Cytochrome P450 : Alphabetical drug list
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1A2 2C9 2C19 2D6 2E1 3A4
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Drug CYP interaction Clinical consequences
rabeprazole 3A4, 2C19 (no significant interactions. Metabolism similar to that of other PPIs but less dependent on 2C19) ? nil.
ranitidine (See also cimetidine) 2D6 : inhibits (also 1A2, 3A4) ? little clinical significance
rapamycin : See sirolimus
retinol, retinoic acid {even cholecalciferol} inhibit 1A1, 2C8, 2C19 [Xenobiotica 1999 Mar;29(3):231-41] ?
CYP26 : METABOLISM (and induction) [J Biol Chem 2000 Mar 10;275(10):6908-14] ?
1A2, 3A4 : convert retinol to retinal (rate-limiting, in liver) ?
1A1, 1B1 : extrahepatic conversion of retinol to retinal [Drug Metab Dispos 2000 Mar;28(3):315-22] ?
1A1, 1A2, 1B1 and 3A4 convert retinal to retinoic acid [Drug Metab Dispos 2000 Mar;28(3):292-7] ?
2C8 : 4-hydroxylates all-trans retinoic acid [Biochem Pharmacol 1999 Oct 1;58(7):1201-8] ?
rifabutin CYP3A4 : induces Similar to rifampicin
rifampicin (rifampin) CYP3A4 : INDUCES
(and metabolism)
increases eg quinidine clearance also well documented interactions with warfarin, oral contraceptives, cyclosporine, glucocorticoids, ketoconazole, theophylline, digitoxin, and verapamil [Arch Intern Med 1997 Nov 24;157(21):2453-8] as well as protease inhibitors, zidovudine, delavirdine, itraconazole, nifedipine, midazolam, triazolam, nortriptyline, doxycycline.
CYP2C9 : INDUCES less warfarin effect
CYP2E1 : metabolism ?
2C19 : INDUCES ! ?
riluzole CYP1A2 ?
risperidone (antipsychotic) 2D6 : metabolism ?
ritonavir (See also Protease Inhibitors CYP2C9 : INHIBITS ?
2D6 : INHIBITS (Ki 4.8 µmol) ?
3A4 : INHIBITS (Ki 0.14) Lower elimination of other HIV PIs, clarithromycin, ketoconazole, rifabutin
3A4 : metabolism minimal effect of other agents (rifampicin, ketoconazole)! [Clin Pharmacokinet 1998 Oct;35(4):275-91]
2D6 : metabolism ?
rokitamycin 'practically NO CYP3A inhibition' [J Pharm Pharmacol 1999 Oct;51(10):1167-74] although Zhao et al report a Ki of 5.8 µM [Drug Metab Dispos 1999 Jul;27(7):776-85] 'nil' ?
ropinirole (anti-parkinsonian) CYP1A2 : metabolism no interaction with theophylline
ropivacaine CYP1A2 : metabolism ?
CYP3A4 : metabolism ?
rosiglitazone 2C9 : substrate ?

Quick Links:
1A2 2C9 2C19 2D6 2E1 3A4

Page author: jo@anaesthetist.com Last update: 2000-6-22