The plasma time course of orally-administered cyclosporine in the dog.

The plasma concentration time course of orally-administered cyclosporine has been studied in five adult male mongrel dogs. Cyclosporine concentrations were measured by high performance liquid chromatography with ultraviolet absorbance detection. Cyclosporine plasma concentrations were below assay sensitivity within 24 hours after administration. Peak plasma concentrations ranging from 411.8 to 1735.0 ng/ml were attained between post-administration times of 1 and 2.5 hours. Areas under plasma concentration time course curves (AUC = 4.63 +/- 5.60 micrograms/ml X hr, mean +/- SD) suggest that systemic availability is highly variable between animals. Present and previous findings discourage the oral route of cyclosporine administration for canine transplant research and suggest more extensive pharmacokinetic evaluation of cyclosporine following oral administration in humans.