CETIRIZINE, OXATOMIDE, KETOTIFEN AND PLACEBO - PHARMACOLOGICAL EVALUATION OF THEIR RESPECTIVE ANTI-H-1-HISTAMINE, ANTIPRURITIC AND SEDATING EFFECTS

At 1-week intervals, 12 healthy volunteers received oral cetirizine 10mg, oxatomide 30mg, ketotifen 1mg or placebo under randomised double-blind crossover conditions. Wheal and flare were induced by skin prick tests using histamine 100 and 500 g/L before, and 4, 8 and 24 hours after, drug ingestion. At each session volunteers recorded levels of pruritus and sedation on two 10cm visual analogue scales. Cetirizine was significantly more potent than oxatomide (p = 0.0001), ketotifen (p = 0.0002) or placebo (p = 0.0001) in the inhibition of wheals, with similar results for flare (p = 0.0007, 0.0001 and 0.0002, respectively). Relief from pruritus was significantly better with cetirizine than with oxatomide (p = 0.003) or ketotifen (p = 0.002). Cetirizine was slightly better than placebo in relieving pruritus, but this was not statistically significant. Oxatomide and ketotifen were clearly more sedative than cetirizine (p = 0.05 and p = 0.0006, respectively), which was not significantly different from placebo. In conclusion, cetirizine appeared to be better in reducing histamine-induced wheal, flare and pruritus compared with ketotifen and oxatomide, and had less sedative effect.