口服西替利嗪对犬的暴露和抗组胺作用

王帆

Cetirizine per os: exposure and antihistamine effect in the dog

口服西替利嗪对犬的暴露和抗组胺作用

 

作者：Carl Ekstrand , Carina IngvastLarsson, Ulf Bondesson, Mikael Hedeland and Lena Olsén

 

翻译：王帆

 

Abstract

摘要

Background: Cetirizine is an antihistamine used in dogs, but plasma concentrations in relation to effect after oral administration are not well studied. This study investigated cetirizine exposure and the plasma cetirizine concentra tionantihistamine response relation in the dog following oral administration of cetirizine.

Results: Eight Beagle dogs were included in a crossover study consisting of two treatments. In treatment one, cetirizine 2–4 mg/kg was administered per os once daily for 3 days. The other treatment served as a control. Wheal diameter induced by intradermal histamine injections served as responsebiomarker. Cetirizine plasma concentra tion was quantified by UHPLCMS/MS. Median (range) cetirizine plasma terminal halflife was 10 h (7.9–16.5). Cetirizine significantly inhibited wheal formation compared with the premedication baseline. Maximum inhibition of wheal formation after treatment with cetirizine per os was 100% compared with premedication wheal diameter. The median (range) IC50value for reduction in wheal area was 0.33 µg/mL (0.07–0.45). The median (range) value for the sigmoidic ity factor was 1.8 (0.8–3.5). A behavioral study was also conducted and revealed no adverse effects, such as sedation.

Conclusion: The results indicate that a oncedaily dosing regimen of 2–4 mg/kg cetirizine per os clearly provides a sufficient antihistamine effect. Based on this experimental protocol, cetirizine may be an option to treat histamine mediated inflammation in the dog based on this experimental protocol but additional clinical studies are required.

背景：西替利嗪是一种用于犬的抗组胺药，但其口服给药后的血浆浓度与药效之间的关系尚未得到充分研究。本研究旨在探究犬口服西替利嗪后的暴露情况以及血浆西替利嗪浓度与抗组胺药反应之间的关系。

结果：本研究纳入了 8 只比格犬，进行了交叉对照试验，包括两种治疗方案。在第一种治疗方案中，每日口服西替利嗪 2 - 4 毫克/千克，持续 3 天。另一种治疗方案作为对照。通过皮内注射组胺诱导的风团直径来作为反应生物标志物。通过超高效液相色谱 - 串联质谱法对西替利嗪血浆浓度进行定量测定。西替利嗪血浆半衰期的中位值（范围）为 10 小时（7.9 - 16.5）。与用药前的基线相比，西替利嗪显著抑制了风团形成。口服西替利嗪治疗后风团形成的最大抑制率为 100%，而用药前的风团直径为对照组。西替利嗪风团面积减少的中位值（范围）IC50 值为 0.33 微克/毫升（0.07 - 0.45）。S 型曲线的中位值（范围）指数因子为 1.8（0.8 - 3.5）。还进行了一项行为学研究，结果显示没有出现诸如镇静等不良反应。

结论：研究结果表明，每日一次、每次 2 - 4 毫克/千克的口服西替利嗪给药方案能明显提供足够的抗组胺效果。根据这一实验方案，西替利嗪可能是一种用于治疗犬由组胺引起的炎症的药物选择，但还需要更多的临床研究来证实这一点。

 

Keywords: Antiinflammatory, Efficacy, Pharmacodynamics, Pharmacokinetics, Potency

关键词：抗炎、疗效、药效学、药代动力学、效力

 

Background

背景

Inverse histamine 1 (H1) receptor-agonists, usually referred to as H1-receptor antagonists or antihistamines, are frequently used to prevent allergic reactions in humans. Antihistamines can be divided into first generation antihistamines (e.g. hydroxyzine) and second generation antihistamines (e.g. cetirizine). First generation antihistamines are known to produce sedation due to antihistamine effects on the central nervous system. In contrast, sedation is not as common among the effects of second-generation antihista mines due to their higher affinity to the efflux protein P-glycoprotein (Pgp) in the blood–brain barrier. T here are currently few antihistamines labeled for use in dogs in Europe. However, antihistamines have been prescribed off-label with little available scientific data on the pharmacokinetics (PK) and pharmacodynam ics (PD) available. Both PK and PD might vary between species, so efficacy in humans is not a guarantee of efficacy in dogs. For instance, the antihistamines diphen hydramine and clemastine have low bioavailability and clemastine was demonstrated to have low antihistamine effect due to low systemic exposure after oral admin istration in dogs. Compared with clemastine, the antihistamine response to the second generation anti histamine cetirizine (1 mg/kg once daily) in the dog is more efficacious, around 30–80% with a marked vari ations between animals and between studies. T his can be compared with the antihistamine response after oral administration of 2 mg/kg hydroxyzine, which is around 90% and shows lower inter-individual variability. Hydroxyzine is metabolized to cetirizine, which is considered the active substance to the antihis tamine response after hydroxyzine administration. In the studies by Temizel et al. and De Vos et al. plasma concentrations of cetirizine were not reported, so the most probable explanation for the conflicting results for hydroxyzine and cetirizine are variations in systemic exposure of cetirizine due to the low dose and perhaps low bioavailability. In addition, there are no data available that describe the plasma concentra tion–time course of cetirizine and linking the cetirizine exposure to the response using pharmacokinetic/pharmacodynamic (PK/PD) models. The aims of this study were thus to investigate exposure of cetirizine admin istered per os, to link the exposure to the antihistamine effect and to indicate apparent adverse effects.

逆组胺 1 型（H1）受体激动剂，通常被称为 H1 受体拮抗剂或抗组胺药，常用于预防人类的过敏反应。抗组胺药可分为第一代抗组胺药（如羟嗪）和第二代抗组胺药（如西替利嗪）。第一代抗组胺药由于其对中枢神经系统的抗组胺作用而会产生镇静效果。相比之下，第二代抗组胺药由于其对血液-脑屏障中的外排蛋白 P-糖蛋白（Pgp）的亲和力较高，因此镇静效果并不常见。目前在欧洲，用于犬的抗组胺药种类较少。然而，抗组胺药已被用于非标准治疗用途，但可用的药代动力学（PK）和药效动力学（PD）方面的科学数据很少。PK 和 PD 可能在不同物种之间有所差异，因此人类的疗效并不能保证在犬中的疗效。例如，抗组胺药苯海拉明和氯马斯汀的生物利用度较低，而氯马斯汀由于口服给药后在犬体内的系统暴露量较低，被证明具有较低的抗组胺效果。与氯马斯汀相比，犬对第二代抗组胺药西替利嗪（1 毫克/千克，每日一次）的抗组胺反应更为有效，效果约为 30%至 80%，且不同动物之间以及不同研究之间存在显著差异。这可以与口服 2 毫克/千克羟嗪后的抗组胺反应进行比较，其效果约为 90%，且个体间差异较小。羟嗪会代谢为西替利嗪，而西替利嗪被认为是羟嗪给药后抗组胺反应的活性物质。在 Temizel 等人和 De Vos 等人的研究中，未报告西替利嗪的血浆浓度，因此羟嗪和西替利嗪结果存在冲突的最可能解释是由于低剂量和可能的低生物利用度导致的西替利嗪全身暴露程度的差异。此外，也没有可用的数据描述西替利嗪的血浆浓度-时间曲线，并利用药代动力学/药效动力学（PK/PD）模型将西替利嗪暴露与反应联系起来。本研究的目的在于：探究口服西替利嗪的暴露情况，将这种暴露与抗组胺效果联系起来，并指出可能的不良反应。

 

Methods

方法

This study was approved by the Animal Ethics Commit tee, Uppsala, Sweden (C100/14).

本研究已获瑞典乌普萨拉动物伦理委员会批准（C100/14）。

 

Eight female Beagle dogs, 4–7 years old and weighing 10.0–13.5 kg, were given racemic cetirizine dihydrochloride (Cetirizin Sandoz 10 mg, Sandoz AS, Copenhagen, Denmark) as tablets in meat-balls or a control treatment (meat-balls) orally in a two-treatment cross-over design. Cetirizine was administered at 0, 24 and 48 h. The first administered dose was 4 mg/kg body weight. The second and third administered doses were 4 mg/kg in four dogs and 2 mg/kg in four dogs. Blood was collected in heparinized tubes before cetirizine was administered at 0, 24, 48 h and at 50, 51, 52, 55, 57, 59, 72, 76, 81 and 96 h. Blood samples were centrifuged at 1500g for 10 min (+ 4 °C). The plasma was then stored at − 70 °C pending analysis.

选取了 8 只雌性比格犬，年龄在 4 至 7 岁之间，体重在 10.0 至 13.5 千克之间，将其分为两组进行交叉试验。一组口服含外消旋盐酸西替利嗪的肉丸制剂，另一组则接受对照治疗（即口服肉丸）。西替利嗪的给药时间为 0 小时、24 小时和 48 小时。首次给药剂量为每千克体重 4 毫克。第二次和第三次给药剂量分别为每千克体重 4 毫克（在 4 只犬中）和 2 毫克（在 4 只犬中）。在西替利嗪给药后的 0 小时、24 小时、48 小时以及 50 小时、51 小时、52 小时、55 小时、57 小时、59 小时、72 小时、76 小时、81 小时和 96 小时，采集血液样本，使用肝素抗凝管采集，在 1500g 条件下离心 10 分钟（4°C）。随后将血浆储存在 -70°C 下待分析。

 

Recording of the pharmacodynamic response to cetirizine exposure

记录西替利嗪暴露后的药效学反应

Wheal-formation induced by intradermal histamine injection (0.07 mL of 0.1 mg/mL solution) was used to evaluate the antihistamine response. Before the start of each treatment, the dogs were bilaterally shaved on the thorax with electric clippers. A total volume of 0.07 mL of histamine hydrochloride (Soluprick, 10 mg/mL, ALK-Abello A/S, Horsholm, Denmark) diluted in saline (Natriumklorid Fresenius Kabi 9 mg/mL, Fresenius Kabi AB, Uppsala, Sweden) to a final concentration of 0.1 mg/ mL was injected using a 0.4 × 19 mm (27 gauge) needle before each blood sample. The diameter of the wheal induced by histamine was determined 20 min after his tamine injection, as the mean of two perpendicular diameters measured using a digital Vernier caliper. Two injections were performed at each time-point and the largest reaction was used for further calculations. Sterile saline (0.07 mL) served as a negative control.

通过皮内注射组胺（0.07 毫升，浓度为 0.1 毫克/毫升的溶液）来形成风团，以此来评估抗组胺药物的反应。在每次治疗开始前，会对犬的胸部两侧进行剃毛处理，使用电动剪刀。每次采集血样前，将 0.07 毫升的盐酸组胺与生理盐水以最终浓度 0.1 毫克/毫升的比例稀释后，用 0.4×19 毫米（27 号）的针头注射。在注射组胺后 20 分钟，通过使用数字游标卡尺测量的两个垂直直径的平均值来确定组胺引起的风团直径。在每个时间点进行两次注射，并使用最大反应值进行进一步计算。无菌生理盐水（0.07 毫升）作为阴性对照。

 

Behavioral study

行为研究

To detect any adverse effects such as sedation a behavio ral study was conducted. The dogs were filmed when kept in their home environment at 1.5–2.5 and 3.0–4.5 h after drug administration on days one and two of the trial. The f ilms were analyzed and behaviors were recorded accord ing to two different protocols: The total time that each dog performed the behaviors drinking water, urinating, defecating, panting, yawning, barking, playing and licking (body, paws or lips) was calculated. Frequency of barking, lip licking and shaking the body was also noted.

为了检测任何不良反应（如镇静作用），我们进行了行为学研究。在试验的第一天和第二天，当给犬用药后 1.5 - 2.5 小时以及 3.0 - 4.5 小时，我们让它们待在家中环境中，并对其进行拍摄。拍摄的影片被分析，行为也被按照两种不同的方案记录下来：计算每只犬在饮水、排尿、排便、喘气、打哈欠、吠叫、玩耍和舔舐（身体、爪子或嘴唇）等行为上所花费的总时间。同时，还记录了吠叫的频率、舔唇的频率以及身体颤抖的频率。

 

For each dog, the behaviors sitting, lying, and active (including walking, jumping and standing) were also recorded during 4 min in every 20 min of films. Behav iors at 12 sample points at 20 s intervals within the 4 min period were recorded on score sheets.

对于每只犬，还在影片的每 20 分钟内记录了 4 分钟内的坐姿、躺姿和活跃行为（包括行走、跳跃和站立）。在 4 分钟时间段内，每隔 20 秒记录 12 个样本点的行为，并将其记录在评分表上。

 

Analytical method

分析方法

Determination of cetirizine was performed at the National Veterinary Institute (SVA) in Uppsala, Swe den. The sample pretreatment for plasma was as fol lows: To 100 µL of Li-heparin plasma (calibrators, QCs or study samples), 50 µL of the internal standard solu tion containing 2H4-cetirizine (0.11 µg/mL) were added. For protein precipitation, 100 µL of trichloroacetic acid (20%, w/v) were added, and the samples were mixed for 10 min followed by centrifugation for 5 min at 10,000g. T he supernatants were transferred to vials and 10 µL of each sample were injected into an ultra-high-perfor mance liquid chromatography-tandem mass spectrom etry (UHPLC-MS/MS) system composed of an Acquity UPLC coupled to a Quattro Ultima Pt tandem quadru pole mass spectrometer with an electrospray interface operating in the positive mode (Waters Corporation, Milford, MA). The column was an Acquity UPLC BEH C18 (length 100 mm, I.D. 2.1 mm, particle size 1.7 µm) kept at 60 °C. The mobile phase consisted of (A) 10 mM ammonium formate in water and (B) 0.1% formic acid in acetonitrile. The elution was carried out as follows: initially at 20% B for 1.0 min, increase to 90% B during 1 min, constant at 90% B for 1.0 min, decrease to 20% B during 0.1 min, constant at 20% B for 1.9 min. The total run time was 5.0 min and the flow-rate was 400 µL/min. T he analyte was quantified using a positive capillary volt age of 0.90 kV and a cone voltage of 35 V. The desolvation and source block temperatures was 300 °C and 120 °C, respectively, and desolvation gas flow was 950 L/h. The quantification was performed in the selected reaction monitoring (SRM) mode with the collision cell filled with argon gas at a pressure of 1.95 × 10−3 mBar. The mass transitions used in SRM were m/z 389 → 201 for cetirizine (collision energy 20 eV) and m/z 393 → 201 for [2H4]-cetirizine (collision energy 20 eV). The dwell time was 0.100 s. The reference standard cetirizine and the internal standard [2H4]-cetirizine were both obtained from Toronto Research Chemicals (North York, ON, Canada). The calibration curves were constructed using the chromatographic peak area ratio (analyte/internal standard) as a function of analyte concentration. The cali bration functions were calculated by linear curve fit using a weighting factor of 1/x2. The calibration range was 0.3 10,000 ng/mL and the precision (relative standard devia tion) was in the range of 0.6–7.3% and the accuracy was 98–114%.

西替利嗪的测定是在瑞典乌普萨拉的国家兽医研究所（SVA）进行的。血浆样本的预处理步骤如下：向 100 微升的肝素锂血浆（标准品、质控品或研究样本）中加入 50 微升含有 2H4-西替利嗪（0.11 微克/毫升）的内标溶液。为了进行蛋白质沉淀，加入 100 微升三氯乙酸（20%，质量/体积比），然后将样品混合 10 分钟，随后以 10，000g 的转速离心 5 分钟。上清液转移至小瓶中，每份样品注入超高效液相色谱-串联质谱（UHPLC-MS/MS）系统，该系统由 Acquity UPLC 与 Quattro Ultima Pt 串联四极杆质谱仪组成，电喷雾接口以正离子模式工作（沃特世公司，马萨诸塞州米尔福德）。色谱柱为 Acquity UPLC BEH C18（长度 100 毫米，内径 2.1 毫米，颗粒大小 1.7 微米），保持在 60 摄氏度。流动相由（A）10 毫摩尔/升氨甲酸水溶液和（B）0.1%甲酸乙腈溶液组成。洗脱过程如下进行：起初以 20% 的 B 浓度持续 1.0 分钟，随后在 1 分钟内增加至 90% 的 B 浓度，保持在 90% 的 B 浓度 1 分钟，接着在 0.1 分钟内降低至 20% 的 B 浓度，保持在 20% 的 B 浓度 1.9 分钟。总运行时间为 5.0 分钟，流速为 400 微升/分钟。定量使用正极板电压 0.90 千伏和锥电压 35 伏。脱溶剂和源块的温度分别为 300 摄氏度和 120 摄氏度，脱溶剂气体流量为 950 升/小时。定量在选择反应监测（SRM）模式下进行，碰撞室填充有氩气，压力为 1.95×10−3 毫巴。SRM 中使用的质量转换为 m/z 389 → 201（碰撞能量 20 电子伏特）和 m/z 393 → 201（碰撞能量 20 电子伏特）。停留时间为 0.100 秒。参考标准盐酸西替利嗪和内标 [2H4]-盐酸西替利嗪均来自多伦多研究化学品公司（安大略省北雅克逊市）。校准曲线是使用色谱峰面积比（分析物/内标）作为分析物浓度的函数构建的。校准函数是通过使用权重因子 1/x² 的线性曲线拟合来计算的。校准范围为 0.3 至 10，000 纳克/毫升，精密度（相对标准偏差）在 0.6% 至 7.3% 之间，准确度在 98% 至 114% 之间。

 

Data analyses

数据分析

A one compartment model was fitted to experimen tal cetirizine data from each dog in order to predict and describe the cetirizine plasma concentration–time course. Individual concentration–time profiles were then used in an inhibitory function and ‘drove’ a turno ver model in the PK/PD analyses (Fig. 1). The cetirizine plasma concentration–time course was described as:

针对每只犬的实验用西替利嗪数据，构建了一个单室模型，以预测并描述西替利嗪的血浆浓度-时间曲线。随后，将个体的浓度-时间曲线用于抑制函数中，并“驱动”了 PK/PD 分析中的“转轮验证”模型（图 1）。西替利嗪的血浆浓度-时间曲线描述为：

 

Cp = ka·F ·Dosepo V ·(ka −k) · e−k·(t−tlag) − e−ka·(t−tlag) (1)

 

where Cp is the plasma concentration of cetirizine and Dosepo is the dose administered per os. The model parameters were V/F, which is the ratio between volume and the bioavailability, t and tlag represent time and the lag time, respectively, and ka and k are the absorption rate constant and the elimination rate constant, respectively. T he terminal half-life (t1/2z) of cetirizine in plasma was calculated as

其中 Cp 是西替利嗪的血浆浓度，Dosepo 是口服给药的剂量。模型参数包括 V/F，即体积与生物利用度的比值；t 和 tlag 分别代表时间与滞后时间；ka 和 k 分别为吸收速率常数和消除速率常数。西替利嗪在血浆中的终末半衰期（t1/2z）的计算公式为

 

t1/2z = ln(2) k (2)

 

Cetirizine was assumed to directly inhibit histamine induced weal formation described as

西替利嗪被认为可以直接抑制组胺诱导的血管形成

 

I(Cp) = 1− Cnp ICn 50 + Cn p (3)

 

where I(C), IC50 and n are the inhibitory drug mechanism function, the cetirizine plasma concentration at 50% reduction of the response and the sigmoidicity factor, respectively. The turnover of histamine-induced wheal formation with the inhibitory drug mechanism incorpo rated was described by

其中 I(C)、IC50 和 n 分别代表抑制性药物作用机制、抑制药物使反应减弱 50% 时的特非那定血药浓度以及 S 型曲线系数。由包含抑制性药物作用机制的组胺诱导的风团形成过程所描述的转化情况为

 

dR dt =kin · 1− Cnp ICn 50 + Cn p −kout · R (4)

 

where dR dt is the rate of change over time, kin and kout are the turnover rate for the production of response and the f irst-order fractional turnover rate for loss of response, respectively, and R is the response.

其中 dR/dt 表示随时间的变化率，kin 和 kout 分别代表响应生成的周转率以及响应丧失的零级分数性周转率，而 R 则代表响应。

 

Model evaluation

模型评估

One- and two compartment models with and without lag-time were fitted to the data. The most appropriate model was chosen based on visual inspection of diagnos tic plots, objective function values, Akaike Information Criterion (AIC) and Schwarz Criterion (SC).

对包含和不包含延迟时间的单室和双室模型进行了拟合，以适应数据。根据诊断图的直观观察、客观函数值、阿基卡信息准则（AIC）和施瓦茨准则（SC），选择了最合适的模型。

 

Statistics

统计学

The effect of treatment was subjected to statistical hypothesis testing by means of a one-sided Wilcoxon Rank Sum test for paired data observations. Statisti cal significance was considered when P < 0.004 (Šisák corrected P-value for repeated measurements).

治疗效果通过单侧威尔科克森配对秩和检验进行了统计假设检验。当 P < 0.004（重复测量的舍斯亚克校正 P 值）时，认为具有统计学意义。

 

The behavioral data were subjected to statistical hypothesis testing by means of a two-sided Wilcoxon Rank Sum test for paired data observations. Statistical significance was considered when P < 0.05.

行为数据通过双侧威尔科克森配对秩和检验进行了统计假设检验。当 P < 0.05 时，认为具有统计学意义。

 

All statistical analyses were performed using the statis tical software R version 3.4.0 (The R Foundation for Sta tistical Computing, Vienna, Austria).

所有统计分析均使用统计软件 R 版本 3.4.0（奥地利维也纳的 R 基金会统计计算机构）进行。

 

Results

结果

Cetirizine concentration–time course analyses

西替利嗪浓度-时间曲线分析

After treatment with 4 mg/kg cetirizine followed by 2 mg/kg cetirizine once daily, median (range) maximum observed plasma concentration was 2.7 µg/mL (2.5–2.8) and observed 4 h after the last administration of ceti rizine (Fig. 2). Before cetirizine was administered at 24 h and 48 h, median (range) plasma concentrations were 1.1 µg/mL (0.6–1.3) and 0.7 µg/mL (0.5–0.8), respec tively. After treatment with 4 mg/kg cetirizine once daily for 3 days, median (range) maximum observed plasma concentration was 5.6 µg/mL (4.6–10.8) and observed 7 h after the last administration of cetirizine. Before ceti rizine administration at 24 h and 48 h, median (range) plasma concentration was 1.3 µg/mL (1.2–1.7) and 2.2 µg/mL (1.5–4.7), respectively. The median (range) model parameter estimates for V F , ka, k and tlag were 0.8 (0.6–0.9), 1.0 per h (0.4–4.0), 0.07 per h (0.04–0.09) and 1.8 h (0.7–2.8), respectively. The plasma half-life was 10 h (7.9–16.5).

在给予 4 毫克/千克的西替利嗪后，接着每日给予 2 毫克/千克的西替利嗪，观察到的中位（范围）最大血浆浓度为 2.7 微克/毫升（2.5 - 2.8），且在最后一次给予西替利嗪 4 小时后被检测到（图 2）。在给予西替利嗪 24 小时和 48 小时之前，中位（范围）血浆浓度分别为 1.1 微克/毫升（0.6 - 1.3）和 0.7 微克/毫升（0.5 - 0.8）。在给予 4 毫克/千克的西替利嗪每日治疗 3 天后，观察到的中位（范围）最大血浆浓度为 5.6 微克/毫升（4.6 - 10.8），且在最后一次给予西替利嗪 7 小时后被检测到。在给予西替利嗪 24 小时和 48 小时之前，中位（范围）血浆浓度分别为 1.3 微克/毫升（1.2 - 1.7）和 2.2 微克/毫升（1.5 - 4.7）。模型参数的中位（范围）估计值为 V F 为 0.8（0.6 - 0.9），ka 为 1.0 每小时（0.4 - 4.0），k 为 0.07 每小时（0.04 - 0.09），tlag 为 1.8 小时（0.7 - 2.8）。血浆半衰期为 10 小时（7.9 - 16.5）。

 

Wheal diametertime course

风团直径与时间的关系

Compared with the pre-medication wheal diame ter, median (range) relative wheal diameters was 88% (48–171%) in the control treatment and 46% (0–111%) when the dogs were treated with cetirizine (Fig. 3). There was no difference in wheal diameter between treatment with cetirizine and control treatment at time = 0 (P = 0.73). However, wheal diameter was sig nificantly (P < 0.004, Šisák-corrected P-value) smaller after treatment with cetirizine from 24 h (the first observation after cetirizine administration) to 57 h and from 76 h to 81 h (the penultimate observation) compared with the control treatment. The P-value at 59 h and 71 h was P = 0.007 and P = 0.02, respectively. There was no significant difference between the two treatments at the final observation (96 h, P = 0.53). The variation in wheal diameter between animals was lower after treatment with cetirizine than after control treatment (Fig. 3). There was no difference in wheal response between the two cetirizine dosing protocols (4, 2, 2 mg/kg and 4, 4, 4 mg/kg). The PD model fit ted to experimental wheal data accurately mimicked the wheal diameter-time course (Fig. 4). The median (range) IC50-value for the reduction of wheal area was 0.33 µg/mL (0.07–0.45). The median (range) value for the sigmoidicity factor (n) was 1.8 (0.8–3.5).

与用药前的风团直径相比，对照组治疗后的平均相对风团直径为 88%（48 - 171%），而使用西替利嗪治疗的犬的平均相对风团直径为 46%（0 - 111%）（图 3）。在时间 = 0 时，使用西替利嗪治疗与对照组治疗之间的风团直径没有差异（P = 0.73）。然而，从 24 小时（西替利嗪给药后的首次观察）到 57 小时以及从 76 小时到 81 小时（最后两次观察）使用西替利嗪治疗后的风团直径明显小于对照组治疗（P < 0.004，Šisák 校正的 P 值）。在 59 小时和 71 小时的 P 值分别为 P = 0.007 和 P = 0.02。在最终观察（96 小时）时，两种治疗之间的 P 值（P = 0.53）没有显著差异。使用西替利嗪治疗后的动物间风团直径的变异低于对照组（图 3）。两种西替利嗪给药方案（4、2、2 毫克/千克和 4、4、4 毫克/千克）之间的风团反应没有差异。PD 模型准确地拟合了实验风团数据，模拟了风团直径 - 时间曲线（图 4）。减轻风团面积的中位（范围）IC50 值为 0.33 微克/毫升（0.07 - 0.45）。斜率因子（n）的中位（范围）值为 1.8（0.8 - 3.5）。

 

Behavioral study

行为研究

No differences in total time of different behaviors were noted. The frequency of lip licking was sufficiently high in six dogs and to be analyzed statistically, but was found not to be significantly different when the dogs were treated with cetirizine compared with the control treatment. For the behaviors sitting, lying, and activity that were observed every 20 min, only four dogs could be included in the statistical analysis. Those dogs were visible on the video film for 70–100% of the observation period. One dog was moved to another compartment and three dogs were not visible on the video for more than 50% of the observed time. Those four dogs were excluded from the analyses. No significant differences could be established for any of these behaviors.

不同行为的总时长没有差异。六只犬的舔唇频率相当高，足以进行统计分析，但与对照组相比，在使用西替利嗪治疗的犬中，其舔唇频率并未显示出显著差异。对于每 20 分钟观察一次的坐、躺和活动等行为，只有四只犬的数据能够纳入统计分析。这些犬在视频中的可见时间占观察总时长的 70%至 100%。有一只犬被转移到了另一个隔间，另外三只犬在观察时间内有超过 50%的时间未在视频中出现。这四只犬被排除在分析之外。对于这些行为，均未发现显著差异。

 

Discussion

讨论

This study is the first to report plasma concentrations of cetirizine, the concentration–time profile of cetirizine and PD parameters for the antihistamine response after administration of cetirizine per os in the dog. The results indicate that systemic exposure to cetirizine after oral treatment may inhibit histamine-induced wheal forma tion by up to 100% (Fig. 3). The antihistamine response in this study is consistent with the reported antihistamine response to cetirizine after administration of 2 mg/kg hydroxyzine per os daily in dogs, while medication with 1 mg/kg cetirizine orally once daily results in a lower antihistamine response. These conflicting results may be explained by insufficient plasma exposure when lower doses of cetirizine than in this study are used. Due to the fairly long half-life (median 10 h) of cetirizine, 2 mg/kg daily dose is sufficient to maintain plasma con centration exceeding the median IC50 value (0.33 µg/ mL) for 24 h. This quantitative information is similar to the median half-life of cetirizine (9.7 h) and the IC50 value (0.6 µg/mL), after administration of hydroxyzine, reported by Bizikova et al..

本研究首次报道了犬口服西替利嗪后血浆中西替利嗪的浓度、西替利嗪的浓度-时间曲线以及抗组胺反应的药代动力学参数。结果表明，口服治疗后犬体内的西替利嗪系统暴露量可使组胺诱导的风团形成抑制高达 100%（图 3）。本研究中的抗组胺反应与犬每日口服 2 毫克/千克羟嗪后报告的西替利嗪抗组胺反应一致，而每日口服 1 毫克/千克西替利嗪的药物治疗则导致较低的抗组胺反应。这些相互矛盾的结果可能是由于使用低于本研究中的剂量的西替利嗪时，血浆暴露不足所致。由于西替利嗪的半衰期较长（中位值为 10 小时），每日 2 毫克/千克的剂量足以使血浆浓度超过 24 小时内中位 IC50 值（0.33 微克/毫升）。这些定量信息与 Bizikova 等人报告的羟嗪每日口服 2 毫克/千克后的西替利嗪的半衰期（9.7 小时）和 IC50 值（0.6 微克/毫升）相似。

 

Antihistamines are widely used in human medicine. When used in dogs with atopic dermatitis, some dog owners report satisfactory improvement of the clinical signs. In clinical studies, the outcome of treatment with antihistamine is lower: 0–30% of patients are satis factorily improved. The very sparse available PK/ PD data on antihistamines in the dog make interpreta tion of these data difficult and it is impossible to evaluate whether the dose produces a pharmacologically relevant exposure. From this perspective, further experimental PK/PD-studies on antihistamines, combined with drug concentration assessment in plasma at the time of obser vation in clinical studies, are warranted.

抗组胺药在人类医学中被广泛应用。在特应性皮炎患犬上使用时，一些犬主报告称临床症状有了明显的改善。在临床研究中，使用抗组胺药的治疗效果较低：约 0%至 30%的患犬症状得到了明显改善。关于抗组胺药在犬中的可用药代动力学/药效学数据非常稀少，这使得对这些数据的解读变得困难，也无法评估该剂量是否能产生具有药理学意义的暴露量。从这个角度来看，有必要对抗组胺药进行更多的实验性药代动力学/药效学研究，并结合临床研究中观察时的血浆药物浓度评估，以进一步完善相关研究。

 

In clinical studies with high quality scientific evidence (i.e. randomized, blinded and placebo controlled), the results are conflicting. Hsiao et al. were unable to demonstrate any difference in pruritus score between cetirizine and control treatments in a study pop ulation of 50 dogs whereas Eichenseer et al.reported reduction of pruritus after medication with antihista mines (dimethindene or chlorpheniramine/hydroxyzine) in a cross-over study using a study population of 20 dogs. T he limited number of dogs included in those studies lowers the statistical power and discrete improvements may have been missed. Despite this, the antihistamine combination chlorpheniramine/hydroxyzine in the latter study significantly decreased skin lesions, an effect not observed after treatment with dimethindene. After pretreatment for 24 h, neither 0.5 mg/kg cetirizine nor 2 mg/kg hydroxyzine was effective in preventing skin lesions in experimentally induced dermatitis. A dose of 0.5 mg/kg cetirizine is unlikely to give plasma concen trations above the potency (IC50) value. Hydroxyzine at 2 mg/kg prevents wheal and flare reactions due to intra dermal skin injections, mainly due to the effects of the active metabolite cetirizine. The reduction in skin lesion score shown in the study by Eichenseer et al. may be due to the higher total dose of antihistamines given by means of combining two different antihista mines. However, the effect of antihistamines on clinical signs of atopic dermatitis is likely to be limited. It is most likely that inflammatory mediators other than hista mine are involved in canine atopic dermatitis and that the efficacy of antihistamines is greater when given as a prophylactic to prevent the effects of released histamine. Cetirizine should therefore be administered before onset of clinical signs and preferentially in patients with milder symptoms. When the disease is already estab lished, the antihistaminic response to cetirizine is limited to being an adjunct to other therapies in the control of atopic dermatitis.

在具有高质量科学依据（即随机分组、双盲和安慰剂对照）的临床研究中，研究结果存在分歧。肖等人在一项针对 50 只犬的研究群体中未能证明西替利嗪与对照治疗在瘙痒评分方面存在任何差异，而艾希森等人在一项交叉研究中使用 20 只犬的研究群体中报告了使用抗组胺药（二甲茚定或扑尔敏/羟嗪）治疗后瘙痒的减轻情况。这些研究中所纳入的犬数量有限，降低了统计效力，可能因此遗漏了一些细微的改善。尽管如此，后者研究中使用的抗组胺药组合扑尔敏/羟嗪显著减少了皮肤病变，而使用二甲茚定治疗后未观察到这种效果。在 24 小时的预处理后，无论是 0.5 毫克/千克的西替利嗪还是 2 毫克/千克的羟嗪都无法有效预防实验性皮炎引起的皮肤病变。0.5 毫克/千克的西替利嗪的剂量不太可能使血浆浓度高于有效浓度（IC50）值。羟嗪（2 毫克/千克）能够预防皮内注射引起的风团和红斑反应，这主要是由于其活性代谢产物西替利嗪的作用所致。艾希森等人的研究中所显示的皮肤病变评分的降低，可能是由于通过联合使用两种不同的抗组胺药而给予的更高总剂量的抗组胺药所致。然而，抗组胺药对特应性皮炎临床症状的影响可能较为有限。很可能是除了组胺之外的其他炎症介质参与了犬特应性皮炎的发病过程，而且抗组胺药作为预防释放组胺影响的预防性用药时，其疗效会更好。因此，应将西替利嗪在临床症状出现之前给予，并优先在症状较轻的患犬中使用。当疾病已经形成时，西替利嗪对它的抗组胺反应仅限于作为其他控制特应性皮炎疗法的辅助治疗手段。

 

No adverse effect was observed in our behavioral study. One of the most common unwanted responses to anti histamines in humans is dry mouth, which is produced by an antagonistic effect on muscarinic receptors. This was not observed in this study in dogs, in which both drinking and licking the lips might indicate dry mouth as these behaviors were not different between the treatment with cetirizine and control treatment. These results are reasonable in light of the fact that cetirizine has low affinity for muscarinic receptors and high affinity and high selectivity for H1-receptors. Sedation could be another possible unwanted response. Clinical experi ence and experimental studies both indicate that hydrox yzine can produce light sedation in dogs. However, cetirizine is a substrate for Pgp and produces less sedation than antihistamines, which are not and therefore enter the CNS to a larger extent. In the behavioral study reported here, no significant differences were seen in behaviors thought to indicate the degree of sedation (sitting, lying, and active) during the different treatments. This is consistent with the low frequency of sedation reported in clinical studies on both humans and dogs .

在我们的行为研究中未观察到任何不良反应。人类对抗组胺药最常见的不期望反应之一是口干，这是由于对毒蕈碱受体的拮抗作用所引起的。但在本研究中并未观察到这种情况，在犬上，喝水和舔嘴唇的行为可能表明口干，因为这两种行为在使用西替利嗪治疗组和对照组之间没有差异。鉴于西替利嗪对毒蕈碱受体的亲和力较低，而对 H1 受体的亲和力和选择性较高，这些结果是合理的。镇静可能是另一种可能的不良反应。临床经验和实验研究都表明，羟嗪在犬上可以产生轻微的镇静作用。然而，西替利嗪是 Pgp 的底物，产生的镇静作用比抗组胺药少，而抗组胺药不是，因此进入中枢神经系统的量更大。在本文报告的行为研究中，在不同治疗期间被认为能表明镇静程度（坐、躺和活跃）的行为方面未观察到显著差异。这与人类和犬临床研究中所报告的镇静作用较弱的情况相一致。

 

Conclusions

结论

Cetirizine at 2 mg/kg daily is effective in preventing wheal formation induced by intradermal histamine injections without any obvious unwanted effect. The long half-life of cetirizine in plasma results in plasma cetirizine concentrations that are likely be maintained above the IC50-value for wheal-inhibition using a once daily dosing regimen. Therefore, cetirizine has the potential to prevent the symptoms of allergic responses mediated by histamine. It is unlikely to be effective against established atopic dermatitis as sole therapy but may prove beneficial as an adjunct to other medication.

每日一次，服用 2 毫克/千克的西替利嗪能够有效预防皮内注射组胺所引起的风团形成，且未出现任何明显的不良反应。西替利嗪在血浆中的半衰期较长，这使得其血浆浓度能够维持在抑制风团形成的 IC50 值之上，从而适合采用每日一次的给药方案。因此，西替利嗪有可能用于预防由组胺介导的过敏反应症状。单独使用它不太可能对已形成的特应性皮炎有效，但作为其他药物的辅助治疗手段可能会有益。

王帆

犬西替利嗪剂量：每日一次每次每公斤2mg，po

扶手

第一次听说这种药

王明扬

南海

学习

zhangenzyme

学习

南海

南海

不乖