Rifampicin Corticosteroids

RIFAMPICIN CORTICOSTEROIDS 1 plasma concentrations of corticosteroids and risk of poor or inadequate therapeutic response, which would be undesirable if used for e.g. cerebral oedema Due to induction of the hepatic metabolism by the CYP3A4 isoenzymes Monitor therapeutic response closely -clinically, with ophthalmoscopy and radiologically - and t dose of corticosteroids for desired therapeutic effect... 

Corticosteroids Pbenytoin Rifampicin Increased metabolism with possibility of tberapeutic failure... 

Rifampicin is a potent inducer of cytochrome P450 enzymes and thus can diminish the activity of a multitude of other agents such as warfarin, gluco-corticosteroids, cyclosporin, oral contraceptives and sulphonylurea-type oral antidiabetic agents. 

The time of administration can also affect drug response e.g. INH and rifampicin (anti-tubercular drugs) are taken in early morning empty stomach. The corticosteroids when taken in morning as single dose cause less adrenal-pituitary suppression. 

Kyriazopoulou V, Parparousi O, Vagenakis AG. Rifampicin-induced adrenal crisis in Addisonian patients receiving corticosteroid replacement therapy. J Clin Endocrinol Metab 1984 59(6) 1204-6. 

ANTIARRHYTHMICS - disopyramide, propafenone 2. ANTIBIOTICS-chloramphenicol, doxycycline, metronidazole, rifampicin, telithromycin 3. ANTICANCER AND IMMUNOMODULATING DRUGS - carmustine, cidosporin, corticosteroids, doxorubicin, etoposide, ima-tinib, lomustine, paditaxel, tacrolimus, tamoxifen, toremifene, vinca alkaloids 4. ANTICOAGULANTS - ORAL 5. ANTI-... 

ALMOTRIPTAN, ELETRIPTAN IMMUNOMODULATING DRUGS - CORTICOSTEROIDS-DEXAMETHASONE Possible 1 plasma concentrations of almotriptan and risk of inadequate therapeutic efficacy One of the major metabolizing enzymes of almotriptan - CYP3A4 isoenzymes - are induced by rifampicin. As there are alternative metabolic pathways, the effect may not be significant and can vary from individual to individual Be aware of possibility of 1 response to triptan, and consider t dose if considered to be due to interaction... 

Compounds that may diminish the hypoglycaemic effect and thus cause an increase in the dosage requirement of sulphonylurea include rifampicin (Syvalahti et al., 1974). There is a theoretical risk of a diminished hypoglycaemic effect with corticosteroids and with oral contraceptives. It has been stated that the absorption of glibenclamide from the gastrointestinal tract may be reduced if it is taken together with guar gum. 

Rifampicin is a potent liver enzyme inducer, which increases the metabolism of the corticosteroids by the liver," thereby decreasing their levels and reducing their effects. 

Hendrickse W, McKieman J, Picki M, Lowe J. Rifampicin-induced non-responsiveness to corticosteroid treatment in nephrotic s3mdrome. BMJ (1979) i, 306. 

The serum levels of the active metabolite of leflunomide are reduced by activated charcoal, and colestyramine. The manufacturers advise against the concurrent use of alcohol because of the potential for hepatotoxicity. Methotrexate may also increase leflunomide hepatotoxicity, so in general the combination is not recommended. A case of fatal fulminant hepatic failure has been reported in a patient taking leflunomide and itraconazole. A case of peripheral neuropathy has been reported in a patient taking leflunomide and tegafiir/uraciL The manufacturers predict interactions between leflunomide and phenytoin or tolbutamide, and advise caution with rifampicin as it may increase leflunomide metabolite levels. No clinically relevant interaction occurs with cime-tidine, corticosteroids or NSAIDs. 

Drug interactions The extent to which vitamin D supplementation alters drug effectiveness and toxicity in humans has been systematically reviewed. Bile acid sequestrants and lipase inhibitors were found to inhibit the absorption of vitamin D from the gut. Statins, rifampicin, isoniazid, hydroxychloroquine, antiepileptics, corticosteroids, immimo-suppressive and chemotherapeutic agents, antiretroviral drugs and H2 receptor antagonists interfered with vitamin D metabolism. The interaction between vitamin D and thiazide diuretics could result in hypercalcaetnia. Vitamin D supplementation decreases concentrations of atorvastatin, and could cause hypercalcaetnia in elderly individuals or tixose with compromised renal function or hyperparathyroidism [84 ]. 

A patient with Addison s disease in whom the plasma half-life of cortisone was considerably reduced, requiring increased corticosteroid dosage, was described by Edwards et al. (34 ). Cortisone production rates in 4 patients with active pulmonary tuberculosis under treatment with rifampicin were also found to be greatly increased, the mean rate rising from 14.4 to 23.0 mg per 24 hours. It was postulated that these effects were the result of hepatic enzyme induction by rifampicin. 

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