Pharmacology A factor that is likely to increase the duration of action of a drug D that is partially metabolized by CYP3A4 in the liver is: A Chronic administration of phenobarbital with the drug B Chronic administration of cimetidine with the drug C Displacement from tissues binding sites by another drug D Chronic administration of rifampicin 💡 Explanation A factor that is likely to increase the duration of action of a drug D that is partially metabolized by CYP3A4 in the liver is: ✓ Correct Answer: B. Chronic administration of cimetidine with the drug