Synthesis and Antinociception Activities of New Substituted Aminobenzothiazole Analogs of Lidocaine

Abstract

Local anesthetics are the most widely used drugs in practical medicine which provide the loss of sensation in a specific body part without loss of consciousness or impairment of central control of vital functions. Lidocaine (I) is the most common local anesthetic drug which has been widely used in all cases because of its excellent diffusing and penetrating properties as well as rapid onset of surgical analgesia. In this study, new aminobenzothiazole analogs (with many useful biological and pharmacological properties) were synthesized by changing the amine moiety of I. The acute and chronic pain properties of new compounds (II – VI) were studied using the tail immersion and formalin tests on mice and the results were compared to control and lidocaine groups. According to the obtained results, aminobenzothiazole derivatives are better candidates than diethylamine group for replacement in the amine moiety of I. In addition, derivatives with electron-withdrawing groups on this amine (V and VI) could decrease pain better than compounds (II and III) with electron-donating groups (especially in position 6 of this amine, II and V) which may be concern to more blockades of specific sodium channels by these compounds.