Influence of lovastatin on the pharmacokinetics, toxicity and immunologic response of cyclosporine in the obese Zucker rat.

The combined use of lovastatin, a hypolipidemic agent effective in the reduction of cholesterol levels, and the lipophilic immunosuppressant, cyclosporine, was studied in the obese rat model. Pharmacokinetics, immunosuppressive activity, lipid levels, and creatinine clearances were compared between groups administered drug-free vehicle, lovastatin or cyclosporine alone, or concomitant cyclosporine and lovastatin. All groups were pre-treated with either oral lovastatin 2.5 mg kg-1 day-1 or propylene glycol vehicle for 1 week. Although no differences in renal function were observed in rat groups administered cyclosporine or lovastatin alone, there was a significant reduction in baseline creatinine clearance following combination therapy compared to placebo controls (70 +/- 18 vs 121 +/- 16 per cent of baseline; p less than 0.05). No differences in trough cyclosporine concentrations were observed between groups. Similarly, mean areas under the whole blood concentration-time profiles were not significantly different with or without concomitant lovastatin (61823 +/- 27295 vs 41470 +/- 10312 ng h ml-1; p = 0.13). No differences in systemic clearance or volume of distribution of parent cyclosporine were observed with combination therapy. Furthermore, lipid levels and T-lymphocyte activity were unchanged with the addition of lovastatin. Per cent increases in creatine kinase were significantly correlated with percentage drop in baseline renal function, suggesting the development of rhabdomyolysis. The present data support the interaction between cyclosporine and lovastatin observed clinically, resulting in acute renal dysfunction. Caution should be exercised in their combined use.