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CARDIOVASCULAR SYSTEM › ANTIHYPERTENSIVES › ANTIADRENERGIC AGENTS, PERIPHERALLY ACTING › Alpha-adrenoreceptor antagonists
trimazosin
C02CA03
Forms & Strengths
- Oral tablets: 1 mg
- Oral tablets: 2.5 mg
- Oral tablets: 5 mg
Adult Dosing
- Initial dose: 1 to 5 mg orally twice daily
- Titration: Gradually increase based on blood pressure response and patient tolerance
- Maintenance dose: Typically 15 to 50 mg daily divided into 2 to 3 doses
- Maximum daily dose: Up to 150 mg daily in divided doses
Pediatric Dosing
- Safety and efficacy in pediatric patients have not been established
- Not recommended for use in children
Indications
- Management of essential hypertension
- Used alone or in combination with other antihypertensive agents such as diuretics or beta-blockers
Mechanism of Action
- Competitive postsynaptic alpha-1 adrenergic receptor antagonist
- Produces peripheral vasodilation of both resistance (arterioles) and capacitance (veins) vessels
- Reduces total peripheral resistance and lowers blood pressure with minimal reflex tachycardia
Contraindications
- Known hypersensitivity to trimazosin, other quinazolines, or any component of the formulation
- History of syncopal episodes related to the first dose of alpha-blockers
Adverse Reactions
- First-dose phenomenon (severe postural hypotension, dizziness, syncope)
- Dizziness, lightheadedness, and drowsiness
- Palpitations, tachycardia, and chest pain
- Headache and asthenia
- Nausea, dry mouth, and abdominal discomfort
- Nasal congestion
Drug Interactions
- Enhanced hypotensive effect when co-administered with other antihypertensive agents or vasodilators
- Potential for additive hypotensive effects with phosphodiesterase-5 (PDE-5) inhibitors (e.g., sildenafil)
- Possible attenuation of antihypertensive response when used concurrently with non-steroidal anti-inflammatory drugs (NSAIDs)
Curated Content: Needs Vetting Before Put to Clinical Use