클로르페니라민

항히스타민제 (알킬아민계)

클로르페니라민은 1세대 알킬아민계 항히스타민제로, 수의학에서는 주로 항히스타민 및 항소양(가려움증 완화) 효과를 위해 사용됩니다. **주요 임상 포인트:** * **1세대 항히스타민제:** 혈액뇌장벽(BBB)을 통과하기 때문에 중추신경 억제(진정)를 자주 유발하며, 때로는 가벼운 진정제로 치료에 활용되기도 합니다. * **고양이 소양증:** 알레르기성 피부 질환 및 가려움증 관리를 위해 고양이에게 가장 흔하게 사용되는 항히스타민제 중 하나입니다. * **비만세포종:** 전신적인 히스타민 방출의 영향을 차단하기 위해 비만세포종 화학요법의 보조 치료제로 자주 사용됩니다. * **역설적 흥분:** 개에서는 일반적으로 진정을 유발하지만, 고양이에서는 오히려 역설적인 흥분 반응을 보일 수 있습니다.

작용 기전: 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.

동물 종별 용량

Cats

General antihistamine use · 2 mg (total dose) per cat PO every 12 hours · PO · q12h
General antihistamine use · 2-4 mg per cat q12-24h PO · PO · q12-24h
General antihistamine use · 2 mg per cat two to three times daily · PO · BID-TID · Most common dosage in cats
Pruritus · 2-4 mg/cat twice daily; rarely may be maintained on once daily dosing. · PO · BID · 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.
Pruritus · 0.5-2 mg (total dose; ¼ - ½ of a 4 mg tablet) PO 2-3 times per day · PO · BID-TID
Mild sedative · 1-2 mg per cat q12-24h (low dose), 2-4 mg per cat PO q12-24h (high dose) · PO · q12-24h

Ferrets

General antihistamine use · 1-2 mg/kg PO 2-3 times a day · PO · BID-TID

Birds

General use / Feather damaging behavior · One 4 mg tablet in one cup (240 mL; 8 oz.) of bottled water to be used as drinking water; changed daily. · PO · q24h

Dogs

투여 경로

금기

Hypersensitivity to chlorpheniramine or other alkylamine antihistamines

이상반응

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

약물 상호작용

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) · Additive CNS depression and sedation · moderate
Anticholinergic drugs · Additive anticholinergic effects (dry mouth, tachycardia, urinary retention) · moderate

모니터링

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

과용량

### 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**.

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