Abstract
Discussions on biopharmaceutical phenomena were given on the bases of the adsorption by carbon black from aqueous solution and the permeation through Visking tube of barbituric acid derivatives. The absorption of drug was considered to proceed through the two succesive steps : 1) adsorption or uptake onto the membrane surface and 2) transport through the membrane. The results showed that the absorption might be controlled by adsorption or uptake by membrane. The permeation through Visking tube, as an experimental model for the transport process in the absorption, decreased with the increase of the molecular volume of barbituric acid derivatives, as was explained to be a simple diffusion through pore and was contrary to the actual absorption tendency. Plotting the absorption data6, 11) against the adsorbability of barbituric acid derivatives by carbon black, a very good correlation was given, demonstrating that such an adsorption study was useful to estimate the absorbability in vivo. Plotting the data of the binding to bovine serum albumin13) against the adsorbability of barbituric acid derivatives by carbon black, a good correlation was given, suggesting that the adsorption by such a hydrophobic substance as carbon black might have some relation to the pharmacological action. Moreover, a fairly good correlation was observed between the existing pharmacological data and the adsorbability of barbituric acid derivatives by carbon black.
