DETERMINATION OF CINNARIZINE IN PHARMACEUTICAL PREPARATIONS BY SPECTROPHOTOMETRY, ATOMIC-ABSORPTION SPECTROMETRY AND POTENTIOMETRY

New methods are developed for the determination of cinnarizine in vari ous dosage forms. They are based on the reaction of cinnarizinium cati on with cobalt tetrathiocyanate anion, whereby a sparingly soluble blu e 2:1 drug: reagent ion-pair complex is quantitatively formed. The com plex is (a) extracted with nitrobenzene and spectrophotometrically mea sured at 622 nm; (b) extracted with nitrobenzene and nebulized in an a ir-acetylene flame for atomic absorption spectrometric monitoring of c obalt at 242.5 nm; and (c) dispersed in a PVC membrane plasticized wit h 2-nitrophenyloctyl ether and used as a sensor for direct potentiomet ric determination of the drug. Optimum reaction conditions and perform ances of the three analytical techniques are evaluated and compared. A t the 25 mg level of cinnarizine, the three methods give results with equal accuracy and precision. The average recovery is 98-99% of the no minal and the mean standard deviation is 0.7%. No significant interfer ences are caused by drug excipients and diluents.