Efficacy of dimetinden and hydroxyzine/chlorpheniramine in atopic dogs: a randomised, controlled, double‐blinded trial

Abstract

Antihistaminic drugs are commonly used as symptomatic therapy of atopic dermatitis in dogs. Unfortunately, their clinical benefit is largely unsubstantiated. In a double-blinded, placebo-controlled, cross-over trial, the influence of dimetinden and of a combination of chlorpheniramine and hydroxyzine on pruritus and lesions was evaluated in 19 dogs. They were treated with either product or a placebo orally for 14 days, each time followed by a 14-day washout period. Before and after each period, the dogs were examined and the Canine Atopic Dermatitis Extent and Severity Index (CADESI) determined by a clinician, and the pruritus and general condition by the owner. Dimetinden improved the pruritus significantly (P=0.014) but not the CADESI (P=0.087), the combination of hydroxyzine and chlorpheniramine improved the CADESI (P=0.049) and pruritus (P=0.05) significantly. Ten of 17 dogs improved by more than 25 per cent in pruritus with the combination of hydroxyzine and chlorpheniramine, 12 of 18 with dimetindenmaleate and only 2 of 19 with placebo. Antihistamines can help to reduce pruritus in atopic dogs, but in most cases, the improvement is limited and additional treatment may be needed.

Efficacy of ultra‐micronized palmitoylethanolamide in canine atopic dermatitis: an open‐label multi‐centre study

“…Although the present study was an open design, the mean percentage reduction in pruritus was higher than that previously reported for the placebo in controlled studies, which ranged between 11% and 20% . Among published reports, the percentage of dogs whose pruritus improved more than 50% at study end ranged from 11% to about 80% . Our result of 35% lies in the middle, being lower than that of prednisolone and higher than antihistamines .…”

Effects of ibrutinib on proliferation and histamine release in canine neoplastic mast cells

“…Additional clinical symptoms, such as pruritus or oedema, can be provoked by MC‐derived mediators, such as histamine . These mediator‐induced effects can often be controlled by histamine receptor (HR)1 and HR2 antagonists . At present, the only curative treatment approach is wide‐margin surgery .…”

Cetirizine per os: exposure and antihistamine effect in the dog

“…When used in dogs with atopic dermatitis, some dog owners report satisfactory improvement of the clinical signs [13]. In clinical studies, the outcome of treatment with antihistamine is lower: 0–30% of patients are satisfactorily improved [14–17]. The very sparse available PK/PD data on antihistamines in the dog make interpretation of these data difficult and it is impossible to evaluate whether the dose produces a pharmacologically relevant exposure.…”

“…randomized, blinded and placebo controlled), the results are conflicting [17, 18]. Hsiao et al [18] were unable to demonstrate any difference in pruritus score between cetirizine and control treatments in a study population of 50 dogs whereas Eichenseer et al [17] reported reduction of pruritus after medication with antihistamines (dimethindene or chlorpheniramine/hydroxyzine) in a cross-over study using a study population of 20 dogs. The limited number of dogs included in those studies lowers the statistical power and discrete improvements may have been missed.…”

“…Hydroxyzine at 2 mg/kg prevents wheal and flare reactions due to intradermal skin injections, mainly due to the effects of the active metabolite cetirizine [12]. The reduction in skin lesion score shown in the study by Eichenseer et al [17] may be due to the higher total dose of antihistamines given by means of combining two different antihistamines. However, the effect of antihistamines on clinical signs of atopic dermatitis is likely to be limited.…”