Comparative Pharmacology
Head-to-head clinical analysis: HYDRALAZINE HYDROCHLORIDE W HYDROCHLOROTHIAZIDE 50 50 versus METAHYDRIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: HYDRALAZINE HYDROCHLORIDE W HYDROCHLOROTHIAZIDE 50 50 versus METAHYDRIN.
HYDRALAZINE HYDROCHLORIDE W/ HYDROCHLOROTHIAZIDE 50/50 vs METAHYDRIN
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 via mechanisms involving interference with calcium ion movement and possibly nitric oxide release. Hydrochlorothiazide is a thiazide diuretic that inhibits the sodium-chloride symporter 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.
1 tablet (hydralazine 50 mg/hydrochlorothiazide 50 mg) orally twice daily, maximum 2 tablets daily.
Oral, 50-100 mg once daily. Maximum 200 mg/day.
None Documented
None Documented
Hydralazine: 2-8 hours (acetylator phenotype dependent; slow acetylators up to 8h, fast acetylators 1-2h). Hydrochlorothiazide: 6-15 hours (mean 10h).
18-30 hours (clinically relevant for once-daily dosing in hypertension; prolonged in renal impairment)
Hydralazine: 80% renal (mainly as metabolites, 1-2% unchanged), 10% fecal. Hydrochlorothiazide: >95% renal (unchanged) via organic anion transporters.
Renal: 30% (fecal: 70% as unabsorbed drug, primarily biliary elimination; <1% unchanged in urine)
Category A/B
Category C
Thiazide Diuretic
Thiazide Diuretic