Lymphotropic delivery of cyclosporin A by intramuscular injection of biodegradable microspheres in mice.

Biodegradable microspheres containing cyclosporin A (CsA), an immunosuppressant, enabled the lymphotropic delivery of the drug over the long term by parenteral administration in mice. The CsA encapsulated in the microspheres of polylactic acid polymer (Mw, 9000) was released over 30 days in vitro. The intramuscular injection of the microspheres containing CsA in the femoral site of mice maintained the drug at a high level in the inguinal lymph nodes over 1 month, although only low blood levels of the drug were observed.