Effect of artemether on analgesia and inflammation in mice and rats

Abstract

Artemether, currently one of the first-line antimalarials in Nigeria was evaluated for its ability to reduce pain and inflammation, which are common symptoms of malaria. This study was to ascertain whether artemether has an analgesic / anti-inflammatory effect to complement its anti-parasitic activity against Plasmodium species. Acetic-acid-induced writhing test was used to measure peripheral-analgesic activity in mice while the tail-flick and hot-plate methods were used for central-analgesic activity. Fluid-volume-displacement by egg-albumin-induced hind-paw oedema in rats was used to assess for anti-inflammatory effect. Artemether was administered i.p., at three-doses equivalent to therapeutic-dose (1.5 mg/kg) as well as 5 and 10-times higher (7.5 and 15 mg/kg), once (acute) and daily for 7 days (sub-acute). Artemether inhibited peripheral-pain dose-dependently, but this was not significant at 1.5 mg/kg. Statistically significant pain-inhibition (P<0.05) greater than that due to dipyrone was provided only at the doses of 7.5 and 15 mg/kg artemether. Analgesic assessment using tail-flick and hot-plate methods did not show any detectable effect even at higher doses, indicating that any pain-relief due to artemether was not centrally-mediated. Artemether reduced the readiness / degree of fluid accumulation after an initial-transitory (30-60 minutes) increase in oedema, following albumin injection. These effects were similar to, but less than those of indomethacin. The data showed that artemether exhibited only mild peripheral analgesic and anti-inflammatory activities which may not be observable at therapeutic-doses and therefore may not, on its own contribute significantly to the relief of pain / inflammation in the treatment of malaria.

Keywords: Artemether; Analgesia; Inflammation; Mice; Rats

Journal of Pharmacy and Bioresources Vol. 4 (2) 2007: pp. 39-48