Beyond the histamine receptor: effect of antihistamines on mast cells

Many antihistamines exhibit inhibition of mediator release from mast cells and basophils, in in vitro studies in addition to H₁ antagonism. The underlying mechanism is unclear but is unrelated to H₁-receptor antagonism. Clinical studies of antihistamins in antigen challenge and seasonal allergy demonstrate reduction of mast cell mediators in nasal lavage. It is not known what mechanism(s) underly these observations, although the concentrations required in in vitro studies suggests that a direct effect on mast cells is unlikely. Furthermore, the therapeutic contribution of this effect is difficult to assess because of concomitant clinically significant H₁ antagonism. This and other potential anti-allergic effects may enhance the therapeutic benefit of antihistamines and long-term studies are underway to explore this possibility.     

玉屏风散加味联合抗组胺药治疗慢性荨麻疹疗效与安全性Meta分析

目的： 评价玉屏风散联合抗组胺药治疗慢性荨麻疹的临床疗效及 安全性。方法： 检索中国知网、万方、维普、PubMed、EMbase 及 Cochrane library 等数据库建库至2017年11月期间发表的使用玉屏风散加味联合抗组胺药治疗慢性荨麻疹的随机对照试验（RCTs）。由两名研究者独立筛选文献并提取数据,根据Cochrane 偏倚风险评估工具对纳入研究进行方法学质量评估,用Rev Man 5.3软件进行Meta分析。结果：共纳入15篇文献, 133 6例患者。Meta分析结果显示,玉屏风散联合抗组胺药组与单用抗组胺药组比较,有效率高（P<0.00001）,复发率低（P<0.00001）,不良反应发生率低（P=0.003）。结论：玉屏风散加味联合抗组胺药治疗慢性荨麻疹疗效优于单用抗组胺药,且更安全。     

Antihistamines and their role as antipruritics

Antihistamines that bind to the histamine 1 receptor (H1) serve as important therapeutic agents to counter the effects of histamine in the skin. Two generations of antihistamines exist; however, second-generation agents are more advantageous because they cause less sedation, have a longer half life and are more selective for the H1 receptor. While H1 antihistamines have proven to be effective at reversing the pruritus and cutaneous lesions of chronic urticaria, their ability to treat pruritus associated with other cutaneous and systemic diseases is unproven.     

第2代抗组胺药儿科用药分析

目的促进抗组胺药的临床合理用药。方法随机抽查医院门诊处方近3823张,对其中使用抗组胺药的171张处方进行分析。结果与结论第2代抗组胺药是治疗I型变态反应性疾病比较安全有效的药物,但不同药物的药代动力学、临床疗效及不良反应等存在一定的差异,在儿科应用时应加以注意。     

抗组胺H1受体药在儿童过敏性鼻炎的临床应用

儿童过敏性鼻炎（allergic rhinitis， AR）的发病率逐年增高，抗组胺H1受体药可通过阻断组胺与H1受体的结合而起到控制变态反应性疾病的作用。第二代抗组胺H1受体药与H1受体的结合更稳定，有更好的特异性，几乎不通过血脑屏障，中枢抑制作用低，毒蕈碱样副反应少，作用时间长，且能有效地改善鼻部和眼部的症状，是治疗儿童AR的一线药物。目前尚缺乏客观的检测手段来评估抗组胺药物的有效性和安全性，所以儿童用药剂量应按体重调整，选择合适的剂型，并注意年龄限制，剂量品种应尽量个体化并应用合理的疗程。     

Infiltration Pain and Local Anesthetic Effects of Buffered vs Plain 1% Diphenhydramine

Objective: To compare the levels of infiltration pain and local anesthetic effects of plain and buffered 1% diphenhydramine.
Methods: A prospective, randomized. double-blind, paired study was performed using 30 adult volunteers. Intradermal injections (0.5 mL) of plain and buffered 1% diphenhydramine were made in the subjects' forearms. one in the left and the other in the right. The pain of infiltration was recorded on a previously validated 10-cm visual analog scale (VAS). The volunteers also were asked which injection was less painful. Sequential measurements of the diameter of anesthesia to pinprick were made at 1, 2, 5, 10, 15, 20, 25, and 30 minutes. The VAS scores and anesthetic diameters were compared for plain and buffered diphenhydramine using a paired Wilcoxon rank sum test.
Results: There was no statistically significant difference between buffered diphenhydramine and plain diphenhydramine for pain of injection (23.5 ± 19.2 mm vs 28.2 ± 18.7 mm. p = 0.24). Repeated-measures analysis of variance for anesthetic diameters demonstrated no significant difference between buffered diphenhydramine and plain diphenhydramine (p = 0.87). At no single measurement period were the anesthetic diameters different.
Conclusions: In a study with a sample size large enough to detect an 11-mm difference in VAS scores (power = 80%,), no difference was found in pain of infiltration and anesthetic effects when plain 1% diphenhydramine was compared with buffered 1% diphenhydramine. Buffering of diphenhydramine does not appear to result in a clinically significant reduction in the pain of infiltration.     

Duration of the inhibitory activity on histamine-induced skin weals of sedative and non-sedative antihistamines

The inhibitory effect of orally administered dexchlorfeniramine (4 mg/day), cyproheptadine (8 mg/day), astemizole (20 mg/day), loratadine (40 mg/day) and terfenadine (120 mg/day) on the size of histamine-induced weals was tested by skin prick test with histamine in an open study including 23 healthy individuals. The antihistamines were administered for 2 days in the nationally recommended therapeutic doses. For all drugs the maximal weal suppression with the dosage chosen was recorded the day after the last dosage, being 29% (for dexchlorfeniramine), 72% (for cyproheptadine), 50% (for astemizole), 62% (for loratadine), and 56% (for terfenadine) of the baseline value. For the drugs in the same order the duration of the inhibitory effect of the drugs after the last dose administered was between 3-4, 7-11, 17-28, 4-7, and 4-7 days, respectively.