Improved outcomes in patients with acute allergic syndromes who are treated with combined H1 and H2 antagonists. Famotidine in the treatment of acute urticaria. Oral agents in the management of urticaria: patient perception of effectiveness and level of satisfaction with treatment. Differential effects of fluticasone propionate on allergen-evoked bronchoconstriction and increased urinary leukotriene E4 excretion.
Although the addition of H(2) blockers to H(1) antagonists has been promoted for use in anaphylaxis, there have been no large studies establishing the advantage of this approach in treating acute allergic syndromes. In this study we tested the hypothesis that combined H(1) and H(2) blockage results in improved outcomes in patients treated for acute allergic syndromes compared with treatment with H(1) blockade alone.
                In a randomized, double-blind, placebo-controlled trial, 91 adult patients with acute allergic syndromes were treated with either 50 mg of diphenhydramine and saline solution (control group) or with 50 mg of diphenhydramine and 50 mg of ranitidine (active group). These patients were treated with parenteral administration. Patients were recruited from an emergency department at an urban academic medical center. The primary endpoints were resolution of urticaria, angioedema, or erythema at 2 hours after protocol treatment. Areas of cutaneous involvement, heart rates, blood pressures, respiratory findings, and symptom scores were also assessed at baseline, 1 hour, and 2 hours.
                There were significantly more patients without urticaria at 2 hours among the patients in the active group compared with those in the control group. Both groups had similar proportions of urticaria at baseline. Logistic regression models to predict resolution of urticaria, which accounted for baseline urticarial involvement, showed odds ratios in favor of the active group treatment. Similar findings were observed when the absence of both urticaria and angioedema was considered as the dependent variable. There was not a significant difference between the 2 groups with regard to the absence of erythema or angioedema (irrespective of the presence of urticaria) at 2 hours. Blood pressure and symptoms did not show differences between the 2 groups over time. Lower heart rates were observed 1 hour after treatment in the active treatment group (mean reduction 10 beats/min) compared with those found in the placebo group (mean reduction 6 beats/min).
                These data show that adding H(2) blockers to H(1) antagonists results in additional improvement of certain cutaneous outcomes for patients presenting with acute allergic syndromes. These findings favor the recommendation for using combined H(1) and H(2) antihistamines in acute allergic syndromes. Recent studies suggest that histamine H2-receptor antagonists may be useful in the treatment of urticaria. This study was conducted to determine whether famotidine, a H2 antagonist, is effective in the treatment of acute urticaria and compare its effect with that of the H1 antagonist diphenhydramine. In this prospective, double-blind, controlled trial, 25 patients with urticaria of less than 72 h duration were randomized to receive a single dose of either famotidine 20 mg i.m. or diphenhydramine 50 mg i.m. Prior to treatment and 30 min after treatment, patients rated pruritus and sedation using visual analogue scales, while physicians evaluated intensity of urticaria and percentage of body surface area involved by urticaria. Famotidine was found to reduce pruritus associated with acute urticaria, intensity of urticaria, and body surface area affected by urticaria without causing sedation. Famotidine was comparable to diphenhydramine in efficacy; however, there was a (nonsignificant) trend for diphenhydramine to be more effective than famotidine in the treatment of pruritus, and for famotidine to be more effective in the reduction of surface area of involvement. It is concluded that famotidine merits further investigation as a potential medication for treatment of urticaria. Orally administered diphenhydramine, famotidine, and cromolyn sodium were compared for their abilities to alleviate symptoms of acute urticaria.
                This was a prospective, randomized, blind study, implemented in the emergency departments (EDs) of two teaching hospitals, each with an annual average of 40,000 ED patient visits. Patient perception of the effectiveness of treatment was assessed using a visual analog scale.
                33 adult patients presenting to the EDs were entered into the study over a one-year period. Of these, 8 were lost to follow-up and 5 were noncompliant with medications and not included in data analysis. Twenty adult patients, aged 19-78 years, completed the five-day study: 7 received diphenhydramine, 6 received famotidine, and 7 received cromolyn sodium.
                Patients receiving diphenhydramine reported the greatest satisfaction with treatment: 86 percent (6/7) indicated they would use the medication again. Fifty percent (3/6) in the famotidine group and 43 percent (3/7) in the cromolyn sodium group rated the treatment as worth using again. Patients receiving famotidine reported the greatest occurrence of adverse effects (50 percent, 3/6); the lowest incidence of such effects was seen in the cromolyn sodium group (14 percent, 1/7). Patients receiving diphenhydramine reported adverse effects at a rate of 43 percent (3/7).
                Our results suggest that patients receiving diphenhydramine are more satisfied with their treatment than are patients receiving famotidine or cromolyn sodium. Allergen challenge is associated with an increased excretion of urinary leukotriene E4. The source of this increase is unknown, although the lack of effect of inhaled beta-agonists and sodium cromoglycate suggests that airway mast cells may not be involved. We investigated this further using a new and topically potent inhaled glucocorticoid, fluticasone propionate (FP). A group of 10 mild atopic asthmatic subjects (6 males; FEV1 > 60% of predicted; PC20 histamine < or = 8 mg/ml; and on inhaled beta 2-agonists only) were studied before and after a 2-wk period of FP (1,000 micrograms/day) or placebo administered by metered-dose inhalers as two puffs twice per day through a large-volume spacer. Treatments were assigned in a double-blind crossover fashion separated by a 3-wk washout period. The PC20 histamine was measured at the start and end of each treatment when subjects also received a bronchial allergen challenge. Urine was collected for 4 h after allergen challenge for determination of LTE4 using HPLC-RIA, and 2 h later the PC20 histamine measurement was repeated. The 2-wk treatment with FP significantly inhibited both early and late responses to allergen: the maximum % fall in FEV1 during the early (0 to 2 h) and late response (2 to 6 h) was 32.6 +/- 3.4 and 19.6 +/- 5.2, respectively, following placebo versus 19.5 +/- 4.5 and 3.6 +/- 2.6 following FP (both p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)
The very limited evidence provided by this review was based on a few old studies of a relatively small size, which we categorised as having high to unclear risk of bias. Thus, at present, the review does not allow confident decision-making about the use of H2-receptor antagonists for urticaria. Although some of these studies have reported a measure of relief of symptoms of urticaria and rather minimal clinical improvement in some of the participants, the evidence was weak and unreliable. We have emphasised the lack of precision and limitations in the reported data where appropriate in this review.