Overview
Moxonidine is a centrally acting antihypertensive agent that selectively stimulates imidazoline I1 receptors in the rostral ventrolateral medulla, reducing sympathetic outflow and lowering blood pressure. It is used primarily for the treatment of essential hypertension.
Mechanism of Action
Moxonidine is a selective agonist of imidazoline I1 receptors in the rostral ventrolateral medulla of the brainstem. This action reduces sympathetic outflow from the central nervous system, leading to decreased peripheral vascular resistance, heart rate, and blood pressure. It has minimal affinity for alpha-2 adrenergic receptors, which reduces sedative side effects compared to older centrally acting agents.
Indications
- Essential hypertension
Dosage
Initial dose: 0.2 mg once daily. Maintenance dose: 0.2-0.4 mg once daily. Maximum dose: 0.6 mg daily in divided doses. Dose adjustments may be needed in renal impairment.
Contraindications
- Hypersensitivity to moxonidine
- Sick sinus syndrome
- Severe bradycardia (heart rate <50 bpm)
- Atrioventricular block (2nd or 3rd degree)
- Severe heart failure (NYHA class IV)
- Severe renal impairment (GFR <30 mL/min)
- Concurrent use with tricyclic antidepressants
Side Effects
- Dry mouth
- Headache
- Dizziness
- Fatigue
- Somnolence
- Nausea
- Insomnia
- Vertigo
- Bradycardia
- Orthostatic hypotension
- Skin rash
Interactions
- Tricyclic antidepressants (may reduce antihypertensive effect)
- Other antihypertensive agents (additive hypotensive effects)
- Sedatives and CNS depressants (additive sedative effects)
- Alcohol (may enhance sedative effects)
- Beta-blockers (may potentiate bradycardia)