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Commonly Observed: The most commonly observed adverse events associated with the use of ProSom (estazolam) , not seen at an equivalent incidence among placebo-treated patients were somnolence, hypokinesia, dizziness, and abnormal coordination.
Associated with Discontinuation of Treatment: Approximately 3% of 1277 patients who received ProSom (estazolam) in US premarketing clinical trials discontinued treatment because of an adverse clinical event. The only event commonly associated with discontinuation, accounting for 1.3% of the total, was somnolence.
Incidence in Controlled Clinical Trials: The table below enumerates adverse events that occurred at an incidence of 1% or greater among patients with insomnia who received ProSom (estazolam) in 7-night, placebo-controlled trials. Events reported by investigators were classified into standard dictionary (COSTART) terms to establish event frequencies. Event frequencies reported were not corrected for the occurrence of these events at baseline. The frequencies were obtained from data pooled across six studies: ProSom (estazolam) , N=685; placebo, N=433. The prescriber should be aware that these figures cannot be used to predict the incidence of side effects in the course of usual medical practice in which patient characteristics and other factors differ from those that prevailed in these six clinical trials. Similarly, the cited frequencies cannot be compared with figures obtained from other clinical investigators involving related drug products and uses, since each group of drug trials was conducted under a different set of conditions. However, the cited figures provide the physician with a basis of estimating the relative contribution of drug and nondrug factors to the incidence of side effects in the population studied.
INCIDENCE OF ADVERSE EXPERIENCES IN PLACEBO-CONTROLLED CLINICAL
TRIALS (Percentage of Patients Reporting)
|Body System/Adverse Event*||ProSom
|Body as a Whole|
|Lower extremity pain||3||2|
|Skin and Appendages|
|*Events reported by at least 1% of ProSom patients.|
Other Adverse Events
During clinical trials conducted by Abbott, some of which were not placebo-controlled, ProSom (estazolam) was administered to approximately 1300 patients. Untoward events associated with this exposure were recorded by clinical investigators using terminology of their own choosing. To provide a meaningful estimate of the proportion of individuals experiencing adverse events, similar types of untoward events must be grouped into a smaller number of standardized event categories. In the tabulations that follow, a standard COSTART dictionary terminology has been used to classify reported adverse events. Thefrequencies presented, therefore, represent the proportion of the 1277 individuals exposed to ProSom (estazolam) who experienced an event of the type cited on at least one occasion while receiving ProSom (estazolam) . All reported events are included except those already listed in the previous table, those COSTART terms too general to be informative, and those events where a drug cause was remote. Events are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are defined as those occurring on one or more occasions in at least 1/100 patients; infrequent adverse events are those occurring in 1/100 to 1/1000 patients; rare events are those occurring in less than 1/1000 patients. It is important to emphasize that, although the events reported did occur during treatment with ProSom (estazolam) , they were not necessarily caused by it.
Nervous System - Frequent: anxiety; Infrequent: agitation, amnesia, apathy, emotional lability, euphoria, hostility, paresthesia, seizure, sleep disorder, stupor, twitch; Rare: ataxia, circumoral paresthesia, decreased libido, decreased reflexes, hallucinations, neuritis, nystagmus, tremor.
Minor changes in EEG patterns, usually low-voltage fast activity, have been observed in patients during ProSom (estazolam) therapy or withdrawal and are of no known clinical significance.
Urogenital System - Infrequent: frequent urination, menstrual cramps, urinary hesitancy, urinary urgency, vaginal discharge/itching; Rare: hematuria, nocturia, oliguria, penile discharge, urinary incontinence.
Postintroduction Reports - Voluntary reports of non-US postmarketing experience with estazolam have included rare occurrences of photosensitivity, Stevens-Johnson syndrome, and agranulocytosis. Because of the uncontrolled nature of these spontaneous reports, a causal relationship to estazolam treatment has not been determined.
Drug Abuse And Dependence
Controlled Substance: ProSom (estazolam) tablets are a controlled substance in Schedule IV.
Abuse and Dependence: Withdrawal symptoms similar to those noted with sedatives/hypnotics and alcohol have occurred following the abrupt discontinuation of drugs in the benzodiazepine class. The symptoms can range from mild dysphoria and insomnia to a major syndrome that may include abdominal and muscle cramps, vomiting, sweating, tremors, and convulsions.
Although withdrawal symptoms are more commonly noted after the discontinuation of higher than therapeutic doses of benzodiazepines, a proportion of patients taking benzodiazepines chronically at therapeutic doses may become physically dependent on them. Available data, however, cannot provide a reliable estimate of the incidence of dependency or the relationship of the dependency to dose and duration of treatment. There is some evidence to suggest that gradual reduction of dosage will attenuate or eliminate some withdrawal phenomena. In most instances, withdrawal phenomena are relatively mild and transient; however, life-threatening events (eg, seizures, delirium, etc.) have been reported.
Gradual withdrawal is the preferred course for any patient taking benzodiazepines for a prolonged period. Patients with a history of seizures, regardless of their concomitant antiseizure drug therapy, should not be withdrawn abruptly from benzodiazepines.
Individuals with a history of addiction to or abuse of drugs or alcohol should be under careful surveillance when receiving benzodiazepines because of the risk of habituation and dependence to such patients.
Read the Prosom (estazolam) Side Effects Center for a complete guide to possible side effects
If ProSom (estazolam) is given concomitantly with other drugs acting on the central nervous system, careful consideration should be given to the pharmacology of all agents. The action of the benzodiazepines may be potentiated by anticonvulsants, antihistamines, alcohol, barbiturates, monoamine oxidase inhibitors, narcotics, phenothiazines, psychotropic medications, or other drugs that produce CNS depression. Smokers have an increased clearance of benzodiazepines as compared to nonsmokers; this was seen in studies with estazolam (see CLINICAL PHARMACOLOGY).
While no in vivo drug-drug interaction studies were conducted between estazolam and inducers of CYP3A, compounds that are potent CYP3A inducers (such as carbamazepine, phenytoin, rifampin, and barbiturates) would be expected to decrease estazolam concentrations.
Estazolam Interaction with Drugs that Inhibit Metabolism via Cytochrome P450 3A (CYP3A): The metabolism of estazolam to the major circulating metabolite 4-hydroxy-estazolam and the metabolism of other triazolobenzodiazepines is catalyzed by CYP3A. Consequently, estazolam should be avoided in patients receiving ketoconazole and itraconazole, which are very potent inhibitors of CYP3A (see CONTRAINDICATIONS). With drugs inhibiting CYP3A to a lesser, but still significant degree, estazolam should be used only with caution and consideration of appropriate dosage reduction. The following are examples of drugs known to inhibit the metabolism of other related benzodiazepines, presumably through inhibition of CYP3A: nefazodone, fluvoxamine, cimetidine, diltiazem, isoniazide, and some macrolide antibiotics.
Drug Interaction with Fluoxetine: A multiple-dose study was conducted to assess the effect of fluoxetine 20 mg BID on the pharmacokinetics of estazolam 2 mg QHS after seven days. The pharmacokinetics of estazolam (Cmax and AUC) were not affected during multiple-dose fluoxetine, suggesting no clinically significant pharmacokinetic interaction.
Estazolam Interaction with Other Drugs that are Metabolized by Cytochrome P450 (CYP): At clinically relevant concentrations, in vitro studies indicate that estazolam (0.6ÁM) was not inhibitory towards the major cytochrome P450 isoforms CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A. Therefore, based on these in vitro data, estazolam is very unlikely to inhibit the biotransformation of other drugs metabolized by these CYP isoforms.
Read the Prosom Drug Interactions Center for a complete guide to possible interactions
Last reviewed on RxList: 6/19/2008
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