Experimental corticosteroid myopathy

Summary The steroids triamcinolone, dexamethasone, beta-methasone, and cortisone were administered i.p. to adult rats for 14–63 days. The extensor digitorum longus (EDL, white muscle) and soleus (SOL, red muscle) muscles were examined histologically and histochemically. Triamcinolone was the most potent lesion-producing drug. Selective involvement of muscles, and of the fiber types within them was observed: Neerotic changes were seen only in the type 1 fibers of the SOL; atrophic fibers were observed in the type 2 fibers of both the SOL and the EDL.