ESTAZOLAM

Estazolam, a triazolobenzodiazepine derivative, is an oral hypnotic agent. Estazolam occurs as a fine, white, odorless powder that is soluble in alcohol and practically insoluble in water. The chemical name for estazolam is 8-chloro-6-phenyl-4H- s -triazolo[4,3-α][1,4]benzodiazepine. The structural formula is represented as follows: Each tablet, for oral administration, contains either 1 mg or 2 mg of estazolam, USP. In addition, each tablet contains the following inactive ingredients: anhydrous lactose, colloidal silicon dioxide, corn starch, lactose monohydrate and magnesium stearate. In addition, the 2 mg tablet contains yellow iron oxide and red iron oxide. structure

INDICATIONS & USAGE Estazolam is indicated for the short-term management of insomnia characterized by difficulty in falling asleep, frequent nocturnal awakenings, and/or early morning awakenings. Both outpatient studies and a sleep laboratory study have shown that estazolam administered at bedtime improved sleep induction and sleep maintenance (see CLINICAL PHARMACOLOGY ). Because insomnia is often transient and intermittent, the prolonged administration of estazolam is generally neither necessary nor recommended. Since insomnia may be a symptom of several other disorders, the possibility that the complaint may be related to a condition for which there is a more specific treatment should be considered. There is evidence to support the ability of estazolam to enhance the duration and quality of sleep for intervals up to 12 weeks (see CLINICAL PHARMACOLOGY ).

DOSAGE & ADMINISTRATION The recommended initial dose for adults is 1 mg at bedtime; however, some patients may need a 2 mg dose. In healthy elderly patients, 1 mg is also the appropriate starting dose, but increases should be initiated with particular care. In small or debilitated older patients, a starting dose of 0.5 mg, while only marginally effective in the overall elderly population, should be considered. Discontinuation or Dosage Reduction of Estazolam To reduce the risk of withdrawal reactions, use a gradual taper to discontinue estazolam or reduce the dosage. If a patient develops withdrawal reactions, consider pausing the taper or increasing the dosage to the previous tapered dosage level. Subsequently decrease the dosage more slowly (see WARNINGS, Dependence and Withdrawal Reactions and DRUG ABUSE AND DEPENDENCE, Dependence ).

Estazolam is contraindicated with ketoconazole and itraconazole, since these medications significantly impair oxidative metabolism mediated by CYP3A (see WARNINGS and PRECAUTIONS, Drug Interactions ).

Commonly Observed The most commonly observed adverse events associated with the use of 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 estazolam in U.S. 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 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: 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* Estazolam (N = 685) Placebo (N = 433) Body as a Whole Headache 16 27 Asthenia 11 8 Malaise 5 5 Lower extremity pain 3 2 Back pain 2 2 Body pain 2 2 Abdominal pain 1 2 Chest pain 1 1 Digestive System Nausea 4 5 Dyspepsia 2 2 Musculoskeletal System Stiffness 1 - Nervous System Somnolence 42 27 Hypokinesia 8 4 Nervousness 8 11 Dizziness 7 3 Coordination abnormal 4 1 Hangover 3 2 Confusion 2 - Depression 2 3 Dream abnormal 2 2 Thinking abnormal 2 1 Respiratory System Cold symptoms 3 5 Pharyngitis 1 2 Skin and Appendages Pruritus 1 - *Events reported by at least 1% of estazolam patients. Other Adverse Events During clinical trials, some of which were not placebo-controlled, 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. The frequencies presented, therefore, represent the proportion of the 1277 individuals exposed to estazolam who experienced an event of the type cited on at least one occasion while receiving 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 estazolam, they were not necessarily caused by it. Body as a Whole - Infrequent: allergic reaction, chills, fever, neck pain, upper extremity pain; Rare: edema, jaw pain, swollen breast. Cardiovascular System - Infrequent: flushing, palpitation; Rare: arrhythmia, syncope. Digestive System - Frequent: constipation, dry mouth; Infrequent: decreased appetite, flatulence, gastritis, increased appetite, vomiting; Rare: enterocolitis, melena, ulceration of the mouth. Endocrine System - Rare: thyroid nodule. Hematologic and Lymphatic System - Rare: leukopenia, purpura, swollen lymph nodes. Metabolic/Nutritional Disorders - Infrequent: thirst; Rare: increased SGOT, weight gain, weight loss. Musculoskeletal System - Infrequent: arthritis, muscle spasm, myalgia; Rare: arthralgia. 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 estazolam therapy or withdrawal and are of no known clinical significance. Respiratory System - Infrequent: asthma, cough, dyspnea, rhinitis, sinusitis; Rare: epistaxis, hyperventilation, laryngitis. Skin and Appendages - Infrequent: rash, sweating, urticaria; Rare: acne, dry skin. Special Senses - Infrequent: abnormal vision, ear pain, eye irritation, eye pain, eye swelling, perverse taste, photophobia, tinnitus; Rare: decreased hearing, diplopia, scotomata. 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-U.S. 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.

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 GABA A 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 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 (C max 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 (0.6μM) 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. Carcinogenesis, Mutagenesis, Impairment of Fertility Two-year carcinogenicity studies were conducted in mice and rats at dietary doses of 0.8, 3, and 10 mg/kg/day and 0.5, 2, and 10 mg/kg/day, respectively. Evidence of tumorigenicity was not observed in either study. Incidence of hyperplastic liver nodules increased in female mice given the mid and high dose levels. The significance of such nodules in mice is not known at this time. In vitro and in vivo mutagenicity tests including the Ames test, DNA repair in B. subtilis , in vivo cytogenetics in mice and rats, and the dominant lethal test in mice did not show a mutagenic potential for estazolam. Fertility in male and female rats was not affected by doses up to 30 times the usual recommended human dose.