SUBCUTANEOUS INJECTION OF ORAL CYCLOSPORINE-A SOLUTION

Cyclosporin A (CyA) is the agent of choice for immunosuppression in th e majority of rodent organ and tissue allotransplantation experiments. Subcutaneous injection of suitably dissolved pure CyA powder preparat ion is the acceptable standard of drug administration. We investigated the possibility of using oral CyA solution in an injectable form and compared its availability with that of the standard solution in a rat model. Oral CyA solution diluted in placebo (olive oil) and standard s olution prepared from pure compound were injected subcutaneously at a dose of 5 mg/kg/day to two groups of rats. Trough whole blood CyA conc entrations were measured on day 10 following initiation of treatment. Blood CyA levels of the standard solution group (1,167 +/- 246-mu-g/li ter, mean +/- SD) were virtually identical to those of the oral soluti on group (1,105 +/- 179-mu-g/liter; P > 0.05). In addition, the oral s olution was easier to prepare and caused less injection site morbidity than the standard solution. We conclude that placebo-diluted oral CyA solution may be safely injected subcutaneously to rats and results in consistent blood levels, comparable to those achieved with standard s olution prepared from pure compound.