RESUMO
Ritonavir (RTV) is not only an inhibitor but also an immunoreactive inducer of both P-glycoprotein (Pgp) and cytochrome P450 (CYP) 3A in terms of its chronic use. The aim of present study was to test the hypothesis that the power balance between inhibition effects of RTV and induced activities of Pgp and CYP3A depends on the time after last RTV treatment (TimeR) in the chronic use of RTV; rhodamine 123 (Rho) and midazolam (MDZ) were administered at predetermined TimeR to rats pretreated with RTV for 7 days. After oral administration of Rho and MDZ to rats pretreated with RTV for 7 days, the areas under the plasma concentration-time curve of Rho and MDZ were significantly altered depending on TimeR: 1.27-, 0.79-, 0.95-, and 0.11-fold increases over that of the control for Rho at TimeR = 0, 3, 9, and 24 h and 3.12-, 1.50-, 1.27-, and 0.17-fold increases over that of the control for MDZ at TimeR = 0, 3, 9, and 24 h, respectively. These results revealed the presence of the time-dependent interaction of RTV with concomitant drugs in chronic use and should be taken into account in therapeutic strategies for HIV infection.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Citocromo P-450 CYP3A/metabolismo , Inibidores da Protease de HIV/administração & dosagem , Inibidores da Protease de HIV/farmacocinética , Ritonavir/administração & dosagem , Ritonavir/farmacocinética , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/antagonistas & inibidores , Animais , Inibidores do Citocromo P-450 CYP3A , Interações Medicamentosas , Infecções por HIV/tratamento farmacológico , Inibidores da Protease de HIV/metabolismo , Inibidores da Protease de HIV/farmacologia , Humanos , Masculino , Midazolam/administração & dosagem , Midazolam/metabolismo , Midazolam/farmacocinética , Midazolam/farmacologia , Ratos , Ratos Wistar , Rodamina 123/administração & dosagem , Rodamina 123/metabolismo , Rodamina 123/farmacocinética , Rodamina 123/farmacologia , Ritonavir/metabolismo , Ritonavir/farmacologiaRESUMO
Atazanavir (ATV) has been successfully used in HIV patients with severe hyperlipidemia (HL); however, little is known about the pharmacokinetics of ATV in HL. The aim of this study was to investigate the pharmacokinetics of ATV in HL. With the increase of serum lipids, the protein binding rate in HL rats (approximately 97%) was significantly higher than that in control (approximately 87%). After intravenous (iv), oral (po) and intraportal (ip) administration of ATV at a dosage of 7 mg/kg, AUCs in HL rats were 12.41, 5.24 and 8.89 microg/mLh, respectively, and were significantly higher than those in control rats (4.09, 1.70 and 3.38 microg/mLh). Despite the decrease of distribution volume (Vd(ss)), the terminal half-life (t(1/2)) in HL tended to be shorter than in control, and hepatic distribution of ATV in HL rats was 4.8-fold increases. These results suggested that the uptake of ATV into liver might counteract the decrease of Vd(ss). On the other hand, there was no significant difference in bioavailability, and the lymphatic transport to AUC showed no statistical change. In conclusion, although the protein binding rate and AUC were significantly increased, the pharmacokinetics of ATV might be tolerated in HL.
