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:
Chronic administration of phenobarbital with the drug
Chronic administration of cimetidine with the drug
Displacement from tissues binding sites by another drug
Chronic administration of rifampicin
- Microsomal enzyme inducers- Rifampicin, Phenobarbital- will increase the activity of enzymes, leading to decreased duration of action of a drug.
- Microsomal enzyme inhibitor- Cimetidine- will decrease the activity of enzyme resulting in increased duration of action of the drug.
- A drug displaced from the binding site gets easily metabolized.