Circadian stage-dependent prolongation by cyclosporine of segmental pancreatic allograft function in the rat

While the toxicity of many drugs has been reduced by their administration at certain circadian rhythm stages (if not at certain times of day), as shown herein, direct therapeutic benefit from the improvement of the desired effect can be obtained by the circadian timing of intraperitoneal cyclosporine (Cs) for Lewis rats bearing an ACI segmental pancreas allograft. Under conditions of light (L) and darkness (D) alternating at 12-hour intervals, staggered by 8 h in 3 rooms kept at 24 degrees C, the effect of Cs in delaying graft rejection was improved by timing. When the mean time to rejection during the L span is equated to 100%, graft function is prolonged by 40% at the right time (injection daily during the D span) as compared to the wrong time (injection daily during the L span).