Abstract
The mechanism of the uniformity of diazepam absorption rate from medium chain triglyceride (MCT) solution was investigated in comparison with the absorption from an aqueous suspension. The metabolism of MCT in the stomach was examined in vitro using the enzyme extract of the rat stomach. The content of a metabolite, medium chain monoglyceride (MCM), increased up to 1.5% at pH 3.6 during incubation for 30 min. Experiments using a newly devised gastric emptying simulator suggested that improved dispersibility of MCT solution, by virtue of the formed MCM, resulted in the uniform gastric emptying rate (GER) of this preparation. In the case of diazepam aqueous suspension, both GER and the gastric absorption rate of the drug seemed to be significant factors in the variable absorption rate of diazepam, though GER was considered to be the major factor. In experiments with the gastric emptying simulator, the GER of the aqueous suspension seemed more variable than that of the MCT solution containing MCM. Consequently, the apparent uniform absorption rate of diazepam-MCT preparation is considered to be attributable to the relatively uniform GER of the MCT digestion mixture which is formed in the stomach.
