ZALEPLON

Zaleplon, USP is a nonbenzodiazepine hypnotic from the pyrazolopyrimidine class. The chemical name of zaleplon, USP is N-[3-(3-cyanopyrazolo[1,5-a]pyrimidin-7-yl)phenyl]-N-ethylacetamide. Its empirical formula is C 17 H 15 N 5 O, and its molecular weight is 305.34. The structural formula is shown below. Zaleplon, USP is a white to off-white powder that is practically insoluble in water and sparingly soluble in alcohol or propylene glycol. Its partition coefficient in octanol/water is constant (log PC = 1.23) over the pH range of 1 to 7. Zaleplon capsules, USP contain zaleplon, USP as the active ingredient. Inactive ingredients consist of lactose monohydrate, pregelatinized starch, microcrystalline cellulose, silicon dioxide, magnesium stearate, gelatin, titanium dioxide, FD&C blue #1, FD&C red #40, and FD&C yellow #5. Ink constituents are: shellac, dehydrated alcohol, isopropyl alcohol, butyl alcohol, propylene glycol, strong ammonia solution, black iron oxide and potassium hydroxide. Complies with USP dissolution Test 2. molecular structure

Zaleplon capsules are indicated for the short-term treatment of insomnia. Zaleplon capsules have been shown to decrease the time to sleep onset for up to 30 days in controlled clinical studies (see Clinical Trials under CLINICAL PHARMACOLOGY ). It has not been shown to increase total sleep time or decrease the number of awakenings. The clinical trials performed in support of efficacy ranged from a single night to 5 weeks in duration. The final formal assessments of sleep latency were performed at the end of treatment.

The dose of zaleplon capsules should be individualized. The recommended dose of zaleplon capsules for most nonelderly adults is 10 mg. For certain low weight individuals, 5 mg may be a sufficient dose. Although the risk of certain adverse events associated with the use of zaleplon capsules appears to be dose dependent, the 20 mg dose has been shown to be adequately tolerated and may be considered for the occasional patient who does not benefit from a trial of a lower dose. Doses above 20 mg have not been adequately evaluated and are not recommended. Zaleplon capsules should be taken immediately before bedtime or after the patient has gone to bed and has experienced difficulty falling asleep (see PRECAUTIONS ). Taking zaleplon capsules with or immediately after a heavy, high-fat meal results in slower absorption and would be expected to reduce the effect of zaleplon capsules on sleep latency (see Pharmacokinetics under CLINICAL PHARMACOLOGY ). Special Populations Elderly patients and debilitated patients appear to be more sensitive to the effects of hypnotics, and respond to 5 mg of zaleplon capsules. The recommended dose for these patients is therefore 5 mg. Doses over 10 mg are not recommended. Hepatic insufficiency: Patients with mild to moderate hepatic impairment should be treated with zaleplon capsules 5 mg because clearance is reduced in this population. Zaleplon capsules are not recommended for use in patients with severe hepatic impairment. Renal insufficiency: No dose adjustment is necessary in patients with mild to moderate renal impairment. Zaleplon capsules have not been adequately studied in patients with severe renal impairment. An initial dose of 5 mg should be given to patients concomitantly taking cimetidine because zaleplon clearance is reduced in this population (see Drug Interactions under PRECAUTIONS ).

Zaleplon is contraindicated in patients: who have experienced complex sleep behaviors after taking zaleplon (see WARNINGS ). with hypersensitivity to zaleplon or any excipients in the formulation (see PRECAUTIONS ).

The premarketing development program for zaleplon included zaleplon exposures in patients and/or normal subjects from 2 different groups of studies: approximately 900 normal subjects in clinical pharmacology/pharmacokinetic studies; and approximately 2,900 exposures from patients in placebo-controlled clinical effectiveness studies, corresponding to approximately 450 patient exposure years. The conditions and duration of treatment with zaleplon varied greatly and included (in overlapping categories) open-label and double-blind phases of studies, inpatients and outpatients, and short-term or longer-term exposure. Adverse reactions were assessed by collecting adverse events, results of physical examinations, vital signs, weights, laboratory analyses, and ECGs. Adverse events during exposure were obtained primarily by general inquiry and recorded by clinical investigators using terminology of their own choosing. Consequently, it is not possible to provide a meaningful estimate of the proportion of individuals experiencing adverse events without first grouping similar types of events into a smaller number of standardized event categories. In the tables and tabulations that follow, COSTART terminology has been used to classify reported adverse events. 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 while receiving therapy following baseline evaluation. Adverse Findings Observed in Short-Term, Placebo-Controlled Trials Adverse Events Associated With Discontinuation of Treatment In premarketing placebo-controlled, parallel-group phase 2 and phase 3 clinical trials, 3.1% of 744 patients who received placebo and 3.7% of 2,149 patients who received zaleplon discontinued treatment because of an adverse clinical event. This difference was not statistically significant. No event that resulted in discontinuation occurred at a rate of ≥ 1%. Adverse Events Occurring at an Incidence of 1% or More Among Zaleplon 20 mg-Treated Patients Table 1 enumerates the incidence of treatment-emergent adverse events for a pool of three 28-night and one 35-night placebo-controlled studies of zaleplon at doses of 5 mg or 10 mg and 20 mg. The table includes only those events that occurred in 1% or more of patients treated with zaleplon 20 mg and that had a higher incidence in patients treated with zaleplon 20 mg than in placebo-treated patients. The prescriber should be aware that these figures 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 figures obtained from other clinical investigations involving different treatments, uses, and investigators. The cited figures, 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. Table 1 Incidence (%) of Treatment-Emergent Adverse Events in Long-Term (28 and 35 Nights) Placebo-Controlled Clinical Trials of Zaleplon a Body System Placebo Zaleplon 5 mg or 10 mg Zaleplon 20 mg Preferred Term (n=344) (n=569) (n=297) Body as a whole Abdominal pain 3 6 6 Asthenia 5 5 7 Headache 35 30 42 Malaise < 1 < 1 2 Photosensitivity reaction < 1 < 1 1 Digestive system Anorexia < 1 < 1 2 Colitis 0 0 1 Nausea 7 6 8 Metabolic and nutritional Peripheral edema < 1 < 1 1 Nervous system Amnesia 1 2 4 Confusion < 1 < 1 1 Depersonalization < 1 < 1 2 Dizziness 7 7 9 Hallucinations < 1 < 1 1 Hypertonia < 1 1 1 Hypesthesia < 1 < 1 2 Paresthesia 1 3 3 Somnolence 4 5 6 Tremor 1 2 2 Vertigo < 1 < 1 1 Respiratory system Epistaxis < 1 < 1 1 Special senses Abnormal vision < 1 < 1 2 Ear pain 0 < 1 1 Eye pain 2 4 3 Hyperacusis < 1 1 2 Parosmia < 1 < 1 2 Urogenital system Dysmenorrhea 2 3 4 a Events for which the incidence for zaleplon 20 mg-treated patients was at least 1% and greater than the incidence among placebo-treated patients. Incidence greater than 1% has been rounded to the nearest whole number. Other Adverse Events Observed During the Premarketing Evaluation of Zaleplon Listed below are COSTART terms that reflect treatment-emergent adverse events as defined in the introduction to the ADVERSE REACTIONS section. These events were reported by patients treated with zaleplon at doses in a range of 5 mg/day to 20 mg/day during premarketing phase 2 and phase 3 clinical trials throughout the United States, Canada, and Europe, including approximately 2,900 patients. All reported events are included except those already listed in Table 1 or elsewhere in labeling, those events for which a drug cause was remote, and those event terms that were so general as to be uninformative. It is important to emphasize that although the events reported occurred during treatment with zaleplon, they were not necessarily caused by it. Events are further categorized by body system and listed in order of decreasing frequency according to the following definitions: frequent adverse events are those occurring on one or more occasions in at least 1/100 patients; infrequent adverse events are those occurring in less than 1/100 patients but at least 1/1,000 patients; rare events are those occurring in fewer than 1/1,000 patients. Body as a whole - Frequent: back pain, chest pain, fever; Infrequent: chest pain substernal, chills, face edema, generalized edema, hangover effect, neck rigidity. Cardiovascular system - Frequent: migraine; Infrequent: angina pectoris, bundle branch block, hypertension, hypotension, palpitation, syncope, tachycardia, vasodilatation, ventricular extrasystoles; Rare: bigeminy, cerebral ischemia, cyanosis, pericardial effusion, postural hypotension, pulmonary embolus, sinus bradycardia, thrombophlebitis, ventricular tachycardia. Digestive system - Frequent: constipation, dry mouth, dyspepsia; Infrequent: eructation, esophagitis, flatulence, gastritis, gastroenteritis, gingivitis, glossitis, increased appetite, melena, mouth ulceration, rectal hemorrhage, stomatitis; Rare: aphthous stomatitis, biliary pain, bruxism, cardiospasm, cheilitis, cholelithiasis, duodenal ulcer, dysphagia, enteritis, gum hemorrhage, increased salivation, intestinal obstruction, abnormal liver function tests, peptic ulcer, tongue discoloration, tongue edema, ulcerative stomatitis. Endocrine system - Rare: diabetes mellitus, goiter, hypothyroidism. Hemic and lymphatic system - Infrequent: anemia, ecchymosis, lymphadenopathy; Rare: eosinophilia, leukocytosis, lymphocytosis, purpura. Metabolic and nutritional - Infrequent: edema, gout, hypercholesteremia, thirst, weight gain; Rare: bilirubinemia, hyperglycemia, hyperuricemia, hypoglycemia, hypoglycemic reaction, ketosis, lactose intolerance, AST (SGOT) increased, ALT (SGPT) increased, weight loss. Musculoskeletal system - Frequent: arthralgia, arthritis, myalgia; Infrequent: arthrosis, bursitis, joint disorder (mainly swelling, stiffness, and pain), myasthenia, tenosynovitis; Rare: myositis, osteoporosis. Nervous system - Frequent: anxiety, depression, nervousness, thinking abnormal (mainly difficulty concentrating); Infrequent: abnormal gait, agitation, apathy, ataxia, circumoral paresthesia, emotional lability, euphoria, hyperesthesia, hyperkinesia, hypotonia, incoordination, insomnia, libido decreased, neuralgia, nystagmus; Rare: CNS stimulation, delusions, dysarthria, dystonia, facial paralysis, hostility, hypokinesia, myoclonus, neuropathy, psychomotor retardation, ptosis, reflexes decreased, reflexes increased, sleep talking, sleep walking, slurred speech, stupor, trismus. Respiratory system - Frequent: bronchitis; Infrequent: asthma, dyspnea, laryngitis, pneumonia, snoring, voice alteration; Rare: apnea, hiccup, hyperventilation, pleural effusion, sputum increased. Skin and appendages - Frequent: pruritus, rash; Infrequent: acne, alopecia, contact dermatitis, dry skin, eczema, maculopapular rash, skin hypertrophy, sweating, urticaria, vesiculobullous rash; Rare: melanosis, psoriasis, pustular rash, skin discoloration. Special senses - Frequent: conjunctivitis, taste perversion; Infrequent: diplopia, dry eyes, photophobia, tinnitus, watery eyes; Rare: abnormality of accommodation, blepharitis, cataract specified, corneal erosion, deafness, eye hemorrhage, glaucoma, labyrinthitis, retinal detachment, taste loss, visual field defect. Urogenital system - Infrequent: bladder pain, breast pain, cystitis, decreased urine stream, dysuria, hematuria, impotence, kidney calculus, kidney pain, menorrhagia, metrorrhagia, urinary frequency, urinary incontinence, urinary urgency, vaginitis; Rare: albuminuria, delayed menstrual period, leukorrhea, menopause, urethritis, urinary retention, vaginal hemorrhage. Postmarketing Reports Anaphylactic/anaphylactoid reactions, including severe reactions and nightmares.

As with all drugs, the potential exists for interaction with other drugs by a variety of mechanisms. CNS-Active Drugs Ethanol: Zaleplon 10 mg potentiated the CNS-impairing effects of ethanol 0.75 g/kg on balance testing and reaction time for 1 hour after ethanol administration and on the digit symbol substitution test (DSST), symbol copying test, and the variability component of the divided attention test for 2.5 hours after ethanol administration. The potentiation resulted from a CNS pharmacodynamic interaction; zaleplon did not affect the pharmacokinetics of ethanol. Imipramine: Coadministration of single doses of zaleplon 20 mg and imipramine 75 mg produced additive effects on decreased alertness and impaired psychomotor performance for 2 to 4 hours after administration. The interaction was pharmacodynamic with no alteration of the pharmacokinetics of either drug. Paroxetine: Coadministration of a single dose of zaleplon 20 mg and paroxetine 20 mg daily for 7 days did not produce any interaction on psychomotor performance. Additionally, paroxetine did not alter the pharmacokinetics of zaleplon, reflecting the absence of a role of CYP2D6 in zaleplon's metabolism. Thioridazine: Coadministration of single doses of zaleplon 20 mg and thioridazine 50 mg produced additive effects on decreased alertness and impaired psychomotor performance for 2 to 4 hours after administration. The interaction was pharmacodynamic with no alteration of the pharmacokinetics of either drug. Venlafaxine: Coadministration of a single dose of zaleplon 10 mg and multiple doses of venlafaxine ER (extended release) 150 mg did not result in any significant changes in the pharmacokinetics of either zaleplon or venlafaxine. In addition, there was no pharmacodynamic interaction as a result of coadministration of zaleplon and venlafaxine ER. Promethazine: Coadministration of a single dose of zaleplon and promethazine (10 and 25 mg, respectively) resulted in a 15% decrease in maximal plasma concentrations of zaleplon, but no change in the area under the plasma concentration-time curve. However, the pharmacodynamics of coadministration of zaleplon and promethazine have not been evaluated. Caution should be exercised when these 2 agents are coadministered. Drugs That Induce CYP3A4 Rifampin: CYP3A4 is ordinarily a minor metabolizing enzyme of zaleplon. Multiple-dose administration of the potent CYP3A4 inducer rifampin (600 mg every 24 hours, q24h, for 14 days), however, reduced zaleplon C max and AUC by approximately 80%. The coadministration of a potent CYP3A4 enzyme inducer, although not posing a safety concern, thus could lead to ineffectiveness of zaleplon. An alternative non-CYP3A4 substrate hypnotic agent may be considered in patients taking CYP3A4 inducers such as rifampin, phenytoin, carbamazepine, and phenobarbital. Drugs That Inhibit CYP3A4 CYP3A4 is a minor metabolic pathway for the elimination of zaleplon because the sum of desethylzaleplon (formed via CYP3A4 in vitro ) and its metabolites, 5-oxo-desethylzaleplon and 5-oxo-desethylzaleplon glucuronide, account for only 9% of the urinary recovery of a zaleplon dose. Coadministration of single, oral doses of zaleplon with erythromycin (10 mg and 800 mg respectively), a strong, selective CYP3A4 inhibitor, produced a 34% increase in zaleplon's maximal plasma concentrations and a 20% increase in the area under the plasma concentration-time curve. The magnitude of interaction with multiple doses of erythromycin is unknown. Other strong selective CYP3A4 inhibitors such as ketoconazole can also be expected to increase the exposure of zaleplon. A routine dosage adjustment of zaleplon is not considered necessary. Drugs That Inhibit Aldehyde Oxidase The aldehyde oxidase enzyme system is less well studied than the cytochrome P450 enzyme system. Diphenhydramine: Diphenhydramine is reported to be a weak inhibitor of aldehyde oxidase in rat liver, but its inhibitory effects in human liver are not known. There is no pharmacokinetic interaction between zaleplon and diphenhydramine following the administration of a single dose (10 mg and 50 mg, respectively) of each drug. However, because both of these compounds have CNS effects, an additive pharmacodynamic effect is possible. Drugs That Inhibit Both Aldehyde Oxidase and CYP3A4 Cimetidine: Cimetidine inhibits both aldehyde oxidase ( in vitro ) and CYP3A4 ( in vitro and in vivo ), the primary and secondary enzymes, respectively, responsible for zaleplon metabolism. Concomitant administration of zaleplon (10 mg) and cimetidine (800 mg) produced an 85% increase in the mean C max and AUC of zaleplon. An initial dose of 5 mg should be given to patients who are concomitantly being treated with cimetidine (see DOSAGE AND ADMINISTRATION ). Drugs Highly Bound to Plasma Protein Zaleplon is not highly bound to plasma proteins (fraction bound 60%±15%); therefore, the disposition of zaleplon is not expected to be sensitive to alterations in protein binding. In addition, administration of zaleplon to a patient taking another drug that is highly protein bound should not cause transient increase in free concentrations of the other drug. Drugs with a Narrow Therapeutic Index Digoxin: Zaleplon (10 mg) did not affect the pharmacokinetic or pharmacodynamic profile of digoxin (0.375 mg q24h for 8 days). Warfarin: Multiple oral doses of zaleplon (20 mg q24h for 13 days) did not affect the pharmacokinetics of warfarin (R+)- or (S-)-enantiomers or the pharmacodynamics (prothrombin time) following a single 25-mg oral dose of warfarin. Drugs That Alter Renal Excretion Ibuprofen: Ibuprofen is known to affect renal function and, consequently, alter the renal excretion of other drugs. There was no apparent pharmacokinetic interaction between zaleplon and ibuprofen following single dose administration (10 mg and 600 mg, respectively) of each drug. This was expected because zaleplon is primarily metabolized and renal excretion of unchanged zaleplon accounts for less than 1% of the administered dose.

STORAGE CONDITIONS Store at 20°C to 25°C (68°F to 77°F) [see USP Controlled Room Temperature]. Dispense in a light-resistant container as defined in the USP.