Enteric solid dispersion of ciclosporin A (CiA) having potential to deliver CiA into lymphatics

Solid dispersions composed of three components, ciclosporin A (CiA), surfactant (HCO-60) and a pharmaceutical additive, were prepared. As an additive, cellulose acetate phthalate (CAP), methacrylic acid and methacrylic acid methylester copolymer (Eudragit L-100) and hydroxypropylmethylcellulose phthalate (HP-55), which are generally used as enteric coating materials, were employed. The dissolution behavior of CiA from these enteric solid-dispersion system was studied according to the paddle method of JP XI in comparison with that of Sandimmun, an olive oily CiA solution as a reference. Solid dispersion of CiA preparation did not dissolve in the 1st test fluid (pH 1.2) in 2 h. In the 2nd fluid (pH 6.8), about 80% of CiA was dissolved within 12 min, though the dissolution rate was dependent on both the quality and quantity of the additives. An in vivo systemic and lymphatic availability study was performed with rats whose carotid artery and thoracic lymph duct were cannulated. After intrastomach administration of each CiA preparation to rats at a dose of 7 mg/kg, blood and lymph samples were collected for 6 h. One of the HP-55 preparations gave the highest plasma CiA level, Cmax = 0.99 +/- 0.20 (S.E., n = 4) micrograms/ml, and also showed the highest lymphatic availability, the percentage of dose delivered to the lymphatics in 6 h was 1.98 +/- 0.10% and the maximum lymph CiA level was 76.8 +/- 12.86 micrograms/ml. Lymphatic availability of CiA from Sandimmun was 0.78 +/- 0.11% and the peak plasma CiA level was 0.46 +/- 0.10 microgram/ml.(ABSTRACT TRUNCATED AT 250 WORDS)