Table 2.

Cytochrome P450 substrates, inducers, and inhibitors commonly encountered in the ICU [6, 7, 11, 13, 15, 17]

Enzyme	Major substrates	Inducers	Inhibitors
CYP 1A2	Caffeine, ropivacaine, amitriptyline, imipramine, clozapine, haloperidol	Rifampicin, carbamazepine, insulin tobacco	Ciprofloxacin, erythromycin, cimetidine
CYP 2B6	Ketamine, propofol	Phenobarbital	No known inhibitors
CYP 2C9	Irbesartan, losartan, warfarin, phenytoin, voriconazole, glibenclamide, glipizide, glyburide, NSAIDS	Rifampicin, phenobarbital, phenytoin, carbamazepine	Isoniazid, metronidazole, trimethoprim-sulfamethoxazole, paroxetine, sertraline, amiodarone, fluconazole
CYP 2C19	Amitriptyline, escitalopram, imipramine, diazepam, cyclophosphamide (prodrug), PPIs, voriconazole, phenytoin	Rifampicin, phenobarbital, phenytoin, carbamazepine	Fluoxetine, paroxetine, PPIs
CYP 2D6	Serotonin 5HT3 blockers ondansetron, tropisetron, dextromethorphan, codeine, tramadol (prodrugs), lidocaine, amitriptyline, fluoxetine, venlafaxine, imipramine, paroxetine, haloperidol, perphenazine, risperidone, beta-blockers	Rifampicin, dexamethasone	Paroxetine, sertraline, amiodarone chlorpheniramine, hydroxyzine, promethazine, cimetidine, ranitidine celecoxib, cocaine
CYP 2E1	Acetaminophen, inhaled anaesthetics: enflurane, isoflurane, sevoflurane, ethanol	Isoniazid, ethanol, tobacco	Alcoholism recovery, disulfiram
CYP 3A4	Alfentanil, fentanyl, lidocaine, clarithromycin, erythromycin, carbamazepine, haloperidol, diazepam, midazolam, amlodipine, diltiazem, nifedipine, verapamil, statins: atorvastatin, lovastatin (prodrug), simvastatin (prodrug) hydrocortisone, methylprednisolone, HIV protease inhibitors, hormones, estradiol, progesterone, cyclosporine, tacrolimus	Rifampicin, macrolides, imidazoles, carbamazepine, phenytoin, phenobarbital, steroids, HIV NNRTIs, pioglitazone	Ciprofloxacin, clarithromycin, erythromycin, amiodarone, fluconazole, itraconazole, ketoconazole diltiazem, verapamil, amlodipine cimetidine HIV protease inhibitors

HIV human immunodeficiency virus protease inhibitors—indinavir, nelfinavir, ritonavir, saquinavir, ICU intensive care unit, NNRTIs non-nuclease reverse transcriptase inhibitors, NSAIDs nonsteroidal anti-inflammatory drugs—celecoxib, diclofenac, ibuprofen, naproxen, PPIs proton pump inhibitors—lansoprazole, omeprazole, pantoprazole, beta-blockers—carvedilol, metoprolol propranolol