Fendiline (N-[1-phenylethyl]-3,3-diphenylpropylamine hydrochloride, trade name: Sensit) is a β-receptor blocker and a Ca antagonist. It is a viscous oil and even its crystalline hydrochloride is a very hydrophobic and sparingly soluble compound in water.β-Cyclodextrin complexes fendiline base in a molar ratio of 2∶1. In aqueousβ-cyclodextrin solution, the significantly increased solubility and the intensive induced circular dichroism prove the formation of true inclusion complexes with both the base and the hydrochloride. In artificial gastric juice, the solubility of the complexed forms of the fendiline base and its hydrochloride is 40 and 22 times higher, respectively, than that of free drugs. The complexation withβCD resulted in a two-threefold increase in the rate constants of diffusion and absorption determined in a Sartorius apparatus.