Effect of efavirenz on the pharmacokinetics of ketoconazole in HIV-infected patients
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- Sriwiriyajan, S., Mahatthanatrakul, W., Ridtitid, W. et al. Eur J Clin Pharmacol (2007) 63: 479. doi:10.1007/s00228-007-0282-8
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To investigate the effect of efavirenz on the ketoconazole pharmacokinetics in HIV-infected patients.
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.
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%.
Efavirenz has a strong inducing effect on the metabolism of ketoconazole.