Product Monograph - Ivadal (Sanofi-Aventis Canada, 10 mg)
ACTIONS AND CLINICAL PHARMACOLOGY
IVADAL (zolpidem tartrate), an imidazopyridine derivative, is a short acting hypnotic agent. Zolpidem belongs to a novel chemical class, which is structurally unrelated to existing hypnotics. While zolpidem is a hypnotic agent with chemical structure unrelated to benzodiazepines, barbiturates, or other drugs with known hypnotic properties, it interacts with a GABA-BZ receptor complex and shares some of the pharmacological properties of the benzodiazepines.
With hypnotic drugs, the duration of hypnotic effect and the profile of unwanted effects may be influenced by the alpha (distribution) and beta (elimination) half-lives of the administered drug and any active metabolites formed. When half-lives are long, the drug or metabolite may accumulate during periods of nightly administration and be associated with impairment of cognitive and motor performance during waking hours. If half-lives are short, the drug and metabolites will be cleared before the next dose is ingested, and carry-over effects related to sedation or CNS depression should be minimal or absent. If the drug has a very short elimination half-life, it is possible that a relative deficiency (i.e., in relation to the receptor site) may occur at some point in the interval between each night's use. This sequence of events may account for two clinical findings reported to occur after several weeks of nightly use of rapidly eliminated hypnotics: 1) increased wakefulness during the last third of the night and 2) the appearance of increased day-time anxiety (See WARNINGS).
Pharmacodynamics:
Subunit modulation of the GABAA, receptor chloride channel macromolecular complex is hypothesized to be responsible for sedative, anticonvulsant, anxioytic, and myorelexant drug properties. The major modulatory site of the GABAA receptor complex is located on its alpha (α) subunit and is referred to as the benzodiazepine (BZ) or omega (ω) receptor. At least three subtypes of the (ω) receptor have been identified.
While zolpidem is a hypnotic agent with a chemical structure unrelated to benzodiazepines, barbiturates, or other drugs with known hypnotic properties, it interacts with a GABA-BZ receptor complex and shares some of the pharmacological properties of the benzodiazepines. In contrast to the benzodiazepines, which nonselectively bind to and activate all omega receptor subtypes, zolpidem, in vitro binds the (ω1) receptor preferentially with a high affinity ratio of the alpha1/alpha5 subunits. The (ω1) receptor is found primarily on the Lamina IV of the sensorimotor cortical regions, substantia nigra (pars reticulate), cerebellum molecular layer, olfactory bulb, ventral thalamic complex, pons, inferior colliculus, and globus pallidus. This selective binding of zolpidem on the (ω1) receptor is not absolute, but it may explain the relative absence of the myrorelaxant and anticonvulsant effects in animal studies as well as the preservation of deep sleep (stages 3 and 4) in human studies of zolpidem at hypnotic doses.
Pharmacokinetics:
The pharmacokinetic profile of IVADAL is characterized by rapid absorption from the GI tract and a short elimination half-life (T½) in healthy subjects. In a single-dose crossover study in 45 healthy subjects administered 5- and 10-mg zolpidem tartrate tablets, the mean peak concentrations (Cmax) were 59 (range: 29 to 113) and 121 (range: 58-272) ng/mL, respectively, occurring at a mean time (Tmax) of 1.6 hours for both. The mean IVADAL elimination half-life was 2.6 (range: 1.4 to 4.5) and 2.5 (range: 1.4 to 3.8) hours, for the 5-and 10-mg tablets, respectively. IVADAL is converted to inactive metabolites that are eliminated primarily by renal excretion. IVADAL demonstrated linear kinetics in the dose range of 5 to 20 mg. Total protein binding was found to be 92.5 ± 0.1% and remained constant, independent of concentration between 40 and 790 ng/mL. Zolpidem did not accumulate in young adults following nightly dosing with 20-mg zolpidem tartrate tablets for 2 weeks.
Food Effects:
A food-effect study in 30 healthy male volunteers compared the pharmacokinetics of IVADAL 10 mg when administered while fasting or 20 minutes after a meal. Results demonstrated that with food, mean AUC and Cmax were decreased by 15% and 25% respectively, while mean Tmax was prolonged by 60% (from 1.4 to 2.2 hr). The half-life remained unchanged. These results suggest that, for faster sleep onset, IVADAL should not be administered with or immediately after a meal.
Elderly:
In the elderly, the dose for IVADAL should be 5 mg (See PRECAUTIONS and DOSAGE AND ADMINISTRATION). This recommendation is based on several studies in which the mean Cmax, T½, and AUC were significantly increased when compared to results in young adults. In one study of eight elderly subjects (> 70 years), the means for Cmax, T½, and AUC significantly increased by 50% (255 vs 384 ng/mL), 32% (2.2 vs 2.9 hr) and 64% (955 vs 1,562 ng hr/mL), respectively, as compared to younger adults (20 to 40 years) following a single 20-mg oral zolpidem dose. IVADAL did not accumulate in elderly subjects following nightly oral dosing of 10 mg for 1 week.
Hepatic Insufficiency:
The pharmacokinetics of IVADAL in eight patients with chronic hepatic insufficiency were compared to results in healthy subjects. Following a single 20-mg oral zolpidem dose, mean Cmax and AUC were found to be two times (250 vs 499 ng/mL) and five times (788 vs 4,203 ng hr/mL) higher, respectively, in hepatically compromised patients. Tmax did not change. The mean half-life in cirrhotic patients of 9.9 hr (range: 4.1 to 25.8 hr) was greater than that observed in normals of 2.2 hr (range: 1.6 to 2.4 hr). Dosing should be modified accordingly in patients with mild to moderate hepatic insufficiency. IVADAL has not been studied in patients with severe hepatic insufficiency (See CONTRAINDICATIONS, PRECAUTIONS and DOSAGE AND ADMINISTRATION).
Renal Insufficiency:
IVADAL pharmacokinetics were not significantly different in renally impaired patients. No dosage adjustment is necessary in patients with compromised renal function. As a general precaution, these patients should be closely monitored.
The pharmacokinetics of zolpidem tartrate were studied in 11 patients with end-stage renal failure (mean ClCr=6.5 ± 1.5 mL/min) undergoing hemodialysis three times a week, who were dosed with zolpidem 10 mg orally each day for 14 or 21 days. No statistically significant differences were observed for Cmax, Tmax half-life, and AUC between the first and last day of drug administration when baseline concentration adjustments were made. On day 1, Cmax was 172 ± 29 ng/mL (range: 46 to 344 ng/mL). After repeated dosing for 14 or 21 days, Cmax was 203 ± 32 ng/mL (range: 28 to 316 ng/mL). On day 1, Tmax was 1.7 ± 0.3 hr (range: 0.5 to 3.0 hr); after repeated dosing Tmax was 0.8 ± 0.2 hr (range: 0.5 to 2.0 hr). This variation is accounted for by noting that last-day serum sampling began 10 hours after the previous dose, rather than after 24 hours. This resulted in residual drug concentration and a shorter period to reach maximal serum concentration. On day 1, T½ was 2.4 ± 0.4 hr (range: 0.4 to 5.1 hr). After repeated dosing, T½ was 2.5 ± 0.4 hr (range: 0.7 to 4.2 hr). AUC was 796 ± 159 ng hr/mL after the first dose and 818 ± 170 ng hr/mL after repeated dosing. Zolpidem was not hemodialyzable. No accumulation of unchanged drug appeared after 14 to 21 days.
Clinical Trials:
Transient Insomnia: Normal adults experiencing transient insomnia (n=462) during the first night in a sleep laboratory were evaluated in a double-blind, parallel group, single-night trial comparing two doses of zolpidem (7.5 and 10 mg) and placebo. Both zolpidem doses were superior to placebo on objective (polysomnographic) measures of sleep latency, sleep duration, and number of awakenings.
Normal elderly adults (mean age 68) experiencing transient insomnia (n=35) during the first two nights in a sleep laboratory were evaluated in a double-blind, crossover, 2-night trial comparing four doses of zolpidem (5,10,15 and 20 mg) and placebo. All zolpidem doses were superior to placebo on the two primary PSG parameters (sleep latency and efficiency) and all four subjective outcome measures (sleep duration, sleep latency, number of awakening, and sleep quality).
Chronic Insomnia: Adult outpatients with chronic insomnia (n=75) were evaluated in a double blind, parallel group, 5-week trial comparing two doses of zolpidem tartrate (10 and 15 mg) and placebo. On objective (polysomnographic) measures of sleep latency and sleep efficiency, zolpidem 15 mg was superior to placebo of all 5 weeks; zolpidem 10 mg was superior to placebo on sleep latency for the first 4 weeks and on sleep efficiency for weeks 2 and 4. Zolpidem was comparable to placebo on number of awakenings at both doses studies.
Adult outpatients (n=141) with chronic insomnia were evaluated in a double-blind parallel group, 4-week trial comparing two doses of zolpidem (10 and 15 mg) and placebo. Zolpidem 10 mg was superior to placebo on a subjective measure of sleep latency for all 4 weeks, and on subjective measures of total sleep time, number of awakenings and sleep quality for the first treatment week. Zolpidem 15 mg was superior to placebo on a subjective measure of sleep latency for the first 3 weeks, on a subjective measure of total sleep for the first week, and on the number of awakenings and sleep quality for the first two weeks.
Next day residual effects: There was no evidence of residual next-day effects seen with IVADAL (zolpidem tartrate) in several studies utilizing the Multiple Sleep Latency Test (MSLT), the Digit Symbol Substitution Test (DSST), and patient ratings of alertness. In one study involving elderly patients, there was a small but statistically significant decrease in one measure of performance, the DSST, but no impairment was seen in the MSLT in this study. In another study involving elderly patients with chronic insomnia, there was no evidence of residual next-day effects utilizing DSST.
Rebound Effects: There was no objective (polysomnographic) evidence of rebound insomnia at recommended doses seen in studies evaluating sleep on the nights following discontinuation of IVADAL. There was subjective evidence of impaired sleep in the elderly on the first post-treatment night at doses above the recommended elderly dose of 5 mg.
Memory impairment: Controlled studies in adults utilizing objective measures of memory yielded no consistent evidence of next-day memory impairment following the administration of IVADAL. However, in one study involving zolpidem doses of 10 and 20 mg, there was a significant decrease in-next-morning recall of information presented to subjects during peak drug effect 90 minutes post-dose, i.e., these subjects experienced anterograde amnesia. There was also subjective evidence form adverse event data for anterograde amnesia occurring in association with the administration of IVADAL, predominantly at doses above 10 mg.
Effects on Sleep Stages: In studies that measured the percentage of sleep time spent in each sleep stage, IVADAL has generally been shown to preserve sleep stages. Sleep time spent in stages 3 and 4 (deep sleep) was found to be comparable to placebo with only inconsistent, minor changes in REM (paradoxical) sleep at the recommended dose.
INDICATIONS AND CLINICAL USE
Since sleep disturbances may be the presenting manifestation of a physical and/or psychiatric disorder, symptomatic treatment of insomnia should be initiated only after a careful evaluation of the patient.
Adults:
IVADAL (zolpidem tartrate) is indicated for the short-term treatment and symptomatic relief of insomnia characterized by difficulty in falling asleep, frequent nocturnal awakenings and/or early morning awakenings.
Treatment with IVADAL should usually not exceed 7 to 10 consecutive days. Use for more than 2-3 consecutive weeks requires complete re-evaluation of the patient.
Prescriptions for IVADAL should be written for short-term use (7-10 days) and it should not be prescribed in quantities exceeding a 1-month supply.
The use of hypnotics should be restricted for insomnia where disturbed sleep results impaired daytime functioning.
Geriatrics (≥ 65 years of age):
Elderly patients are especially susceptible to dose-related adverse effects, such as drowsiness, dizziness, or impaired coordination. Inappropriate, heavy sedation may result in accidental events/falls. Therefore, the recommended IVADAL dosage is 5 mg in such patients (See PRECAUTIONS, Geriatrics; DOSAGE and ADMINISTRATION).
Pediatrics (< 18 years of age):
Safety and effectiveness of zolpidem in pediatric patients under the age of 18 years have not been established. Therefore, zolpidem should not be prescribed in this population (See PRECAUTIONS, Pediatrics; DOSAGE and ADMINISTRATION).
CONTRAINDICATIONS
IVADAL (zolpidem tartrate) is contraindicated in patients with a known hypersensitivity to the drug or any component of its formulation, severe hepatic insufficiency and in those with acute and/or severe impairment of respiratory function, e.g. significant sleep apnea syndrome.
IVADAL is contraindicated in patients with a personal or family history of sleepwalking.
WARNINGS COMPLEX SLEEP-RELATED BEHAVIOURS:
Complex sleep-related behaviours such as “sleep-driving” (i.e., driving while not fully awake after ingestion of a sedative-hypnotic, with amnesia for the event) have been reported in patients who have taken IVADAL. Other potentially dangerous behaviours have been reported in patients who got out of bed after taking a sedative-hypnotic and were not fully awake, including preparing and eating food, making phone calls, leaving the house, etc. As with “sleep-driving”, patients usually do not remember these events. Although complex sleep-related behaviours may occur with IVADAL alone at therapeutic doses, the use of alcohol and other CNS-depressants with IVADAL appears to increase the risk of such behaviours, as does the use of IVADAL at doses exceeding the maximum recommended dose.
- IVADAL is contraindicated in patients with a personal or family history of sleepwalking (see CONTRAINDICATIONS). Although complex-sleep behaviours have been reported in patients with or without history of sleepwalking, it is possible that some predisposed patients are at increased risk of experiencing these complex behaviours during treatment with IVADAL.
- IVADAL is not to be taken with alcohol.
- Caution is needed with concomitant use of other CNS depressants drugs (see DRUG INTERACTIONS).
- The use of IVADAL in patients with other disorders known to affect sleep and induce frequent awakenings (e.g. sleep apnea, Periodic Limb Movement Disorder, Restless Legs Syndrome) is discouraged, as they may be also at increased risk of complex sleep-related behaviours.
- Continuous use of IVADAL is limited to a short duration (see INDICATIONS, DOSAGE AND ADMINISTRATION).
- Patients should be instructed not to exceed the recommended dose.
- Caution should be exercised with concomitant use of potent CYP3A4 inhibitors (see DRUG INTERACTIONS).
- Due to the risk to the patient and the community, discontinuation of IVADAL should be strongly considered for patients who report any such complex sleep-related behaviours.
General:
Benzodiazepine and benzodiazepine-like compounds should be used with extreme caution in patients with a history of substance or alcohol abuse.
Because some of the important adverse effects of IVADAL (zolpidem tartrate) may be dose related, the smallest possible effective dose should be prescribed, especially for elderly patients.
Inappropriate heavy sedation in the elderly may result in accidental events/falls.
The cause of insomnia should be identified wherever possible and the underlying factors treated before a hypnotic is prescribed. The failure of insomnia to remit after 7-10 days of treatment may indicate the presence of a primary psychiatric and/or medical illness, which should be evaluated at regular intervals.
Worsening of insomnia or the emergence of new thinking or behavior abnormalities may be the consequence of an unrecognized psychiatric or physical disorder. Such findings have emerged during the course of treatment with benzodiazepine and benzodiazepine-like drugs, including IVADAL.
IVADAL should be used with caution in patients who in the past manifested paradoxical reactions to alcohol and/or sedative medications.
Lactose is a non-medicinal ingredient in IVADAL. Patients with rare hereditary diseases of galactose intolerance (galactosemia or glucose-galactose malabsorption) should not take this medicine.
Severe Anaphylactic and Anaphylactoid Reactions:
Rare cases of angioedema involving the tongue, glottis or larynx have been reported in patients after taking the first or subsequent doses of sedative-hypnotics, including IVADAL. Some patients have had additional symptoms such as dyspnea, throat closing or nausea and vomiting that suggest anaphylaxis. Some patients have required medical therapy in the emergency department. If angioedema involves the throat, glottis or larynx, airway obstruction may occur and be fatal. Patients who develop angioedema after treatment with IVADAL should not be rechallenged with the drug.
Use in Patients with Concomitant Illness:
Clinical experience with IVADAL in patients with concomitant systemic illness is limited.
Caution is advisable in using IVADAL in patients with diseases or conditions that could affect metabolism or hemodynamic responses.
Although studies did not reveal respiratory depressant effects at hypnotic doses of IVADAL in patients with normal respiratory function or in mild or moderate COPD (Chronic Obstructive Pulmonary Disease), precautions should be observed if IVADAL is prescribed to patients with compromised respiratory function, since sedative/hypnotics have the capacity to depress respiratory drive. Post -marketing reports of respiratory insufficiency, most of which involved patients with pre-existing respiratory impairment, have been received. IVADAL should be used with caution in patients with sleep apnea syndrome. IVADAL is contraindicated in patients with acute and/or severe respiratory impairment, e.g. significant apnea syndrome (See CONTRAINDICATIONS).
Data in end-stage renal failure patients repeatedly treated with IVADAL did not demonstrate drug accumulation or alterations in pharmacokinetic parameters. No dosage adjustment in renally impaired patients is required; however, these patients should be closely monitored (See ACTIONS AND CLINICAL PHARMACOLOGY).
A study in subjects with hepatic impairment did reveal prolonged elimination in this group; therefore, treatment should be initiated with 5 mg in patients with hepatic compromise, and they should be closely monitored. IVADAL is contraindicated in patients with severe hepatic insufficiency (See ACTIONS AND CLINICAL PHARMACOLOGY, CONTRAINDICATIONS and DOSAGE AND ADMINISTRATION).
IVADAL should be used with caution in patients who have myasthenia gravis.
Pregnancy:
Benzodiazepines may cause fetal damage when administered during pregnancy. During the first trimester of pregnancy, several studies have suggested an increased risk of congenital malformations associated with the use of benzodiazepines.
There are no adequate and well-controlled studies in pregnant women. IVADAL should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. As a precautionary measure, it is preferable to avoid the use of IVADAL during pregnancy.
If IVADAL is prescribed to a woman of child-bearing potential, the patient should be warned of the potential risk to a fetus and advised to consult her physician regarding the discontinuation of the drug if she intends to become pregnant or suspects that she is pregnant.
Studies to assess the effects on children whose mothers took zolpidem during pregnancy have not been conducted. However, children born of mothers taking sedative/hypnotic drugs during the late phase of pregnancy or during labor may be at some risk for physical dependence and withdrawal symptoms from the drug during the postnatal period. Effects on the neonate such as hypothermia and moderate respiratory depression can be expected due to the pharmacological action of the product. In addition, neonatal flaccidity has been reported in infants born of mothers who received sedative/hypnotic drugs during pregnancy.
Cases of severe neonatal respiratory depression have been reported when zolpidem was used at the end of pregnancy, especially when taken with other CNS depressants.
Amnesia:
Anterograde amnesia of varying severity has been reported following therapeutic doses of benzodiazepine and benzodiazepine-like hypnotics. The event is rare with IVADAL. Anterograde amnesia is a dose related phenomenon and elderly subjects may be at particular risk. Cases of transient global amnesia and “traveller's amnesia” have also been reported in association with benzodiazepines, the latter in individuals who have taken the drug often in the middle of the night, to induce sleep while traveling. Transient global amnesia and traveler’s amnesia are unpredictable and not necessarily dose-related phenomena. Patients should be warned not to take IVADAL under circumstances in which a full night's sleep (7-8 hours) and clearance of the drug from the body are not possible before they need to resume full activity.
Abnormal Thinking and other Psychiatric Behavioral Changes: A variety of abnormal thinking and other behavior changes have been reported to occur in association with the use of compounds that interact with the benzodiazepine receptors, including IVADAL, although rarely. Some of these changes may be characterized by decreased inhibition (eg. aggression and extroversion that seemed out of character), similar to effects produced by alcohol and other CNS depressants. Psychotic behavioral changes have included abnormal behavior, irritability, hallucination, anger, nightmare and depersonalization. Other neuropsychiatric symptoms may occur unpredictably. Abnormal behaviors associated with the use of benzodiazepines or benzodiazepine-like agents have been reported more with chronic use and/or high doses but they may occur during the acute, maintenance or withdrawal phases of treatment.
It can rarely be determined with certainty whether a particular instance of the abnormal behaviors listed above are drug induced, spontaneous in origin, or a result of an underlying psychiatric or physical disorder. Nonetheless, the emergence of any new behavioral sign or symptom of concern requires careful and immediate evaluation. Should these occur, use of the product should be discontinued. These reactions are more likely to occur in the elderly.
In controlled trials, <1% of adults with insomnia who received zolpidem reported hallucinations.
Cognitive Function:
Benzodiazepines and benzodiazepine-like compounds may affect concentration, attention and vigilance. This risk is greater in the elderly and in patients with cerebral impairment.
Complex sleep-related behaviours:
See boxed WARNINGS: COMPLEX SLEEP-RELATED BEHAVIOURS.
Depression:
Although no clinically significant pharmacokinetic and pharmacodynamic interactions with Selective Serotonin Reuptake Inhibitors (SSRIs) have been demonstrated (See DRUG INTERACTIONS section), as with other sedative/hypnotic drugs, caution should be exercised if IVADAL is prescribed to patients with signs or symptoms of depression that could be intensified by hypnotic drugs. The potential for self-harm (e.g. intentional overdose) is high in patients with depression and thus the least amount of IVADAL that is feasible should be available to them at any one time. Pre-existing depression may be unmasked during use of IVADAL. Since insomnia may be a symptom of depression, the patient should be re-evaluated if insomnia persists.
In primarily depressed patients, worsening of depression, including suicidal thinking, has been reported in association with the use of sedative/hypnotics.
Psychomotor Effects:
IVADAL, like other hypnotic/sedative drugs, has CNS-depressant effects. Due to the rapid onset of action, IVADAL should only be ingested immediately prior to going to bed.
Patients should be cautioned against engaging in hazardous occupations requiring complete mental alertness or motor coordination such as operating machinery or driving a motor vehicle after ingesting the drug, including potential impairment of the performance of such activities that may occur the day following ingestion of IVADAL. In order to minimize this risk a full night sleep (7-8h) is recommended.
IVADAL showed additive effects when combined with alcohol and should not be taken with alcohol. Patients should also be cautioned about possible combined effects with other CNS-depressant drugs. Dosage adjustments may be necessary when IVADAL is administered with such agents because of the potentially additive effects.
Anxiety/Restlessness:
Although not seen with IVADAL to date, an increase in daytime anxiety and/or restlessness has been observed during treatment with other hypnotics with a short elimination half-life. This is believed to be due to interdose withdrawal.
PRECAUTIONS
Abuse:
Studies of abuse potential in former drug abusers found that the effects of single doses of IVADAL 40 mg were similar, but not identical, to diazepam 20 mg, while zolpidem tartrate 10 mg was difficult to distinguish from placebo.
Tolerance:
Some loss of efficacy to the hypnotic effects of benzodiazepine and benzodiazepine-like agents including IVADAL may develop after repeated use for a few weeks.
Dependence:
Use of sedative/hypnotic agents like IVADAL may lead to the development of physical and psychological dependence. When IVADAL is used in accordance with the recommendations for dosage, duration of treatment and warnings, the risk of withdrawal symptoms or rebound phenomena occurring is minimal. The risk of dependence increases with dose and duration of treatment; it is also greater in patients with a history of psychiatric disorders and/or history of addiction to, or abuse of, drugs or alcohol. Tolerance, withdrawal or rebound phenomena have been observed when using IVADAL outside recommendations for use in these patients. As with any other hypnotic, these patients should be under careful surveillance when receiving IVADAL.
Once physical dependence has developed, abrupt termination of treatment will be accompanied by withdrawal symptoms. Benzodiazepine and benzodiazepine-like agents have produced withdrawal signs and symptoms following abrupt discontinuation. These reported symptoms range from mild dysphoria and insomnia to a withdrawal syndrome that may include abdominal and muscle cramps, vomiting, sweating, tremors, and convulsions.
Other symptoms include headache, extreme anxiety and tension, restlessness, confusion and irritability. In severe cases the following symptoms may occur: derealization, depersonalization, hyperacusis, numbness and tingling of the extremities, hypersensitivity to light, noise and physical contact, hallucinations and epileptic seizures.
The following possible withdrawal symptoms were reported during clinical trials following placebo substitution occurring within 48 hours following last zolpidem treatment: fatigue, nausea, flushing, lightheadedness, uncontrolled crying, emesis, stomach cramps, panic attack, nervousness, and abdominal discomfort. These reported adverse events occurred at an incidence of 1% or less. Consequently, abrupt discontinuation should be avoided and a gradual dosage-tapering schedule is recommended for patients taking the drug for more than a few weeks.
Rebound Insomnia:
A transient syndrome whereby the symptoms that led to treatment with sedative/hypnotic agents recur in an enhanced form, may occur on withdrawal of hypnotic treatment. It may be accompanied by other reactions including mood changes, anxiety and restlessness.
It is important that the patient should be aware of the possibility of rebound phenomena, thereby minimizing anxiety over such symptoms should they occur when the medicinal product is discontinued.
In the case of benzodiazepine and benzodiazepine-like agents with a short duration of action, withdrawal phenomena can become manifest within the dosage interval.
As with all hypnotics, repeat prescriptions should be limited to those who are under medical supervision.
Psychotic Illness:
Hypnotics such as IVADAL are not recommended for the primary treatment of psychotic illness.
Labor and Delivery:
IVADAL has no established use in labor and delivery.
Nursing Mothers:
Studies in lactating mothers indicate that the half-life of zolpidem is similar to that in young normal volunteers (2.6 ± 0.3 hr). Between 0.004 and 0.019% of the total administered dose is excreted into milk, but the effect of zolpidem on the infant is unknown. The use of IVADAL in nursing mothers is not recommended.
Pediatrics (< 18 years of age):
Safety and effectiveness of zolpidem have not been established in patients below the age of 18 years. Therefore, zolpidem should not be prescribed in this population. In an 8-week study in pediatric patients (aged 6-17 years) with insomnia associated with attention-deficit/hyperactivity disorder (ADHD), psychiatric and nervous system disorders comprised the most frequent treatment emergent adverse events observed with zolpidem versus placebo and included dizziness (23.5% vs. 1.5%), headache (12.5% vs. 9.2%), and hallucinations (7.4% vs. 0%) (see DOSAGE AND ADMINISTRATION, Pediatrics).
Geriatrics (≥ 65 years of age):
Elderly patients are especially susceptible to dose-related adverse effects, such as drowsiness, dizziness, or impaired coordination. Inappropriate, heavy sedation may result in accidental events/falls. Therefore, the recommended IVADAL dosage is 5 mg in such patients (See DOSAGE and ADMINISTRATION section).
A total of 154 patients in U.S. controlled clinical trials and 897 patients in non-U.S. clinical trials who received zolpidem were >60 years of age. For a pool of U.S. patients receiving zolpidem at doses of ≤10 mg or placebo, there were three adverse events occurring at an incidence of at least 3% for zolpidem and for which the zolpidem incidence was at least twice the placebo incidence (i.e., they could be considered drug related).
Adverse Event Zolpidem Placebo
Dizziness 3% 0%
Drowsiness 5% 2%
Diarrhea 3% 1%
A total of 30/1,959 (1.5%) non-U.S. patients receiving zolpidem reported falls, including 28/30 (93%) who were ≥ 70 years of age. Of these 28 patients, 23 (82%) were receiving zolpidem doses > 10 mg. A total of 24/1,959 (1.2%) non-U.S. patients receiving zolpidem reported confusion, including 18/24 (75%) who were ≥ 70 years of age. Of these 18 patients, 14 (78%) were receiving zolpidem doses >10 mg.
DRUG INTERACTIONS
Alcohol:
Concomitant intake with alcohol is not recommended. The sedative effect may be enhanced when the product is used in combination with alcohol (see WARNINGS, Complex-sleep related behaviours). This affects the ability to drive or use machines.
CNS-Active Drugs:
Since systemic evaluations of zolpidem tartrate in combination with other CNS-active drugs have been limited, careful consideration should be given to the pharmacology of any CNS-active drug to be used with IVADAL.
IVADAL may produce additive CNS depressant effects when co-administered with sedative antihistamines, anticonvulsants, narcotic analgesics, anesthetics or psychotropic medications (as antipsychotics (neuroleptics), hypnotics, anxiolytics, sedatives and antidepressant agents) which themselves produce CNS depression. However, In the case of SSRI antidepressant agents (fluoxetine and sertraline), no clinical significant pharmacokinetic or pharmacodynamic interactions have been observed. In the case of narcotic analgesics enhancement of euphoria may also occur leading to an increase in psychological dependence.
Drugs Affecting Cytochrome P450 Enzymes:
Compounds which inhibit cytochrome P450 may enhance the activity of some hypnotics like IVADAL. Zolpidem is metabolized via several hepatic cytochrome P450 enzymes: the main enzyme being CYP3A4 with the contribution of CYP1A2.
CYP 3A4 Inducer: The pharmacodynamic effect of zolpidem is decreased when it is administered with rifampicin (a CYP3A4 inducer).
CYP 3A4 Inhibitor:
A randomized, double-blind, crossover interaction study in ten healthy volunteers between itraconazole (200 mg once daily for 4 days) and a single dose of zolpidem (10 mg) given 5 hours after the last dose of itraconazole resulted in a 34% increase in AUC0-∞ of zolpidem.
Co-administration of a single 5 mg dose of zolpidem and ketoconazole (200 mg twice daily for 2 days), a potent CYP3A4 inhibitor, prolonged zolpidem elimination half-life, increased total AUC, and decreased apparent oral clearance when compared to IVADAL plus placebo. Co-administration with ketoconazole caused an increase in the AUC (67%) and Cmax (35%) of zolpidem and enhanced the pharmacodynamic effects of zolpidem.
The use of IVADAL with ketoconazole or other potent CYP3A4 inhibitors may enhance sedation and other effects of the drug (see WARNINGS, COMPLEX SLEEP-RELATED BEHAVIOURS). If used concomitantly with potent CYP3A4 inhibitors, caution should be exercised. Consideration should be given to using a lower dose of IVADAL.
Other drugs:
Co-administration of cimetidine / zolpidem and ranitidine / zolpidem had no effect of either drug on the pharmacokinetics or pharmacodynamics of zolpidem. Zolpidem had no effect on digoxin kinetics and did not affect prothrombin time when given with warfarin in normal subjects. Zolpidem’s sedative/hypnotic effect was reversed by flumazenil; however no significant alterations in zolpidem pharmacokinetics were found.
Drug/Laboratory Test Interactions:
Zolpidem is not known to interfere with commonly employed clinical laboratory tests. In addition, clinical data indicate that zolpidem does not cross-react with benzodiazepines, opiates, barbiturates, cocaine, cannabinoids or amphetamines in two standard urine drug screens.
ADVERSE REACTIONS
Associated with Discontinuation of Treatment: Approximately 4%, of 1,701 patients who received zolpidem at all doses in U.S. premarketing clinical trials discontinued treatment because of an adverse clinical event. Events most commonly associated with discontinuation from U.S. trials were daytime drowsiness (0.5%), dizziness (0.4%), headache (0.5%), nausea (0.6%), and vomiting (0.5%).
Approximately 4% of 1,959 patients who received zolpidem at all doses in similar non-U.S. trials discontinued treatment because of an adverse event. Events most commonly associated with discontinuation from these trials were daytime drowsiness (1,1%), dizziness/vertigo (0.8%), amnesia (0.5%), nausea (0.5%), headache (0.4%), and falls (0.4%).
Most Commonly Observed Adverse Events in Controlled Trials: During short-term treatment (up to 10 nights) with IVADAL (zolpidem tartrate) at doses up to 10 mg, the most commonly observed adverse events associated with the use of zolpidem and seen at statistically significant differences from placebo-treated patients were drowsiness (reported by 2% of zolpidem patients), dizziness (1%), and diarrhea (1%). During longer-term treatment (28 to 35 nights) with zolpidem at doses up to 10 mg, the most commonly observed adverse events associated with the use of zolpidem and seen at statistically significant differences from placebo-treated patients were dizziness (5%)
and drugged feelings (3%).
Adverse Events Observed at an Incidence of ≥ 1% in Controlled Trials:
Adults
The following tables enumerate treatment-emergent adverse event frequencies that were observed at an incidence of at least 1% and at greater frequency than in the placebo group among patients with insomnia who received IVADAL in U.S. placebo-controlled trials. Events reported by investigators were classified utilizing a modified World Health Organization (WHO) dictionary of preferred terms for the purpose of establishing event frequencies. 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 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 is conducted under a different set of conditions. However, the cited figures provide the physician with a basis for estimating the relative contribution of drug and nondrug factors to the incidence of side effects in the population studies.
The following table was derived from a pool of 11 placebo-controlled short-term U.S. efficacy trials involving zolpidem in doses ranging from 1.25 to 20 mg. The table is limited to data from doses up to and including 10 mg, the highest dose recommended for use.
Incidence of Treatment-Emergent Adverse Experiences (1% and higher than placebo) in Short-term Placebo-Controlled Clinical Trials in Adults
(Percentage of patients reporting) Body System/
Adverse Event
Zolpidem (≤ 10 mg) (N=685)
Placebo (N=473)
Central and Peripheral Nervous System
Headache
Drowsiness
Dizziness
–
–
Gastrointestinal System
Diarrhea 1 –
The following table was derived from a pool of three placebo-controlled long-term efficacy trials involving IVADAL. These trials involved patients with chronic insomnia who were treated for 28 to 35 nights with zolpidem at doses of 5, 10, or 15 mg. The table is limited to data from doses up to and including 10 mg, the highest dose recommended for use. The table includes only adverse events occurring at an incidence of at least 1% for zolpidem patients and at greater frequency than in the placebo group.
Incidence of Treatment-Emergent Adverse Experiences (1% and higher than placebo) in Long-term Placebo-Controlled Clinical Trials in Adults (Percentage of patients reporting)
Body System/ Adverse Event Zolpidem
(≤ 10 mg) (N=152)
Placebo (N=161)
Autonomic Nervous System
Dry mouth 3 1 Body as a Whole
Allergy 4 1 Back pain 3 2 Influenza-like symptoms 2 -- Chest pain 1 -- Cardiovascular System
Palpitation 2 -- Central and Peripheral Nervous System
Drowsiness 8 5 Dizziness 5 1 Lethargy 3 1 Drugged feeling 3 -- Lightheadedness 2 1 Depression 2 1 Abnormal dreams 1 -- Amnesia 1 -- Sleep disorder 1 -- Gastrointestinal System
Diarrhea 3 2 Constipation 2 1 Respiratory System
Sinusitis 4 2 Pharyngitis 3 1 Skin and Appendages
Rash 2 1
Pediatrics
Adverse Events Observed in Children with Insomnia associated with ADHD:
The following table was derived from an 8-week study in pediatric patients (aged 6-17 years) with insomnia associated with attention-deficit/hyperactivity disorder (ADHD). In this study, psychiatric and nervous system disorders comprised the most frequent treatment emergent adverse events observed with zolpidem versus placebo and included dizziness (23.5% vs. 1.5%), headache (12.5% vs. 9.2%), and hallucinations (7.4% vs. 0%) (see PRECAUTIONS, Pediatrics and DOSAGE AND ADMINISTRATION, Pediatrics).
Incidence (%) of Treatment-Emergent Adverse Experiences (1% and higher than placebo ) in a Placebo-Controlled Clinical Trials in children with insomnia associated with ADHD Body System/
Adverse Event
Zolpidem
(N=136)
Placebo (N=65)
Eye Disorders Diplopia 2.2 0 Gastrointestinal Disorders Diarrhea 2.9 1.5 Infections and infestations Nasopharyngitis 2.9 1.5 Gastroenteritis 2.9 0 Ear infection 1.5 0 Gastroenteritis viral 1.5 0 Meningitis viral 1.5 0 Pharyngitis streptococcal 1.5 0 Injury, Poisoning and Procedural
Complications
Fall 2.9 1.5 Excoriation 2.2 1.5 Injury 2.2 1.5 Joint sprain 1.5 0 Nervous System Disorders Dizziness 23.5 1.5 Headache 12.5 9.2 Drooling 1.5 0 Dysgeusia 1.5 0 Memory impairment 1.5 0 Tremor 1.5 0 Musculoskeletal and Connective Tissue
Disorders
Pain in extremity 1.5 0 Psychiatric Disorders Affect lability 2.9 0 Hallucination, visual 2.9 0 Anxiety 2.2 0 Body System/
Adverse Event
Zolpidem (N=136)
Placebo (N=65)
Hallucination 2.2 0 Hypnagogic hallucination 2.2 0 Sleep walking 2.2 0 Abnormal dreams 1.5 0 Disorientation 1.5 0 Renal and Urinary Disorders Enuresis 2.9 0
Dose Relationship for Adverse Events:
There is evidence from dose comparison trials suggesting a dose relationship for many of the adverse events associated with zolpidem use, particularly for certain CNS and gastrointestinal adverse events. Elderly patients are especially susceptible to dose-related adverse effects, such as drowsiness, dizziness, or impaired coordination.
Adverse Event Incidence Across the Entire Preapproval Database: IVADAL was administered to 3,660 subjects in clinical trials throughout the U.S., Canada, and Europe. Treatment-emergent adverse events associated with clinical trial participation were recorded by clinical investigators using terminology of their own choosing. To provide a meaningful estimate of the proportion of individuals experiencing treatment-emergent adverse events, similar types of untoward events were grouped into a smaller number of standardized event categories and classified utilizing a modified World Health Organization (WHO) dictionary of preferred terms. The frequencies presented, therefore, represent the proportions of the 3,660 individuals exposed to zolpidem, at all doses, who experienced an event of the type cited on at least one occasion while receiving zolpidem. All reported treatment-emergent adverse events are included, except those already listed in the table above of adverse events in placebo-controlled studies, those coding terms that are so general as to be uninformative, and those events where a drug cause was remote. It is important to emphasize that, although the events reported did occur during treatment with IVADAL, they were not necessarily caused by it.
Adverse 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 in greater than 1/100 subjects; infrequent adverse events are those occurring in 1/100 to 1/1,000 patients; rare events are those occurring in less than 1/1,000 patients.
Autonomic nervous system:
Infrequent: increased sweating, pallor, postural hypotension, syncope. Rare: abnormal accommodation, altered saliva, flushing, glaucoma, hypotension, impotence, increased saliva, tenesmus.
Body as a whole:
Frequent: asthenia, fatigue
Infrequent: edema, falling, fever, malaise, and trauma.
Rare: allergic reaction, allergy aggravated, abdominal body sensation, anaphylactic shock, face edema, hot flashes, increased ESR, pain, restless legs, rigors, tolerance increased, weight decrease.
Cardiovascular system:
Infrequent: cerebrovascular disorder, hypertension, tachycardia.
Rare: angina pectoris, arrhythmia, arteritis, circulatory failure, extrasystoles, hypertension aggravated, myocardial infarction, phlebitis, pulmonary embolism, pulmonary edema, varicose veins, ventricular tachycardia.
Central and peripheral nervous system:
Frequent: anxiety, ataxia, confusion, euphoria, headache, insomnia, nervousness vertigo. Infrequent: agitation, decreased cognition, detached, difficulty concentrating, dysarthria, emotional Iability, hallucination, hypoesthesia, illusion, leg cramps, migraine, paresthesia, sleeping (after daytime dosing), speech disorder, stupor, tremor. Rare: abnormal gait, abnormal thinking, aggressive reaction, apathy, appetite increased, decreased libido, delusion, dementia, depersonalization, dysphasia, feeling strange, hypokinesia, hypotonia, hysteria, intoxicated feeling, manic reaction, neuralgia, neuritis, neuropathy, neurosis, panic attacks, paresis, personality disorder, somnambulism (See WARNINGS, Complex sleep-related behaviours), suicide attempts, tetany, yawning.
Gastrointestinal system:
Frequent: abdominal pain, anorexia, dyspepsia, hiccup, nausea, vomiting. Infrequent: constipation, dysphagia, flatulence, gastroenteritis.
Rare: enteritis, eructation, esophagospasm, gastritis, hemorrhoids, intestinal obstruction, rectal hemorrhage, tooth caries.
Hematologic and lymphatic system:
Rare: anemia, hyperhemoglobulinemia, leukopenia, lymphadenopathy, macrocytic anemia, purpura, thrombosis.
Immunologic system:
Frequent: Infection.
Rare: abscess, herpes simplex, herpes zoster, otitis externa, otitis media.
Liver and biliary system:
Infrequent: abnormal hepatic function, increased SGPT.
Rare: bilirubinemia, increased SGOT.
Metabolic and nutritional:
Infrequent: hyperglycemia, thirst.
Rare: gout, hypercholesteremia, hyperlipidemia, increased alkaline phosphatase, increased BUN, periorbital edema.
Musculoskeletal system:
Frequent: arthralgia, myalgia.
Infrequent: arthritis.
Rare: arthrosis, muscle weakness, sciatica, tendinitis.
Reproduction system:
Infrequent: menstrual disorder, vaginitis.
Rare: breast fibroadenosis, breast neoplasm, breast pain.
Respiratory system:
Frequent: rhinitis, upper respiratory infection.
Infrequent: bronchitis, coughing, dyspnea.
Rare: bronchospasm, epistaxis, hypoxia, laryngitis, pneumonia.
Skin and appendages:
Infrequent: pruritus.
Rare: acne, bullous eruption, dermatitis, furunculosis, injection-site inflammation, photosensitivity reaction, urticaria.
Special senses:
Frequent: diplopia, vision abnormal.
Infrequent: eye irritation, eye pain, scleritis, taste perversion, tinnitus. Rare: conjunctivitis, corneal ulceration, lacrimation abnormal, parosmia, photopsia.
Urogenital system:
Frequent: urinary tract infection
Infrequent: cystitis, urinary incontinence.
Rare: acute renal failure, dysuria, micturition frequent, nocturia, polyuria, pyelonephritis, renal pain, urinary retention.
Postmarket Experience:
Postmarket reports of skin reactions have been reported, such as angioneurotic oedema, rash, urticaria, pruritus, and hyperhidrosis.
Cases of depressed level of consciousness have been reported, mainly in the context of a drug overdose or misuse, including high doses in elderly patients (10 mg), and also with zolpidem taken at recommended doses, mostly with concomitant CNS-depressants or CYP3A4 inhibitors or substrates. A few cases of depressed level of consciousness were reported in patients taking zolpidem alone at recommended doses.
SYMPTOMS AND TREATMENT OF OVERDOSE
Signs and Symptoms:
In cases of overdose involving zolpidem alone or with other CNS-depressant agents (including alcohol), impairment of consciousness up to coma, and more severe symptomatology, including fatal outcomes have been reported.
Recommended Treatment:
General symptomatic and supportive measures should be used along with immediate gastric lavage where appropriate. If there is no advantage in emptying the stomach, activated charcoal should be given to reduce absorption. Intravenous fluids should be administered as needed.
Flumazenil (Anexate®) is a benzodiazepine antagonist that is used as a specific antidote in known or suspected overdose with benzodiazepines or benzodiazepine-like agents. (For conditions of use see Anexate Product Monograph). Use of flumazenil may be considered where serious symptoms are observed. However, flumazenil administration may contribute to the appearance of neurological symptoms (agitation, anxiety, and convulsions).
As in all cases of drug overdose, respiration, pulse, blood pressure, and other appropriate signs should be monitored and general supportive measures employed. Hypotension and CNS depression should be monitored and treated by appropriate medical intervention. Sedating drugs should be withheld following zolpidem overdosage, even if excitation occurs.
The value of dialysis in the treatment of overdosage has not been determined, although hemodialysis studies in patients with renal failure receiving therapeutic doses have demonstrated that IVADAL is not dialyzable.
Poison Control Center:
As with the management of all overdosage, the possibility of multiple drug ingestion should be considered. The physician may wish to consider contacting a poison control center for up-to-date information on the management of hypnotic drug product overdosage.
DOSAGE AND ADMINISTRATION
As with all hypnotics, long-term use of IVADAL is not recommended. Treatment with IVADAL (zolpidem tartrate) should usually not exceed 7-10 consecutive days. Use for more than 2-3 consecutive weeks requires complete re-evaluation of the patient.
IVADAL is for oral use only. If a 5 mg dose is prescribed, patients should be instructed to split the 10 mg tablet in the score line.
Adult Dose:
The recommended daily dose for adults is 10 mg.
IVADAL acts rapidly and therefore should be taken immediately before retiring, or in bed.
Downward dosage adjustments may be necessary when IVADAL is administered with agents having known CNS-depressant effects because of the potentially additive effects (See DRUG INTERACTIONS section).
Pediatrics (< 18 years of age):
Safety and effectiveness of IVADAL in pediatric patients under the age of 18 years have not been established. Therefore, IVADAL should not be prescribed in this population (see PRECAUTIONS: Pediatric Patients).
Geriatric (≥ 65 years of age):
Since elderly or debilitated patients may be especially sensitive to the effects of IVADAL, a 5 mg dose (one-half of a 10 mg tablet) is recommended in these subjects. The total IVADAL dose should not exceed 10 mg in this population.
Hepatic impairment:
As clearance and metabolism of IVADAL is reduced in hepatic impairment, dosage should begin at 5 mg (one-half of a 10 mg tablet) in patients with mild to moderate hepatic impairment, with particular caution being exercised in elderly patients. In adults (under 65 years) dosage may be increased to 10 mg only where the clinical response is inadequate and the drug is well tolerated. IVADAL is contraindicated in severe hepatic impairment (See CONTRAINDICATIONS).
PHARMACEUTICAL INFORMATION
Drug Substance
Proper Name: Zolpidem tartrate (U.S.A.N.)
Chemical Name: 2-(4-Methylphenyl)-N,N,6-trimethylimidazo [1,2-a]pyridine-3-acetamide tartrate (2:1)
Structural Formula:
Molecular Weight: 764.88
Molecular Formula: (C19H21N30)2-C4H6O6 OR C42H48N6O8
Description:
Appearance: White to off-white, odorless, microcrystalline powder
Melting point: 193-197º C
Solubility: Sparingly soluble in water (23 mg/ml at 20ºC) (Solubility has been determined over the pH range 1-10 at
37ºC)
pKa: 6.2
pH: 4.0-5.5 (1% aqueous suspension)
Partition Coefficient: 2.42 (octano/water at pH 7.4)
Composition:
Each 10 mg tablet contains 10 mg zolpidem tartrate. Non-medicinal ingredients: cellulose, hypromellose, lactose, magnesium stearate, sodium starch glycolate. Film coating contains hypromellose, macrogol 400 and titanium dioxide. The 10 mg tablet can be split into two equal parts of 5 mg.
Storage:
Store at 15 – 30ºC.
AVAILABILITY
IVADAL 10 mg is available as while to off-white, film coated oblong tablets, scored and engraved with SN10 on one side and the supplied in blister strips of 10 tablets to yield 30, 100 or 150 tablets per carton.