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Dolezal T, Krsiak M.

Department of Pharmacology, 3rd Faculty of Medicine, Charles University of Prague, Ruska 87, 100 34 Prague, Czech Republic. Tomas.Dolezal@lf3.cuni.cz

AIM OF INVESTIGATION: guaifenesin is used as an expectorant and it has been reported to possess muscle relaxant and sedative activity.

guaifenesin has been used as a component of composite OTC analgesics containing paracetamol for many years. The aim of our study was to ascertain effects of guaifenesin on paracetamol analgesic activity and locomotor performance.

METHODS: Antinociceptive efficacy was tested in mice using an acetic acid (0.7%) writhing test. Locomotor performance was tested in rota-rod test and activity cage. All drugs were given orally and tested in mice.

RESULTS: In combination with a subeffective dose of guaifenesin (200 mg/kg), the ED(50) for paracetamol in the writhing test was significantly lower (82.2 mg/kg) than that of paracetamol administered alone (233.7 mg/kg). guaifenesin alone did not show an analgesic effect. guaifenesin did not produce statistically significant locomotor impairment in the rota-rod test at doses enhancing analgesic activity of paracetamol, although there was a trend for decreased locomotor activity in activity cage.

CONCLUSION: The present results indicate that guaifenesin may enhance analgesic activity of paracetamol.

PMID: 12444496 [PubMed - indexed for MEDLINE]