[Adsorption of substances on active charcoal. Part 1: Basic esters of phenylcarbamic acid with local anaesthetic effect].

Active charcoal is one of important adsorbents capable of binding on their surface other substances in a relatively large amount. This property is often used in pharmacy as well as in the studies of the structure--biological activity relationships, where active charcoal serves as a model substance for the study of hyrophobic interactions. The present paper investigates the adsorptivity of eight potential local anaesthetics from the group of 1-methyl-2-piperidinoethylesters of 2-, 3- and 4-alkoxyphenylcarbamic acids to adjusted active charcoal, which complies with the requirements of Slovak Pharmacopoeia 1. Adsorptivity of substances is evaluated according to Freundlich model and according to the amount of the bound substance beta in per cents in dependence on time. The dependence of adsorptivity of substances beta on local anaesthetic activity in topical local anaesthesia, which increases with increasing lipophilicity, is evaluated.