Belbien is an imidazopyridine derivative that acts by binding to the benzodiazepine (BZD) receptors of the GABA receptor complex resulting in neuronal hyperpolarisation, action potential inhibition, increased in chloride conductance and decreased in neuronal excitability. It has strong sedative action but only minimal anxiolytic, myorelaxant and anticonvulsant properties due to its selectivity for the BZ1-receptor over the BZ2-receptor. Belbien has a rapid onset but short duration of hypnotic action.

Effects on the central nervous system (CNS)

This drug has CNS depressant effects, which may include somnolence, decreased alertness, sedation, drowsiness, dizziness, and other changes in psychomotor function . Due to the above effects, the FDA has recommended an initial dose of zolpidem (immediate-acting) is a single dose of 5 mg for women and a single dose of 5 or 10 mg for men, immediately before bedtime with at least 7-8 hours remaining before the planned time of awakening . Refer to product labeling for detailed information , .

Effects on memory

Uses

Belbien is used for the short-term treatment of insomnia characterized by difficulties with sleep initiation. Belbien 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.

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

How Belbien works

Belbien, 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

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 Belbien should not exceed 10 mg once daily immediately before bedtime. Belbien 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 Belbien 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 Belbien in these patients is 5 mg once daily immediately before bedtime. Avoid Belbien use in patients with severe hepatic impairment as it may contribute toencephalopathyUse With CNS Depressants: Dosage adjustment may be necessary when Belbien is combined with other CNS depressant drugs because of the potentially additive effects

The effect of Belbien 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

Belbien 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

Belbien 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. Belbien 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 .