dihydralazine and diuretics

C02LG01

Forms & Strengths

Combination tablet: dihydralazine sulfate 25 mg + hydrochlorothiazide 12.5 mg (or similar fixed-dose thiazide diuretic)
Combination tablet: dihydralazine sulfate 50 mg + clopamide or other diuretic components depending on regional availability

Adult Dosing

Initial: 1 tablet daily, adjusted based on blood pressure response
Maintenance: 1 to 2 tablets daily in divided doses
Maximum daily dose: Determined by individual component tolerances, typically not exceeding 150 mg of dihydralazine daily

Pediatric Dosing

Indications

Treatment of moderate to severe essential hypertension inadequately controlled by monotherapy
Hypertension requiring a combination of a direct-acting vasodilator and a diuretic

Mechanism of Action

Dihydralazine exerts a direct relaxing effect on vascular smooth muscle, predominantly affecting arterioles to reduce peripheral vascular resistance
Diuretic component inhibits sodium and chloride reabsorption in the distal renal tubules, leading to increased excretion of water, sodium, and potassium, thereby reducing extracellular fluid volume

Contraindications

Known hypersensitivity to hydralazine derivatives, sulfonamide-derived drugs, or any component
Idiopathic systemic lupus erythematosus (SLE) and related syndromes
Severe tachycardia and heart failure with high cardiac output
Myocardial insufficiency due to mechanical obstruction (e.g., aortic or mitral stenosis)
Severe renal impairment (anuria) or severe hepatic impairment
Refractory hypokalemia, hyponatremia, or hypercalcemia

Adverse Reactions

Common: Tachycardia, palpitations, flushing, headache, dizziness, gastrointestinal disturbances
Diuretic-related: Electrolyte imbalances (hypokalemia, hyponatremia, hypomagnesemia, hyperuricemia), dehydration, hyperglycemia
Severe/Rare: Lupus-like syndrome (especially with prolonged use or high doses), peripheral neuropathy, blood dyscrasias (leukopenia, thrombocytopenia), hypersensitivity reactions

Drug Interactions

Other antihypertensive agents, vasodilators, and alcohol: May potentiate the blood pressure-lowering effect leading to severe hypotension
Lithium: Diuretics reduce renal clearance of lithium, increasing the risk of lithium toxicity
NSAIDs: May attenuate the antihypertensive and diuretic efficacy and increase the risk of renal impairment
Corticosteroids or ACTH: May intensify electrolyte depletion, particularly hypokalemia
MAO inhibitors: May cause significant enhancement of hypotensive effects

Curated Content: Needs Vetting Before Put to Clinical Use