암로디핀

칼슘 채널 차단제

암로디핀은 **디히드로피리딘계 칼슘 채널 차단제(CCB)**로, 수의학에서는 주로 강력한 **말초 동맥 혈관 확장제**로 사용됩니다. - **고양이 의학**: 만성 신장 질환(CKD), 갑상선 기능 항진증 또는 비대성 심근병증에 속발하는 **고양이 전신 고혈압** 관리의 **표준 치료제**이자 1차 선택약입니다. 고양이에서는 단일 약제로도 매우 효과적입니다. - **개 의학**: 개에서는 난치성 울혈성 심부전(CHF)의 후부하 감소 보조제나 2차 항고혈압제로 주로 사용됩니다. 개에서 고용량으로 단독 사용할 경우 레닌-안지오텐신-알도스테론계(RAAS)를 활성화할 수 있으므로, 이를 완화하기 위해 주로 ACE 억제제(예: 에날라프릴)와 병용합니다. - **임상 요점**: 작용 발현이 비교적 느려 급성 저혈압 위기를 예방하는 데 도움이 되지만, 투약을 거르면 급격한 반동성 고혈압이 발생할 수 있습니다.

작용 기전: Amlodipine selectively inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle by blocking **L-type voltage-gated calcium channels**. - **Vascular Smooth Muscle** → Relaxation and vasodilation → Significant reduction in **peripheral vascular resistance (afterload)** → Decreased systemic blood pressure. - It has a much higher affinity for vascular smooth muscle than cardiac muscle, meaning it produces profound vasodilation with minimal negative inotropic (contractility) or chronotropic (heart rate) effects at therapeutic doses. - **Cardiac Muscle** → Mildly depresses impulse formation (automaticity) and conduction velocity.

동물 종별 용량

Dogs

Adjunctive therapy for refractory heart failure (advanced mitral valve degeneration as an afterload reducer) · 0.2-0.4 mg/kg PO twice daily. Initiate therapy at 0.1 mg/kg PO twice daily and up-titrate weekly while monitoring blood pressure. · PO · q12h · After ACE inhibitor maintenance therapy has been established.
Arterial vasodilator for refractory CHF secondary to mitral regurgitation · 0.1 mg/kg q12-24h initially; titrate up as needed to 0.25 mg/kg PO q12-24h · PO · q12-24h · Monitor blood pressure.
Systemic hypertension in dogs with chronic renal disease · 0.1-0.5 mg/kg PO once daily (q24h) · PO · q24h · Most often combined with an ACE inhibitor. May require weeks to months to achieve satisfactory control.
Systemic hypertension (2nd step drug) · 0.1 mg/kg q24h; step up to 0.2 mg/kg q24h if needed · PO · q24h · Used after enalapril/benazepril. Each step added if after 1-2 weeks systolic BP > 160 mmHg.
Systemic hypertension · 0.05-0.1 mg/kg (titrate upwards weekly as required, up to 0.5 mg/kg) · PO · q12-24h · Long-term · Monitor blood pressure regularly. Consider concurrent ACE inhibitor.

Cats

Systemic hypertension (1st step drug) · 0.625 mg per cat q24h, if cat greater then 6 kg, 1.25 mg/cat q24h · PO · q24h · Add ACE inhibitor if proteinuric.
Systemic hypertension · 0.625-1.25 mg (total dose) PO once daily · PO · q24h · Drug of choice; often successful as a single agent. Maximum effect seen within 7 days.
Systemic hypertension · 0.625-1.25 mg/cat · PO · q24h (may increase slowly or increase frequency to q12h if necessary) · Long-term · Blood pressure monitoring is essential. Appears safe even with concurrent renal failure.

투여 경로

금기

Patients with cardiogenic shock
Advanced aortic stenosis (relative contraindication)
Use with caution in patients with heart failure (due to slight negative inotropic effects)
Use with caution in patients with hepatic dysfunction

이상반응

Cats: Infrequent azotemia, lethargy, hypokalemia, reflex tachycardia, weight loss
Dogs: Gingival hyperplasia (with long-term use)
Anorexia and hypotension (early in therapy)

약물 상호작용

Diuretics · Concomitant use may cause additive hypotension. · moderate
Beta-blockers · Concomitant use may cause additive hypotension. · moderate
Vasodilators · Concomitant use may cause additive hypotension.
Fentanyl · May cause hypotension if used concurrently.
Grapefruit juice/powder · May alter bioavailability of amlodipine.
Cimetidine · May impair hepatic metabolism of amlodipine, increasing circulating levels · moderate
Cyclosporine · May impair hepatic metabolism of amlodipine, increasing circulating levels · moderate
Ketoconazole · May impair hepatic metabolism of amlodipine, increasing circulating levels · moderate
Itraconazole · May impair hepatic metabolism of amlodipine, increasing circulating levels · moderate
Rifampin · CYP3A4 inducer; may reduce circulating amlodipine levels · moderate
ACE inhibitors · Increased risk of hypotension when combined · moderate

모니터링

Systemic blood pressure (frequent monitoring during dose titration)
Ophthalmic exam (to assess for hypertensive retinopathy/retinal detachment)
Renal values and electrolytes (especially if combined with ACE inhibitors)
Clinical signs of hypotension (lethargy, weakness)

과용량

Overdoses pose a significant risk for **profound hypotension** and **reflex tachycardia** (though bradycardia is also possible). Common clinical signs in dogs and cats include lethargy and vomiting. **Treatment**: - When possible, massive overdoses should be managed with gut emptying (emesis/lavage) and activated charcoal. - Provide aggressive supportive treatment (IV fluids). - **Specific therapies** may include beta-agonists, intravenous lipid emulsion (ILE) therapy, and intravenous calcium to counteract the calcium channel blockade.

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