Dyslipidemia
Undesirable alterations in lipids have been observed in patients treated with atypical antipsychotics. Pooled data from 7 placebo-controlled, 3- to 8- week, fixed- or flexible-dose studies in adult subjects with schizophrenia or bipolar mania are presented in Table 4.
Table 4. Change in Random Lipids from Seven Placebo-Controlled, 3- to 8-Week, Fixed- or Flexible-Dose Studies in Adult Subjects with Schizophrenia or Bipolar Mania | | Risperidone
|
|---|
| Placebo | 1-8 mg/day | >8-16 mg/day |
|---|
| Mean change from baseline (mg/dL) |
| Cholesterol | n=559 | n=742 | n=156 |
| Change from baseline | 0.6 | 6.9 | 1.8 |
| Triglycerides | n=183 | n=307 | n=123 |
| Change from baseline | -17.4 | -4.9 | -8.3 |
| Proportion of patients With Shifts |
| Cholesterol | 2.7% | 4.3% | 6.3% |
| (<200 mg/dL to ≥240 mg/dL) | (10/368) | (22/516) | (6/96) |
| Triglycerides | 1.1% | 2.7% | 2.5% |
| (<500 mg/dL to ≥500 mg/dL) | (2/180) | (8/301) | (3/121) |
In longer-term, controlled and uncontrolled studies, Risperidone was associated with a mean change in (a) non-fasting cholesterol of +4.4 mg/dL at Week 24 (n=231) and +5.5 mg/dL at Week 48 (n=86); and (b) non-fasting triglycerides of +19.9 mg/dL at Week 24 (n=52).
Pooled data from 3 placebo-controlled, 3- to 6-week, fixed-dose studies in children and adolescents with schizophrenia (13-17 years of age), bipolar mania (10-17 years of age), or autistic disorder (5-17 years of age) are presented in Table 5.
Table 5. Change in Fasting Lipids from Three Placebo-Controlled, 3- to 6-Week, Fixed-Dose Studies in Children and Adolescents with Schizophrenia (13-17 Years of Age), Bipolar Mania (10-17 Years of Age), or Autistic Disorder (5 to 17 Years of Age) | | Risperidone
|
|---|
| Placebo | 0.5-6 mg/day |
|---|
| Mean change from baseline (mg/dL) |
| Cholesterol | n=74 | n=133 |
| Change from baseline | -0.3 | 0.3 |
| LDL | n=22 | n=22 |
| Change from baseline | 3.7 | -0.5 |
| HDL | n=22 | n=22 |
| Change from baseline | 1.6 | -1.9 |
| Triglycerides | n=77 | n=138 |
| Change from baseline | -0.9 | -2.6 |
| Proportion of patients with shifts |
| Cholesterol | 2.4% | 3.8% |
| (<170 mg/dL to ≥200 mg/dL) | (1/42) | (3/80) |
| LDL | 0% | 0% |
| (<110 mg/dL to ≥130 mg/dL) | (0/16) | (0/16) |
| HDL | 0% | 10% |
| (≥40 mg/dL to <40 mg/dL) | (0/19) | (2/20) |
| Triglycerides | 1.5% | 7.1% |
| (<150 mg/dL to ≥200 mg/dL) | (1/65) | (8/113) |
In longer-term, uncontrolled, open-label extension pediatric studies, Risperidone was associated with a mean change in (a) fasting cholesterol of +2.1 mg/dL at Week 24 (n=114); (b) fasting LDL of -0.2 mg/dL at Week 24 (n=103); (c) fasting HDL of +0.4 mg/dL at Week 24 (n=103); and (d) fasting triglycerides of +6.8 mg/dL at Week 24 (n=120).
Weight Gain
Weight gain has been observed with atypical antipsychotic use. Clinical monitoring of weight is recommended.
Data on mean changes in body weight and the proportion of subjects meeting a weight gain criterion of 7% or greater of body weight from 7 placebo-controlled, 3- to 8- week, fixed- or flexible-dose studies in adult subjects with schizophrenia or bipolar mania are presented in Table 6.
Table 6. Mean Change in Body Weight (kg) and the Proportion of Subjects with ≥7% Gain in Body Weight From Seven Placebo-Controlled, 3- to 8-Week, Fixed-or Flexible-Dose Studies in Adult Subjects With Schizophrenia or Bipolar Mania | | Risperidone
|
|---|
| Placebo (n=597) | 1-8 mg/day (n=769) | >8-16 mg/day (n=158) |
|---|
| Weight (kg) | | | |
| Change from baseline | -0.3 | 0.7 | 2.2 |
| Weight Gain | | | |
| ≥7% increase from baseline | 2.9% | 8.7% | 20.9% |
In longer-term, controlled and uncontrolled studies, Risperidone was associated with a mean change in weight of +4.3 kg at Week 24 (n=395) and +5.3 kg at Week 48 (n=203).
Data on mean changes in body weight and the proportion of subjects meeting the criterion of ≥7% gain in body weight from nine placebo-controlled, 3- to 8-week, fixed-dose studies in children and adolescents with schizophrenia (13-17 years of age), bipolar mania (10-17 years of age), autistic disorder (5-17 years of age), or other psychiatric disorders (5-17 years of age) are presented in Table 7.
Table 7. Mean Change in Body Weight (kg) and the Proportion of Subjects With ≥7% Gain in Body Weight From Nine Placebo-Controlled, 3- to 8-Week, Fixed-Dose Studies in Children and Adolescents With Schizophrenia (13-17 Years of Age), Bipolar Mania (10-17 Years of Age), Autistic Disorder (5 to 17 Years of Age) or Other Psychiatric Disorders (5-17 Years of Age) | Placebo (n=375) | Risperidone 0.5-6 mg/day (n=448) |
|---|
| Weight (kg) | | |
| Change from baseline | 0.6 | 2.0 |
| Weight Gain | | |
| ≥7% increase from baseline | 6.9% | 32.6% |
In longer-term, uncontrolled, open-label extension pediatric studies, Risperidone was associated with a mean change in weight of +5.5 kg at Week 24 (n=748) and +8.0 kg at Week 48 (n=242).
In a long-term, open-label extension study in adolescent patients with schizophrenia, weight increase was reported as a treatment-emergent adverse event in 14% of patients. In 103 adolescent patients with schizophrenia, a mean increase of 9.0 kg was observed after 8 months of Risperidone treatment. The majority of that increase was observed within the first 6 months.
The average percentiles at baseline and 8 months, respectively, were 56 and 72 for weight, 55 and 58 for height, and 51 and 71 for body mass index.
In long-term, open-label trials (studies in patients with autistic disorder or other psychiatric disorders), a mean increase of 7.5 kg after 12 months of Risperidone treatment was observed, which was higher than the expected normal weight gain (approximately 3 to 3.5 kg per year adjusted for age, based on Centers for Disease Control and Prevention normative data). The majority of that increase occurred within the first 6 months of exposure to Risperidone. The average percentiles at baseline and 12 months, respectively, were 49 and 60 for weight, 48 and 53 for height, and 50 and 62 for body mass index.
In one 3-week, placebo-controlled trial in children and adolescent patients with acute manic or mixed episodes of bipolar I disorder, increases in body weight were higher in the Risperidone groups than the placebo group, but not dose related (1.90 kg in the Risperidone 0.5-2.5 mg group, 1.44 kg in the Risperidone 3-6 mg group, and 0.65 kg in the placebo group). A similar trend was observed in the mean change from baseline in body mass index.
When treating pediatric patients with Risperidone for any indication, weight gain should be assessed against that expected with normal growth.
Commonly-Observed Adverse Reactions in Double-Blind, Placebo-Controlled Clinical Trials-Bipolar Mania
Pediatric Patients with Bipolar Mania
Table 12 lists the adverse reactions reported in 5% or more of Risperidone-treated pediatric patients with bipolar mania in a 3-week double-blind, placebo-controlled trial.
Table 12. Adverse Reactions in ≥5% of Risperidone-Treated Pediatric Patients (and greater than placebo) with Bipolar Mania in Double-Blind, Placebo-Controlled Trials | Percentage of Patients Reporting Reaction |
|---|
| Risperidone
| |
|---|
System/Organ Class Adverse Reaction | 0.5–2.5 mg per day (N=50) | 3–6 mg per day (N=61) | Placebo (N=58) |
|---|
| Eye Disorders | | | |
| Vision blurred | 4 | 7 | 0 |
| Gastrointestinal Disorders | | | |
| Abdominal pain upper | 16 | 13 | 5 |
| Nausea | 16 | 13 | 7 |
| Vomiting | 10 | 10 | 5 |
| Diarrhea | 8 | 7 | 2 |
| Dyspepsia | 10 | 3 | 2 |
| Stomach discomfort | 6 | 0 | 2 |
| General Disorders | | | |
| Fatigue | 18 | 30 | 3 |
| Metabolism and Nutrition Disorders | | | |
| Increased appetite | 4 | 7 | 2 |
| Nervous System Disorders | | | |
| Sedation | 42 | 56 | 19 |
| Dizziness | 16 | 13 | 5 |
| Parkinsonism Parkinsonism includes musculoskeletal stiffness, extrapyramidal disorder, bradykinesia, and nuchal rigidity. Dystonia includes dystonia, laryngospasm, and muscle spasms. Akathisia includes restlessness and akathisia. | 6 | 12 | 3 |
| Dystonia | 6 | 5 | 0 |
| Akathisia | 0 | 8 | 2 |
| Psychiatric Disorders | | | |
| Anxiety | 0 | 8 | 3 |
| Respiratory, Thoracic and Mediastinal Disorders | | | |
| Pharyngolaryngeal pain | 10 | 3 | 5 |
| Skin and Subcutaneous Tissue Disorders | | | |
| Rash | 0 | 7 | 2 |
Commonly-Observed Adverse Reactions in Double-Blind, Placebo-Controlled Clinical Trials - Autistic Disorder
Table 13 lists the adverse reactions reported in 5% or more of Risperidone-treated pediatric patients treated for irritability associated with autistic disorder in two 8-week, double-blind, placebo-controlled trials and one 6-week double-blind, placebo-controlled study.
Table 13. Adverse Reactions in ≥5% of Risperidone-Treated Pediatric Patients (and greater than placebo) Treated for Irritability Associated with Autistic Disorder in Double-Blind, Placebo-Controlled Trials | Percentage of Patients Reporting Reaction |
|---|
| System/Organ Class | Risperidone
0.5–4.0 mg/day | Placebo |
|---|
| Adverse Reaction | (N=107) | (N=115) |
|---|
| Gastrointestinal Disorders | | |
| Vomiting | 20 | 17 |
| Constipation | 17 | 6 |
| Dry mouth | 10 | 4 |
| Nausea | 8 | 5 |
| Salivary hypersecretion | 7 | 1 |
| General Disorders and Administration Site Conditions | | |
| Fatigue | 31 | 9 |
| Pyrexia | 16 | 13 |
| Thirst | 7 | 4 |
| Infections and Infestations | | |
| Nasopharyngitis | 19 | 9 |
| Rhinitis | 9 | 7 |
| Upper respiratory tract infection | 8 | 3 |
| Investigations | | |
| Weight increased | 8 | 2 |
| Metabolism and Nutrition Disorders | | |
| Increased appetite | 44 | 15 |
| Nervous System Disorders | | |
| Sedation | 63 | 15 |
| Drooling | 12 | 4 |
| Headache | 12 | 10 |
| Tremor | 8 | 1 |
| Dizziness | 8 | 2 |
| Parkinsonism Parkinsonism includes musculoskeletal stiffness, extrapyramidal disorder, muscle rigidity, cogwheel rigidity, and muscle tightness. | 8 | 1 |
| Renal and Urinary Disorders | | |
| Enuresis | 16 | 10 |
| Respiratory, Thoracic and Mediastinal Disorders | | |
| Cough | 17 | 12 |
| Rhinorrhea | 12 | 10 |
| Nasal congestion | 10 | 4 |
| Skin and Subcutaneous Tissue Disorders | | |
| Rash | 8 | 5 |
Other Adverse Reactions Observed During the Clinical Trial Evaluation of Risperidone
The following additional adverse reactions occurred across all placebo-controlled, active-controlled, and open-label studies of Risperidone in adults and pediatric patients.
Blood and Lymphatic System Disorders: anemia, granulocytopenia, neutropenia
Cardiac Disorders: sinus bradycardia, sinus tachycardia, atrioventricular block first degree, bundle branch block left, bundle branch block right, atrioventricular block
Ear and Labyrinth Disorders: ear pain, tinnitus
Endocrine Disorders: hyperprolactinemia
Eye Disorders: ocular hyperemia, eye discharge, conjunctivitis, eye rolling, eyelid edema, eye swelling, eyelid margin crusting, dry eye, lacrimation increased, photophobia, glaucoma, visual acuity reduced
Gastrointestinal Disorders: dysphagia, fecaloma, fecal incontinence, gastritis, lip swelling, cheilitis, aptyalism
General Disorders: edema peripheral, thirst, gait disturbance, influenza-like illness, pitting edema, edema, chills, sluggishness, malaise, chest discomfort, face edema, discomfort, generalized edema, drug withdrawal syndrome, peripheral coldness, feeling abnormal
Immune System Disorders: drug hypersensitivity
Infections and Infestations: pneumonia, influenza, ear infection, viral infection, pharyngitis, tonsillitis, bronchitis, eye infection, localized infection, cystitis, cellulitis, otitis media, onychomycosis, acarodermatitis, bronchopneumonia, respiratory tract infection, tracheobronchitis, otitis media chronic
Investigations: body temperature increased, blood prolactin increased, alanine aminotransferase increased, electrocardiogram abnormal, eosinophil count increased, white blood cell count decreased, blood glucose increased, hemoglobin decreased, hematocrit decreased, body temperature decreased, blood pressure decreased, transaminases increased
Metabolism and Nutrition Disorders: decreased appetite, polydipsia, anorexia
Musculoskeletal and Connective Tissue Disorders: joint stiffness, joint swelling, musculoskeletal chest pain, posture abnormal, myalgia, neck pain, muscular weakness, rhabdomyolysis
Nervous System Disorders: balance disorder, disturbance in attention, dysarthria, unresponsive to stimuli, depressed level of consciousness, movement disorder, transient ischemic attack, coordination abnormal, cerebrovascular accident, speech disorder, syncope, loss of consciousness, hypoesthesia, tardive dyskinesia, dyskinesia, cerebral ischemia, cerebrovascular disorder, neuroleptic malignant syndrome, diabetic coma, head titubation
Psychiatric Disorders: agitation, blunted affect, confusional state, middle insomnia, nervousness, sleep disorder, listlessness, libido decreased, and anorgasmia
Renal and Urinary Disorders: enuresis, dysuria, pollakiuria, urinary incontinence
Reproductive System and Breast Disorders: menstruation irregular, amenorrhea, gynecomastia, galactorrhea, vaginal discharge, menstrual disorder, erectile dysfunction, retrograde ejaculation, ejaculation disorder, sexual dysfunction, breast enlargement
Respiratory, Thoracic, and Mediastinal Disorders: wheezing, pneumonia aspiration, sinus congestion, dysphonia, productive cough, pulmonary congestion, respiratory tract congestion, rales, respiratory disorder, hyperventilation, nasal edema
Skin and Subcutaneous Tissue Disorders: erythema, skin discoloration, skin lesion, pruritus, skin disorder, rash erythematous, rash papular, rash generalized, rash maculopapular, acne, hyperkeratosis, seborrheic dermatitis
Vascular Disorders: hypotension, flushing
Discontinuations Due to Adverse Reactions
Schizophrenia - Adults
Approximately 7% (39/564) of Risperidone-treated patients in double-blind, placebo-controlled trials discontinued treatment due to an adverse reaction, compared with 4% (10/225) who were receiving placebo. The adverse reactions associated with discontinuation in 2 or more Risperidone-treated patients were:
Table 14. Adverse Reactions Associated With Discontinuation in 2 or More Risperidone-Treated Adult Patients in Schizophrenia Trials | Risperidone
| |
|---|
| Adverse Reaction | 2–8 mg/day (N=366) | >8–16 mg/day (N=198) | Placebo (N=225) |
|---|
| Dizziness | 1.4% | 1.0% | 0% |
| Nausea | 1.4% | 0% | 0% |
| Vomiting | 0.8% | 0% | 0% |
| Parkinsonism | 0.8% | 0% | 0% |
| Somnolence | 0.8% | 0% | 0% |
| Dystonia | 0.5% | 0% | 0% |
| Agitation | 0.5% | 0% | 0% |
| Abdominal pain | 0.5% | 0% | 0% |
| Orthostatic hypotension | 0.3% | 0.5% | 0% |
| Akathisia | 0.3% | 2.0% | 0% |
Discontinuation for extrapyramidal symptoms (including Parkinsonism, akathisia, dystonia, and tardive dyskinesia) was 1% in placebo-treated patients, and 3.4% in active control-treated patients in a double-blind, placebo- and active-controlled trial.
Schizophrenia - Pediatrics
Approximately 7% (7/106), of Risperidone-treated patients discontinued treatment due to an adverse reaction in a double-blind, placebo-controlled trial, compared with 4% (2/54) placebo-treated patients. The adverse reactions associated with discontinuation for at least one Risperidone-treated patient were dizziness (2%), somnolence (1%), sedation (1%), lethargy (1%), anxiety (1%), balance disorder (1%), hypotension (1%), and palpitation (1%).
Bipolar Mania - Adults
In double-blind, placebo-controlled trials with Risperidone as monotherapy, approximately 6% (25/448) of Risperidone-treated patients discontinued treatment due to an adverse event, compared with approximately 5% (19/424) of placebo-treated patients. The adverse reactions associated with discontinuation in Risperidone-treated patients were:
Table 15. Adverse Reactions Associated With Discontinuation in 2 or More Risperidone-Treated Adult Patients in Bipolar Mania Clinical Trials| Adverse Reaction | Risperidone
1–6 mg/day (N=448) | Placebo (N=424) |
|---|
| Parkinsonism | 0.4% | 0% |
| Lethargy | 0.2% | 0% |
| Dizziness | 0.2% | 0% |
| Alanine aminotransferase increased | 0.2% | 0.2% |
| Aspartate aminotransferase increased | 0.2% | 0.2% |
Bipolar Mania - Pediatrics
In a double-blind, placebo-controlled trial 12% (13/111) of Risperidone-treated patients discontinued due to an adverse reaction, compared with 7% (4/58) of placebo-treated patients. The adverse reactions associated with discontinuation in more than one Risperidone-treated pediatric patient were nausea (3%), somnolence (2%), sedation (2%), and vomiting (2%).
Autistic Disorder - Pediatrics
In the two 8-week, placebo-controlled trials in pediatric patients treated for irritability associated with autistic disorder (n = 156), one Risperidone-treated patient discontinued due to an adverse reaction (Parkinsonism), and one placebo-treated patient discontinued due to an adverse event.
Dose Dependency of Adverse Reactions in Clinical Trials
Extrapyramidal Symptoms
Data from two fixed-dose trials in adults with schizophrenia provided evidence of dose-relatedness for extrapyramidal symptoms associated with Risperidone treatment.
Two methods were used to measure extrapyramidal symptoms (EPS) in an 8-week trial comparing 4 fixed doses of Risperidone (2, 6, 10, and 16 mg/day), including (1) a Parkinsonism score (mean change from baseline) from the Extrapyramidal Symptom Rating Scale, and (2) incidence of spontaneous complaints of EPS:
Table 16.| Dose Groups | Placebo | Risperidone 2 mg | Risperidone 6 mg | Risperidone 10 mg | Risperidone 16 mg |
|---|
| Parkinsonism | 1.2 | 0.9 | 1.8 | 2.4 | 2.6 |
| EPS Incidence | 13% | 17% | 21% | 21% | 35% |
Similar methods were used to measure extrapyramidal symptoms (EPS) in an 8-week trial comparing 5 fixed doses of Risperidone (1, 4, 8, 12, and 16 mg/day):
Table 17.| Dose Groups | Risperidone 1 mg | Risperidone 4 mg | Risperidone 8 mg | Risperidone 12 mg | Risperidone 16 mg |
|---|
| Parkinsonism | 0.6 | 1.7 | 2.4 | 2.9 | 4.1 |
| EPS Incidence | 7% | 12% | 17% | 18% | 20% |
Dystonia
Class Effect: Symptoms of dystonia, prolonged abnormal contractions of muscle groups, may occur in susceptible individuals during the first few days of treatment. Dystonic symptoms include: spasm of the neck muscles, sometimes progressing to tightness of the throat, swallowing difficulty, difficulty breathing, and/or protrusion of the tongue. While these symptoms can occur at low doses, they occur more frequently and with greater severity with high potency and at higher doses of first generation antipsychotic drugs. An elevated risk of acute dystonia is observed in males and younger age groups.
Other Adverse Reactions
Adverse event data elicited by a checklist for side effects from a large study comparing 5 fixed doses of Risperidone (1, 4, 8, 12, and 16 mg/day) were explored for dose-relatedness of adverse events. A Cochran-Armitage Test for trend in these data revealed a positive trend (p<0.05) for the following adverse reactions: somnolence, vision abnormal, dizziness, palpitations, weight increase, erectile dysfunction, ejaculation disorder, sexual function abnormal, fatigue, and skin discoloration.
Changes in Body Weight
Weight gain was observed in short-term, controlled trials and longer-term uncontrolled studies in adult and pediatric patients [see Warnings and Precautions (5.5), Adverse Reactions (6), and Use in Specific Populations (8.4)].
Changes in ECG Parameters
Between-group comparisons for pooled placebo-controlled trials in adults revealed no statistically significant differences between risperidone and placebo in mean changes from baseline in ECG parameters, including QT, QTc, and PR intervals, and heart rate. When all Risperidone doses were pooled from randomized controlled trials in several indications, there was a mean increase in heart rate of 1 beat per minute compared to no change for placebo patients. In short-term schizophrenia trials, higher doses of risperidone (8–16 mg/day) were associated with a higher mean increase in heart rate compared to placebo (4–6 beats per minute). In pooled placebo-controlled acute mania trials in adults, there were small decreases in mean heart rate, similar among all treatment groups.
In the two placebo-controlled trials in children and adolescents with autistic disorder (aged 5-16 years) mean changes in heart rate were an increase of 8.4 beats per minute in the Risperidone groups and 6.5 beats per minute in the placebo group. There were no other notable ECG changes.
In a placebo-controlled acute mania trial in children and adolescents (aged 10-17 years), there were no significant changes in ECG parameters, other than the effect of Risperidone to transiently increase pulse rate (< 6 beats per minute). In two controlled schizophrenia trials in adolescents (aged 13-17 years), there were no clinically meaningful changes in ECG parameters including corrected QT intervals between treatment groups or within treatment groups over time.
Effect of Risperidone on other drugs
Lithium
Repeated oral doses of Risperidone (3 mg twice daily) did not affect the exposure (AUC) or peak plasma concentrations (Cmax) of lithium (n=13). Dose adjustment for lithium is not recommended.
Valproate
Repeated oral doses of Risperidone (4 mg once daily) did not affect the pre-dose or average plasma concentrations and exposure (AUC) of valproate (1000 mg/day in three divided doses) compared to placebo (n=21). However, there was a 20% increase in valproate peak plasma concentration (Cmax) after concomitant administration of Risperidone. Dose adjustment for valproate is not recommended.
Digoxin
Risperidone (0.25 mg twice daily) did not show a clinically relevant effect on the pharmacokinetics of digoxin. Dose adjustment for digoxin is not recommended.
Centrally-Acting Drugs and Alcohol
Given the primary CNS effects of risperidone, caution should be used when Risperidone is taken in combination with other centrally-acting drugs and alcohol.
Drugs with Hypotensive Effects
Because of its potential for inducing hypotension, Risperidone may enhance the hypotensive effects of other therapeutic agents with this potential.
Levodopa and Dopamine Agonists
Risperidone may antagonize the effects of levodopa and dopamine agonists.
Clozapine
Chronic administration of clozapine with Risperidone may decrease the clearance of risperidone.
Risk Summary
Adequate and well controlled studies with Risperidone have not been conducted in pregnant women. Neonates exposed to antipsychotic drugs (including Risperidone) during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery. There was no increase in the incidence of malformations in embryo-fetal studies in rats and rabbits at 0.4–6 times MHRD. Increased pup mortality was noted at all doses in peri-postnatal studies in rats. Risperidone should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Clinical Considerations
Fetal/Neonatal Adverse Reactions
Monitor neonates exhibiting extrapyramidal or withdrawal symptoms. Some neonates recover within hours or days without specific treatment; others may require prolonged hospitalization.
Data
Human Data
There have been reports of agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, and feeding disorder in neonates following in utero exposure to antipsychotics in the third trimester. These complications have varied in severity; while in some cases symptoms have been self-limited, in other cases neonates have required intensive care unit support and prolonged hospitalization.
There was one report of a case of agenesis of the corpus callosum in an infant exposed to risperidone in utero. The causal relationship to Risperidone therapy is unknown.
Animal Data
The teratogenic potential of risperidone was studied in three Segment II studies in Sprague-Dawley and Wistar rats (0.63–10 mg/kg or 0.4 to 6 times the maximum recommended human dose [MRHD] on a mg/m2 body surface area basis) and in one Segment II study in New Zealand rabbits (0.31–5 mg/kg or 0.4 to 6 times the MRHD on a mg/m2 body surface area basis). There were no teratogenic effects in offspring of rats or rabbits given 0.4 to 6 times the MRHD on a mg/m2 body surface area basis. In three reproductive studies in rats (two Segment III and a multigenerational study), there was an increase in pup deaths during the first 4 days of lactation at doses of 0.16–5 mg/kg or 0.1 to 3 times the MRHD on a mg/m2 body surface area basis. It is not known whether these deaths were due to a direct effect on the fetuses or pups or to effects on the dams.
There was no no-effect dose for increased rat pup mortality. In one Segment III study, there was an increase in stillborn rat pups at a dose of 2.5 mg/kg or 1.5 times the MRHD on a mg/m2 body surface area basis. In a cross-fostering study in Wistar rats, toxic effects on the fetus or pups were observed, as evidenced by a decrease in the number of live pups and an increase in the number of dead pups at birth (Day 0), and a decrease in birth weight in pups of drug-treated dams. In addition, there was an increase in deaths by Day 1 among pups of drug-treated dams, regardless of whether or not the pups were cross-fostered. Risperidone also appeared to impair maternal behavior in that pup body weight gain and survival (from Day 1 to 4 of lactation) were reduced in pups born to control but reared by drug-treated dams. These effects were all noted at the one dose of risperidone tested, i.e., 5 mg/kg or 3 times the MRHD on a mg/m2 body surface area basis.
Placental transfer of risperidone occurs in rat pups.
Approved Pediatric Indications
Schizophrenia
The efficacy and safety of Risperidone in the treatment of schizophrenia were demonstrated in 417 adolescents, aged 13-17 years, in two short-term (6 and 8 weeks, respectively) double-blind controlled trials [see Indications and Usage (1.1), Adverse Reactions (6.1), and Clinical Studies (14.1)]. Additional safety and efficacy information was also assessed in one long-term (6-month) open-label extension study in 284 of these adolescent patients with schizophrenia.
Safety and effectiveness of Risperidone in children less than 13 years of age with schizophrenia have not been established.
Bipolar I Disorder
The efficacy and safety of Risperidone in the short-term treatment of acute manic or mixed episodes associated with Bipolar I Disorder in 169 children and adolescent patients, aged 10-17 years, were demonstrated in one double-blind, placebo-controlled, 3-week trial [see Indications and Usage (1.2), Adverse Reactions (6.1), and Clinical Studies (14.2)].
Safety and effectiveness of Risperidone in children less than 10 years of age with bipolar disorder have not been established.
Autistic Disorder
The efficacy and safety of Risperidone in the treatment of irritability associated with autistic disorder were established in two 8-week, double-blind, placebo-controlled trials in 156 children and adolescent patients, aged 5 to 16 years [see Indications and Usage (1.3), Adverse Reactions (6.1) and Clinical Studies (14.4)]. Additional safety information was also assessed in a long-term study in patients with autistic disorder, or in short- and long-term studies in more than 1200 pediatric patients with psychiatric disorders other than autistic disorder, schizophrenia, or bipolar mania who were of similar age and weight, and who received similar dosages of Risperidone as patients treated for irritability associated with autistic disorder.
A third study was a 6-week, multicenter, randomized, double-blind, placebo-controlled, fixed-dose study to evaluate the efficacy and safety of a lower than recommended dose of risperidone in subjects 5 to 17 years of age with autistic disorder and associated irritability, and related behavioral symptoms. There were two weight-based, fixed doses of risperidone (high-dose and low-dose). The high dose was 1.25 mg per day for patients weighing 20 to < 45 kg, and it was 1.75 mg per day for patients weighing ≥ 45 kg. The low dose was 0.125 mg per day for patients for patients weighing 20 to < 45 kg, and it was 0.175 mg per day for patients weighing ≥ 45 kg. The study demonstrated the efficacy of high-dose risperidone, but it did not demonstrate efficacy for low-dose risperidone.
Adverse Reactions in Pediatric Patients
Tardive Dyskinesia
In clinical trials in 1885 children and adolescents treated with Risperidone, 2 (0.1%) patients were reported to have tardive dyskinesia, which resolved on discontinuation of Risperidone treatment [see also Warnings and Precautions (5.4)].
Weight Gain
Weight gain has been observed in children and adolescents during treatment with Risperidone. Clinical monitoring of weight is recommended during treatment.
Data derive from short-term placebo-controlled trials and longer-term uncontrolled studies in pediatric patients (ages 5 to 17 years) with schizophrenia, bipolar disorder, autistic disorder, or other psychiatric disorders. In the short-term trials (3 to 8 weeks), the mean weight gain for Risperidone-treated patients was 2 kg, compared to 0.6 kg for placebo-treated patients. In these trials, approximately 33% of the Risperidone group had weight gain ≥7%, compared to 7% in the placebo group. In longer-term, uncontrolled, open-label pediatric studies, the mean weight gain was 5.5 kg at Week 24 and 8 kg at Week 48 [see Warnings and Precautions (5.5) and Adverse Reactions (6.1)].
Somnolence
Somnolence was frequently observed in placebo-controlled clinical trials of pediatric patients with autistic disorder. Most cases were mild or moderate in severity. These events were most often of early onset with peak incidence occurring during the first two weeks of treatment, and transient with a median duration of 16 days. Somnolence was the most commonly observed adverse reaction in the clinical trial of bipolar disorder in children and adolescents, as well as in the schizophrenia trials in adolescents. As was seen in the autistic disorder trials, these adverse reactions were most often of early onset and transient in duration [see Adverse Reactions (6.1 and 6.2)]. Patients experiencing persistent somnolence may benefit from a change in dosing regimen [see Dosage and Administration (2.1, 2.2, and 2.3)].
Hyperprolactinemia
Risperidone has been shown to elevate prolactin levels in children and adolescents as well as in adults [see Warnings and Precautions (5.6)]. In double-blind, placebo-controlled studies of up to 8 weeks duration in children and adolescents (aged 5 to 17 years) with autistic disorder or psychiatric disorders other than autistic disorder, schizophrenia, or bipolar mania, 49% of patients who received Risperidone had elevated prolactin levels compared to 2% of patients who received placebo. Similarly, in placebo-controlled trials in children and adolescents (aged 10 to 17 years) with bipolar disorder, or adolescents (aged 13 to 17 years) with schizophrenia, 82–87% of patients who received Risperidone had elevated levels of prolactin compared to 3–7% of patients on placebo. Increases were dose-dependent and generally greater in females than in males across indications.
In clinical trials in 1885 children and adolescents, galactorrhea was reported in 0.8% of Risperidone-treated patients and gynecomastia was reported in 2.3% of Risperidone-treated patients.
Growth and Sexual Maturation
The long-term effects of Risperidone on growth and sexual maturation have not been fully evaluated in children and adolescents.
Juvenile Animal Studies
Juvenile dogs were treated for 40 weeks with oral risperidone doses of 0.31, 1.25, or 5 mg/kg/day. Decreased bone length and density were seen, with a no-effect dose of 0.31 mg/kg/day. This dose produced plasma levels (AUC) of risperidone plus its active metabolite paliperidone (9-hydroxy-risperidone) which were similar to those in children and adolescents receiving the maximum recommended human dose (MRHD) of 6 mg/day. In addition, a delay in sexual maturation was seen at all doses in both males and females. The above effects showed little or no reversibility in females after a 12 week drug-free recovery period.
In a study in which juvenile rats were treated with oral risperidone from days 12 to 50 of age, a reversible impairment of performance in a test of learning and memory was seen, in females only, with a no-effect dose of 0.63 mg/kg/day. This dose produced plasma levels (AUC) of risperidone plus paliperidone about half those observed in humans at the MRHD. No other consistent effects on neurobehavioral or reproductive development were seen up to the highest testable dose (1.25 mg/kg/day). This dose produced plasma levels (AUC) of risperidone plus paliperidone which were about two thirds of those observed in humans at the MRHD.
Absorption
Risperidone is well absorbed. The absolute oral bioavailability of risperidone is 70% (CV=25%). The relative oral bioavailability of risperidone from a tablet is 94% (CV=10%) when compared to a solution.
Plasma concentrations of risperidone, its major metabolite, 9-hydroxyrisperidone, and risperidone plus 9-hydroxyrisperidone are dose proportional over the dosing range of 1 to 16 mg daily (0.5 to 8 mg twice daily). Following oral administration of solution or tablet, mean peak plasma concentrations of risperidone occurred at about 1 hour. Peak concentrations of 9-hydroxyrisperidone occurred at about 3 hours in extensive metabolizers, and 17 hours in poor metabolizers. Steady-state concentrations of risperidone are reached in 1 day in extensive metabolizers and would be expected to reach steady-state in about 5 days in poor metabolizers. Steady-state concentrations of 9-hydroxyrisperidone are reached in 5–6 days (measured in extensive metabolizers).
Food Effect
Food does not affect either the rate or extent of absorption of risperidone. Thus, Risperidone can be given with or without meals.
Distribution
Risperidone is rapidly distributed. The volume of distribution is 1–2 L/kg. In plasma, risperidone is bound to albumin and α1-acid glycoprotein. The plasma protein binding of risperidone is 90%, and that of its major metabolite, 9-hydroxyrisperidone, is 77%. Neither risperidone nor 9-hydroxyrisperidone displaces each other from plasma binding sites. High therapeutic concentrations of sulfamethazine (100 mcg/mL), warfarin (10 mcg/mL), and carbamazepine (10mcg/mL) caused only a slight increase in the free fraction of risperidone at 10 ng/mL and 9-hydroxyrisperidone at 50 ng/mL, changes of unknown clinical significance.
Metabolism
Risperidone is extensively metabolized in the liver. The main metabolic pathway is through hydroxylation of risperidone to 9-hydroxyrisperidone by the enzyme, CYP 2D6. A minor metabolic pathway is through N-dealkylation. The main metabolite, 9-hydroxyrisperidone, has similar pharmacological activity as risperidone. Consequently, the clinical effect of the drug results from the combined concentrations of risperidone plus 9-hydroxyrisperidone.
CYP 2D6, also called debrisoquin hydroxylase, is the enzyme responsible for metabolism of many neuroleptics, antidepressants, antiarrhythmics, and other drugs. CYP 2D6 is subject to genetic polymorphism (about 6%–8% of Caucasians, and a very low percentage of Asians, have little or no activity and are "poor metabolizers") and to inhibition by a variety of substrates and some non-substrates, notably quinidine. Extensive CYP 2D6 metabolizers convert risperidone rapidly into 9-hydroxyrisperidone, whereas poor CYP 2D6 metabolizers convert it much more slowly. Although extensive metabolizers have lower risperidone and higher 9-hydroxyrisperidone concentrations than poor metabolizers, the pharmacokinetics of risperidone and 9-hydroxyrisperidone combined, after single and multiple doses, are similar in extensive and poor metabolizers.
Risperidone could be subject to two kinds of drug-drug interactions. First, inhibitors of CYP 2D6 interfere with conversion of risperidone to 9-hydroxyrisperidone [see Drug Interactions (7)]. This occurs with quinidine, giving essentially all recipients a risperidone pharmacokinetic profile typical of poor metabolizers. The therapeutic benefits and adverse effects of risperidone in patients receiving quinidine have not been evaluated, but observations in a modest number (n70) of poor metabolizers given Risperidone do not suggest important differences between poor and extensive metabolizers. Second, co-administration of known enzyme inducers (e.g., carbamazepine, phenytoin, rifampin, and phenobarbital) with Risperidone may cause a decrease in the combined plasma concentrations of risperidone and 9-hydroxyrisperidone [see Drug Interactions (7)]. It would also be possible for risperidone to interfere with metabolism of other drugs metabolized by CYP 2D6. Relatively weak binding of risperidone to the enzyme suggests this is unlikely [see Drug Interactions (7)].
In vitro studies indicate that risperidone is a relatively weak inhibitor of CYP 2D6. Therefore, Risperidone is not expected to substantially inhibit the clearance of drugs that are metabolized by this enzymatic pathway. In drug interaction studies, Risperidone did not significantly affect the pharmacokinetics of donepezil and galantamine, which are metabolized by CYP 2D6.
In vitro studies demonstrated that drugs metabolized by other CYP isozymes, including 1A1, 1A2, 2C9, 2C19, and 3A4, are only weak inhibitors of risperidone metabolism.
Excretion
Risperidone and its metabolites are eliminated via the urine and, to a much lesser extent, via the feces. As illustrated by a mass balance study of a single 1 mg oral dose of 14C-risperidone administered as solution to three healthy male volunteers, total recovery of radioactivity at 1 week was 84%, including 70% in the urine and 14% in the feces.
The apparent half-life of risperidone was 3 hours (CV=30%) in extensive metabolizers and 20 hours (CV=40%) in poor metabolizers. The apparent half-life of 9-hydroxyrisperidone was about 21 hours (CV=20%) in extensive metabolizers and 30 hours (CV=25%) in poor metabolizers. The pharmacokinetics of risperidone and 9-hydroxyrisperidone combined, after single and multiple doses, were similar in extensive and poor metabolizers, with an overall mean elimination half-life of about 20 hours.
Drug-Drug Interaction Studies
[See Drug Interactions (7)].
Specific Populations
Renal and Hepatic Impairment
[See Use in Specific Populations (8.6 and 8.7)].
Elderly
In healthy elderly subjects, renal clearance of both risperidone and 9-hydroxyrisperidone was decreased, and elimination half-lives were prolonged compared to young healthy subjects. Dosing should be modified accordingly in the elderly patients [see Use in Specific Populations (8.5)].
Pediatric
The pharmacokinetics of risperidone and 9-hydroxyrisperidone in children were similar to those in adults after correcting for the difference in body weight.
Race and Gender Effects
No specific pharmacokinetic study was conducted to investigate race and gender effects, but a population pharmacokinetic analysis did not identify important differences in the disposition of risperidone due to gender (whether corrected for body weight or not) or race.
Adults
Short-Term Efficacy
The efficacy of Risperidone in the treatment of schizophrenia was established in four short-term (4- to 8-week) controlled trials of psychotic inpatients who met DSM-III-R criteria for schizophrenia.
Several instruments were used for assessing psychiatric signs and symptoms in these studies, among them the Brief Psychiatric Rating Scale (BPRS), a multi-item inventory of general psychopathology traditionally used to evaluate the effects of drug treatment in schizophrenia. The BPRS psychosis cluster (conceptual disorganization, hallucinatory behavior, suspiciousness, and unusual thought content) is considered a particularly useful subset for assessing actively psychotic schizophrenic patients. A second traditional assessment, the Clinical Global Impression (CGI), reflects the impression of a skilled observer, fully familiar with the manifestations of schizophrenia, about the overall clinical state of the patient. In addition, the Positive and Negative Syndrome Scale (PANSS) and the Scale for Assessing Negative Symptoms (SANS) were employed.
The results of the trials follow:
- (1)In a 6-week, placebo-controlled trial (n=160) involving titration of Risperidone in doses up to 10 mg/day (twice-daily schedule), Risperidone was generally superior to placebo on the BPRS total score, on the BPRS psychosis cluster, and marginally superior to placebo on the SANS.
- (2)In an 8-week, placebo-controlled trial (n=513) involving 4 fixed doses of Risperidone (2 mg/day, 6 mg/day, 10 mg/day, and 16 mg/day, on a twice-daily schedule), all 4 Risperidone groups were generally superior to placebo on the BPRS total score, BPRS psychosis cluster, and CGI severity score; the 3 highest Risperidone dose groups were generally superior to placebo on the PANSS negative subscale. The most consistently positive responses on all measures were seen for the 6 mg dose group, and there was no suggestion of increased benefit from larger doses.
- (3)In an 8-week, dose comparison trial (n=1356) involving 5 fixed doses of (1 mg/day, 4 mg/day, 8 mg/day, 12 mg/day, and 16 mg/day, on a twice-daily schedule), the four highest Risperidone dose groups were generally superior to the 1 mg Risperidone dose group on BPRS total score, BPRS psychosis cluster, and CGI severity score. None of the dose groups were superior to the 1 mg group on the PANSS negative subscale. The most consistently positive responses were seen for the 4 mg dose group.
- (4)In a 4-week, placebo-controlled dose comparison trial (n=246) involving 2 fixed doses of Risperidone (4 and 8 mg/day on a once-daily schedule), both Risperidone dose groups were generally superior to placebo on several PANSS measures, including a response measure (>20% reduction in PANSS total score), PANSS total score, and the BPRS psychosis cluster (derived from PANSS). The results were generally stronger for the 8 mg than for the 4 mg dose group.
Long-Term Efficacy
In a longer-term trial, 365 adult outpatients predominantly meeting DSM-IV criteria for schizophrenia and who had been clinically stable for at least 4 weeks on an antipsychotic medication were randomized to Risperidone (2–8 mg/day) or to an active comparator, for 1 to 2 years of observation for relapse. Patients receiving Risperidone experienced a significantly longer time to relapse over this time period compared to those receiving the active comparator.
Pediatrics
The efficacy of Risperidone in the treatment of schizophrenia in adolescents aged 13–17 years was demonstrated in two short-term (6 and 8 weeks), double-blind controlled trials. All patients met DSM-IV diagnostic criteria for schizophrenia and were experiencing an acute episode at time of enrollment. In the first trial (study #1), patients were randomized into one of three treatment groups: Risperidone 1–3 mg/day (n = 55, mean modal dose = 2.6 mg), Risperidone 4–6 mg/day (n = 51, mean modal dose = 5.3 mg), or placebo (n = 54). In the second trial (study #2), patients were randomized to either Risperidone 0.15–0.6 mg/day (n = 132, mean modal dose = 0.5 mg) or Risperidone 1.5–6 mg/day (n = 125, mean modal dose = 4 mg). In all cases, study medication was initiated at 0.5 mg/day (with the exception of the 0.15–0.6 mg/day group in study #2, where the initial dose was 0.05 mg/day) and titrated to the target dosage range by approximately Day 7. Subsequently, dosage was increased to the maximum tolerated dose within the target dose range by Day 14. The primary efficacy variable in all studies was the mean change from baseline in total PANSS score.
Results of the studies demonstrated efficacy of Risperidone in all dose groups from 1–6 mg/day compared to placebo, as measured by significant reduction of total PANSS score. The efficacy on the primary parameter in the 1–3 mg/day group was comparable to the 4–6 mg/day group in study #1, and similar to the efficacy demonstrated in the 1.5–6 mg/day group in study #2. In study #2, the efficacy in the 1.5–6 mg/day group was statistically significantly greater than that in the 0.15–0.6 mg/day group. Doses higher than 3 mg/day did not reveal any trend towards greater efficacy.
Adults
The efficacy of Risperidone in the treatment of acute manic or mixed episodes was established in two short-term (3-week) placebo-controlled trials in patients who met the DSM-IV criteria for Bipolar I Disorder with manic or mixed episodes. These trials included patients with or without psychotic features.
The primary rating instrument used for assessing manic symptoms in these trials was the Young Mania Rating Scale (YMRS), an 11-item clinician-rated scale traditionally used to assess the degree of manic symptomatology (irritability, disruptive/aggressive behavior, sleep, elevated mood, speech, increased activity, sexual interest, language/thought disorder, thought content, appearance, and insight) in a range from 0 (no manic features) to 60 (maximum score). The primary outcome in these trials was change from baseline in the YMRS total score. The results of the trials follow:
- (1)In one 3-week placebo-controlled trial (n=246), limited to patients with manic episodes, which involved a dose range of Risperidone 1–6 mg/day, once daily, starting at 3 mg/day (mean modal dose was 4.1 mg/day), Risperidone was superior to placebo in the reduction of YMRS total score.
- (2)In another 3-week placebo-controlled trial (n=286), which involved a dose range of 1–6 mg/day, once daily, starting at 3 mg/day (mean modal dose was 5.6 mg/day), Risperidone was superior to placebo in the reduction of YMRS total score.
Pediatrics
The efficacy of Risperidone in the treatment of mania in children or adolescents with Bipolar I disorder was demonstrated in a 3-week, randomized, double-blind, placebo-controlled, multicenter trial including patients ranging in ages from 10 to 17 years who were experiencing a manic or mixed episode of bipolar I disorder. Patients were randomized into one of three treatment groups: Risperidone 0.5–2.5 mg/day (n = 50, mean modal dose = 1.9 mg), Risperidone 3–6 mg/day (n = 61, mean modal dose = 4.7 mg), or placebo (n = 58). In all cases, study medication was initiated at 0.5 mg/day and titrated to the target dosage range by Day 7, with further increases in dosage to the maximum tolerated dose within the targeted dose range by Day 10. The primary rating instrument used for assessing efficacy in this study was the mean change from baseline in the total YMRS score.
Results of this study demonstrated efficacy of Risperidone in both dose groups compared with placebo, as measured by significant reduction of total YMRS score. The efficacy on the primary parameter in the 3–6 mg/day dose group was comparable to the 0.5–2.5 mg/day dose group. Doses higher than 2.5 mg/day did not reveal any trend towards greater efficacy.
Short-Term Efficacy
The efficacy of Risperidone in the treatment of irritability associated with autistic disorder was established in two 8-week, placebo-controlled trials in children and adolescents (aged 5 to 16 years) who met the DSM-IV criteria for autistic disorder. Over 90% of these subjects were under 12 years of age and most weighed over 20 kg (16–104.3 kg).
Efficacy was evaluated using two assessment scales: the Aberrant Behavior Checklist (ABC) and the Clinical Global Impression - Change (CGI-C) scale. The primary outcome measure in both trials was the change from baseline to endpoint in the Irritability subscale of the ABC (ABC-I). The ABC-I subscale measured the emotional and behavioral symptoms of autism, including aggression towards others, deliberate self-injuriousness, temper tantrums, and quickly changing moods. The CGI-C rating at endpoint was a co-primary outcome measure in one of the studies.
The results of these trials are as follows:
- (1)In one of the 8-week, placebo-controlled trials, children and adolescents with autistic disorder (n=101), aged 5 to 16 years, received twice daily doses of placebo or Risperidone 0.5–3.5 mg/day on a weight-adjusted basis. Risperidone, starting at 0.25 mg/day or 0.5 mg/day depending on baseline weight (< 20 kg and ≥ 20 kg, respectively) and titrated to clinical response (mean modal dose of 1.9 mg/day, equivalent to 0.06 mg/kg/day), significantly improved scores on the ABC-I subscale and on the CGI-C scale compared with placebo.
- (2)In the other 8-week, placebo-controlled trial in children with autistic disorder (n=55), aged 5 to 12 years, Risperidone 0.02 to 0.06 mg/kg/day given once or twice daily, starting at 0.01 mg/kg/day and titrated to clinical response (mean modal dose of 0.05 mg/kg/day, equivalent to 1.4 mg/day), significantly improved scores on the ABC-I subscale compared with placebo.
A third trial was a 6-week, multicenter, randomized, double-blind, placebo-controlled, fixed-dose study to evaluate the efficacy and safety of a lower than recommended dose of risperidone in subjects (N=96) 5 to 17 years of age with autistic disorder (defined by DSM-IV criteria) and associated irritability and related behavioral symptoms. Approximately 77% of patients were younger than 12 years of age (mean age = 9), and 88% were male. Most patients (73%) weighed less than 45 kg (mean weight = 40 kg). Approximately 90% of patients were antipsychotic-naïve before entering the study.
There were two weight-based, fixed doses of risperidone (high-dose and low-dose). The high dose was 1.25 mg per day for patients weighing 20 to < 45 kg, and it was 1.75 mg per day for patients weighing ≥ 45 kg. The low dose was 0.125 mg per day for patients weighing 20 to < 45 kg, and it was 0.175 mg per day for patients weighing ≥ 45 kg. The dose was administered once daily in the morning, or in the evening if sedation occurred.
The primary efficacy endpoint was the mean change in the Aberrant Behavior Checklist-Irritability subscale (ABC-I) score from baseline to the end of Week 6. The study demonstrated the efficacy of high-dose risperidone, as measured by the mean change in ABC-I score. It did not demonstrate efficacy for low-dose risperidone. The mean baseline ABC-I scores were 29 in the placebo group (n = 35), 27 in the risperidone low-dose group (n = 30), and 28 in the risperidone high-dose group (n = 31). The mean changes in ABC-I scores were -3.5, -7.4, and -12.4 in the placebo, low-dose, and high-dose group respectively. The results in the high-dose group were statistically significant (p< 0.001) but not in the low-dose group (p=0.164).
Long-Term Efficacy
Following completion of the first 8-week double-blind study, 63 patients entered an open-label study extension where they were treated with Risperidone for 4 or 6 months (depending on whether they received Risperidone or placebo in the double-blind study). During this open-label treatment period, patients were maintained on a mean modal dose of Risperidone of 1.8–2.1 mg/day (equivalent to 0.05-0.07 mg/kg/day).
Patients who maintained their positive response to Risperidone (response was defined as 25% improvement on the ABC-I subscale and a CGI-C rating of ‘much improved’ or ‘very much improved’) during the 4-6 month open-label treatment phase for about 140 days, on average, were randomized to receive Risperidone or placebo during an 8-week, double-blind withdrawal study (n=39 of the 63 patients). A pre-planned interim analysis of data from patients who completed the withdrawal study (n=32), undertaken by an independent Data Safety Monitoring Board, demonstrated a significantly lower relapse rate in the Risperidone group compared with the placebo group. Based on the interim analysis results, the study was terminated due to demonstration of a statistically significant effect on relapse prevention. Relapse was defined as ≥ 25% worsening on the most recent assessment of the ABC-I subscale (in relation to baseline of the randomized withdrawal phase).