Zaleplon pharmacokinetics and absolute bioavailability

Biopharm Drug Dispos. 1999 Apr;20(3):171-5. doi: 10.1002/(sici)1099-081x(199904)20:3<171::aid-bdd169>;2-k.


The pharmacokinetics and absolute oral bioavailability of zaleplon were assessed to evaluate the extent of presystemic metabolism of this new nonbenzodiazepine hypnotic agent. A partially randomized, single-dose, four-period crossover study was conducted in 23 healthy subjects. Subjects received 1 and 2.5 mg intravenous (i.v.) infusions of zaleplon during the first and second periods, respectively, and then were randomly assigned to receive a 5 mg oral dose or 5 mg i.v. infusion of zaleplon in a crossover design during the final two periods. Zaleplon pharmacokinetics were determined in 20 subjects (ten men and ten women) after the two 5 mg treatments. The oral and i.v. doses of zaleplon administered in this study were safe and well-tolerated. Following i.v. administration, zaleplon had a moderate to high systemic clearance (mean +/- S.D., 0.94 +/- 0.20 L/h/kg), rapid elimination (half-life, t1/2 = 1.05 +/- 0.13 h), and a steady-state volume of distribution of 1.27 +/- 0.25 L/kg, indicating substantial distribution into extravascular tissues. Zaleplon was rapidly absorbed after oral administration, and the mean apparent elimination t1/2 was similar to that obtained after i.v. infusion. The absolute bioavailability was 30.6 +/- 10.2%.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Acetamides / adverse effects
  • Acetamides / blood
  • Acetamides / pharmacokinetics*
  • Adolescent
  • Adult
  • Biological Availability
  • Cross-Over Studies
  • Female
  • Humans
  • Hypnotics and Sedatives / adverse effects
  • Hypnotics and Sedatives / blood
  • Hypnotics and Sedatives / pharmacokinetics*
  • Male
  • Middle Aged
  • Pyrimidines / adverse effects
  • Pyrimidines / blood
  • Pyrimidines / pharmacokinetics*


  • Acetamides
  • Hypnotics and Sedatives
  • Pyrimidines
  • zaleplon