Polydipsia: Comparative action of two antipsychotics - Pimozide and ziprasidone

Abstract

Background: Primary polydipsia occurs without any central (vasopressin) deficit and/or peripheral (nephrogenic) organic impairment-associated with schizophrenia/obsessive compulsive disorder. In absence of associated symptoms/signs, it is idiopathic (might be preclinical/prodromic). Antipsychotics are tried with some claim but none is satisfactory. Aims and Objective: Unlike ziprasidone, pimozide misses D1/muscarinic/adrenergic/histaminic actions - the experiment assessed its physiological manifestation and clinical potentials against polydipsia. Materials and Methods: Three batches of 21 Wistar male albino rats into two successive phases (viz. Normal and, after a washout period for 30 days, schedule-induced polydipsia) were divided into 3 groups (minimal, half maximal, and maximal dose). These 3 groups were divided into 3 subgroups of control, drug 1 and drug 2-each of 7 rats. Rat doses were “analogous” to permitted human doses. Result: Daily water intake lowering effect was evident only in polydipsic rats. Half-maximal dose of ziprasidone equated to maximal dose of pimozide. Conclusion: Ziprasidone (half maximal dose) can avoid the adverse drug reactions (ADRs) of pimozide (maximal dose) in humans polydipsia - though ADR manifestations may be wide-spread (more receptors involved).