RESUMO
The effect of Ranitidine, the H2-receptor antagonist, was investigated on cutaneous response to intradermal injection of histamine in healthy volunteers in a controlled, randomized, cross over study. The response was compared with that of the H1-receptor blocker; Dimethendine maleate used alone and in combination with the two antagonists. Reduction in the wheal area was significant in subjects pretreated with Ranitidine alone (P less than 0.05), and Dimethendine maleate alone (P less than 0.05); the combination of the two antagonists, did not produce additional reduction. Reduction in erythema area was not significant with Dimethendine maleate alone, but significant with Ranitidine alone (P less than 0.01). With the combination of the two antagonists the reduction was not more significant than with Ranitidine alone. The flare response scoring on visual analogue scale was not reduced significantly by Dimethendine maleate alone but reduced significantly by Ranitidine alone (P less than 0.10), and by combination of Ranitidine and Dimethendine maleate (P less than 0.05). Thus, Ranitidine appears to be more effective than Dimethendine maleate in reducing the erythema area and intensity of flare response and equieffective in reducing wheal response to histamine injection.