The following adverse reactions have been identified during postmarketing use of alprazolam. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Reported events include: liver enzyme elevations, hepatitis, hepatic failure, Stevens-Johnson syndrome, hyperprolactinemia, gynecomastia, and galactorrhea.
The concomitant use of benzodiazepines and opioids increases the risk of respiratory depression because of actions at different receptor sites in the CNS that control respiration. Benzodiazepines interact at GABAA sites and opioids interact primarily at mu receptors. When benzodiazepines and opioids are combined, the potential for benzodiazepines to significantly worsen opioid-related respiratory depression exists. Limit dosage and duration of concomitant use of benzodiazepines and opioids, and monitor patients closely for respiratory depression and sedation.
If alprazolam orally disintegrating tablets are coadministered with other psychotropic agents or anticonvulsant drugs, carefully consider 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, alcohol and other drugs which themselves produce CNS depression.
Because alprazolam orally disintegrating tablets disintegrate in the presence of saliva, and the formulation requires an acidic environment to dissolve, concomitant drugs or diseases that cause dry mouth or raise stomach pH might slow disintegration or dissolution, resulting in slowed or decreased absorption.
The steady state plasma concentrations of imipramine and desipramine can increase by approximately 30% and 20%, respectively, when administered concomitantly with alprazolam in doses up to 4 mg per day. The clinical significance of these changes is unknown.
The initial step in alprazolam metabolism is hydroxylation catalyzed by cytochrome P450 3A (CYP3A). Drugs which inhibit this metabolic pathway can have a profound effect on the clearance of alprazolam [see Contraindications ( 4) and Warnings and Precautions (5.8)].
7.5 Drugs Demonstrated to be CYP3A Inhibitors of Possible Clinical Significance on the Basis of Clinical Studies Involving Alprazolam
Use caution during coadministration of Alprazolam and the following drugs:
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%.
7.6 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
Use caution during the coadministration of Alprazolam and the following:
Available data from clinical studies of benzodiazepines other than alprazolam suggest a possible drug interaction between alprazolam and 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 between alprazolam and 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 mg to 150 mg per 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 between benzodiazepines and the following: ergotamine, cyclosporine, amiodarone, nicardipine, and nifedipine [see Warnings and Precautions (5.8)].
Carbamazepine can increase alprazolam metabolism and therefore can decrease plasma levels of alprazolam.
Pregnancy Category D.
Benzodiazepines can potentially cause fetal harm when administered to a pregnant woman. The possibility that a woman of childbearing potential may be pregnant at the time of institution of therapy should be considered. 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 [see Warnings and Precautions (5.5)].
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.
The potential effect of alprazolam in labor and delivery in humans has not been studied. However, perinatal complications have been reported in neonates exposed to benzodiazepines late in pregnancy. The findings are suggestive of excess benzodiazepine exposure or withdrawal phenomena.
Benzodiazepines are excreted in human milk. It should be assumed that alprazolam is excreted in human milk. Chronic administration of diazepam to nursing mothers has been reported to cause their infants to become lethargic and to lose weight. Because of the potential for serious adverse reactions in nursing infants from alprazolam, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. As a general rule, nursing should not be undertaken by mothers who must use alprazolam.
Safety and effectiveness of alprazolam in individuals below 18 years of age have not been studied.
The elderly may be more sensitive to the effects of benzodiazepines. They exhibit higher plasma alprazolam concentrations due to reduced clearance of the drug, 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 ( 12) and Dosage and Administration ( 2)].
Changes in the absorption, distribution, metabolism and excretion of benzodiazepines have 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.
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