Enteric solid dispersion of cyclosporin A (CyA) having potential to improve availability of CyA in rabbit

The availability of cyclosporin A (CyA) administered as an enteric solid dispersion preparation of which the composition is CyA:HCO-60:HP-55 = 1:2:8 was evaluated in rabbits. The additives are surfactant (polyoxyethylated, 60 mumol, castor oil derivative, HCO-60) and enteric coating material (hydroxypropylmethyl cellulose phthalate, HP-55), which are generally used as pharmaceutical additives. Both the systemic and lymphatic availabilities of CyA from this solid preparation were measured in rabbits after intrastomach administration, 7 mg CyA/kg, and were compared with those from conventional oily solution, Sandimmun. The mean systemic availability of CyA from the solid preparation was 57% which is about 1.5 times greater than that obtained from Sandimmun. The amounts of CyA transferred into the thoracic lymphatics within 12 h from solid dosage form and Sandimmun are 0.62 +/- 0.16(S.D.)% and 0.13 +/- 0.05% of the administered CyA dose. These results support the usefulness of the new solid dosage form of CyA.