AIIMS November 2011 – MCQ 102

Correct match of drug and its metabolic enzyme are all except?
A. Digoxin – P glycoprotein
B. Simvastatin – Glucuronidation
C. Verapamil – CYP3A4
D. Carvedilol- CYP2D6

Correct answer : B. Simvastatin – glucuronidation (Simvastatin is metabolised by CYP2D6 – refer table given below)

Molecular Pathways Mediating Drug Disposition

Molecule	Substrates	Inhibitors
CYP3A	Calcium channel blockers Antiarrhythmics (lidocaine, quinidine, mexiletine) HMG-CoA reductase inhibitors (statins) Cyclosporine, tacrolimus Indinavir, saquinavir, ritonavir	Amiodarone Ketoconazole, itraconazole Erythromycin, clarithromycin Ritonavir
CYP2D6	Timolol, metoprolol, carvedilol Phenformin Codeine Propafenone, flecainide Tricyclic antidepressants Fluoxetine, paroxetine	Quinidine (even at ultra-low doses) Tricyclic antidepressants Fluoxetine, paroxetine
CYP2C9	Warfarin Phenytoin Glipizide Losartan	Amiodarone Fluconazole Phenytoin
CYP2C19	Omeprazole Mephenytoin Clopidogrel	Omeprazole
Thiopurine S-methyltransferase	6-Mercaptopurine, azathioprine
N-acetyltransferase	Isoniazid Procainamide Hydralazine Some sulfonamides
UGT1A1	Irinotecan
Pseudocholinesterase	Succinylcholine
P-glycoprotein	Digoxin HIV-protease inhibitors Many CYP3A substrates	Quinidine Amiodarone Verapamil Cyclosporine Itraconazole Erythromycin

Ref: Harrison 18th, chapter 5 : Table 5-1