We present the cases of two patients with short-bowel syndrome who failed to achieve therapeutic cyclosporine serum concentrations on oral drug but were successful on intravenous administration. One patient received cyclosporine after renal transplantation for renal failure secondary to enteric oxalosis; the second received cyclosporine for active Crohn's disease. The rapid bowel transit time was the critical factor in limiting cyclosporine absorption in both cases. In studying oral and intravenous pharmacokinetic profiles, we support a zero-order kinetic model for oral cyclosporine absorption.

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The pharmacokinetics of 3H-Triamcinolone Acetonide-21-palmitate entrapped in liposomes with neutral, negative and positive surface charge was investigated in the male New Zealand White rabbit after a single intravenous bolus injection. Drug concentration-time data monitored in whole blood showed bi-exponential decay and were analysed by a least-squares regression analysis procedure to obtain pertinent pharmacokinetic parameters. The significance of the observed differences in the pharmacokinetics after administration of each type of liposome was assessed by the Analysis of Variance test method. Significant differences (p less than 0.05) were found in alpha, beta, (t 0.5)alpha, K12, and Vc. Positive liposomes apparently encountered a larger initial apparent volume of distribution than the neutral or negative type, and consequently exhibited demonstrably lower initial blood drug concentration, (Cb)0. Liposomes with different surface properties were removed from circulation at different rates and this resulted in significant difference (p less than 0.01) in the concentration of circulating liposomes an hour following injection of each type of liposome. A mean of 66 per cent of the initial concentration of positive liposomes remained in circulation an hour after injection whereas 11 and 23 per cent respectively of the neutral and negative type remained in circulation during the same time period. Liposomes with different surface properties apparently exhibited similar total body clearance of the encapsulated compound.

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