Comparative Pharmacology
Head-to-head clinical analysis: HYDRALAZINE versus THEROXIDIL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: HYDRALAZINE versus THEROXIDIL.
Hydralazine vs THEROXIDIL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Hydralazine is a direct-acting vasodilator that relaxes arteriolar smooth muscle, leading to decreased peripheral vascular resistance and blood pressure. Its exact mechanism is unclear but may involve interference with calcium movement and increased cGMP levels.
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.
10-50 mg orally every 6 hours, titrate to maximum 300 mg/day; 10-20 mg intramuscularly or intravenously every 4-6 hours as needed.
5 mg orally once daily, increased to 10 mg after 4 weeks as tolerated.
None Documented
None Documented
Clinical Note
moderateHydralazine + Benzydamine
"Hydralazine may decrease the antihypertensive activities of Benzydamine."
Clinical Note
moderateHydralazine + Droxicam
"Hydralazine may decrease the antihypertensive activities of Droxicam."
Clinical Note
moderateHydralazine + Loxoprofen
"Hydralazine may decrease the antihypertensive activities of Loxoprofen."
Clinical Note
moderateHydralazine + Clonixin
"Hydralazine may decrease the antihypertensive activities of Clonixin."
The terminal elimination half-life of hydralazine is approximately 2-4 hours in patients with normal renal function. However, the duration of antihypertensive effect may be longer (6-12 hours) due to tissue binding and slow release from vascular smooth muscle. In renal impairment, half-life may extend to 7-16 hours, necessitating dose adjustment.
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 and hydroxylation. Approximately 80-90% of the drug is eliminated in urine as metabolites, with less than 10% excreted unchanged. A small fraction appears in feces via biliary excretion.
Approximately 60% renal (15% unchanged, 45% as glucuronide metabolites), 40% fecal/biliary as metabolites
Category A/B
Category C
Vasodilator
Vasodilator