Ranitidine (150 mg daily) inhibits wheal, flare, and itching reactions in skin-prick tests

Abstract

H(1)-receptor antagonists are known to suppress reactions in skin-prick tests (SPTs); however, the effect of H(2)-receptor antagonists, which are widely used in our everyday practice, remains unclear. The aim of this study was to determine the influence of ranitidine on wheal, flare, and itching sensation in SPTs. Twenty-one atopic patients (5 women and 16 men) with an average age of 28.04 years (SD, +/-8.24) were tested with histamine, codeine, negative control solution, and standard allergen extracts. Ranitidine (150 mg daily), loratadine (10 mg daily), or placebo were given to the volunteers for 5 days in a double-blind manner with 14 days of washout period. SPTs were applied to the volar surface of a forearm. There was no difference in wheal, flare, and itching between SPTs performed after placebo and washout period. The analysis revealed a statistically significant suppression of wheal and flare by ranitidine and loratadine (p = 0.013 and <0.00001, respectively, for wheals after allergens solutions tests, Wilcoxon rank-sum test). We found a significant suppression of itching induced by ranitidine (reduction of 26.85%; p = 0.005) and loratadine (29.6%; p = 0.005) as compared with placebo (p = 0.068 versus washout). Our data show a suppressive effect of ranitidine on the wheal, flare, and itching sensation in SPT. Because the sensitivity and specificity of skin testing requires withholding medication that could change the skin reactivity, it seems important to take into account the possible influence of H(2)-receptor antagonists on allergy diagnosis and therapy.

Atopy is a Risk Factor for Acute Appendicitis? A Prospective Clinical Study

“…H 2 -receptor antagonists, some tricyclic antidepressants (Desipramine and Doxepin), and antihistamines are the most likely drugs to interfere with skin tests. [24][25][26] They have a suppressive effect on the wheal, flare, and itching sensation in SPT. In this study, patients who take such medications are excluded.…”

Analysis of Histamine Receptor Knockout Mice in Models of Inflammation

“…Therefore, from a clinical point of view, the use of H 2 Rantagonists would be indicated for both Th1-and Th2-driven diseases, such as autoimmune diseases and IgE-mediated allergies, respectively, and indeed, in principle a clinical effect of H 2 R antagonists, specifically ranitidine, in the atopic reaction has already been shown (Lin et al, 2000;Watson et al, 2000;Kupczyk et al, 2007). However, by use of the knockout mouse approaches, to date, new definite indications for the use of H 1 R and H 2 R antagonists in humans have yet to be elaborated.…”

Hypersensitivity reaction to ranitidine: Description of a case and review of the literature

“…The prophylactic use of H2 antihistamines in combination with anti-H1 agents is thought to give better protection against anaphylactic or anaphylactoid reactions than the administration of single drugs, although other evidences do not support this hypothesis. (4,31) Moreover, some findings seem to suggest that the presumptive protective effect of ranitidine can be nullified, and its use may become even dangerous in patients who develop anaphylaxis because of the increased risk of heart block or bronchial hyperreactivity. (32,33) …”