Study of interaction of nifedipine with haloperidol on conditioned avoidance response and catalepsy in rats

Abstract

Background: To study the interaction of calcium channel blocker (Nifedipine) with Antipsychotic drug (Haloperidol) on Conditioned avoidance Response and catalepsy in Rats. Methods: Every group consisted of 10 healthy albino rats of either sex. Different groups received Nifedipine (5, 10 & 20 mg/kg, i.p.), Haloperidol (ED 50 -0.2mg/kg for CAR & 0.4mg/kg for catalepsy) alone and combined doses of both drugs. The Antipsychotic effect of drugs was measured by Conditioned avoidance response (CAR) using Cook’s Pole climbing apparatus and Adverse drug effect (Extra pyramidal syndrome) was measured by Catalepsy. Results: 5 mg/kg i.p. of Nifedipine inhibited CAR in 50 % of Rats (compared to control, p <0.001). 10mg/kg i.p. of Nifedipine inhibited CAR in 60% of Rats ( p <0.001) & 20 mg/kg i.p. inhibited CAR in 70% of Rats ( p <0.001). When Nifedipine (5 mg/kg i.p) was combined with Haloperidol ED 50 -0.2mg/kg the CAR was inhibited in 70% of the rats ( p <0.01) and after combining Nifedipine (10mg/kg) with Haloperidol ED 50 -0.2mg/kg the CAR was inhibited in 80% Rats ( p <0.001). Nifedipine at the dose of 5 mg/kg and 10 mg/kg (i.p.) did not induce catalepsy in the rats at any testing time interval. At 20 mg/kg i.p., it produced catalepsy in 2 rats at half hour and in 4 rats at 1 hour and 2 hour testing interval each ( p <0.01). In the dose of 5, 10 and 20 mg/kg, pretreatment with Nifedipine significantly increased Haloperidol induced cataleptic scores at all testing intervals ( p <0.05). Conclusions: Nifedipine blocked CAR. Its higher doses induced catalepsy and it is synergistic with haloperidol in blockade of CAR and catalepsy.