The Analgesic Effect of 5- fluorouracil in Mice

The analgesic effect of 5fluorouracil (5-FU) was analyzed in two experimental tests in mice. Two analgesia test, writhing test and hot plate test have been performed in swiss albino mice. The tested substance used was 5-Fluorouracil, i.p. administered in doses of 10 (Lethal Dose 50/10) and 20 mg/kg body weight (bw) (Lethal dose 50/5), 1 hour before tests. In the writhing test, 5-FU has signifi cant analgesic effect when it is administered in dose of 20 mg/kg bw, but has no signifi cant analgesic effect when administered in dose of 10 mg/kg bw. In the hot plate test, 5-FU increased jumping latency, that was statistically signifi cant at both administered doses of 10 mg/kg bw and 20 mg/kg bw. In the same conditions (hot plate test), the fore paw licking latency was not statistically signifi cant influenced. These results suggest that the analgesia produced by 5-FU probably involves a central opioid mechanism. The similarity of 5-FU and opioid analgesic in analgesic effect is also found in gemcitabine, that seemed to act via cGMP. Still, given its chemical structure, 5-FU is more likely to act on cAMP and not cGMP. The fact that both gemcitabine and 5-FU interact with cGMP and cAMP, respectively and have analgesic effect suggest the need of developing new analgesic drugs which use this mechanism, but devoid of important toxicity as with these anticancer drugs.