CYP isoenzymes
# = found in lung tissue
CYP3 1 subfamily, 3 genes, 2 pseudogenes
(drug metabolism) 3A3 is an artefact.
Isoenzyme Substrates Inducer Inhibitor Alleles Effects (alleles, interactions)
(about 30% of liver CYP, 70% of small intestinal CYP)
terfenadine, astemizole, azelastine, (fexofenadine is safe), midazolam, alprazolam, triazolam, cyclosporin A, tacrolimus, haloperidol, tirilazad, Ca channel blockers (diltiazem, verapamil, felodopine, ..), cisapride,
alfentanil, sufentanil, fentanyl, erythromycin, TCA, dextromethorphan, codeine, granisetron, lignocaine, ropivacaine, hydrocortisone, dexamethasone, ethinyl oestradiol, testosterone, carbamazepine, glyburide, ketoconazole, lovastatin, (theophylline), HIV protease inhibitors, taxol, lansoprazole, ? propafenone metabolites coumarin activation!
rifampicin, rifabutin, glucocorticoids, carbamazepine, phenobarbitone, phenytoin, artemisinin, ? nevirapine

In addition some xenobiotics stimulate CYP3A4 mediated degradation of other substrates ("positive cooperativity"), or even themselves. [flavonoids and some steroids]

clotrimazole, ketoconazole, itraconazole > fluconazole, miconazole;
HIV PI's: ritonavir > indinavir ~= saquinavir > nelfinavir;
Ca-channel blockers; cyclosporine;
troleandomycin, erythromycin > clarithromycin >> azithromycin;

SSRIs (sertraline, fluoxetine, ..),
vinblastine, vincristine, ergotamine, progesterone, dexamethasone, bromocriptine, cimetidine { >>> ranitidine },
irreversible inhibition occurs with some 17-alpha ethinyl substituted steroids (ethinyl-estradiol, ?mifepristone), and grapefruit juice!
*1 .. *3 Marked inter-individual variation in activity;
fatal arrhythmias from pimozide + clarithromycin;
astemizole removed from market d/t interactions;

A vast number of potential interactions.

CYP3A5# (and 3A5P1, 3A5P2)
small, variable amounts in liver, GIT )
midazolam, caffeine, diltiazem (cyclosporin)

NOT quinidine or erythromycin

dexamethasone troleandomycin *1, *2 About 1/3 of individuals have significant liver 3A5!
CYP3A7 (steroid metabolism)
The major fetal liver cytochrome

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Last update 2000-1-22 Author