This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
Rifampicin and ritonavir are: 
Select and explain. 
A. Physical antagonist, B. Chemical antagonist, C. Pharmacokinetic antagonist, D. Competitive antagonist
C: Pharmacokinetic antagonist
Answer: C: Pharmacokinetic antagonist 
Explanation: 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.