Metcort Drug Interactions

CYP3A4 Inducers eg, Barbiturates, Phenytoin, Primidone, Rifampicin, Rifabutin, Aminoglutethamide, Carbamazepine and Other Drugs that Stimulate Hepatic Metabolism: These drugs may enhance methylprednisolone metabolism, shorten its plasma t_½ and lead to decreased plasma concentrations of methylprednisolone. Increased methylprednisolone dosage may be required.
CYP3A4 Inhibitors eg, Antifungals (Itraconazole, Ketoconazole), Antiemetics (Aprepitant, Fosaprepitant), Immunosuppressants (Ciclosporin, Cyclophosphamide, Tacrolimus), Macrolide Antibiotics (Clarithromycin, Erythromycin, Troleandomycin), HIV-Protease Inhibitors, Diltiazem, Grapefruit Juice: These may decrease methylprednisolone metabolism thereby increasing plasma concentrations of corticosteroids.
Increased activity of both ciclosporin and corticosteroids may occur when the 2 are used concomitantly. Convulsions have been reported with concomitant use.
Ketoconazole decreases the metabolism of certain corticosteroids by up to 60% leading to an increased risk of corticosteroid adverse effects.
CYP3A4 Substrates eg, Calcium Antagonists (Mibefradil), Histamine₂-Receptor Antagonists (Cimetidine), Contraceptives (Ethinylestradiol/Norethindrone) and Calcium Channel Blockers (Nifedipine, Felodipine): The hepatic clearance of methylprednisolone may be inhibited or induced in the presence of another CYP3A4 substrate. It is possible that the adverse events associated with the use of either drug alone may be more likely to occur when used concomitantly.
Sympathomimetics (eg, Salbutamol, Salmeterol, Terbutaline, Formoterol): Co-administration with high doses of corticosteroids may result in an increased risk of hypokalemia.
Antivirals: Protease inhibitors (ie, indinavir and ritonavir) may increase plasma concentrations of corticosteroids. On the other hand, corticosteroids may induce the metabolism of HIV-protease inhibitors resulting in reduced plasma concentrations.
Antacids: Antacids may decrease the absorption of corticosteroids when given concomitantly. Dose adjustments may be required in patients receiving small doses of corticosteroids.
Oral Contraceptives and Estrogen: These can cause alterations in plasma protein binding and metabolism of corticosteroids which can result in exposure of women to increased levels of the unbound corticosteroid for long periods of time. Dose adjustments may be warranted when commencing or stopping oral contraceptive therapy. There have also been isolated reports of contraceptive failure in women receiving corticosteroid therapy.
Aspirin or Other Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): Concomitant use results in increased risk of gastrointestinal adverse effects eg, gastrointestinal bleeding and ulceration.
Use aspirin cautiously in conjunction with corticosteroids. The clearance of salicylates may be increased with concomitant use which could lead to increased salicylate toxicity when methylprednisolone is withdrawn.
Oral Anticoagulants (Warfarin): There is conflicting data on the effect of methylprednisolone and anticoagulants. There are reports of enhanced as well as diminished effects of anticoagulants when given concomitantly. Monitor coagulation indices [eg, international normalized ratio (INR) and prothrombin time] frequently to maintain the desired anticoagulant effect.
Diuretics (eg, Potassium-Depleting Diuretics eg, Furosemide and Thiazide or Carbonic Anhydrase Inhibitors eg, Acetazolamide): Observe patients closely for the development of hypokalemia.
Mifepristone: The effect of corticosteroids may be reduced for 3-4 days after taking mifepristone.
Amphotericin-B: Concomitant use may increase the risk of hypokalemia.
Anticholinergic Agents: Acute myopathy has been reported with concomitant use of high doses of corticosteroids and anticholinergics eg, neuromuscular blocking agents.
In patients taking corticosteroids, antagonism of the neuromuscular blocking effects of pancuronium and vecuronium may occur. This interaction may be expected with all competitive neuromuscular blockers.
Insulin and Oral Antidiabetic Agents: Corticosteroids eg, methylprednisolone may increase blood glucose concentrations and may cause impaired glucose tolerance. Dosage adjustment of antidiabetic agents may be required when these 2 drugs are used concomitantly.
Digitalis Glycosides: Patients may be at increased risk of arrhythmias due to hypokalemia.
Toxoids and Live or Inactivated Vaccines: Patients on prolonged corticosteroid therapy may exhibit diminished response to toxoids and live or inactivated vaccines due to inhibition of antibody response.