Cyclosporine nephrotoxicity in rheumatoid arthritis: no effect of short term misoprostol treatment.

We assessed the effect of the prostaglandin E1 analog misoprostol on cyclosporine nephrotoxicity in patients with rheumatoid arthritis (RA). Thirteen patients with RA were given cyclosporine with misoprostol tablets, 800 micrograms/day for one week in a randomized, double blind, placebo controlled crossover trial. All had cyclosporine nephrotoxicity, documented by an increase in serum creatinine of at least 15% over the values before the start of cyclosporine treatment. Mean glomerular filtration rate (GFR) (single shot 51Cr-EDTA plasma clearance) at baseline was 77.3 ml/min (SD, 22.0). After misoprostol, it was 80.0 ml/min (SD, 18.9); after placebo, 79.1 ml/min (SD, 20.0). None of these changes were statistically significant. Serum creatinine levels and whole blood cyclosporine levels were also unchanged. Power to detect at least a 5 ml/min rise in GFR was 0.92. Short term misoprostol treatment does not improve the GFR of patients with RA on cyclosporine.