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クロルフェニラミン

Chlorpheniramine

Chlorpheniramine maleate

抗ヒスタミン薬（アルキルアミン系）PO犬猫フェレット鳥

別名: Chlor-Trimetron · Chlo-Amine · Aller-Chlor · Allergy Relief · Chlor-Trimeton Allergy · Efidac 24 · QDALL AR · ED-CHLOR-TAN · Pediox-S · Piriton · chlorphenamini maleas · chlorpheniramine maleate

VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス

4-8 mg (maximum of 0.5 mg/kg) PO q8-12h POPO· q8-12h
— 🐕

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

動物種別用量

🌎 NA — North America🌍 EU — Europe

犬

適応用量経路頻度期間地域
Adjunctive treatment of chemotherapy of mast cell tumors4-8 mg (maximum of 0.5 mg/kg) PO q8-12h POPOq8-12h—🌎 NA
General antihistamine use4-12 mg (total dose) two to three times dailyPOBID-TID—🌎 NA
General antihistamine use2-8 mg (total dose) per dog PO every 12 hours, not to exceed 0.5 mg/kg every 12 hoursPOq12h—🌎 NA
Trial for pruritus in atopic dogs0.4-0.8 mg/kg two to three times dailyPOBID-TID—🌎 NA
Pruritus0.2-0.8 mg/kg PO 2-3 times a dayPOBID-TID—🌎 NA
Mild sedative0.22 mg/kg PO q8h; 4-20 mg (total dose per day) divided q8-12hPOq8-12h—🌎 NA

猫

適応用量経路頻度期間地域
General antihistamine use2 mg (total dose) per cat PO every 12 hoursPOq12h—🌎 NA
General antihistamine use2-4 mg per cat q12-24h POPOq12-24h—🌎 NA
General antihistamine use2 mg per cat two to three times dailyPOBID-TID—🌎 NA
Pruritus2-4 mg/cat twice daily; rarely may be maintained on once daily dosing.POBID—🌎 NA
Pruritus0.5-2 mg (total dose; ¼ - ½ of a 4 mg tablet) PO 2-3 times per dayPOBID-TID—🌎 NA
Mild sedative1-2 mg per cat q12-24h (low dose), 2-4 mg per cat PO q12-24h (high dose)POq12-24h—🌎 NA
  • General antihistamine use: Most common dosage in cats
  • Pruritus: Palatability may be enhanced by dipping the split tablet into tuna fish 'juice', butter or petrolatum; placing split tablets into empty gelatin capsules or sprinkling or mixing timed release beads (partial contents of an 8 mg capsule) with food.

フェレット

適応用量経路頻度期間地域
General antihistamine use1-2 mg/kg PO 2-3 times a dayPOBID-TID—🌎 NA

鳥

適応用量経路頻度期間地域
General use / Feather damaging behaviorOne 4 mg tablet in one cup (240 mL; 8 oz.) of bottled water to be used as drinking water; changed daily.POq24h—🌎 NA

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

診察中ですか？VetSheet の AI が薬剤・用量・投与期間を構造化された診察記録に直接記入します。VetSheet の仕組みを見る

概要

クロルフェニラミンは第一世代のアルキルアミン系抗ヒスタミン薬であり、獣医療では主に抗ヒスタミン作用および止痒作用を目的として使用されます。

​臨床上のポイント:​

  • ​第一世代抗ヒスタミン薬:​ 血液脳関門を通過するため、中枢神経抑制（鎮静）を引き起こすことが多く、軽度の鎮静剤として治療に利用されることもあります。
  • ​猫のそう痒症:​ アレルギー性皮膚疾患やそう痒の管理において、猫で最もよく使用される抗ヒスタミン薬の一つです。
  • ​肥満細胞腫:​ 全身的なヒスタミン放出の影響を遮断するため、肥満細胞腫の化学療法プロトコルにおける補助療法としてしばしば使用されます。
  • ​奇異反応（興奮）:​ 犬では通常鎮静を引き起こしますが、猫では逆に興奮状態を示すことがあります。

作用機序

Chlorpheniramine acts as a competitive H1-receptor antagonist.

  • ​Histamine Blockade:​ It competitively inhibits histamine from binding to H1 receptors on effector cells (such as smooth muscle and endothelial cells) → prevents histamine-induced vasodilation, increased capillary permeability, and smooth muscle spasms.
  • ​Note:​ It does not inactivate histamine or prevent its release from mast cells; it only blocks its action at the receptor site.
  • ​Additional Properties:​ Like many first-generation antihistamines, it possesses varying degrees of anticholinergic (muscarinic blockade) and CNS depressant activity.

安全性・警告

禁忌

  • Hypersensitivity to chlorpheniramine or other alkylamine antihistamines

有害事象

  • CNS depression (lethargy, somnolence, sedation)
  • GI effects (diarrhea, vomiting, anorexia)
  • Anticholinergic effects (dry mouth, urinary retention)
  • Paradoxical excitement (especially in cats)
  • Decreased performance in working dogs due to sedation

注意事項

Warnings and Precautions

  • ​Anticholinergic Effects:​ Use with caution in patients with angle closure glaucoma, prostatic hypertrophy, pyloroduodenal or bladder neck obstruction, and COPD (if mucosal secretions are a problem).
  • ​Systemic Disease:​ Use cautiously in patients with hyperthyroidism, cardiovascular disease, or hypertension.
  • ​Working Dogs:​ Sedative effects may adversely affect the performance of working dogs.
  • ​Laboratory Testing:​ Antihistamines can decrease the wheal and flare response to antigen skin testing. It is generally recommended to discontinue antihistamines at least 4 days prior to intradermal allergy testing.
  • ​Nursing/Pregnancy:​ FDA Category B in humans. It is unknown if it is excreted in milk; use with caution in nursing dams.

医薬品相互作用

Anticoagulants (heparin, warfarin)

Antihistamines may partially counteract the anticoagulation effects of heparin or warfarin.

MAO Inhibitors (amitraz, selegiline)

May prolong and exacerbate the anticholinergic effects of the antihistamine.

CNS Depressants

Increased sedation and CNS depression can occur when used concurrently.

CNS Depressants (e.g., opioids, sedatives, barbiturates)Moderate

Additive CNS depression and sedation

Anticholinergic drugsModerate

Additive anticholinergic effects (dry mouth, tachycardia, urinary retention)

監視

  • Clinical efficacy (reduction in pruritus, allergic signs, or adequate sedation)
  • Adverse effects (excessive sedation, GI upset, anticholinergic signs)

薬物動態

吸収

In humans, well absorbed after oral administration, but undergoes a relatively high degree of first-pass metabolism in the GI mucosa and liver, resulting in only 25-60% systemic bioavailability. Pharmacokinetics have not been described in domestic species.

分布

Well distributed after IV injection; highest distribution occurs in the lungs, heart, kidneys, brain, small intestine, and spleen. In humans, the apparent steady-state volume of distribution is 2.5-3.2 L/kg and about 70% is bound to plasma proteins.

代謝

Metabolized in the liver.

消失

Practically all the drug (as metabolites and unchanged drug) is excreted in the urine.

過剰投与

Overdose Signs

Overdosage may cause CNS stimulation (ranging from excitement to seizures) or CNS depression (lethargy to coma), anticholinergic effects, respiratory depression, and death.

​Case report:​ A 9-month-old dachshund ingesting 25 mg/kg showed signs of ataxia, tremors, bradycardia, coma, and cardiac arrest, dying within 11 hours of ingestion.

Treatment

  • ​Decontamination:​ Empty the gut using standard protocols if ingestion was oral. Induce emesis if the patient is alert and CNS status is stable. Follow with a saline cathartic and/or activated charcoal.
  • ​Supportive Care:​ Treat other clinical signs symptomatically.
  • ​Seizure Control:​ ​Phenytoin (IV)​ is recommended in the treatment of seizures caused by antihistamine overdoses in humans; barbiturates and diazepam should be avoided.

製品

製剤

  • Oral tablets
  • Chewable tablets
  • Extended-release tablets
  • Extended-release capsules
  • Oral syrup
  • Oral suspension

ヒト用医薬品

  • Chlorpheniramine Maleate Oral Tablets: 2 mg (chewable), 4 mg
  • Chlorpheniramine Maleate Extended-release Tablets & Capsules: 8 mg, 12 mg & 16 mg
  • Chlorpheniramine Caplets: 8 mg (as tannate)
  • Chlorpheniramine Maleate Oral Syrup: 2 mg/5 mL
  • Chlorpheniramine Maleate Oral Suspension: 4 mg/5 mL

規制ステータス

European Union✓ 承認済み処方箋医薬品EMA

Human formulations used under the cascade.

United Kingdom✓ 承認済みVMD

Classified as POM (Prescription Only Medicine) for injectables and GSL (General Sales List) for certain oral forms.

規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU

保管・安定性

Store tablets and sustained-release tablets in tight containers. Sustained-release capsules should be stored in well-closed containers. Oral solution should be stored in light-resistant containers; avoid freezing. All chlorpheniramine products should be stored at room temperature (15-30°C).

飼主向け情報

飼い主向け情報

  • ​期待される効果:​ この薬は一般的にアレルギーや痒みの治療に使用されます。ペットが眠気を感じることがあります。
  • ​猫に関する注意:​ 犬は通常眠くなりますが、猫は時折逆の反応を示し、活動的になったり興奮したりすることがあります。
  • ​投与方法:​ 徐放性（長時間作用型）の製品を使用している場合、​錠剤を砕いたり、ペットに噛ませたりしないでください​。徐放性カプセルの中身を食事に振りかけることは可能ですが、溶ける前にすぐに食べさせる必要があります。
  • ​人用医薬品について:​ クロルフェニラミンはFDAに承認された人用医薬品であり、市販薬としてもよく見られます。多くの人用の風邪薬やアレルギー薬には、ペットにとって非常に有毒な他の成分（充血除去薬や鎮痛薬など）が含まれているため、必ず獣医師が推奨した特定の製品と用量のみを使用してください。

VetSheet医薬品リファレンスは獣医専門家の臨床意思決定支援を目的としており、専門的判断または製造業者の最新医薬品情報の代替にはなりません。