Amlodipine: Dosage, Uses, and Side Effects

Amlodipine for Dogs, Cats, and Birds: Dosage, Uses, and Side Effects Guide

Overview

• Calcium-channel antagonist, with predominant action affecting peripheral arteriolar vasculature, causing vasodilation and reducing afterload.
• Has mild negative inotropic and chronotropic effects, which are negligible at therapeutic doses.

Uses of Amlodipine

• Cats:
  • Management of systemic hypertension, including hypertension secondary to chronic kidney disease, hyperthyroidism, or hyperadrenocorticism.
  • Reduction of proteinuria in hypertensive cats.
  • Restores vision in some cases of hypertensive retinopathy.
• Dogs:
  • Treatment of systemic hypertension, often secondary to renal disease or hyperadrenocorticism.
  • Adjunctive therapy in refractory heart failure for afterload reduction.
• Birds:
  • Management of systemic hypertension (e.g., psittacines). Limited studies suggest its efficacy in avian species.

Dose of Amlodipine

Dose of Amlodipine In Dogs:

• Initial dose: 0.05–0.1 mg/kg p.o. q12–24h.
• Gradual titration up to 0.5 mg/kg/day, based on blood pressure response.
• Monitoring: Regular blood pressure checks during dose adjustments.

Dose of Amlodipine In Cats:

• Initial dose: 0.625–1.25 mg/cat p.o. q24h (not mg/kg).
• Adjustments:
  • If blood pressure remains >150 mmHg, increase dose or frequency to q12h.
  • Monitor systolic blood pressure to maintain target levels (≤150 mmHg).
• Maximum dose: Up to 2.5 mg/cat/day in severe hypertension.

Dose of Amlodipine In Birds:

• Initial dose: 0.4 mg/kg p.o. q24h.
• Adjust dose based on blood pressure monitoring and clinical response.

Side Effects of Amlodipine

• Common side effects:
  • Lethargy, hypotension, and inappetence (mild and rare).
  • Reversible gingival hyperplasia in long-term use, more commonly observed in dogs.
• Less common side effects:
  • Reflex tachycardia.
  • Mild azotemia, hypokalemia, or weight loss in cats.
  • Peripheral edema reported in dogs.
• Birds:
  • Limited data; no significant adverse effects reported at therapeutic doses.

Contraindications of Amlodipine

Avoid use in:

1. Patients with:
   • Cardiogenic shock or severe hepatic failure.
   • Severe aortic stenosis (risk of inadequate cardiac output due to vasodilation).
   • Documented hypotension.
2. Pregnant or lactating animals due to a lack of established safety data.

Some Notes:

• Hepatic Considerations:
  • Amlodipine is extensively metabolized in the liver; dosage adjustments are essential in hepatic disease.
• Combination Therapy:
  • When used alone in dogs, amlodipine may activate the RAAS, leading to glomerular hypertension. Combining with an ACE inhibitor (e.g., enalapril or benazepril) mitigates this risk.
• Monitoring:
  • Blood pressure monitoring is critical, particularly during dose titration.
  • Fundic exams are recommended to assess for hypertensive retinopathy and retinal detachment.
• Proteinuria Management:
  • In cats, amlodipine can reduce proteinuria associated with hypertension, improving survival.