Phenprocoumon Diclofenac

Probe drugs used for CYP2C9 phenotyping are tolbutamide, S-warfarin, phenytoin and losartan. Diclofenac, flurbiprofen, phenprocoumone and torasemide have also been used. For safety concerns, the current preferred probe is tolbutamide, despite some risk of hypoglycemia. 

Also analyzed acebutolol, acetaminophen, alprazolam, amphetamine, atenolol, betaxolol, brotizolam, caffeine, camazepam, captopril, chloroquine, clobazam, clomipramine, cloth-iapine, clotiazepam, cloxazolam, cocaine, codeine, diclofenac, dihydralazine, dihydrocodeine, dihydroergotamine, diphenhydramine, domperidone, doxepin, droperidol, ergota-mine, ethyl loflazepate, fenethylline, fluoxetine, flupentixol, flurazepam, furosemide, gliclazide, hydrochlorothiazide, hydroxyzine, ibuprofen, imipramine, ketazolam, loprazo-1am, lorazepam, lormetazepam, maprotUine, medazepam, mepyramine, methadone, methaqualone, methyldopa, methylphenidate, metoclopramide, metoprolol, mexiletine, mianserin, midazolam, minoxidil, morphine, nadolol, nitrazepam, oxprenolol, papaverine, pentazocine, phenprocoumon, phenylbutazone, pipamperone, piritramide, practolol, pra-zepam, prazosin, promazine, promethazine, propoxyphene, propranolol, prothipendyl, quinine, sotalol, sulpride, thioridazine, trazodone, triazolam, trimipramine, tripelennamine, lyramine, verapeunil, yohimbine... 

Studies surest that diclofenac does not alter the anticoagulant effect of acenocoumarol, phenprocoumon or warfarin, su esting dose adjustments are unlikely to be needed. Isolated cases of raised INRs have been described. Note that all NSAIDs increase the risk of gastrointestinal bleeding, and an increased risk is seen when they are combined with anticoagulants. 

In a crossover study in 29 patients stabilised on acenocoumarol, diclofenac 25 mg four times daily for one week did not alter the anticoagulant effect (prothrombin value) of acenocoumarol, when compared with placebo. Other studies similarly eonlirm that diclofenac does not alter the anticoagulant effect of either phenprocoumon or warfarin. ... 

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