Rifampicin and ritonavir are:
Physical antagonist
Chemical antagonist
Pharmacokinetic antagonist
Competitive antagonist
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.
General Pharmacology