The construction and general performance characteristics of potentiometric amitriptyline–plastic membrane sensors, based on ion-pair complexes with triphenylstibenylborate and tetra(2-chlorophenyl)borate, respectively, are described. Both electrodes show near-Nernstian responses over the range 1 × 10^–2–7 × 10^–6 mol dm^–3 with a detection limit of about 5 × 10^–6 mol dm^–3. The electrodes proved useful in the determination of amitriptyline hydrochloride in pure drug substances and pharmaceutical preparations. They were also applied to the determination of content uniformity and dissolution rate of sugar-coated amitriptyline tablets. The physical processes were numerically simulated by typical equations.