European Journal of Clinical Pharmacology

, Volume 63, Issue 5, pp 479–483

Effect of efavirenz on the pharmacokinetics of ketoconazole in HIV-infected patients

  • Somchai Sriwiriyajan
  • Werawath Mahatthanatrakul
  • Wibool Ridtitid
  • Sutep Jaruratanasirikul
Pharmacokinetics and Disposition

DOI: 10.1007/s00228-007-0282-8

Cite this article as:
Sriwiriyajan, S., Mahatthanatrakul, W., Ridtitid, W. et al. Eur J Clin Pharmacol (2007) 63: 479. doi:10.1007/s00228-007-0282-8

Abstract

Objective

To investigate the effect of efavirenz on the ketoconazole pharmacokinetics in HIV-infected patients.

Methods

Twelve HIV-infected patients were assigned into a one-sequence, two-period pharmacokinetic interaction study. In phase one, the patients received 400 mg of ketoconazole as a single oral dose on day 1; in phase two, they received 600 mg of efavirenz once daily in combination with 150 mg of lamivudine and 30 or 40 mg of stavudine twice daily on days 2 to 16. On day 16, 400 mg of ketoconazole was added to the regimen as a single oral dose. Ketoconazole pharmacokinetics were studied on days 1 and 16.

Results

Pretreatment with efavirenz significantly increased the clearance of ketoconazole by 201%. Cmax and AUC0−24 were significantly decreased by 44 and 72%, respectively. The T½ was significantly shorter by 58%.

Conclusion

Efavirenz has a strong inducing effect on the metabolism of ketoconazole.

Keywords

Drug interaction Efavirenz Ketoconazole HIV-infected patients Pharmacokinetics 

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Somchai Sriwiriyajan
    • 1
  • Werawath Mahatthanatrakul
    • 2
  • Wibool Ridtitid
    • 2
  • Sutep Jaruratanasirikul
    • 1
  1. 1.Department of Medicine, Faculty of MedicinePrince of Songkla UniversitySongkhlaThailand
  2. 2.Department of Pharmacology, Faculty of SciencePrince of Songkla UniversitySongkhlaThailand

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