipated in humans because only trace amounts of the 2-N-methyl metabolite (<0.6% of lamotrigine dose) have been found in human urine [see Clinical Pharmacology (12.3)]. However, it is conceivable that plasma concentrations of this metabolite could be increased in patients with a reduced capacity to glucuronidate lamotrigine (e.g., in patients with liver disease).
Absorption: Lamotrigine is rapidly and completely absorbed after oral administration with negligible first-pass metabolism (absolute bioavailability is 98%). The bioavailability is not affected by food. Peak plasma concentrations occur anywhere from 1.4 to 4.8 hours following drug administration. The lamotrigine chewable/dispersible tablets were found to be equivalent, whether they were administered as dispersed in water, chewed and swallowed, or swallowed as whole, to the lamotrigine compressed tablets in terms of rate and extent of absorption. In terms of rate and extent of absorption, lamotrigine orally disintegrating tablets whether disintegrated in the mouth or swallowed whole with water were equivalent to the lamotrigine compressed tablets swallowed with water.
Dose Proportionality: In healthy volunteers not receiving any other medications and given single doses, the plasma concentrations of lamotrigine increased in direct proportion to the dose administered over the range of 50 to 400 mg. In 2 small studies (n = 7 and 8) of patients with epilepsy who were maintained on other AEDs, there also was a linear relationship between dose and lamotrigine plasma concentrations at steady state following doses of 50 to 350 mg twice daily.
Distribution: Estimates of the mean apparent volume of distribution (Vd/F) of lamotrigine following oral administration ranged from 0.9 to 1.3 L/kg. Vd/F is independent of dose and is similar following single and multiple doses in both patients with epilepsy and in healthy volunteers.
Protein Binding: Data from in vitro studies indicate that lamotrigine is approximately 55% bound to human plasma proteins at plasma lamotrigine concentrations from 1 to 10 mcg/mL (10 mcg/mL is 4 to 6 times the trough plasma concentration observed in the controlled efficacy trials). Because lamotrigine is not highly bound to plasma proteins, clinically significant interactions with other drugs through competition for protein binding sites are unlikely. The binding of lamotrigine to plasma proteins did not change in the presence of therapeutic concentrations of phenytoin, phenobarbital, or valproate. Lamotrigine did not displace other AEDs (carbamazepine, phenytoin, phenobarbital) from protein binding sites.
Metabolism: Lamotrigine is metabolized predominantly by glucuronic acid conjugation; the major metabolite is an inactive 2-N-glucuronide conjugate. After oral administration of 240 mg of 14C-lamotrigine (15 μCi) to 6 healthy volunteers, 94% was recovered in the urine and 2% was recovered in the feces. The radioactivity in the urine consisted of unchanged lamotrigine (10%), the 2-N-glucuronide (76%), a 5-N-glucuronide (10%), a 2-N-methyl metabolite (0.14%), and other unidentified minor metabolites (4%).
Enzyme Induction: The effects of lamotrigine on the induction of specific families of mixed-function oxidase isozymes have not been systematically evaluated.
Following multiple administrations (150 mg twice daily) to normal volunteers taking no other medications, lamotrigine induced its own metabolism, resulting in a 25% decrease in t½ and a 37% increase in Cl/F at steady state compared with values obtained in the same volunteers following a single dose. Evidence gathered from other sources suggests that self-induction by lamotrigine may not occur when lamotrigine is given as adjunctive therapy in patients receiving carbamazepine, phenytoin, phenobarbital, primidone, or rifampin.
Elimination: The elimination half-life and apparent clearance of lamotrigine following administration of LAMOTRIGINE to adult patients with epilepsy and healthy volunteers is summarized in Table 14. Half-life and apparent oral clearance vary depending on concomitant AEDs.
Drug Interactions: The apparent clearance of lamotrigine is affected by the coadministration of certain medications [see Warnings and Precautions (5.8, 5.12), Drug Interactions (7)].
The net effects of drug interactions with LAMOTRIGINE are summarized in Tables 13 and 15, followed by details of the drug interaction studies below.
| Drug | Drug Plasma Concentration With Adjunctive LAMOTRIGINE From adjunctive clinical trials and volunteer studies. | Lamotrigine Plasma Concentration With Adjunctive Drugs Net effects were estimated by comparing the mean clearance values obtained in adjunctive clinical trials and volunteers studies. |
| ↔ = No significant effect. ? = Conflicting data. | ||
| Oral contraceptives (e.g., ethinylestradiol/levonorgestrel) The effect of other hormonal contraceptive preparations or hormone replacement therapy on the pharmacokinetics of lamotrigine has not been systematically evaluated in clinical trials, although the effect may be similar to that seen with the ethinylestradiol/levonorgestrel combinations. | ↔ Modest decrease in levonorgestrel. | ↓ |
| Bupropion | Not assessed | ↔ |
| Carbamazepine (CBZ) | ↔ | ↓ |
| CBZ epoxide Not administered, but an active metabolite of carbamazepine. | ? | |
| Felbamate | Not assessed | ↔ |
| Gabapentin | Not assessed | ↔ |
| Levetiracetam | ↔ | ↔ |
| Lithium | ↔ | Not assessed |
| Olanzapine | ↔ | ↔ Slight decrease, not expected to be clinically relevant. |
| Oxcarbazepine | ↔ | ↔ |
| 10-monohydroxy oxcarbazepine metabolite Not administered, but an active metabolite of oxcarbazepine. | ↔ | |
| Phenobarbital/primidone | ↔ | ↓ |
| Phenytoin (PHT) | ↔ | ↓ |
| Pregabalin | ↔ | ↔ |
| Rifampin | Not assessed | ↓ |
| Topiramate | ↔ Slight increase not expected to be clinically relevant. | ↔ |
| Valproate | ↓ | ↑ |
| Valproate + PHT and/or CBZ | Not assessed | ↔ |
| Zonisamide | Not assessed | ↔ |
Estrogen-Containing Oral Contraceptives: In 16 female volunteers, an oral contraceptive preparation containing 30 mcg ethinylestradiol and 150 mcg levonorgestrel increased the apparent clearance of lamotrigine (300 mg/day) by approximately 2-fold with a mean decrease in AUC of 52% and in Cmax of 39%. In this study, trough serum lamotrigine concentrations gradually increased and were approximately 2-fold higher on average at the end of the week of the inactive hormone preparation compared with trough lamotrigine concentrations at the end of the active hormone cycle.
Gradual transient increases in lamotrigine plasma levels (approximate 2-fold increase) occurred during the week of inactive hormone preparation ("pill-free" week) for women not also taking a drug that increased the clearance of lamotrigine (carbamazepine, phenytoin, phenobarbital, primidone, or rifampin). The increase in lamotrigine plasma levels will be greater if the dose of LAMOTRIGINE is increased in the few days before or during the "pill-free" week. Increases in lamotrigine plasma levels could result in dose-dependent adverse effects. In the same study, coadministration of LAMOTRIGINE (300 mg/day) in 16 female volunteers did not affect the pharmacokinetics of the ethinylestradiol component of the oral contraceptive preparation. There were mean decreases in the AUC and Cmax of the levonorgestrel component of 19% and 12%, respectively. Measurement of serum progesterone indicated that there was no hormonal evidence of ovulation in any of the 16 volunteers, although measurement of serum FSH, LH, and estradiol indicated that there was some loss of suppression of the hypothalamic-pituitary-ovarian axis.
The effects of doses of LAMOTRIGINE other than 300 mg/day have not been systematically evaluated in controlled clinical trials.
The clinical significance of the observed hormonal changes on ovulatory activity is unknown. However, the possibility of decreased contraceptive efficacy in some patients cannot be excluded. Therefore, patients should be instructed to promptly report changes in their menstrual pattern (e.g., break-through bleeding).
Dosage adjustments may be necessary for women receiving estrogen-containing oral contraceptive preparations [see Dosage and Administration (2.1)].
Other Hormonal Contraceptives or Hormone Replacement Therapy: The effect of other hormonal contraceptive preparations or hormone replacement therapy on the pharmacokinetics of lamotrigine has not been systematically evaluated. It has been reported that ethinylestradiol, not progestogens, increased the clearance of lamotrigine up to 2-fold, and the progestin-only pills had no effect on lamotrigine plasma levels. Therefore, adjustments to the dosage of LAMOTRIGINE in the presence of progestogens alone will likely not be needed.
Bupropion: The pharmacokinetics of a 100-mg single dose of LAMOTRIGINE in healthy volunteers (n = 12) were not changed by coadministration of bupropion sustained-release formulation (150 mg twice a day) starting 11 days before LAMOTRIGINE.
Carbamazepine: LAMOTRIGINE has no appreciable effect on steady-state carbamazepine plasma concentration. Limited clinical data suggest there is a higher incidence of dizziness, diplopia, ataxia, and blurred vision in patients receiving carbamazepine with lamotrigine than in patients receiving other AEDs with lamotrigine [see Adverse Reactions (6.1)]. The mechanism of this interaction is unclear. The effect of lamotrigine on plasma concentrations of carbamazepine-epoxide is unclear. In a small subset of patients (n = 7) studied in a placebo-controlled trial, lamotrigine had no effect on carbamazepine-epoxide plasma concentrations, but in a small, uncontrolled study (n = 9), carbamazepine-epoxide levels increased.
The addition of carbamazepine decreases lamotrigine steady-state concentrations by approximately 40%.
Felbamate: In a study of 21 healthy volunteers, coadministration of felbamate (1,200 mg twice daily) with lamotrigine (100 mg twice daily for 10 days) appeared to have no clinically relevant effects on the pharmacokinetics of lamotrigine.
Folate Inhibitors: Lamotrigine is a weak inhibitor of dihydrofolate reductase. Prescribers should be aware of this action when prescribing other medications that inhibit folate metabolism.
Gabapentin: Based on a retrospective analysis of plasma levels in 34 patients who received lamotrigine both with and without gabapentin, gabapentin does not appear to change the apparent clearance of lamotrigine.
Levetiracetam: Potential drug interactions between levetiracetam and lamotrigine were assessed by evaluating serum concentrations of both agents during placebo-controlled clinical trials. These data indicate that lamotrigine does not influence the pharmacokinetics of levetiracetam and that levetiracetam does not influence the pharmacokinetics of lamotrigine.
Lithium: The pharmacokinetics of lithium were not altered in healthy subjects (n = 20) by coadministration of lamotrigine (100 mg/day) for 6 days.
Olanzapine: The AUC and Cmax of olanzapine were similar following the addition of olanzapine (15 mg once daily) to lamotrigine (200 mg once daily) in healthy male volunteers (n = 16) compared with the AUC and Cmax in healthy male volunteers receiving olanzapine alone (n = 16).
In the same study, the AUC and Cmax of lamotrigine were reduced on average by 24% and 20%, respectively, following the addition of olanzapine to lamotrigine in healthy male volunteers compared with those receiving lamotrigine alone. This reduction in lamotrigine plasma concentrations is not expected to be clinically relevant.
Oxcarbazepine: The AUC and Cmax of oxcarbazepine and its active 10-monohydroxy oxcarbazepine metabolite were not significantly different following the addition of oxcarbazepine (600 mg twice daily) to lamotrigine (200 mg once daily) in healthy male volunteers (n = 13) compared with healthy male volunteers receiving oxcarbazepine alone (n = 13).
In the same study, the AUC and Cmax of lamotrigine were similar following the addition of oxcarbazepine (600 mg twice daily) to LAMOTRIGINE in healthy male volunteers compared with those receiving LAMOTRIGINE alone. Limited clinical data suggest a higher incidence of headache, dizziness, nausea, and somnolence with coadministration of lamotrigine and oxcarbazepine compared with lamotrigine alone or oxcarbazepine alone.
Phenobarbital, Primidone: The addition of phenobarbital or primidone decreases lamotrigine steady-state concentrations by approximately 40%.
Phenytoin: Lamotrigine has no appreciable effect on steady-state phenytoin plasma concentrations in patients with epilepsy. The addition of phenytoin decreases lamotrigine steady-state concentrations by approximately 40%.
Pregabalin: Steady-state trough plasma concentrations of lamotrigine were not affected by concomitant pregabalin (200 mg 3 times daily) administration. There are no pharmacokinetic interactions between lamotrigine and pregabalin.
Rifampin: In 10 male volunteers, rifampin (600 mg/day for 5 days) significantly increased the apparent clearance of a single 25-mg dose of lamotrigine by approximately 2-fold (AUC decreased by approximately 40%).
Topiramate: Topiramate resulted in no change in plasma concentrations of lamotrigine. Administration of lamotrigine resulted in a 15% increase in topiramate concentrations.
Valproate: When lamotrigine was administered to healthy volunteers (n = 18) receiving valproate, the trough steady-state valproate plasma concentrations decreased by an average of 25% over a 3-week period, and then stabilized. However, adding lamotrigine to the existing therapy did not cause a change in valproate plasma concentrations in either adult or pediatric patients in controlled clinical trials.
The addition of valproate increased lamotrigine steady-state concentrations in normal volunteers by slightly more than 2-fold. In one study, maximal inhibition of lamotrigine clearance was reached at valproate doses between 250 mg/day and 500 mg/day and did not increase as the valproate dose was further increased.
Zonisamide: In a study of 18 patients with epilepsy, coadministration of zonisamide (200 to 400 mg/day) with lamotrigine (150 to 500 mg/day for 35 days) had no significant effect on the pharmacokinetics of lamotrigine.
Known Inducers or Inhibitors of Glucuronidation: Drugs other than those listed above have not been systematically evaluated in combination with lamotrigine. Since lamotrigine is metabolized predominately by glucuronic acid conjugation, drugs that are known to induce or inhibit glucuronidation may affect the apparent clearance of lamotrigine and doses of lamotrigine may require adjustment based on clinical response.
Other: Results of in vitro experiments suggest that clearance of lamotrigine is unlikely to be reduced by concomitant administration of amitriptyline, clonazepam, clozapine, fluoxetine, haloperidol, lorazepam, phenelzine, risperidone, sertraline, or trazodone).
Results of in vitro experiments suggest that lamotrigine does not reduce the clearance of drugs eliminated predominantly by CYP2D6.
Special Populations: Patients With Renal Impairment: Twelve volunteers with chronic renal failure (mean creatinine clearance: 13 mL/min; range: 6 to 23) and another 6 individuals undergoing hemodialysis were each given a single 100-mg dose of lamotrigine. The mean plasma half-lives determined in the study were 42.9 hours (chronic renal failure), 13.0 hours (during hemodialysis), and 57.4 hours (between hemodialysis) compared with 26.2 hours in healthy volunteers. On average, approximately 20% (range: 5.6 to 35.1) of the amount of lamotrigine present in the body was eliminated by hemodialysis during a 4-hour session [see Dosage and Administration (2.1)].
Hepatic Disease: The pharmacokinetics of lamotrigine following a single 100-mg dose of lamotrigine were evaluated in 24 subjects with mild, moderate, and severe hepatic impairment (Child-Pugh Classification system) and compared with 12 subjects without hepatic impairment. The patients with severe hepatic impairment were without ascites (n = 2) or with ascites (n = 5). The mean apparent clearances of lamotrigine in patients with mild (n = 12), moderate (n = 5), severe without ascites (n = 2), and severe with ascites (n = 5) liver impairment were 0.30 ± 0.09, 0.24 ± 0.1, 0.21 ± 0.04, and 0.15 ± 0.09 mL/min/kg, respectively, as compared with 0.37 ± 0.1 mL/min/kg in the healthy controls. Mean half-life of lamotrigine in patients with mild, moderate, severe without ascites, and severe with ascites hepatic impairment were 46 ± 20, 72 ± 44, 67 ± 11, and 100 ± 48 hours, respectively, as compared with 33 ± 7 hours in healthy controls [see Dosage and Administration (2.1)].
Age: Pediatric Patients: The pharmacokinetics of lamotrigine following a single 2-mg/kg dose were evaluated in 2 studies of pediatric patients (n = 29 for patients 10 months to 5.9 years of age and n = 26 for patients 5 to 11 years of age). Forty-three patients received concomitant therapy with other AEDs and 12 patients received lamotrigine as monotherapy. Lamotrigine pharmacokinetic parameters for pediatric patients are summarized in Table 16.
Population pharmacokinetic analyses involving patients 2 to 18 years of age demonstrated that lamotrigine clearance was influenced predominantly by total body weight and concurrent AED therapy. The oral clearance of lamotrigine was higher, on a body weight basis, in pediatric patients than in adults. Weight-normalized lamotrigine clearance was higher in those subjects weighing less than 30 kg, compared with those weighing greater than 30 kg. Accordingly, patients weighing less than 30 kg may need an increase of as much as 50% in maintenance doses, based on clinical response, as compared with subjects weighing more than 30 kg being administered the same AEDs [see Dosage and Administration (2.2)]. These analyses also revealed that, after accounting for body weight, lamotrigine clearance was not significantly influenced by age. Thus, the same weight-adjusted doses should be administered to children irrespective of differences in age. Concomitant AEDs which influence lamotrigine clearance in adults were found to have similar effects in children.
| Pediatric Study Population | Number of Subjects | Tmax (hr) | t½ (hr) | Cl/F (mL/min/kg) |
| Ages 10 months-5.3 years | ||||
| Patients taking carbamazepine, phenytoin, phenobarbital, or primidone Carbamazepine, phenobarbital, phenytoin, and primidone have been shown to increase the apparent clearance of lamotrigine. Estrogen-containing oral contraceptives and rifampin have also been shown to increase the apparent clearance of lamotrigine [see Drug Interactions (7)]. | 10 | 3.0 (1.0-5.9) | 7.7 (5.7-11.4) | 3.62 (2.44-5.28) |
| Patients taking AEDs with no known effect on the apparent clearance of lamotrigine | 7 | 5.2 (2.9-6.1) | 19.0 (12.9-27.1) | 1.2 (0.75-2.42) |
| Patients taking valproate only | 8 | 2.9 (1.0-6.0) | 44.9 (29.5-52.5) | 0.47 (0.23-0.77) |
| Ages 5-11 years | ||||
| Patients taking carbamazepine, phenytoin, phenobarbital, or primidone | 7 | 1.6 (1.0-3.0) | 7.0 (3.8-9.8) | 2.54 (1.35-5.58) |
| Patients taking carbamazepine, phenytoin, phenobarbital, or primidone | 8 | 3.3 (1.0-6.4) | 19.1 (7.0-31.2) | 0.89 (0.39-1.93) |
| Patients taking valproate only Two subjects were included in the calculation for mean Tmax. | 3 | 4.5 (3.0-6.0) | 65.8 (50.7-73.7) | 0.24 (0.21-0.26) |
| Ages 13-18 years | ||||
| Patients taking carbamazepine, phenytoin, phenobarbital, or primidone | 11 | Parameter not estimated. | 1.3 | |
| Patients taking carbamazepine, phenytoin, phenobarbital, or primidone* plus valproate | 8 | 0.5 | ||
| Patients taking valproate only | 4 | 0.3 |
Elderly: The pharmacokinetics of lamotrigine following a single 150-mg dose of LAMOTRIGINE were evaluated in 12 elderly volunteers between the ages of 65 and 76 years (mean creatinine clearance = 61 mL/min, range: 33 to 108 mL/min). The mean half-life of lamotrigine in these subjects was 31.2 hours (range: 24.5 to 43.4 hours), and the mean clearance was 0.40 mL/min/kg (range: 0.26 to 0.48 mL/min/kg).
Gender: The clearance of lamotrigine is not affected by gender. However, during dose escalation of LAMOTRIGINE in one clinical trial in patients with epilepsy on a stable dose of valproate (n = 77), mean trough lamotrigine concentrations, unadjusted for weight, were 24% to 45% higher (0.3 to 1.7 mcg/mL) in females than in males.
Race: The apparent oral clearance of lamotrigine was 25% lower in non-Caucasians than Caucasians.
Monotherapy With LAMOTRIGINE in Adults With Partial Seizures Already Receiving Treatment With Carbamazepine, Phenytoin, Phenobarbital, or Primidone as the Single AED: The effectiveness of monotherapy with LAMOTRIGINE was established in a multicenter, double-blind clinical trial enrolling 156 adult outpatients with partial seizures. The patients experienced at least 4 simple partial, complex partial, and/or secondarily generalized seizures during each of 2 consecutive 4-week periods while receiving carbamazepine or phenytoin monotherapy during baseline. LAMOTRIGINE (target dose of 500 mg/day) or valproate (1,000 mg/day) was added to either carbamazepine or phenytoin monotherapy over a 4-week period. Patients were then converted to monotherapy with LAMOTRIGINE or valproate during the next 4 weeks, then continued on monotherapy for an additional 12-week period.
Study endpoints were completion of all weeks of study treatment or meeting an escape criterion. Criteria for escape relative to baseline were: (1) doubling of average monthly seizure count, (2) doubling of highest consecutive 2-day seizure frequency, or (3) emergence of a new seizure type (defined as a seizure that did not occur during the 8-week baseline) that is more severe than seizure types that occur during study treatment. The primary efficacy variable was the proportion of patients in each treatment group who met escape criteria.
The percentages of patients who met escape criteria were 42% (32/76) in the group receiving LAMOTRIGINE and 69% (55/80) in the valproate group. The difference in the percentage of patients meeting escape criteria was statistically significant (p= 0.0012) in favor of LAMOTRIGINE. No differences in efficacy based on age, sex, or race were detected.
Patients in the control group were intentionally treated with a relatively low dose of valproate; as such, the sole objective of this study was to demonstrate the effectiveness and safety of monotherapy with LAMOTRIGINE, and cannot be interpreted to imply the superiority of LAMOTRIGINE to an adequate dose of valproate.
Adjunctive Therapy With LAMOTRIGINE in Adults With Partial Seizures: The effectiveness of LAMOTRIGINE as adjunctive therapy (added to other AEDs) was established in 3 multicenter, placebo-controlled, double-blind clinical trials in 355 adults with refractory partial seizures. The patients had a history of at least 4 partial seizures per month in spite of receiving one or more AEDs at therapeutic concentrations and, in 2 of the studies, were observed on their established AED regimen during baselines that varied between 8 to 12 weeks. In the third, patients were not observed in a prospective baseline. In patients continuing to have at least 4 seizures per month during the baseline, LAMOTRIGINE or placebo was then added to the existing therapy. In all 3 studies, change from baseline in seizure frequency was the primary measure of effectiveness. The results given below are for all partial seizures in the intent-to-treat population (all patients who received at least one dose of treatment) in each study, unless otherwise indicated. The median seizure frequency at baseline was 3 per week while the mean at baseline was 6.6 per week for all patients enrolled in efficacy studies.
One study (n = 216) was a double-blind, placebo-controlled, parallel trial consisting of a 24-week treatment period. Patients could not be on more than 2 other anticonvulsants and valproate was not allowed. Patients were randomized to receive placebo, a target dose of 300 mg/day of LAMOTRIGINE, or a target dose of 500 mg/day of LAMOTRIGINE. The median reductions in the frequency of all partial seizures relative to baseline were 8% in patients receiving placebo, 20% in patients receiving 300 mg/day of LAMOTRIGINE, and 36% in patients receiving 500 mg/day of LAMOTRIGINE. The seizure frequency reduction was statistically significant in the 500-mg/day group compared with the placebo group, but not in the 300-mg/day group.
A second study (n = 98) was a double-blind, placebo-controlled, randomized, crossover trial consisting of two 14-week treatment periods (the last 2 weeks of which consisted of dose tapering) separated by a 4-week washout period. Patients could not be on more than 2 other anticonvulsants and valproate was not allowed. The target dose of LAMOTRIGINE was 400 mg/day. When the first 12 weeks of the treatment periods were analyzed, the median change in seizure frequency was a 25% reduction on LAMOTRIGINE compared with placebo (p<0.001).
The third study (n = 41) was a double-blind, placebo-controlled, crossover trial consisting of two 12-week treatment periods separated by a 4-week washout period. Patients could not be on more than 2 other anticonvulsants. Thirteen patients were on concomitant valproate; these patients received 150 mg/day of LAMOTRIGINE. The 28 other patients had a target dose of 300 mg/day of LAMOTRIGINE. The median change in seizure frequency was a 26% reduction on LAMOTRIGINE compared with placebo (p<0.01).
No differences in efficacy based on age, sex, or race, as measured by change in seizure frequency, were detected.
Adjunctive Therapy With LAMOTRIGINE in Pediatric Patients With Partial Seizures: The effectiveness of LAMOTRIGINE as adjunctive therapy in pediatric patients with partial seizures was established in a multicenter, double-blind, placebo-controlled trial in 199 patients 2 to 16 years of age (n = 98 on LAMOTRIGINE, n = 101 on placebo). Following an 8-week baseline phase, patients were randomized to 18 weeks of treatment with LAMOTRIGINE or placebo added to their current AED regimen of up to 2 drugs. Patients were dosed based on body weight and valproate use. Target doses were designed to approximate 5 mg/kg/day for patients taking valproate (maximum dose: 250 mg/day) and 15 mg/kg/day for the patients not taking valproate (maximum dose: 750 mg/day). The primary efficacy endpoint was percentage change from baseline in all partial seizures. For the intent-to-treat population, the median reduction of all partial seizures was 36% in patients treated with LAMOTRIGINE and 7% on placebo, a difference that was statistically significant (p<0.01).
Adjunctive Therapy With LAMOTRIGINE in Pediatric and Adult Patients With Lennox-Gastaut Syndrome: The effectiveness of LAMOTRIGINE as adjunctive therapy in patients with Lennox-Gastaut syndrome was established in a multicenter, double-blind, placebo-controlled trial in 169 patients 3 to 25 years of age (n = 79 on LAMOTRIGINE, n = 90 on placebo). Following a 4-week single-blind, placebo phase, patients were randomized to 16 weeks of treatment with LAMOTRIGINE or placebo added to their current AED regimen of up to 3 drugs. Patients were dosed on a fixed-dose regimen based on body weight and valproate use. Target doses were designed to approximate 5 mg/kg/day for patients taking valproate (maximum dose: 200 mg/day) and 15 mg/kg/day for patients not taking valproate (maximum dose: 400 mg/day). The primary efficacy endpoint was percentage change from baseline in major motor seizures (atonic, tonic, and major myoclonic). For the intent-to-treat population, the median reduction of major motor seizures was 32% in patients treated with LAMOTRIGINE and 9% on placebo, a difference that was statistically significant (p<0.05). Drop attacks were significantly reduced by LAMOTRIGINE (34%) compared with placebo (9%).
Mfd. by: Taro Pharmaceutical Industries Ltd., Haifa Bay, Israel 26110
Dist. by: Taro Pharmaceuticals U.S.A., Inc., Hawthorne, NY 10532
Repackaged by: Rebel Distributors Corp, Thousand Oaks, CA 91320
Revised: September, 2009
70496-0909-2