Evaluation of the local anaesthetic activity of dimetindene maleate by means of laser algesimetry in healthy volunteers.

Dimetindene maleate (DMM, Fenistil, CAS 3614-69-5) a specific H1-receptor antagonist, is therapeutically used for the treatment of respiratory allergies, urticaria, itching dermatoses and generally pruritic sensations occurring with various diseases. As it exhibits local anaesthetic activity in the rabbit cornea and the local anaesthetic activity of a couple of H1-antagonists was found to be linearly correlated to the H1-potency represented by the pA2-values--and dimethindene maleate demonstrates a high pA2-value--it seemed worth investigating the local anaesthetic potency in man making use of an objective and well validated pain model, the Laser algesimetry. The study was carried out with 24 healthy volunteers in a double-blind placebo- and reference-controlled, randomized, cross-over design. Three different medications were applied with occlusive dressing: DMM, lidocaine, and placebo. Selective thermo-noxious stimulation of A-delta- and C-fibers was induced by a CO2-laser. Somato-sensory evoked vertex potentials (SEPs) were simultaneously recorded. Both verum treatments showed a remarkable analgesic potency compared to placebo. Effects were preferably concentrated on the peripheral N1-component of the SEPs. The overall means of the N1-amplitudes were suppressed compared to placebo by both active drugs, with the effects being more pronounced for DMM.