Nevirapine Antacids

Drugs that may affect itraconazole include antacids, carbamazepine, didanosine, H2 antagonists, hydantoins, macrolide antibiotics, nevirapine, phenobarbital, phenytoin, protease inhibitors, proton pump inhibitors, and rifamycins. 

Drugs that may affect atazanavir include the following antacids and buffered medications, clarithromycin, didanosine (buffered formulation only), efavirenz, H2-receptor antagonists, indinavir, itraconazole, ketoconazole, nevirapine, proton pump inhibitors, rifampin, ritonavir, St. John s wort, tenofovir, voriconazole. 

After oral administration, nevirapine is rapidly absorbed with a bioavailability of 93%, and peak plasma concentrations are achieved in 4h. Food or antacids do not interfere with its absorption. It is very lipophilic, crosses the placenta and its presence has been reported in breast milk. Nevirapine is mainly metabolized by the cytochrome P-450 system (CYP3A4 and CYP2B6) to hydroxy-lated metabolites, and after metabolism, the primary route of excretion is through urine. It has an elimination half-life of 25-30 h. Nevirapine can induce its own metabolism by stimulating the cytochrome P-450 system, which results in the reduction of the half-life of subsequent doses. In combination with other antiretroviral agents, nevirapine is recommended for the treatment of HIV infection in adults and children. It should not be administered alone since resistance develops rapidly. 

Nevirapine is well absorbed, and its bioavailability is not altered by food or antacids. The drug readily crosses the placenta and has been found in breast milk, a feature that has encouraged use of nevirapine for prevention of mother-to-child transmission of HIV. 

Antacids roughly halve the AUC of delavirdine, and the 112-receptor antagonists or proton pump inhibitors would be expected to interact similarly. Aluminium/magnesium antacids do not interact to a clinically relevant extent with efavirenz or nevirapine, and famotidine does not alter the absorption of efavirenz. 

Lamson M, Cort S, Macy H, Love J, Korpalski D, Pav J, Keims J. Effects of food or antacid on the bioavailability of nevirapine 200 mg tablets. 11 International Conference on AIDS, Vancouver, 1996. Abstract Tu.B.2323. 

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