Molar partition coefficients for amphiphilic N-[2-(2-alkyl-oxyphenyl-carbamoyloxy)-ethyl]-piperidinium chlorides (PAA) between small unilamellar egg yolk phosphatidyl choline liposomes and saline, as determined by ultraviolet difference spectroscopy at 22 degrees C, pH 5-6, v = 34640 cm-1, and at 100 mumol/l PAA concentration, were 149, 1990, and 7474 for PAA with 5, 7, and 9 carbon atoms in the alkyloxy substituent, respectively. At the PAA concentration used, the cut-off in biological activities of PAAs with long alkyloxy substituents could not be caused by the self-association of PAA molecules in the aqueous phase.

Faculty of Pharmacy J A Comenius University Bratislava Czechoslovakia