ciclosporin UK /ˌsʌɪ.klə(ʊ)ˈspɔː.ɹɪn/US /ˌsaɪ.kləˈspɔɹ.ɪn/ noun1 •An immunosuppressive drug C₆₂H₁₁₁N₁₁O₁₂ that is a cyclic polypeptide obtained as a metabolite from a fungus (Tolypocladium inflatum) and is used especially to prevent rejection of transplanted organs and in the treatment of rheumatoid arthritis and psoriasis. formsciclosporins