Preliminary studies on the analgesic activity of latex of Calotropris procera

In this study we have evaluated the analgesic activity of dry latex (DL) of Calotropis procera. A single oral dose of DL ranging from 165 to 830 mg/kg produced a significant dose dependent analgesic effect against acetic acid induced writhings. The effect of DL at a dose of 415 mg/kg was more pronounced as compared to a 100 mg/kg oral dose of aspirin. On the other hand DL (830 mg/kg) produced marginal analgesia in a tail-flick model which was comparable to aspirin. The analgesic effect of DL was delayed by 1 h by naloxone at a dose of 0. 5 mg/kg, i.p., which completely blocked the analgesic effect of morphine (10 mg/kg, i.p.). However, the effect of aspirin was not blocked by naloxone. The 830 mg/kg oral dose of DL did not produce toxic effects in mice and the LD(50) was found to be 3 g/kg.