Volumetric studies of aqueous solutions of local anesthetical drug compounds [hydrochlorides of procaine (PC HCl), lidocaine (LC HCl) and tetracaine (TC HCl)] at 298.15Â K

► Partial molar volumes of PC, LC and TC HCl in water at 298.15 K are reported. ► CMC and aggregation number for drug molecules are calculated by pseudo-phase model. ► The results for PC HCl-H2O are interpreted in terms of dimerization equilibria. ► The volume changes due to micellization type equilibria are evaluated. ► Hydrophobic hydration/structural characteristics of the molecules are important.