3 EXPLORATIVE STUDIES ON THE EFFICACY OF THE ANTIHISTAMINE MEBHYDROLINE (OMERIL)

The efficacy of a multiple oral dose treatment with mebhydroline (Omer il coated tablets, 100 mg t.i.d.) was examined in 3 studies which were performed in a randomized, double-blind and placebo-controlled 2-way cross-over design. A second target was to investigate the suitability of different pharmacodynamic models for testing the efficacy of antihi stamines. Study A involved a nasal provocation with a specific allerge n in 11 symptom-free patients suffering from seasonal allergic rhiniti s. In study B, a nasal provocation with histamine was investigated in 11 healthy volunteers. Study C involved a cutaneous provocation with a specific allergen in 12 symptom-free patients suffering from seasonal allergic rhinitis/atopy. The mebhydroline treatment's superiority ove r placebo was shown statistically at the 95% confidence level for the symptoms itchy nose in study A and for nasal congestion in study B. In study C, allergen-induced weals (planimetric measurement) and itching (visual analog scale) were significantly changed by mebhydroline. A q ualitative evaluation revealed a reaction intensity that differed betw een the 2 treatments to a clinically relevant degree, however, without reaching significance. On the basis of the data it is expected that t he clinical efficacy of mebhydroline may be further substantiated in c onfirmatory clinical trials which should include placebo and positive controls. The test methods used differed in their suitability for meas uring the pharmacodynamic effects of antihistamines. Overall, the most clear-cut results were seen in hay fever patients using a specific al lergen for provocation. The planimetric assessment of weal response sh ould be preferred as a cutaneous model. Both AR and AARM have their cl inical relevance. Based on highly significant results of a subgroup an alysis there are indications in favor to AR, but momentary there is no definite conclusion in favor of or against either of the 2 methods.