Cimetidine does not interact with prednisolone,prednisone ordexamethasone, and ranitidine does not interact with prednisone.
Clinical evidence,mechanism, importance and management
Prednisone is a pro-drug, which must be converted to prednisolone within body to become active. A double-blind crossover study in 9 healthy subjects found that cimetidine 300mg every 6 hrs or ranitidine 150mg twice daily for 4 days did not significantly alter pharmacokinetics of prednisolone after a single 40mg oral dose of prednisone (See reference number 1). Another double-blind,crossover study found that cimetidine 1 g daily only caused minor changes in plasma prednisolone levels following a 10mg dose of enteric-coated prednisolone (See reference number 2). Similarly, another study found that cimetidine 600mg twice daily for 7 days had no effect on pharmacokinetics of a single 8mg intravenous dose of dexamethasone sodium phosphate (See reference number 3).
There would therefore seem to be no reason for avoiding concurrent use. Information about other corticosteroids appears to be lacking,but no interaction is anticipated.
1. Sirgo MA,Rocci ML, Ferguson RK, Eshelman FN Vlasses PH. Effects of cimetidine and ranitidine on the conversion of prednisone to prednisolone. Clin Pharmacol Ther (1985) 37, 534–
8.
Morrison PJ,Rogers HJ, Bradbrook ID, Parsons C. Concurrent administration of cimetidineand enteric-coated prednisolone: effect on plasma levels of prednisolone. Br J Clin Pharmacol (1980) 10, 87–9.
Peden NR,Rewhorn I, Champion MC, Mussani R, Ooi TC. Cortisol and dexamethasone elimination during treatment with cimetidine. Br J Clin Pharmacol (1984) 18, 101–3.