性状   

二盐酸西替利嗪的化学名为 ：（RS）2-[2-（4-（对氯-苯基苄基）-1-哌嗪基）乙氧基]醋酸·二盐酸盐。

分子式 ：C21H25CIN2O3·2HCI

分子量 ：461.8。

本品辅料为甘油、丙二醇、糖精钠、尼泊金甲酯、对羟基苯甲酸丙脂、醋酸钠、纯水。

本品为无色的澄清液体。
药理作用   

动物实验证明，西替利嗪是一种H1受体拮抗剂，无抗胆碱或抗5-羟色胺作用。在药效剂量范围内。西替利嗪不会引起困倦或行为变化，这可从西替利嗪不能通过血脑屏障解释。

在人体药理方面，西替利嗪证实可抑制外源性组胺的作用。这种抑制能力迅速产生，西替利嗪也能抑制如由48/80在体内诱发的内源性组胺的作用。最后，西替利嗪可抑制由参与变态反应的VIP（肠血管活性肽）及P物质、神经肽所引起的皮肤反应。

西替利嗪可抑制由组胺介导的皮肤速发相变态反应。同时还可明显减少与迟发性皮肤变态反应相关的炎性细胞（如嗜酸性粒细胞）的移动以及炎性介质的释放。

西替利嗪明显降低哮喘病患者对组胺所引起的支气管高反应性，西替利嗪降低由特异过敏原所引起的变态反应。心理测验或脑电图测定显示，西替利嗪无任何中枢神经作用。 

药代动力学   

口服二盐酸西替利嗪在5-60 mg 剂量范围内，血浆浓度水平和给药剂量呈线性关系。

成年人血浆半衰期大约为10小时，表观分布容积为0.5 L/kg。在每天服用10 mg ，连续服用10天二盐酸西替利嗪后，未发现有蓄积作用。稳态血药浓度峰值为300 ng/mL，给药后1±0.5小时达峰。西替利嗪与血浆蛋白结合牢固，血浆蛋白结合率为93±0.3%。西替利嗪的代谢没有首过效应，给药剂量的2/3由尿液以原型药物排出。西替利嗪的吸收不受进食影响。西替利嗪的溶液剂、胶囊和片剂的生物利用度是相仿的，吸收是一致的。

特殊人群的药代动力学

老年人 ：试验数据表明，口服单剂量10 mg 二盐酸西替利嗪后，老年研究对象的平均血浆半衰期为11.8小时 ；肌酐清除率下降40%的老年患者，其血浆半衰期较肌酐清除率正常的老年患者增加了50% ；肾功能正常的老年患者并不需要减少剂量。

儿童 ：6-12岁的儿童，其西替利嗪的血浆半衰期大约为6小时 ；
2-6岁的幼儿其西替利嗪的血浆半衰期大约为5小时 ；
6-24个月的婴儿，其西替利嗪的血浆半衰期大约为3.1小时。
肾功能不全的患者 ：轻度肾功能不全的患者（肌酐清除率大于40 mL/分钟）与正常志愿者相比，其西替利嗪的药代动力学参数相仿。中度肾功能不全患者的西替利嗪血浆半衰期较肾功能正常者增加3倍，药物的清除率较肾功能正常者低70%。西替利嗪难以通过血液透析的方法清除，因此中度和重度肾功能不全患者，必须调整给药剂量。
肝功能不全的患者 ：患有慢性肝脏疾病的患者（肝细胞、胆汁郁结、胆汁性肝硬变）在单剂量给药10 mg或20 mg西替利嗪后，与肝功能正常者比较，药物血浆半衰期延长了50%，药物清除率下降40%。对于肝功能不全的患者，只有在患者同时具有肾功能不全症状时，才需要调整给药剂量。 
适应症   
治疗季节性鼻炎、常年性过敏性鼻炎以及非鼻部症状眼结膜炎、过敏引起的瘙痒和荨麻疹症状。 
用法用量   
推荐成年人和1岁以上儿童使用。
成年人 ：在大多数正常情况下，推荐剂量为每日10 mg，一次口服。从本品治疗适应症来看，建议可在晚餐期间用少量液体送服此药。
若病人对不良反应敏感，可每日早晚2次服用，每次5 mg。

6岁以上儿童 ：早上和晚上各服用5 mg，或每天1次10 mg。

2-6岁儿童 ：早上和晚上各服用0.25 mL滴剂 (2.5 mg，约5滴）或每天1次0.5 mL（5 mg，约10滴）。

1-2岁儿童 ：早上和晚上各服用0.25 mL滴剂（2.5 mg，约5滴）。
1岁以下儿童 ：虽然有6个月以上到1岁婴儿服用西替利嗪的临床数据，但相关评估尚未完全结束，如需使用，谨慎使用。

老年患者 ：肾功能正常的老年患者，参照成人推荐剂量。

肾功能不全的老年患者，参见肾功能不全患者推荐剂量。

肾功能不全的患者 ：建议减半服用推荐剂量。即 ：

成年或老年患者 ：推荐剂量为每日5 mg，一次口服。

6岁以上的儿童 ：早上和晚上各服用2.5 mg，或每天1次5 mg。

1-6岁的儿童 ：每天1次0.25 mL滴剂（2.5 mg，约5滴）。

肝功能不全患者 ：如没有同时患有肾功能不全症状，无需调整给药剂量。

口服滴剂 ：

20滴（1 mL)=10 mg

10滴（0.5 mL）=5 mg

5滴（0.25 mL）=2.5 mg。 

不良反应   

偶尔报告病人有轻微和短暂的不良反应，如头痛、头晕、嗜睡、激动、口干、肠胃不适。在测定精神运动功能的客观实验中，本品对镇静的影响和安慰剂相似。稀有报道过敏反应。 

禁忌症   

禁用于对本品任何成分过敏者 ；严重肾功能不全患者（肌酐清除率小于10 mL/分钟）。 

注意事项   

在治疗剂量下，本品不会强化酒精作用（血液浓度0.8 g/L），但是必须小心。

驾驶或操作机械 ：在健康自愿者每日服用20或25 mg试验中，并未证实对警戒性及反应时间有任何改变。不过建议病人不要超过推荐剂量。 

孕妇及哺乳期妇女用药   

动物致畸试验显示无任何致畸作用，但是为了预防，二盐酸西替利嗪不应给怀孕初期至3个月内的孕妇服用，也不应给授乳妇女使用。 

药物相互作用   

至今未有同其它药物相互作用的报告，但同时服用镇静剂（安眠药）时要小心。 

药物过量   

一次口服50 mg，能引起嗜睡作用。到目前为止，尚无特别的解毒剂。在大量过量的情况下，应尽快进行胃肠灌洗，除进行一般急救支持性治疗外，还必须定时监测所有的生命参数。 

贮藏/有效期    室温(15-25°C)贮藏
【原产地英文商品名】ZYRTEC OTC 1MG/MLSYRUP 236ML/bottle
【原产地英文药品名】CETIRIZINE HCL
【中文参考商品译名】ZYRTEC OTC1毫克/毫升糖浆 236毫升/瓶
【中文参考药品译名】西替利嗪
【生产厂家中文参考译名】MCNEIL CONSUMER
【生产厂家英文名】MCNEIL CONSUMER

Zyrtec

Generic Name: cetirizine (se TIR a zeen)

Brand Names: All Day Allergy, Zyrtec

What is Zyrtec?

Zyrtec is an antihistamine that reduces the natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Zyrtec is used to prevent or treat symptoms of hay fever and to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose.

Zyrtec is also used to treat itching and swelling caused by chronic urticaria (hives).

Zyrtec may also be used for other purposes not listed in this medication guide.

Important information about Zyrtec

Zyrtec can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert. Avoid drinking alcohol. It can increase some of the side effects of Zyrtec. Tell your doctor if you regularly use other medicines that make you sleepy (such as other cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by Zyrtec. Call your doctor if your symptoms do not improve, if they get worse, or if you also have a fever.

Before taking Zyrtec

You should not use Zyrtec if you are allergic to cetirizine.

Before taking Zyrtec, tell your doctor about all of your medical conditions

FDA pregnancy category B. This medication is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Cetirizine can pass into breast milk and may harm a nursing baby. Do not use Zyrtec without telling your doctor if you are breast-feeding a baby.

Older adults may need to take a lower than normal dose. Follow your doctor's instructions.

How should I take Zyrtec?

Take Zyrtec exactly as directed on the label, or as prescribed by your doctor. Do not use it in larger amounts or for longer than recommended.

You may take Zyrtec with or without food.

The chewable tablet must be chewed before you swallow it.

Measure liquid medicine with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

Call your doctor if your symptoms do not improve, if they get worse, or if you also have a fever. Store Zyrtec at room temperature away from moisture and heat

What happens if I miss a dose?

Take the missed dose as soon as you remember. If it is almost time for your next dose, wait until then to take the medicine and skip the missed dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention if you think you have used too much of this medicine.

Overdose symptoms may include feeling restless or nervous, and then feeling drowsy.

What should I avoid while taking Zyrtec?

Tell your doctor if you regularly use other medicines that make you sleepy (such as other cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by Zyrtec. This medication can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert. Avoid drinking alcohol. It can increase some of the side effects of Zyrtec.

Zyrtec side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Stop using Zyrtec and call your doctor at once if you have any of these serious side effects:

fast, pounding, or uneven heartbeat;

weakness, tremors (uncontrolled shaking), or sleep problems (insomnia);

severe restless feeling, hyperactivity;

confusion;

problems with vision; or

urinating less than usual or not at all.

Less serious Zyrtec side effects may include:
dizziness, drowsiness;

tired feeling;

dry mouth;

sore throat, cough;

nausea, constipation; or

headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Zyrtec?

There may be other drugs that can interact with Zyrtec. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.