Somex

Uses

Somex is used for the short-term treatment of insomnia characterized by difficulties with sleep initiation. Somex has been shown to decrease sleep latency for up to 35 days in controlled clinical studies The clinical trials performed in support of efficacy were 4-5 weeks in duration with the final formal assessments of sleep latency performed at the end of treatment.

Somex is also used to associated treatment for these conditions: Insomnia

How Somex works

Somex, the active moiety of zolpidem tartrate, is a hypnotic substance with a chemical structure that is not related to the structure benzodiazepines, barbiturates, pyrrolopyrazines, pyrazolopyrimidines or other drugs exerting hypnotic effects. It interacts with a GABA-BZ receptor complex and shares various pharmacological properties with the benzodiazepine class of drugs .

Subunit binding of the GABAA receptor chloride channel macromolecular complex is thought to lead to the sedative, anticonvulsant, anxiolytic, and myorelaxant drug effects of zolpidem. The main regulatory site of the GABAA receptor complex can be found on its alpha (α) subunit and is called the benzodiazepine (BZ) or omega (ω) receptor. At least three different subtypes of the (ω) receptor have been identified to this date .

In contrast to benzodiazepine drugs, which are found to modulate all benzodiazepine receptor subtypes in a non-selective fashion, zolpidem binds the (BZ1) receptor specifically with a potent affinity for the alpha 1/alpha 5 subunits (in vitro) . More recent studies suggest that zolpidem binds primarily to the alpha 1, 2, and 3 subunits of the GABA receptor , , , and not the alpha 5 subunit.

The (BZ1) receptor is found primarily on the Lamina IV of the brain sensorimotor cortical regions, substantia nigra (pars reticulata), cerebellum molecular layer, olfactory bulb, ventral thalamic complex, pons, inferior colliculus, and globus pallidus. Specific and selective binding of zolpidem on the (BZ1) receptor is not considered absolute, however, this binding could potentially explain the relative lack of myorelaxant and anticonvulsant activity in animal studies in addition to the preservation of deep sleep (stages 3 and 4) in human studies of zolpidem at hypnotic doses .

Dosage

Somex dosage

Dosage In Adults: Use the lowesteffective dosefor the patient. The recommended initial dose is 5 mg for women and either 5 or 10 mg for men, taken only once per night immediately before bedtime with at least 7–8 hours remaining before the planned time of awakening. If the 5 mg dose is not effective, the dose can be increased to 10 mg. In some patients, the higher morning blood levels following use of the 10 mg dose increase the risk of next day impairment of driving and other activities that require full alertness. The total dose of Somex should not exceed 10 mg once daily immediately before bedtime. Somex should be taken as a single dose and should not be readministered during the same night.The recommended initial doses for women and men are different because zolpidem clearance is lower in women.Special Populations: Elderly or debilitated patients may be especially sensitive to the effects of zolpidem tartrate. The recommended dose of Somex in these patients is 5 mg once daily immediately before bedtimePatients with mild to moderate hepatic impairment do not clear the drug as rapidly as normal subjects. The recommended dose of Somex in these patients is 5 mg once daily immediately before bedtime. Avoid Somex use in patients with severe hepatic impairment as it may contribute toencephalopathyUse With CNS Depressants: Dosage adjustment may be necessary when Somex is combined with other CNS depressant drugs because of the potentially additive effects

The effect of Somex may be slowed by ingestion with or immediately after a meal.

Side Effects

Atypical thinking and behaviour, hallucination, nightmare, somnolence, somnambulism, headache, nausea, vomiting, dizziness, vertigo, drowsiness, asthenia, ataxia, rebound insomnia, amnesia, GI disturbances, upper and lower respiratory tract infection, fatigue, visual disturbances, increased ALT serum concentrations, abnormal LFT.

Toxicity

Oral (male rat) LD₅₀ = 695 mg/kg .

Overdose

Symptoms of overdose include impairment of consciousness ranging from somnolence to light coma, in addition to cardiorespiratory collapse resulting in fatal outcomes have been reported .

Withdrawal effects

Following rapid decreases in dose or abrupt discontinuation of zolpidem and other sedative/hypnotics, reports of signs and symptoms similar to those associated with withdrawal from other CNS-depressant drugs have been made .

Carcinogenesis

Somex was administered to rats and mice over a span of 2 years at dietary dosages of 4, 18, and 80 mg/kg/day. In mice, these doses are considered 26 to 520 times or 2 to 35 times the maximum 10 mg human dose, respectively. In rats, these doses are 43 to 876 times or 6 to 115 times the maximum 10 mg human dose. No evidence of carcinogenicity was seen in mice. Renal liposarcomas were observed in 4/100 rats (3 males, 1 female) receiving 80 mg/kg/day, and a renal lipoma was observed in one male rat at the 18 mg/kg/day dose. Incidence rates of lipoma and liposarcoma for zolpidem were similar to those seen in historical control cases, and the tumor findings are presumed to be a spontaneous occurrence, not causally related to zolpidem .

Mutagenesis

Somex did not show mutagenic activity in several tests including the Ames test, genotoxicity in mouse lymphoma cells in vitro, chromosomal aberrations in cultured human lymphocytes, abnormal DNA synthesis in rat hepatocytes in vitro, and the micronucleus test performed in mice .

Impairment of fertility

In a rat reproduction study, the high dose (100 mg base/kg) of zolpidem lead to irregular estrus cycles and prolonged precoital intervals, however, there was no effect on male or female fertility after daily oral doses comparable to 5 to 130 times the recommended human dose. No effects on any other fertility parameters were observed .

Use in pregnancy

This drug is considered a pregnancy category C drug. There are currently no sufficient conclusive studies completed in pregnant women to determine the safety of zolpidem use during pregnancy. Somex should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus.

Use in nursing

From 0.004% to 0.019% of the total administered zolpidem dose is excreted into milk. The effect of zolpidem on the nursing infant is unknown at this time. Caution should be observed when zolpidem is administered to a nursing mother .

Precaution

Obstructive sleep apnoea, myasthenia gravis, compromised respiratory function. Patients exhibiting symptoms of depression. History of drug or alcohol abuse. Avoid abrupt withdrawal and rapid dose reduction after prolonged therapy. Re-evaluate if insomnia fail to remit after 7-10 days as this may indicate the presence of underlying psychiatric and/or medical condition. Pregnancy, lactation, childn <18 yr.

Interaction

Co-administration of zolpidem with other CNS depressants increases the risk of CNS depression. Concomitant use of zolpidem with these drugs may increase drowsiness and psychomotor impairment, including impaired driving ability. Somex tartrate was evaluated in healthy volunteers in single-dose interaction studies for several CNS drugs.Imipramine, Chlorpromazine: Imipramine in combination with zolpidem produced no pharmacokinetic interaction other than a 20% decrease in peak levels of imipramine, but there was an additive effect of decreased alertness. Similarly, chlorpromazine in combination with zolpidem produced no pharmacokinetic interaction, but there was an additive effect of decreased alertness and psychomotor performance Haloperidol: A study involving haloperidol and zolpidem revealed no effect of haloperidol on the pharmacokinetics or pharmacodynamics of zolpidem. The lack of a drug interaction following single-dose administration does not predict the absence of an effect following chronic administration Alcohol: An additive adverse effect on psychomotor performance between alcohol and oral zolpidem was demonstrated Sertraline: Concomitant administration of zolpidem and sertraline increases exposure to zolpidemFluoxetine: After multiple doses of zolpidem tartrate and fluoxetine an increase in the zolpidem half-life (17%) was observed. There was no evidence of an additive effect in psychomotor performance

Food Interaction

• Avoid alcohol.
• Take separate from meals. This drug should not be administered with or immediately after a meal.

[Moderate] GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of zolpidem.

Use in combination may result in additive central nervous system depression and
ADJUST DOSING INTERVAL: Administration of zolpidem with food may delay the onset of hypnotic effects.

In 30 healthy subjects, administration of zolpidem 20 minutes after a meal resulted in decreased mean peak plasma drug concentration (Cmax) and area under the concentration-time curve (AUC) by 25% and 15%, respectively, compared to fasting.

The time to reach peak plasma drug concentration (Tmax) was prolonged by 60%, from 1.4 to 2.2 hours.

MANAGEMENT: Patients receiving zolpidem should be advised to avoid the consumption of alcohol.

For faster sleep onset, zolpidem should not be administered with or immediately after a meal.

Somex Drug Interaction

Major: acetaminophen / hydrocodoneModerate: diphenhydramine, duloxetine, escitalopram, pregabalin, metoprolol, metoprolol, alprazolam, cetirizineUnknown: amphetamine / dextroamphetamine, aspirin, rosuvastatin, omega-3 polyunsaturated fatty acids, esomeprazole, albuterol, levothyroxine, acetaminophen, cyanocobalamin, ascorbic acid, cholecalciferol

Somex Disease Interaction

Major: alcohol intox, depression, drug dependence, liver diseaseModerate: glaucoma, liver disease, resp depression, renal dysfunction

Volume of Distribution

0.54 to 0.68 L/kg (in humans) . In patients with long term renal insufficiency who were not yet on hemodialysis, the volume of distribution was found to increase significantly, AUC increased by 60%, and half-life nearly doubled .

Elimination Route

Somex is rapidly absorbed from the gastrointestinal tract. In a single-dose crossover study in 45 healthy subjects given 5 and 10 mg zolpidem tartrate tablets, the average peak zolpidem concentrations (Cmax) were 59 and 121 ng/mL, respectively, occurring at a mean time (Tmax) of 1.6 hours for both doses .

Half Life

The average zolpidem elimination half-life was 2.6 and 2.5 hours, for the 5 and 10 mg tablets, respectively .

Clearance

In a clinical trial, after a 20mg dose, total clearance of zolpidem 0.24 to 0.27 ml/min/kg .

Elimination Route

Somex tartrate tablets are converted to inactive metabolites that are eliminated mainly by renal excretion .

Pregnancy & Breastfeeding use

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Contraindication

Severe hepatic impairment.

Special Warning

Pediatric Use: Somex is not recommended for use in children. Safety and effectiveness of zolpidem in pediatric patients below the age of 18 years have not been established.

Acute Overdose

Symptoms: Drowsiness, impairment of consciousness from somnolence to coma, compromised CV and respiratory function. Management: Treatment is largely symptomatic and supportive. IV fluids should be administered as needed. Activated charcoal may be given if presented w/in 1 hr of ingestion of >1 mg/kg zolpidem in adults or childn. Gastric lavage may be considered if presented w/in 1 hr of ingestion of >100 mg zolpidem and monitor for at least 12 hr. Flumazenil may be used if there is severe CNS depression, but generally not needed. Haemodialysis is unlikely to be useful.

Storage Condition

Store between 20-25° C.

Innovators Monograph

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