Rifampicin and ritonavir are:: (A) Physical antagonist, (B) Chemical antagonist, (C) Pharmacokinetic antagonist, (D) Competitive antagonist
Answer is C. Ans. C. Pharmacokinetic antagonista. Rifampicin is an enzyme inducer of CY3A4 and ritonavir is metabolized by CYP3A4.b. Thus rifampicin can antagonize ritonavir by inducing its metabolism; known as pharmacokinetic antagonism.