Alprazolam Extended-Release Tablets contain alprazolam which is a triazolo analog of the 1,4 benzodiazepine class of central nervous system-active compounds.
The chemical name of alprazolam is 8-chloro-1-methyl-6-phenyl-4H-s-triazolo [4,3-α] [1,4] benzodiazepine. The molecular formula is C17H13ClN4 which corresponds to a molecular weight of 308.76.
The structural formula is:
Alprazolam is a white crystalline powder, which is soluble in methanol or ethanol but which has no appreciable solubility in water at physiological pH.
Each alprazolam extended-release tablet, for oral administration, contains 0.5 mg, 1 mg, 2 mg, or 3 mg of alprazolam. The inactive ingredients are colloidal silicon dioxide, hypromellose, lactose monohydrate, magnesium stearate and povidone. In addition, the 1 mg and 3 mg tablets contain D&C Yellow No. 10 Aluminum Lake and the 2 mg and 3 mg tablets contain FD&C Blue No. 1 Aluminum Lake.
Alprazolam Extended Release - Clinical Pharmacology
Pharmacodynamics
CNS agents of the 1,4 benzodiazepine class presumably exert their effects by binding at stereospecific receptors at several sites within the central nervous system. Their exact mechanism of action is unknown. Clinically, all benzodiazepines cause a dose-related central nervous system depressant activity varying from mild impairment of task performance to hypnosis.
Pharmacokinetics
AbsorptionFollowing oral administration of alprazolam (immediate-release) tablets, alprazolam is readily absorbed. Peak concentrations in the plasma occur in one to two hours following administration. Plasma levels are proportional to the dose given; over the dose range of 0.5 to 3.0 mg, peak levels of 8.0 to 37 ng/mL were observed. Using a specific assay methodology, the mean plasma elimination half-life of alprazolam has been found to be about 11.2 hours (range: 6.3 to 26.9 hours) in healthy adults.
The mean absolute bioavailability of alprazolam from alprazolam extended-release tablets is approximately 90%, and the relative bioavailability compared to alprazolam tablets is 100%. The bioavailability and pharmacokinetics of alprazolam following administration of alprazolam extended-release tablets are similar to that for alprazolam tablets, with the exception of a slower rate of absorption. The slower absorption rate results in a relatively constant concentration that is maintained between 5 and 11 hours after the dosing. The pharmacokinetics of alprazolam and two of its major active metabolites (4-hydroxyalprazolam and α-hydroxyalprazolam) are linear, and concentrations are proportional up to the recommended maximum daily dose of 10 mg given once daily. Multiple dose studies indicate that the metabolism and elimination of alprazolam are similar for the immediate-release and the extended-release products.
Food has a significant influence on the bioavailability of alprazolam extended-release tablets. A high-fat meal given up to 2 hours before dosing with alprazolam extended-release tablets increased the mean Cmax by about 25%. The effect of this meal on Tmax depended on the timing of the meal, with a reduction in Tmax by about ⅓ for subjects eating immediately before dosing and an increase in Tmax by about ⅓ for subjects eating 1 hour or more after dosing. The extent of exposure (AUC) and elimination half-life (t½) were not affected by eating.
There were significant differences in absorption rate for the alprazolam extended-release tablet, depending on the time of day administered, with the Cmax increased by 30% and the Tmax decreased by an hour following dosing at night, compared to morning dosing.
DistributionThe apparent volume of distribution of alprazolam is similar for alprazolam extended-release and alprazolam tablets. In vitro, alprazolam is bound (80%) to human serum protein. Serum albumin accounts for the majority of the binding.
MetabolismAlprazolam is extensively metabolized in humans, primarily by cytochrome P450 3A4 (CYP3A4), to two major metabolites in the plasma: 4-hydroxyalprazolam and α-hydroxyalprazolam. A benzophenone derived from alprazolam is also found in humans. Their half-lives appear to be similar to that of alprazolam. The pharmacokinetic parameters at steady-state for the two hydroxylated metabolites of alprazolam (4-hydroxyalprazolam and α-hydroxyalprazolam) were similar for alprazolam and alprazolam extended-release tablets, indicating that the metabolism of alprazolam is not affected by absorption rate. The plasma concentrations of 4-hydroxyalprazolam and α-hydroxyalprazolam relative to unchanged alprazolam concentration after both alprazolam extended-release and alprazolam tablets were always less than 10% and 4%, respectively. 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. Such low concentrations and the lesser potencies of 4-hydroxyalprazolam and α-hydroxyalprazolam suggest that they are unlikely to contribute much to the pharmacological effects of alprazolam. The benzophenone metabolite is essentially inactive.
EliminationAlprazolam and its metabolites are excreted primarily in the urine. The mean plasma elimination half-life of alprazolam following administration of alprazolam extended-release tablet ranges from 10.7 to 15.8 hours in healthy adults.
Special PopulationsWhile pharmacokinetic studies have not been performed in special populations with alprazolam extended-release tablets, the factors (such as age, gender, hepatic or renal impairment) that would affect the pharmacokinetics of alprazolam after the administration of alprazolam tablets would not be expected to be different with the administration of alprazolam extended-release tablets.
Changes in the absorption, distribution, metabolism, and excretion of benzodiazepines have been reported in a variety of disease states including alcoholism, impaired hepatic function, and impaired renal function. Changes have also been demonstrated in geriatric patients. A mean half-life of alprazolam of 16.3 hours has been observed in healthy elderly subjects (range: 9.0 to 26.9 hours, n=16) compared to 11.0 hours (range: 6.3 to 15.8 hours, n=16) in healthy adult subjects. In patients with alcoholic liver disease the half-life of alprazolam ranged between 5.8 and 65.3 hours (mean: 19.7 hours, n=17) as compared to between 6.3 and 26.9 hours (mean=11.4 hours, n=17) in healthy subjects. In an obese group of subjects the half-life of alprazolam ranged between 9.9 and 40.4 hours (mean=21.8 hours, n=12) as compared to between 6.3 and 15.8 hours (mean=10.6 hours, n=12) in healthy subjects.
Because of its similarity to other benzodiazepines, it is assumed that alprazolam undergoes transplacental passage and that it is excreted in human milk.
Race — Maximal concentrations and half-life of alprazolam are approximately 15% and 25% higher in Asians compared to Caucasians.
Pediatrics — The pharmacokinetics of alprazolam after administration of the alprazolam extended-release tablet in pediatric patients have not been studied.
Gender — Gender has no effect on the pharmacokinetics of alprazolam.
Cigarette Smoking — Alprazolam concentrations may be reduced by up to 50% in smokers compared to non-smokers.
Drug-Drug InteractionsAlprazolam is primarily eliminated by metabolism via cytochrome P450 3A (CYP3A). Most of the interactions that have been documented with alprazolam are with drugs that inhibit or induce CYP3A4.
Compounds that are potent inhibitors of CYP3A would be expected to increase plasma alprazolam concentrations. Drug products that have been studied in vivo, along with their effect on increasing alprazolam AUC, are as follows: ketoconazole, 3.98 fold; itraconazole, 2.70 fold; nefazodone, 1.98 fold; fluvoxamine, 1.96 fold; and erythromycin, 1.61 fold (see CONTRAINDICATIONS, WARNINGS, and PRECAUTIONS–Drug Interactions).
CYP3A inducers would be expected to decrease alprazolam concentrations and this has been observed in vivo. 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 t½ was shortened (from 17.1±4.9 to 7.7±1.7 h) following administration of 300 mg/day carbamazepine for 10 days (see PRECAUTIONS–Drug Interactions). However, the carbamazepine dose used in this study was fairly low compared to the recommended doses (1000 to 1200 mg/day); the effect at usual carbamazepine doses is unknown.
The ability of alprazolam to induce or inhibit human hepatic enzyme systems has not been determined. However, this is not a property of benzodiazepines in general. Further, alprazolam did not affect the prothrombin or plasma warfarin levels in male volunteers administered sodium warfarin orally.
CLINICAL EFFICACY TRIALS
The efficacy of alprazolam extended-release tablets in the treatment of panic disorder was established in two 6-week, placebo-controlled studies of alprazolam extended-release tablets in patients with panic disorder.
In two 6-week, flexible-dose, placebo-controlled studies in patients meeting DSM-III criteria for panic disorder, patients were treated with alprazolam extended-release tablets in a dose range of 1 to 10 mg/day, on a once-a-day basis. The effectiveness of alprazolam extended-release tablets was assessed on the basis of changes in various measures of panic attack frequency, on various measures of the Clinical Global Impression, and on the Overall Phobia Scale. In all, there were seven primary efficacy measures in these studies, and alprazolam extended-release tablets were superior to placebo on all seven outcomes in both studies. The mean dose of alprazolam extended-release tablets at the last treatment visit was 4.2 mg/day in the first study and 4.6 mg/day in the second.
In addition, there were two 8-week, fixed-dose, placebo-controlled studies of alprazolam extended-release tablets in patients with panic disorder, involving fixed alprazolam extended-release tablet doses of 4 and 6 mg/day, on a once-a-day basis, that did not show a benefit for either dose of alprazolam extended-release tablets.
The longer-term efficacy of alprazolam extended-release tablets in panic disorder has not been systematically evaluated.
Analyses of the relationship between treatment outcome and gender did not suggest any differential responsiveness on the basis of gender.
Indications and Usage for Alprazolam Extended Release
Alprazolam extended-release tablets are indicated for the treatment of panic disorder, with or without agoraphobia.
This claim is supported on the basis of two positive studies with alprazolam extended-release tablets conducted in patients whose diagnoses corresponded closely to the DSM-III-R/IV criteria for panic disorder (see CLINICAL EFFICACY TRIALS).
Panic disorder (DSM-IV) is characterized by recurrent unexpected panic attacks, i.e., a discrete period of intense fear or discomfort in which four (or more) of the following symptoms develop abruptly and reach a peak within 10 minutes:
(1) palpitations, pounding heart, or accelerated heart rate;
(2) sweating;
(3) trembling or shaking;
(4) sensations of shortness of breath or smothering;
(5) feeling of choking;
(6) chest pain or discomfort;
(7) nausea or abdominal distress;
(8) feeling dizzy, unsteady, lightheaded, or faint;
(9) derealization (feelings of unreality) or depersonalization (being detached from oneself);
(10) fear of losing control;
(11) fear of dying;
(12) paresthesias (numbness or tingling sensations);
(13) chills or hot flushes.
The longer-term efficacy of alprazolam extended-release tablets has not been systematically evaluated. Thus, the physician who elects to use this drug for periods longer than 8 weeks should periodically reassess the usefulness of the drug for the individual patient.
Contraindications
Alprazolam extended-release tablets are contraindicated in patients with known sensitivity to this drug or other benzodiazepines. Alprazolam extended-release tablets may be used in patients with open angle glaucoma who are receiving appropriate therapy, but is contraindicated in patients with acute narrow angle glaucoma.
Alprazolam extended-release tablets are contraindicated with ketoconazole and itraconazole, since these medications significantly impair the oxidative metabolism mediated by cytochrome P450 3A (CYP3A) (see CLINICAL PHARMACOLOGY, WARNINGS and PRECAUTIONS–Drug Interactions).
Warnings
Dependence and Withdrawal Reactions, Including Seizures
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). 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 tablets, 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 tablets greater than 4 mg/day had more difficulty tapering to zero dose than those treated with less than 4 mg/day.
Relapse or return of illness was defined as a return of symptoms characteristic of panic disorder (primarily panic attacks) to levels approximately equal to those seen at baseline before active treatment was initiated. Rebound refers to a return of symptoms of panic disorder to a level substantially greater in frequency, or more severe in intensity than seen at baseline. Withdrawal symptoms were identified as those which were generally not characteristic of panic disorder and which occurred for the first time more frequently during discontinuation than at baseline.
The rate of relapse, rebound, and withdrawal in patients with panic disorder who received alprazolam extended-release tablets has not been systematically studied. Experience in randomized placebo-controlled discontinuation studies of patients with panic disorder who received alprazolam tablets showed a high rate of rebound and withdrawal symptoms compared to placebo treated patients.
In a controlled clinical trial in which 63 patients were randomized to alprazolam tablets 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.
In two controlled trials of 6 to 8 weeks duration where the ability of patients to discontinue medication was measured, 71% to 93% of patients treated with alprazolam tablets tapered completely off therapy compared to 89% to 96% of placebo treated patients. In a controlled postmarketing discontinuation study of panic disorder patients treated with alprazolam tablets, the duration of treatment (3 months compared to 6 months) had no effect on the ability of patients to taper to zero dose.
Seizures were reported for three patients in panic disorder clinical trials with alprazolam extended-release tablets. In two cases, the patients had completed 6 weeks of treatment with alprazolam extended-release tablets 6 mg/day before experiencing a single seizure. In one case, the patient abruptly discontinued alprazolam extended-release tablets, and in both cases, alcohol intake was implicated. The third case involved multiple seizures after the patient completed treatment with alprazolam extended-release tablets 4 mg/day and missed taking the medication on the first day of taper. All three patients recovered without sequelae.
Seizures have also been observed in association with dose reduction or discontinuation of alprazolam tablets, the immediate release form of alprazolam. Seizures attributable to alprazolam tablets were seen after drug discontinuance or dose reduction in 8 of 1980 patients with panic disorder or in patients participating in clinical trials where doses of alprazolam tablets greater than 4 mg/day for over 3 months were permitted. Five of these cases clearly occurred during abrupt dose reduction, or discontinuation from daily doses of 2 to 10 mg. Three cases occurred in situations where there was not a clear relationship to abrupt dose reduction or discontinuation. In one instance, seizure occurred after discontinuation from a single dose of 1 mg after tapering at a rate of 1 mg every three days from 6 mg daily. In two other instances, the relationship to taper is indeterminate; in both of these cases the patients had been receiving doses of 3 mg daily prior to seizure. The duration of use in the above 8 cases ranged from 4 to 22 weeks. There have been occasional voluntary reports of patients developing seizures while apparently tapering gradually from alprazolam tablets. The risk of seizure seems to be greatest 24 to 72 hours after discontinuation (see DOSAGE AND ADMINISTRATION for recommended tapering and discontinuation schedule).
Status Epilepticus
The medical event voluntary reporting system shows that withdrawal seizures have been reported in association with the discontinuation of alprazolam tablets. In most cases, only a single seizure was reported; however, multiple seizures and status epilepticus were reported as well.
Interdose Symptoms
Early morning anxiety and emergence of anxiety symptoms between doses of alprazolam tablets 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.
Risk of Dose Reduction
Withdrawal reactions may occur when dosage reduction occurs for any reason. This includes purposeful tapering, but also inadvertent reduction of dose (e.g., the patient forgets, the patient is admitted to a hospital). Therefore, the dosage of alprazolam extended-release tablets should be reduced or discontinued gradually (see DOSAGE AND ADMINISTRATION).
CNS Depression and Impaired Performance
Because of its CNS depressant effects, patients receiving alprazolam extended-release tablets should be cautioned against engaging in hazardous occupations or activities requiring complete mental alertness such as operating machinery or driving a motor vehicle. For the same reason, patients should be cautioned about the simultaneous ingestion of alcohol and other CNS depressant drugs during treatment with alprazolam extended-release tablets.
Risk of Fetal Harm
Benzodiazepines can potentially cause fetal harm when administered to pregnant women. If alprazolam is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus. Because of experience with other members of the benzodiazepine class, alprazolam is assumed to be capable of causing an increased risk of congenital abnormalities when administered to a pregnant woman during the first trimester. Because use of these drugs is rarely a matter of urgency, their use during the first trimester should almost always be avoided. The possibility that a woman of childbearing potential may be pregnant at the time of institution of therapy should be considered. Patients should be advised that if they become pregnant during therapy or intend to become pregnant they should communicate with their physicians about the desirability of discontinuing the drug.
Alprazolam Interaction With Drugs That Inhibit Metabolism Via Cytochrome P450 3A
The initial step in alprazolam metabolism is hydroxylation catalyzed by cytochrome P450 3A (CYP3A). Drugs that inhibit this metabolic pathway may have a profound effect on the clearance of alprazolam. Consequently, alprazolam should be avoided in patients receiving very potent inhibitors of CYP3A. With drugs inhibiting CYP3A to a lesser but still significant degree, alprazolam should be used only with caution and consideration of appropriate dosage reduction. For some drugs, an interaction with alprazolam has been quantified with clinical data; for other drugs, interactions are predicted from in vitro data and/or experience with similar drugs in the same pharmacologic class.
The following are examples of drugs known to inhibit the metabolism of alprazolam and/or related benzodiazepines, presumably through inhibition of CYP3A.
Potent CYP3A InhibitorsAzole antifungal agents — Ketoconazole and itraconazole are potent CYP3A inhibitors and have been shown in vivo to increase plasma alprazolam concentrations 3.98 fold and 2.70 fold, respectively. The coadministration of alprazolam with these agents is not recommended. Other azole-type antifungal agents should also be considered potent CYP3A inhibitors and the coadministration of alprazolam with them is not recommended (see CONTRAINDICATIONS).
Drugs demonstrated to be CYP3A inhibitors on the basis of clinical studies involving alprazolam (caution and consideration of appropriate alprazolam dose reduction are recommended during coadministration with the following drugs)Nefazodone — Coadministration of nefazodone increased alprazolam concentration two-fold.
Fluvoxamine — Coadministration of fluvoxamine approximately doubled the maximum plasma concentration of alprazolam, decreased clearance by 49%, increased half-life by 71%, and decreased measured psychomotor performance.
Cimetidine — Coadministration of cimetidine increased the maximum plasma concentration of alprazolam by 86%, decreased clearance by 42%, and increased half-life by 16%.
Other Drugs Possibly Affecting Alprazolam MetabolismOther drugs possibly affecting alprazolam metabolism by inhibition of CYP3A are discussed in the PRECAUTIONS section (see PRECAUTIONS–Drug Interactions).
Precautions
General
SuicideAs with other psychotropic medications, the usual precautions with respect to administration of the drug and size of the prescription are indicated for severely depressed patients or those in whom there is reason to expect concealed suicidal ideation or plans. Panic disorder has been associated with primary and secondary major depressive disorders and increased reports of suicide among untreated patients.
ManiaEpisodes of hypomania and mania have been reported in association with the use of alprazolam tablets in patients with depression.
Uricosuric EffectAlprazolam has a weak uricosuric effect. Although other medications with weak uricosuric effect have been reported to cause acute renal failure, there have been no reported instances of acute renal failure attributable to therapy with alprazolam.
Use in Patients with Concomitant IllnessIt is recommended that the dosage be limited to the smallest effective dose to preclude the development of ataxia or oversedation which may be a particular problem in elderly or debilitated patients (see DOSAGE AND ADMINISTRATION). The usual precautions in treating patients with impaired renal, hepatic, or pulmonary function should be observed. There have been rare reports of death in patients with severe pulmonary disease shortly after the initiation of treatment with alprazolam tablets. A decreased systemic alprazolam elimination rate (e.g., increased plasma half-life) has been observed in both alcoholic liver disease patients and obese patients receiving alprazolam tablets (see CLINICAL PHARMACOLOGY).
Information for Patients
To assure safe and effective use of alprazolam extended-release tablets, the physician should provide the patient with the following guidance.
- Inform your physician about any alcohol consumption and medicine you are taking now, including medication you may buy without a prescription. Alcohol should generally not be used during treatment with benzodiazepines.
- Not recommended for use in pregnancy. Therefore, inform your physician if you are pregnant, if you are planning to have a child, or if you become pregnant while you are taking this medication.
- Inform your physician if you are nursing.
- Until you experience how this medication affects you, do not drive a car or operate potentially dangerous machinery, etc.
- Do not increase the dose even if you think the medication "does not work anymore" without consulting your physician. Benzodiazepines, even when used as recommended, may produce emotional and/or physical dependence.
- Do not stop taking this medication abruptly or decrease the dose without consulting your physician, since withdrawal symptoms can occur.
- Some patients may find it very difficult to discontinue treatment with alprazolam extended-release tablets due to severe emotional and physical dependence. Discontinuation symptoms, including possible seizures, may occur following discontinuation from any dose, but the risk may be increased with extended use at doses greater than 4 mg/day, especially if discontinuation is too abrupt. It is important that you seek advice from your physician to discontinue treatment in a careful and safe manner. Proper discontinuation will help to decrease the possibility of withdrawal reactions that can range from mild reactions to severe reactions such as seizure.
Laboratory Tests
Laboratory tests are not ordinarily required in otherwise healthy patients. However, when treatment is protracted, periodic blood counts, urinalysis, and blood chemistry analyses are advisable in keeping with good medical practice.
Drug Interactions
Use with Other CNS DepressantsIf alprazolam extended-release tablets are to be combined with other psychotropic agents or anticonvulsant drugs, careful consideration should be given to the pharmacology of the agents to be employed, particularly with compounds which might potentiate the action of benzodiazepines. The benzodiazepines, including alprazolam, produce additive CNS depressant effects when coadministered with other psychotropic medications, anticonvulsants, antihistaminics, ethanol and other drugs which themselves produce CNS depression.
Use with Imipramine and DesipramineThe 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 tablets in doses up to 4 mg/day. The clinical significance of these changes is unknown.
Drugs that inhibit alprazolam metabolism via cytochrome P450 3AThe initial step in alprazolam metabolism is hydroxylation catalyzed by cytochrome P450 3A (CYP3A). Drugs which inhibit this metabolic pathway may have a profound effect on the clearance of alprazolam (see CONTRAINDICATIONS and WARNINGS for additional drugs of this type).
Drugs demonstrated to be CYP3A inhibitors of possible clinical significance on the basis of clinical studies involving alprazolam (caution is recommended during coadministration with alprazolam)Fluoxetine — Coadministration of fluoxetine with alprazolam increased the maximum plasma concentration of alprazolam by 46%, decreased clearance by 21%, increased half-life by 17%, and decreased measured psychomotor performance.
Propoxyphene — Coadministration of propoxyphene decreased the maximum plasma concentration of alprazolam by 6%, decreased clearance by 38%, and increased half-life by 58%.
Oral Contraceptives — Coadministration of oral contraceptives increased the maximum plasma concentration of alprazolam by 18%, decreased clearance by 22%, and increased half-life by 29%.
Drugs and other substances demonstrated to be CYP3A inhibitors on the basis of clinical studies involving benzodiazepines metabolized similarly to alprazolam or on the basis of in vitro studies with alprazolam or other benzodiazepines (caution is recommended during coadministration with alprazolam)Available data from clinical studies of benzodiazepines other than alprazolam suggest a possible drug interaction with alprazolam for the following: diltiazem, isoniazid, macrolide antibiotics such as erythromycin and clarithromycin, and grapefruit juice. Data from in vitro studies of alprazolam suggest a possible drug interaction with alprazolam for the following: sertraline and paroxetine. However, data from an in vivo drug interaction study involving a single dose of alprazolam 1 mg and steady state doses of sertraline (50 to 150 mg/day) did not reveal any clinically significant changes in the pharmacokinetics of alprazolam. Data from in vitro studies of benzodiazepines other than alprazolam suggest a possible drug interaction for the following: ergotamine, cyclosporine, amiodarone, nicardipine, and nifedipine. Caution is recommended during the coadministration of any of these with alprazolam (see WARNINGS).
Drugs demonstrated to be inducers of CYP3ACarbamazepine can increase alprazolam metabolism and therefore can decrease plasma levels of alprazolam.
Drug/Laboratory Test Interactions
Although interactions between benzodiazepines and commonly employed clinical laboratory tests have occasionally been reported, there is no consistent pattern for a specific drug or specific test.
Carcinogenesis, Mutagenesis, Impairment of Fertility
No evidence of carcinogenic potential was observed during 2-year bioassay studies of alprazolam in rats at doses up to 30 mg/kg/day (150 times the maximum recommended daily human dose of 10 mg/day) and in mice at doses up to 10 mg/kg/day (50 times the maximum recommended daily human dose).
Alprazolam was not mutagenic in the rat micronucleus test at doses up to 100 mg/kg, which is 500 times the maximum recommended daily human dose of 10 mg/day. Alprazolam also was not mutagenic in vitro in the DNA Damage/Alkaline Elution Assay or the Ames Assay.
Alprazolam produced no impairment of fertility in rats at doses up to 5 mg/kg/day, which is 25 times the maximum recommended daily human dose of 10 mg/day.
Pregnancy
Teratogenic Effects: Pregnancy Category D:(see WARNINGS section).
Nonteratogenic Effects:It should be considered that the child born of a mother who is receiving benzodiazepines may be at some risk for withdrawal symptoms from the drug during the postnatal period. Also, neonatal flaccidity and respiratory problems have been reported in children born of mothers who have been receiving benzodiazepines.
Labor and Delivery
Alprazolam has no established use in labor or delivery.
Nursing Mothers
Benzodiazepines are known to be excreted in human milk. It should be assumed that alprazolam is as well. Chronic administration of diazepam to nursing mothers has been reported to cause their infants to become lethargic and to lose weight. As a general rule, nursing should not be undertaken by mothers who must use alprazolam.
Pediatric Use
Safety and effectiveness of alprazolam in individuals below 18 years of age have not been established.
Geriatric Use
The elderly may be more sensitive to the effects of benzodiazepines. They exhibit higher plasma alprazolam concentrations due to reduced clearance of the drug as compared with a younger population receiving the same doses. The smallest effective dose of alprazolam should be used in the elderly to preclude the development of ataxia and oversedation (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION).
Adverse Reactions
The information included in the subsection on Adverse Events Observed in Short-Term, Placebo-Controlled Trials with alprazolam extended-release tablets is based on pooled data of five 6- and 8-week placebo-controlled clinical studies in panic disorder.
Adverse event reports were elicited either by general inquiry or by checklist, and were recorded by clinical investigators using terminology of their own choosing. The stated frequencies of adverse events represent the proportion of individuals who experienced, at least once, a treatment-emergent adverse event of the type listed. An event was considered treatment emergent if it occurred for the first time or worsened during therapy following baseline evaluation. In the tables and tabulations that follow, standard MedDRA terminology (version 4.0) was used to classify reported adverse events.
Adverse Events Observed in Short-Term, Placebo-Controlled Trials of Alprazolam Extended-Release Tablets
Adverse Events Reported as Reasons for Discontinuation of Treatment in Placebo-Controlled Trials
Approximately 17% of the 531 patients who received alprazolam extended-release tablets in placebo-controlled clinical trials for panic disorder had at least one adverse event that led to discontinuation compared to 8% of 349 placebo-treated patients. The most common events leading to discontinuation and considered to be drug-related (i.e., leading to discontinuation in at least 1% of the patients treated with alprazolam extended-release tablets at a rate at least twice that of placebo) are shown in the following table.
Common Adverse Events Leading to Discontinuation of Treatment in Placebo-Controlled Trials
| System Organ Class/Adverse Event |
Percentage of Patients Discontinuing Due to Adverse Events |
|---|
|
Alprazolam Extended-Release Tablets
(n=531) |
Placebo
(n=349) |
|---|
| Nervous system disorders |
|
|
| Sedation |
7.5 |
0.6 |
| Somnolence |
3.2 |
0.3 |
| Dysarthria |
2.1 |
0 |
| Coordination abnormal |
1.9 |
0.3 |
| Memory impairment |
1.5 |
0.3 |
| General disorders/administration site conditions |
|
|
| Fatigue |
1.7 |
0.6 |
| Psychiatric disorders |
|
|
| Depression |
2.5 |
1.2 |
Adverse Events Occurring at an Incidence of 1% or More Among Patients Treated with Alprazolam Extended-Release Tablets
The prescriber should be aware that adverse event incidence cannot be used to predict the incidence of adverse events in the course of usual medical practice where patient characteristics and other factors differ from those which prevailed in the clinical trials. Similarly, the cited frequencies cannot be compared with event incidence obtained from other clinical investigations involving different treatments, uses, and investigators. The cited values, however, do provide the prescribing physician with some basis for estimating the relative contribution of drug and non-drug factors to the adverse event incidence rate in the population studied.
The following table shows the incidence of treatment-emergent adverse events that occurred during 6- to 8-week placebo-controlled trials in 1% or more of patients treated with alprazolam extended-release tablets where the incidence in patients treated with alprazolam extended-release tablets was greater than the incidence in placebo-treated patients. The most commonly observed adverse events in panic disorder patients treated with alprazolam extended-release tablets (incidence of 5% or greater and at least twice the incidence in placebo patients) were: sedation, somnolence, memory impairment, dysarthria, coordination abnormal, ataxia, libido decreased (see table).
| Treatment-Emergent Adverse Events: Incidence in Short-Term, Placebo-Controlled Clinical Trials with Alprazolam Extended-Release Tablets |
|---|
| System Organ Class/Adverse Event |
Percentage of Patients Reporting Adverse Event |
|---|
|
Alprazolam Extended-Release Tablets
(n=531) |
Placebo
(n=349) |
|---|
| Nervous system disorders |
|
|
| Sedation |
45.2 |
22.6 |
| Somnolence |
23.0 |
6.0 |
| Memory impairment |
15.4 |
6.9 |
| Dysarthria |
10.9 |
2.6 |
| Coordination abnormal |
9.4 |
0.9 |
| Mental impairment |
7.2 |
5.7 |
| Ataxia |
7.2 |
3.2 |
| Disturbance in attention |
3.2 |
0.6 |
| Balance impaired |
3.2 |
0.6 |
| Paresthesia |
2.4 |
1.7 |
| Dyskinesia |
1.7 |
1.4 |
| Hypoesthesia |
1.3 |
0.3 |
| Hypersomnia |
1.3 |
0 |
| General disorders/administration site conditions |
|
|
| Fatigue |
13.9 |
9.2 |
| Lethargy |
1.7 |
0.6 |
| Infections and infestations |
|
|
| Influenza |
2.4 |
2.3 |
| Upper respiratory tract infections |
1.9 |
1.7 |
| Psychiatric disorders |
|
|
| Depression |
12.1 |
9.2 |
| Libido decreased |
6.0 |
2.3 |
| Disorientation |
1.5 |
0 |
| Confusion |
1.5 |
0.9 |
| Depressed mood |
1.3 |
0.3 |
| Anxiety |
1.1 |
0.6 |
| Metabolism and nutrition disorders |
|
|
| Appetite decreased |
7.3 |
7.2 |
| Appetite increased |
7.0 |
6.0 |
| Anorexia |
1.5 |
0 |
| Gastrointestinal disorders |
|
|
| Dry mouth |
10.2 |
9.7 |
| Constipation |
8.1 |
4.3 |
| Nausea |
6.0 |
3.2 |
| Pharyngolaryngeal pain |
3.2 |
2.6 |
| Investigations |
|
|
| Weight increased |
5.1 |
4.3 |
| Weight decreased |
4.3 |
3.7 |
| Injury, poisoning, and procedural complications |
|
|
| Road traffic accident |
1.5 |
0 |
| Reproductive system and breast disorders |
|
|
| Dysmenorrhea |
3.6 |
2.9 |
| Sexual dysfunction |
2.4 |
1.1 |
| Premenstrual syndrome |
1.7 |
0.6 |
| Musculoskeletal and connective tissue disorders |
|
|
| Arthralgia |
2.4 |
0.6 |
| Myalgia |
1.5 |
1.1 |
| Pain in limb |
1.1 |
0.3 |
| Vascular disorders |
|
|
| Hot flushes |
1.5 |
1.4 |
| Respiratory, thoracic, and mediastinal disorders |
|
|
| Dyspnea |
1.5 |
0.3 |
| Rhinitis allergic |
1.1 |
0.6 |
| Skin and subcutaneous tissue disorders |
|
|
