Warfarin sodium

CLINICAL USE

Anticoagulant

DOSE IN NORMAL RENAL FUNCTION

Depends on INR

PHARMACOKINETICS

Molecular weight : 330.3

%Protein binding : 99

%Excreted unchanged in urine : 0

Volume of distribution (L/kg) : 0.14

half-life – normal/ESRD (hrs) : 37/Unchanged

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function

<10 : Dose as in normal renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD : Not dialysed. Dose as in normal renal function

HD : Not dialysed. Dose as in normal renal function

HDF/high flux : Unknown dialysability. Dose as in normal renal function

CAV/VVHD : Not dialysed. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs There Are Many Significant Interactions With Warfarin Prescribe With Care With Regard To The Following: Anticoagulant effect enhanced by: alcohol, amiodarone, anabolic steroids, aspirin, azithromycin, aztreonam, bicalutamide, cephalosporins, chloramphenicol, cimetidine, ciprofloxacin, clarithromycin, clopidogrel, cranberry juice, danazol, danshen, dextropropoxyphene, dipyridamole, disulfiram, entacapone, erythromycin, esomeprazole, exenatide, ezetimibe, fibrates, fluconazole, flutamide, fluvastatin, glucosamine, grapefruit juice, itraconazole, ketoconazole, levamisole, levofloxacin, levothyroxine, macrolides, methylphenidate, metronidazole, miconazole, mirtazepine, nalidixic acid, neomycin, norfloxacin, NSAIDs, ofloxacin, omeprazole, pantoprazole, paracetamol, penicillins, proguanil, propafenone, rosuvastatin, saquinavir, SSRIs, simvastatin, sitaxentan, sulfinpyrazone, sulphonamides, tamoxifen, testosterone, tetracyclines, tigecycline, toremifene, tramadol, trimethoprim, valproate, venlafaxine, voriconazole Anticoagulant effect decreased by: acitretin, atorvastatin, azathioprine, barbiturates, carbamazepine, ginseng, griseofulvin, mercatopurine, mitotane, oral contraceptives, phenytoin, primidone, rifampicin, St John’s wort (avoid concomitant use), sucralfate, vitamin K Anticoagulant effects enhanced/reduced by: amprenavir, anion exchange resins, atazanavir, corticosteroids, dietary changes, nevirapine, ritonavir, tricyclics

Analgesics: increased risk of bleeding with IV diclofenac and ketorolac – avoid concomitant use Antidiabetic agents: enhanced hypoglycaemic effect with sulphonylureas Camomile: enhanced anticoagulation

Ciclosporin: there have been a few reports of altered anticoagulant effect; decreased ciclosporin levels have been seen rarely Cytotoxics: increased risk of bleeding with erlotinib and imatinib; enhanced effect with etoposide, fluorouracil, ifosfamide and sorafenib Melatonin: possibly enhanced INR