From the FDA Drug Label
The mean zolpidem tartrate 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. The half-life of zolpidem is approximately 2.5-2.6 hours in healthy subjects, with a range of 1.4 to 4.5 hours 1.
- The half-life may be increased in certain populations, such as the elderly or those with hepatic impairment.
From the Research
The half-life of zolpidem is approximately 2.4 hours, as reported in the most recent and highest quality study 2. This relatively short half-life explains why zolpidem is effective for sleep initiation but may not maintain sleep throughout the entire night for some patients. The drug is metabolized primarily by the liver through oxidation and hydroxylation, with the resulting metabolites being pharmacologically inactive. Certain populations may experience longer half-lives:
- elderly patients (up to 4 hours),
- those with hepatic impairment (up to 10 hours),
- and women (about 20% longer than men) 3. This extended half-life in specific populations explains why lower doses are often recommended for these groups to prevent morning drowsiness and impairment. The extended-release formulation (Ambien CR) has a similar initial half-life but is designed to release additional medication gradually to maintain therapeutic levels longer throughout the night. It's worth noting that the half-life of zolpidem can vary depending on the formulation, with the immediate-release formulation having a terminal elimination half-life of 2.4 hours 2, and the extended-release formulation having a similar initial half-life but with a longer duration of action. Overall, the half-life of zolpidem is an important consideration in its use for the treatment of insomnia, and healthcare providers should take this into account when prescribing the medication, especially in certain populations that may be more susceptible to its effects 4.