Pathological changes in rats receiving cyclosporin A at immunotherapeutic dosage for 7 weeks

In rats given an immunotherapeutic dose (25 mg/kg orally each day for 7 weeks) of cyclosporin A (Cy A) characteristic drug-induced pathological changes were observed, including impaired liver function, renal proximal tubular cell damage, progressive lymphopenia, lymphocyte depletion in lymphoid organs and marrow hypoplasia. Several additional and previously unreported features of Cy A toxicity were also demonstrated. The changes in renal and hepatic function were biphasic with temporary improvement during the course of the study. The most striking liver damage was in the form of a granulomatous hepatitis and a hypochromic microcytic anaemia developed in all experimental animals.