Abstract
The protein binding of quinotolast to the serum and plasma and its distribution in the blood cells were studied.
1. The blood to plasma consentration ratios of quinotolast were 0.59 ?? 0.60, 0.65 ?? 0.69, 0.65 ?? 0.69 and 0.72 ?? 0.76 respectively for human, rats, dogs and guinea pigs. The distribution extent of quinotolast in the blood cells were less than 20%, showing that quinotolast exists primarily in the plasma of these species in vitro.
2. The serum protein binding of quinotolast in vitro was 98.03 ?? 98.10, 96.49 ?? 96.70, 95.97 ?? 96.20 and 94.05 ?? 94.34% respectively for human, rats, dogs and guinea pigs for a concentration range of 0.1 ?? 10μg/ml. No difference between protein binding to human plasma and serum was found.
3. Quinotolast presumably is mainly bound to albumin of the human serum.
4. Protein binding of quinotolast to human serum in vitro was scarcely affected by prednisolone, procaterol or theophylline which might be used clinically with quinotolast, or by warfarin, diazepam or digitoxin which one mainly bound to albumin.
5. Protein binding of quinotolast to the human plasma in vivo was 98.45 ?? 98.71%. Since there was no difference between in vivo and in vitro binding, it is considered that the metabolites didn't affect the binding of quinotolast to the plasma protein.
