Clinical evaluation of the effect of omeprazole, cimetidine, famotidine and ranitidine on histamine induced cutaneous wheal and flare response.

The effect of H2 receptor antagonists on immediate cutaneous response to allergens remain controversial. In the present study, the effect of 7-day administration of omeprazole, cimetidine, famotidine and ranitidine on histamine induced wheal and flare reaction was evaluated. A single blind randomized parallel group study with within patient comparison of responses was planned in non-ulcer dyspepsia patients eligible to receive H2 antagonists or omeprazole. None of the drugs produced any changes in the area of the wheal in comparison to respective baseline values. The area of flare was decreased by all the drugs and the percentage decrease in this parameter caused by omeprazole, cimetidine, famotidine and ranitidine was 2.4, 12.3, 20.2 and 13.2, respectively. Only famotidine caused a significant decrease in flare area (p < 0.05).