Comparative Pharmacology
Head-to-head clinical analysis: HYDRALAZINE HYDROCHLORIDE W HYDROCHLOROTHIAZIDE 25 25 versus METAHYDRIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: HYDRALAZINE HYDROCHLORIDE W HYDROCHLOROTHIAZIDE 25 25 versus METAHYDRIN.
HYDRALAZINE HYDROCHLORIDE W/ HYDROCHLOROTHIAZIDE 25/25 vs METAHYDRIN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Hydralazine is a direct-acting arteriolar vasodilator that reduces peripheral resistance through relaxation of vascular smooth muscle, likely via nitric oxide-mediated increases in cGMP. Hydrochlorothiazide is a thiazide diuretic that inhibits the Na+/Cl- cotransporter in the distal convoluted tubule, reducing sodium and water reabsorption and decreasing plasma volume.
Metahydrin (trichlormethiazide) is a thiazide diuretic that inhibits the sodium-chloride symporter (NCC) in the distal convoluted tubule of the nephron, reducing sodium and chloride reabsorption and increasing excretion of water, sodium, chloride, and potassium.
One tablet orally twice daily, titrated based on blood pressure response; maximum dose: one tablet four times daily.
Oral, 50-100 mg once daily. Maximum 200 mg/day.
None Documented
None Documented
Hydralazine: 2-8 hours (terminal half-life; prolonged in renal impairment; acetylator phenotype affects clearance); Hydrochlorothiazide: 6-15 hours (terminal half-life; increased in renal impairment).
18-30 hours (clinically relevant for once-daily dosing in hypertension; prolonged in renal impairment)
Hydralazine: 80% renal (as metabolites, 5-10% unchanged); Hydrochlorothiazide: 95% renal (as unchanged drug).
Renal: 30% (fecal: 70% as unabsorbed drug, primarily biliary elimination; <1% unchanged in urine)
Category A/B
Category C
Thiazide Diuretic
Thiazide Diuretic