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 the doses recommended for the treatment
of transient anxiety and anxiety disorder (ie, 0.75 to 4 mg per 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,
the duration of treatment (three months compared to six 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.
The Importance Of Dose And The Risks Of Alprazolam As A
Treatment For Panic Disorder: Because the management of panic disorder
often requires the use of average daily doses of alprazolam above 4 mg, the risk
of dependence among panic disorder patients may be higher than that among those
treated for less severe anxiety. Experience in randomized placebo-controlled
discontinuation studies of patients with panic disorder showed a high rate of
rebound and withdrawal symptoms in patients treated with alprazolam compared to
placebo treated patients.
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.
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.
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 were as follows:
|
| DISCONTINUATION-EMERGENT SYMPTOM INCIDENCE |
|
|
| Percentage of 641 Alprazolam-Treated Panic Disorder Patients Reporting Events |
|
| Body System/Event |
|
|
|
| Neurologic |
| Gastrointestinal |
|
| Insomnia | 29.5 | Nausea/Vomiting | 16.5 |
| Light-headedness | 19.3 | Diarrhea | 13.6 |
| Abnormal involuntary movement | 17.3 | Decreased salivation | 10.6 |
| Headache | 17.0 | Metabolic-Nutritional |
|
| Muscular twitching | 6.9 | Weight loss | 13.3 |
| Impaired coordination | 6.6 | Decreased appetite | 12.8 |
| Muscle tone disorders | 5.9 |
|
|
| Weakness | 5.8 | Dermatological |
|
| Psychiatric |
| Sweating | 14.4 |
| Anxiety | 19.2 |
|
|
| Fatigue and Tiredness | 18.4 | Cardiovascular |
|
| Irritability | 10.5 | Tachycardia | 12.2 |
| Cognitive disorder | 10.3 |
|
|
| Memory impairment | 5.5 | Special Senses |
|
| Depression | 5.1 | Blurred vision | 10.0 |
| Confusional state | 5.0 |
|
|
From the studies cited, it has not been determined whether these symptoms are
clearly related to the dose and duration of therapy with alprazolam in patients
with panic disorder.
In two controlled trials of six to eight weeks duration where the ability of
patients to discontinue medication was measured, 71%-93% of alprazolam treated
patients tapered completely off therapy compared to 89%-96% of placebo treated
patients. In a controlled postmarketing discontinuation study of panic disorder
patients, the duration of treatment (three months compared to six months) had no
effect on the ability of patients to taper to zero dose.
Seizures attributable to alprazolam 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 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. The risk of seizure seems to be greatest 24-72 hours after
discontinuation (see DOSAGE AND
ADMINISTRATION for recommended tapering and discontinuation schedule).
Status Epilepticus And Its Treatment:
The medical event voluntary reporting system shows that
withdrawal seizures have been reported in association with the discontinuation
of alprazolam. In most cases, only a single seizure was reported; however,
multiple seizures and status epilepticus were reported as well. Ordinarily, the
treatment of status epilepticus of any etiology involves use of intravenous
benzodiazepines plus phenytoin or barbiturates, maintenance of a patent airway
and adequate hydration. For additional details regarding therapy, consultation
with an appropriate specialist may be considered.
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 of alprazolam. 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. In these situations, it is
recommended that the same total daily dose be given divided as more frequent
administrations (see DOSAGE AND
ADMINISTRATION).
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 (eg, the patient forgets, the patient is admitted to a hospital, etc.).
Therefore, the dosage of alprazolam should be reduced or discontinued gradually
(see DOSAGE AND
ADMINISTRATION).
Alprazolam is not of value in the treatment of psychotic patients and should
not be employed in lieu of appropriate treatment for psychosis. Because of its
CNS depressant effects, patients receiving alprazolam 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.
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 P4503A:The
initial step in alprazolam metabolism is hydroxylation catalyzed by cytochrome
P450 3A (CYP 3A). 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 CYP 3A. With drugs
inhibiting CYP 3A 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 CYP
3A.
Potent CYP 3A Inhibitors:
Azole antifungal agents--Although in
vivo interaction data with alprazolam are not available, ketoconazole and
intraconazole are potent CYP 3A inhibitors and the coadministration of
alprazolam with them is not recommended. Other azole-type antifungal agents
should also be considered potent CYP 3A inhibitors and the coadministration of
alprazolam with them is not recommended (see CONTRAINDICATIONS).
Drugs Demonstrated To Be CYP 3A Inhibitors On The Basis Of
Clinical Studies Involving Alprazolam (Caution And Consideration Of Appropriate
Alprazolam Dose Reduction Are Recommended Dduring 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 Metabolism:
Other drugs possibly affecting alprazolam metabolism by
inhibition of CYP 3A are discussed in the PRECAUTIONS section (see PRECAUTIONS-Drug
Interactions).