Nylon coated microcapsules containing hydrophilic solvent-soluble anionic, cationic or quaternary drug salts were prepared by interfacial polycondensation techniques. In a first stage, the drug substance to be encapsulated is dissolved in an aqueous phase. Examples of drugs encapsulated are morphine sulfate, diphenhydramine hydrochloride, and methantheline bromide. Next the aqueous drug solution is dispersed in an organic phase. In a second stage complementary polycondensation reactants each in an organic phase are added separately, either sequentially or simultaneously, to the dispersion prepared in the first stage. Microcapsules of nylon form around the hydrophilic solvent soluble core drug substance.