Effect of lidocaine on harmaline-induced tremors in the rat.

The present study was undertaken to investigate the effect of lidocaine on harmaline-induced tremors in the rat. Four groups of Wistar rats weighing 45-50 g were injected with harmaline (50 mg/kg i.p.) for inducing experimental tremors. The rats in group 1 served as control, whereas the animals in groups 2, 3, and 4 were also given lidocaine i.p. at doses of 12.5, 25, and 50 mg/kg, respectively, 10 min after the onset of tremors (therapeutic study). In a separate four groups of animals intraperitoneal lidocaine injection was given 10 min before harmaline (prophylactic study) in the same dose regimen as mentioned above. The latency of onset, intensity, and duration of tremor and electromyographic responses were recorded. Lidocaine dose dependently attenuated harmaline-induced tremors in rats. The latency period was increased, and duration and intensity of harmaline-induced tremors was reduced by lidocaine. Our electromyography (EMG) study also revealed a decrease in the amplitude of harmaline-induced tremors in lidocaine-treated rats. In conclusion, the results of this study clearly suggest beneficial effects of lidocaine in harmaline-induced tremors.