Acute Withdrawal Reactions
The continued use of benzodiazepines, including Alprazolam, may lead to clinically significant physical dependence. Abrupt discontinuation or rapid dosage reduction of Alprazolam after continued use, or administration of flumazenil (a benzodiazepine antagonist) may precipitate acute withdrawal reactions, which can be life-threatening (e.g., seizures) [see Drug Abuse and Dependence (9.3)].
Protracted Withdrawal Syndrome
In some cases, benzodiazepine users have developed a protracted withdrawal syndrome with withdrawal symptoms lasting weeks to more than 12 months [see Drug Abuse and Dependence (9.3)].
Certain adverse clinical events, some life-threatening, are a direct consequence of physical dependence to Alprazolam. These include a spectrum of withdrawal symptoms; the most important is seizure [see Drug Abuse and Dependence (9.3)]. Even after relatively short-term use at doses of ≤4 mg/day, there is some risk of dependence. Spontaneous reporting system data suggest that the risk of dependence and its severity appear to be greater in patients treated with doses greater than 4 mg/day and for long periods (more than 12 weeks). However, in a controlled postmarketing discontinuation study of panic disorder patients who received Alprazolam, the duration of treatment (3 months compared to 6 months) had no effect on the ability of patients to taper to zero dose. In contrast, patients treated with doses of Alprazolam greater than 4 mg/day had more difficulty tapering to zero dose than those treated with less than 4 mg/day.
In a controlled clinical trial in which 63 patients were randomized to Alprazolam and where withdrawal symptoms were specifically sought, the following were identified as symptoms of withdrawal: heightened sensory perception, impaired concentration, dysosmia, clouded sensorium, paresthesias, muscle cramps, muscle twitch, diarrhea, blurred vision, appetite decrease, and weight loss. Other symptoms, such as anxiety and insomnia, were frequently seen during discontinuation, but it could not be determined if they were due to return of illness, rebound, or withdrawal.
Interdose Symptoms
Early morning anxiety and emergence of anxiety symptoms between doses of Alprazolam have been reported in patients with panic disorder taking prescribed maintenance doses. These symptoms may reflect the development of tolerance or a time interval between doses which is longer than the duration of clinical action of the administered dose. In either case, it is presumed that the prescribed dose is not sufficient to maintain plasma levels above those needed to prevent relapse, rebound, or withdrawal symptoms over the entire course of the interdosing interval.
Strong CYP3A Inhibitors
Alprazolam is contraindicated in patients receiving strong inhibitors of CYP3A (such as azole antifungal agents), except ritonavir [see Contraindications (4)]. Ketoconazole and itraconazole have been shown in vivo to increase plasma Alprazolam concentrations 3.98 fold and 2.70 fold, respectively.
Dosage adjustment is necessary when Alprazolam and ritonavir are initiated concomitantly or when ritonavir is added to a stable dosage of Alprazolam [see Dosage and Administration (2.6), Drug Interactions (7.1)].
Drugs demonstrated to be CYP3A inhibitors on the basis of clinical studies involving Alprazolam: nefazodone, fluvoxamine, and cimetidine [see Drug Interaction (7.1), Clinical Pharmacology (12.3)]. Use caution and consider dose reduction of Alprazolam, as appropriate, during co-administration with these drugs.
Adverse Reactions Reported as Reasons for Discontinuation in Treatment of Panic Disorder in Placebo-Controlled Trials
In a larger database comprised of both controlled and uncontrolled studies in which 641 patients received alprazolam, discontinuation-emergent symptoms which occurred at a rate of over 5% in patients treated with alprazolam and at a greater rate than the placebo-treated group are shown in Table 3.
Table 3:Discontinuation-Emergent Symptom Incidence Reported in ≥5% of Alprazolam-treated Patients and > Placebo-treated Patients | Alprazolam-treated Patients n=641 |
|---|
| n=number of patients. |
Nervous system disorders | |
Insomnia | 29.5% |
Light-headedness | 19.3% |
Abnormal involuntary movement | 17.3% |
Headache | 17.0% |
Muscular twitching | 6.9% |
| 6.6% |
Muscle tone disorders | 5.9% |
Weakness | 5.8% |
Psychiatric disorders | |
Anxiety | 19.2% |
Fatigue and Tiredness | 18.4% |
Irritability | 10.5% |
Cognitive disorder | 10.3% |
Memory impairment | 5.5% |
Depression | 5.1% |
Confusional state | 5.0% |
Gastrointestinal disorders | |
Nausea/Vomiting | 16.5% |
Diarrhea | 13.6% |
Decreased salivation | 10.6% |
Metabolism and nutrition disorders | |
Weight loss | 13.3% |
Decreased appetite | 12.8% |
Dermatological disorders | |
Sweating | 14.4% |
Cardiovascular disorders | |
Tachycardia | 12.2% |
Special Senses | |
Blurred vision | 10.0% |
There have also been reports of withdrawal seizures upon rapid decrease or abrupt discontinuation of alprazolam [see Warning and Precautions (5.2) and Drug Abuse and Dependence (9.3)].
Paradoxical reactions such as stimulation, increased muscle spasticity, sleep disturbances, hallucinations, and other adverse behavioral effects such as agitation, rage, irritability, and aggressive or hostile behavior have been reported rarely. In many of the spontaneous case reports of adverse behavioral effects, patients were receiving other CNS drugs concomitantly and/or were described as having underlying psychiatric conditions. Should any of the above events occur, alprazolam should be discontinued. Isolated published reports involving small numbers of patients have suggested that patients who have borderline personality disorder, a prior history of violent or aggressive behavior, or alcohol or substance abuse may be at risk for such events. Instances of irritability, hostility, and intrusive thoughts have been reported during discontinuation of alprazolam in patients with posttraumatic stress disorder.
Pregnancy Exposure Registry
There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to Alprazolam during pregnancy. Healthcare providers are encouraged to register patients by calling the National Pregnancy Registry for Other Psychiatric Medications at 1-866-961-2388 or visiting online at https://womensmentalhealth.org/clinical-and-research-programs/pregnancyregistry/othermedications/.
Risk Summary
Neonates born to mothers using benzodiazepines during the later stages of pregnancy have been reported to experience symptoms of sedation and neonatal withdrawal [see Warnings and Precautions (5.4), Error! Hyperlink reference not valid.)]. Overall available data from published observational studies of pregnant women exposed to alprazolam have not established a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes (see Error! Hyperlink reference not valid.).
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated risk of major birth defects and of miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.
Clinical Considerations
Fetal/Neonatal adverse reactions
Benzodiazepines cross the placenta and may produce respiratory depression and sedation in neonates. Monitor neonates exposed to benzodiazepines during pregnancy and labor for signs of sedation, respiratory depression, withdrawal, and feeding problems and manage accordingly [see Warnings and Precautions (5.4)].
Data
Human Data
Published data from observational studies on the use of benzodiazepines during pregnancy do not report a clear association with benzodiazepines and major birth defects. Although early studies reported an increased risk of congenital malformations with diazepam and chlordiazepoxide, there was no consistent pattern noted. In addition, the majority of recent case-control and cohort studies of benzodiazepine use during pregnancy, which were adjusted for confounding exposures to alcohol, tobacco, and other medications, have not confirmed these findings. At this time, there is no clear evidence that alprazolam exposure in early pregnancy can cause major birth defects. Neonates exposed to benzodiazepines during the late third trimester of pregnancy or during labor have been reported to exhibit sedation and neonatal withdrawal symptoms.
Risk Summary
Limited data from published literature reports the presence of alprazolam in human breast milk. There are reports of sedation and withdrawal symptoms in breastfed neonates and infants exposed to alprazolam. The effects of alprazolam on lactation are unknown.
Because of the potential for serious adverse reactions, including sedation and withdrawal symptoms in breastfed neonates and infants, advise patients that breastfeeding is not recommended during treatment with alprazolam.
Acute Withdrawal Signs and Symptoms
Acute withdrawal signs and symptoms associated with benzodiazepines have included abnormal involuntary movements, anxiety, blurred vision, depersonalization, depression, derealization, dizziness, fatigue, gastrointestinal adverse reactions (e.g., nausea, vomiting, diarrhea, weight loss, decreased appetite), headache, hyperacusis, hypertension, irritability, insomnia, memory impairment, muscle pain and stiffness, panic attacks, photophobia, restlessness, tachycardia, and tremor. More severe acute withdrawal signs and symptoms, including life-threatening reactions, have included catatonia, convulsions, delirium tremens, depression, hallucinations, mania, psychosis, seizures, and suicidality.
Protracted Withdrawal Syndrome
Protracted withdrawal syndrome associated with benzodiazepines is characterized by anxiety, cognitive impairment, depression, insomnia, formication, motor symptoms (e.g., weakness, tremor, muscle twitches), paresthesia, and tinnitus that persists beyond 4 to 6 weeks after initial benzodiazepine withdrawal. Protracted withdrawal symptoms may last weeks to more than 12 months. As a result, there may be difficulty in differentiating withdrawal symptoms from potential re-emergence or continuation of symptoms for which the benzodiazepine was being used.
Tolerance
Tolerance to alprazolam may develop from continued therapy. Tolerance is a physiological state characterized by a reduced response to a drug after repeated administration (i.e., a higher dose of a drug is required to produce the same effect that was once obtained at a lower dose). Tolerance to the therapeutic effect of alprazolam may develop; however, little tolerance develops to the amnestic reactions and other cognitive impairments caused by benzodiazepines.
Absorption
Following oral administration, peak plasma concentration of alprazolam (Cmax) occurs in 1 to 2 hours post dose.
Distribution
Alprazolam is 80% bound to human serum protein, and albumin accounts for the majority of the binding.
Elimination
The mean plasma elimination half-life (T1/2) of alprazolam is approximately 11.2 hours (range: 6.3 to 26.9 hours) in healthy adults.
Metabolism
Alprazolam is extensively metabolized in humans, primarily by cytochrome P450 3A4 (CYP3A4), to 2 major active metabolites in the plasma: 4-hydroxyalprazolam and α-hydroxyalprazolam. The plasma circulation levels of the two active metabolites are less than 4% of the parent. The reported relative potencies in benzodiazepine receptor binding experiments and in animal models of induced seizure inhibition are 0.20 and 0.66, respectively, for 4-hydroxyalprazolam and α-hydroxyalprazolam. The low concentrations and low potencies of 4-hydroxyalprazolam and α-hydroxyalprazolam indicate that they unlikely contribute much to the effects of alprazolam. A benzophenone derived from alprazolam is also found in humans. Their half-lives appear to be similar to that of alprazolam.
Excretion
Alprazolam and its metabolites are excreted primarily in the urine.
Specific Populations
Geriatric Patients
The mean T1/2 of alprazolam was 16.3 hours (range: 9.0 to 26.9 hours) in healthy elderly subjects compared to 11.0 hours (range: 6.3 to -15.8 hours, n=16) in healthy younger adult subjects.
Obese Patients
The mean T1/2 of alprazolam was 21.8 hours (range: 9.9 to 40.4 hours) in a group of obese subjects.
Patients with Hepatic Impairment
The mean T1/2 of alprazolam was 19.7 hours (range: 5.8 to 65.3 hours) in patients with alcoholic liver disease.
Racial or Ethnic Groups
Maximal concentrations and T1/2 of alprazolam are approximately 15% and 25% higher in Asians compared to Caucasians.
Smoking
Alprazolam concentrations may be reduced by up to 50% in smokers compared to non-smokers.
Drug Interaction Studies
In Vivo Studies
Most of the interactions that have been documented with alprazolam are with drugs that modulate CYP3A4 activity.
Compounds that are inhibitors or inducers of CYP3A would be expected to increase or decrease plasma alprazolam concentrations, respectively. Drug products that have been studied in vivo, along with their effect on increasing alprazolam AUC, are as follows: ketoconazole, 3.98 fold; itraconazole, 2.66 fold; nefazodone, 1.98 fold; fluvoxamine, 1.96 fold; and erythromycin, 1.61 fold [see Contraindications (4), Warnings and Precautions (5.5), Drug Interactions (7.2)]. Other studied drugs include:
Cimetidine: Coadministration of cimetidine increased the maximum plasma concentration of alprazolam by 82%, decreased clearance by 42%, and increased T1/2 by 16%.
Fluoxetine: Coadministration of fluoxetine with alprazolam increased the maximum plasma concentration of alprazolam by 46%, decreased clearance by 21%, increased T1/2 by 17%, and decreased measured psychomotor performance.
Oral Contraceptives: Coadministration of oral contraceptives increased the maximum plasma concentration of alprazolam by 18%, decreased clearance by 22%, and increased T1/2 by 29%.
Carbamazepine: The oral clearance of alprazolam (given in a 0.8 mg single dose) was increased from 0.90±0.21 mL/min/kg to 2.13±0.54 mL/min/kg and the elimination T1/2 was shortened (from 17.1±4.9 to 7.7±1.7 hour) following administration of 300 mg per day carbamazepine for 10 days [see Drug Interactions (7.2)]. However, the carbamazepine dose used in this study was fairly low compared to the recommended doses (1000–1200 mg per day); the effect at usual carbamazepine doses is unknown.
Ritonavir: Interactions involving HIV protease inhibitors (e.g., ritonavir) and alprazolam are complex and time dependent. Short-term low doses of ritonavir (4 doses of 200 mg) increased mean AUC of alprazolam by about 2.5-fold, and did not significantly affect Cmax of alprazolam. The elimination T1/2 was prolonged (30 hours versus 13 hours). However, upon extended exposure to ritonavir (500 mg, twice daily for 10 days), CYP3A induction offset this inhibition. Alprazolam AUC and Cmax was reduced by 12% and 16%, respectively, in the presence of ritonavir. The elimination T1/2 of alprazolam was not significantly changed [see Warnings and Precautions (5.5)].
Sertraline: A single dose of alprazolam 1 mg and steady state dose of sertraline (50 mg to 150 mg per day) did not reveal any clinically significant changes in the pharmacokinetics of alprazolam.
Imipramine and Desipramine: The steady state plasma concentrations of imipramine and desipramine have been reported to be increased an average of 31% and 20%, respectively, by the concomitant administration of Alprazolam in doses up to 4 mg per day.
Warfarin: Alprazolam did not affect the prothrombin or plasma warfarin levels in male volunteers administered sodium warfarin orally.
In Vitro Studies
Data from in vitro studies of alprazolam suggest a possible drug interaction of alprazolam with paroxetine. The ability of alprazolam to induce human hepatic enzyme systems has not yet been determined.
Carcinogenesis
No evidence of carcinogenic potential was observed in rats or mice administered alprazolam for 2-years at doses up to 30 and 10 mg/kg day respectively. These doses are 29 times and 4.8 times the maximum recommended human dose of 10 mg/day based on mg/m2 body surface area, respectively.
Mutagenesis
Alprazolam was negative in the in vitro Ames bacterial reverse mutation assay and DNA Damage/Alkaline Elution Assay and in vivo rat micronucleus genetic toxicology assays.
Impairment of Fertility
Alprazolam produced no impairment of fertility in rats at doses up to 5 mg/kg per day, which is approximately 5 times the maximum recommended human dose of 10 mg per day based on mg/m2 body surface area.
Risks from Concomitant Use with Opioids
Advise both patients and caregivers about the risks of potentially fatal respiratory depression and sedation when alprazolam is used with opioids and not to use such drugs concomitantly unless supervised by a healthcare provider. Advise patients not to drive or operate heavy machinery until the effects of concomitant use with the opioid have been determined [see Warnings and Precautions (5.1), Drug Interactions (7.1)].
Abuse, Misuse, and Addiction
Inform patients that the use of alprazolam, even at recommended dosages, exposes users to risks of abuse, misuse, and addiction, which can lead to overdose and death, especially when used in combination with other medications (e.g., opioid analgesics), alcohol, and/or illicit substances. Inform patients about the signs and symptoms of benzodiazepine abuse, misuse, and addiction; to seek medical help if they develop these signs and/or symptoms; and on the proper disposal of unused drug [see Warnings and Precautions (5.2), Drug Abuse and Dependence (9.2)].
Withdrawal Reactions
Inform patients that the continued use of alprazolam may lead to clinically significant physical dependence and that abrupt discontinuation or rapid dosage reduction of alprazolam may precipitate acute withdrawal reactions, which can be life-threatening. Inform patients that in some cases, patients taking benzodiazepines have developed a protracted withdrawal syndrome with withdrawal symptoms lasting weeks to more than 12 months. Instruct patients that discontinuation or dosage reduction of alprazolam may require a slow taper [see Warnings and Precautions (5.3), Drug Abuse and Dependence (9.3)].
Effects on Driving and Operating Machinery
Advise patients not to drive a motor vehicle or operate heavy machinery while taking alprazolam due to its CNS depressant effects. Also advise patients to avoid use of alcohol or other CNS depressants while taking alprazolam [see Warnings and Precautions (5.3)].
Patients with Depression
Advise patients, their families, and caregivers to look for signs of suicidality or worsening depression, and to inform the patient's healthcare provider immediately [see Warnings and Precautions (5.6)].
Concomitant Medications
Advise patients to inform their healthcare provider of all medicines they take, including prescription and nonprescription medications, vitamins and herbal supplements [see Drug Interactions (7)].
Pregnancy
Benzodiazepines cross the placenta and may produce respiratory depression and sedation in neonates. Advise mothers using alprazolam to monitor neonates for signs of sedation, respiratory depression, withdrawal symptoms, and feeding problems. Instruct patients to inform their healthcare provider if they are pregnant or intend to become pregnant during treatment with alprazolam [see Warnings and Precautions (5.4). Advise patients that there is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to alprazolam during pregnancy [see Use in Specific Populations (8.1)].
Lactation
Advise women not to breastfeed during treatment with alprazolam [see Use in Specific Populations (8.2)].
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Revised February 2021