Zolpidem tartrate

Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Stilnox (Sanofi Synthelabo)
10 mg tablets
Approved indication: insomnia
Australian Medicines Handbook Section 18.4.2

Zolpidem acts on benzodiazepine receptors. Although it has a different structure and is said to be more selective in its action, zolpidem has similar effects to the benzodiazepines.

The drug is rapidly absorbed and peak plasma levels are reached within 3 hours. First-pass metabolism reduces bioavailability to 70%. The liver also eliminates most of the drug with only 1% appearing unchanged in the urine. A lower dose is recommended for the elderly and patients with hepatic impairment. Zolpidem has a half-life of two hours, but its hypnotic effect can last up to 6 hours.

In clinical trials, zolpidem has been more effective than placebo in treating chronic insomnia, but does not appear to have any advantage over temazepam.

Adverse effects caused 4% of patients in clinical trials to discontinue zolpidem. These effects included dizziness, headache, nausea and daytime drowsiness. Dizziness was the most common adverse effect reported in patients taking zolpidem for 28-35 nights. All patients should be warned of the possible risk of feeling drowsy the morning after taking zolpidem. The drug interacts with others, such as alcohol, which depress the central nervous system.

Patients complaining of insomnia need to be assessed to exclude underlying causes such as depression. Often insomnia does not require drug treatment. If a patient is prescribed zolpidem, they should take it for less than 4 weeks. The potential for withdrawal, tolerance or rebound insomnia is uncertain. Higher doses should not be used because, like other benzodiazepines, they have been associated with amnesia.