Effects of CYP2B6 Genetic Polymorphisms on Efavirenz Pharmacokinetics

1. To see how the liver breaks down efavirenz by an enzyme called CYP2B6. It is suggested that when Efavirenz is taken repeatedly it may increase the amount of CYP2B6 in your liver and thus speed up your liver's ability to get rid of efavirenz from your body. This may render efavirenz and other medications ineffective. 2. To see how efavirenz interact with other drugs taken at the same time with it. 3. To see if genetic differences can change the way how the liver breaks down efavirenz and its interactions with other co-administered drugs.