Comparative Pharmacology
Head-to-head clinical analysis: HYDRALAZINE HYDROCHLORIDE versus THEROXIDIL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: HYDRALAZINE HYDROCHLORIDE versus THEROXIDIL.
HYDRALAZINE HYDROCHLORIDE vs THEROXIDIL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Vasodilation of arterioles by direct relaxation of vascular smooth muscle, likely involving interference with calcium movement.
Theroxidil is a vasodilator that acts by opening potassium channels in vascular smooth muscle, leading to hyperpolarization and relaxation. It also inhibits platelet aggregation and reduces peripheral vascular resistance.
Oral: Initiate with 10 mg 4 times daily for 2-4 days, then increase to 25 mg 4 times daily for the remainder of the week, then titrate to 50 mg 4 times daily. Maximum daily dose: 300 mg. Intravenous: 5-20 mg IV bolus, may repeat every 20-30 minutes as needed, or continuous IV infusion 0.5-10 mg/hour.
5 mg orally once daily, increased to 10 mg after 4 weeks as tolerated.
None Documented
None Documented
The terminal elimination half-life of hydralazine is approximately 2–4 hours in patients with normal renal function, but it is prolonged in renal impairment (up to 7–16 hours). The antihypertensive effect often lasts longer than the half-life due to persistent binding to arteriolar receptors.
Terminal elimination half-life 24-30 hours; steady-state reached after 4-5 days; clinically significant for once-daily dosing
Hydralazine is primarily metabolized in the liver via N-acetylation (polymorphic) and hydroxylation. Less than 10% of the dose is excreted unchanged in urine. The major metabolites are hydralazine pyruvic acid hydrazone and other conjugates, which are excreted renally. Fecal elimination is negligible.
Approximately 60% renal (15% unchanged, 45% as glucuronide metabolites), 40% fecal/biliary as metabolites
Category A/B
Category C
Vasodilator
Vasodilator