Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
HYDRAP-ES vs ALDORIL 15
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Hydralazine is a direct-acting vasodilator that relaxes arteriolar smooth muscle, leading to decreased systemic vascular resistance and reduced blood pressure. The exact molecular mechanism involves inhibition of inositol trisphosphate (IP3)-induced calcium release from the sarcoplasmic reticulum and activation of guanylate cyclase, increasing c GMP levels.
Methyldopa is a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow from the brainstem, decreasing peripheral vascular resistance and blood pressure. Hydrochlorothiazide is a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule, reducing plasma volume and cardiac output.
Hypertension (alone or in combination with other antihypertensives),Off-label: Heart failure (as adjunctive therapy in African American patients)
Hypertension
Oral: 25-50 mg twice daily, max 200 mg/day. IV: 10-20 mg every 4-6 hours as needed.
1 tablet (hydrochlorothiazide 15 mg, methyldopa 250 mg) orally twice daily; increase as needed up to 2 tablets twice daily.
Terminal elimination half-life is 2-4 hours in patients with normal renal function; prolonged in renal impairment (up to 20 hours in severe cases).
Terminal half-life: 12–17 hours; clinical context: steady-state achieved within 2–3 days; effect persists 12–24 hours
Primarily hepatic via N-acetylation by N-acetyltransferase 2 (NAT2). Metabolites include hydralazine pyruvic acid hydrazone, acetylhydralazine, and others.
Methyldopa is metabolized in the liver via conjugation and O-methylation; active metabolites include methyldopamine and methylnorepinephrine. Hydrochlorothiazide is not significantly metabolized and is excreted unchanged in urine.
Primarily renal (80-90% as unchanged drug); minor biliary/fecal (<10%).
Renal: ~70% unchanged; biliary/fecal: ~30% as metabolites
Approximately 87% bound to plasma proteins (primarily albumin).
~90%, primarily to albumin
0.3-0.5 L/kg, indicating distribution primarily in extracellular fluid.
2–4 L/kg; clinical meaning: extensive tissue distribution, concentrating in vascular smooth muscle
Oral: 50-60% due to first-pass metabolism; Intravenous: 100%.
Oral: 50–60% (extensive first-pass metabolism)
GFR 10-50 m L/min: Administer every 6-8 hours. GFR <10 m L/min: Administer every 8-12 hours.
GFR 30-50 m L/min: maximum 1 tablet twice daily. GFR <30 m L/min: avoid use.
Child-Pugh A: No adjustment. Child-Pugh B: Reduce dose by 50%. Child-Pugh C: Use with caution, reduce dose by 75%.
Child-Pugh A: caution, reduce dose. Child-Pugh B: avoid. Child-Pugh C: contraindicated.
Oral/IV: 0.1-0.5 mg/kg/dose every 6 hours; max initial dose 25 mg/dose.
Not recommended for pediatric use; safety in children under 12 years not established.
Start at 10-25 mg twice daily; titrate slowly due to increased risk of hypotension and electrolyte disturbances.
Start with 1 tablet once daily; monitor for hypotension and electrolyte imbalance. Reduce initial dose by 50%.
No FDA boxed warning for Hydralazine.
None
May cause drug-induced lupus erythematosus (especially in slow acetylators),May cause peripheral neuritis (pyridoxine deficiency),May cause tachycardia, angina, or myocardial infarction in patients with coronary artery disease,May cause hypotension and renal impairment,Monitor for signs of lupus and neuropathy
Sedation, usually transient; may impair ability to drive or operate heavy machinery.,Positive Coombs test with hemolytic anemia (rare); monitor hematocrit and Coombs test.,Hepatotoxicity (hepatic necrosis) with fever, jaundice; discontinue if liver abnormalities occur.,Fluid and electrolyte imbalance (hypokalemia, hyponatremia, hypercalcemia) due to thiazide.,May precipitate gout in hyperuricemic patients.,May exacerbate systemic lupus erythematosus.
Hypersensitivity to hydralazine,Mitral valve rheumatic heart disease,Coronary artery disease (due to reflex tachycardia)
Active hepatic disease (e.g., acute hepatitis, cirrhosis),Prior methyldopa therapy associated with liver disorders,Hypersensitivity to methyldopa or hydrochlorothiazide,Anuria,Sulfonamide allergy (cross-sensitivity with thiazides)
Take with food to reduce gastrointestinal upset. Avoid high-tyramine foods if taking concomitant MAOIs, though hydralazine itself has no direct tyramine interaction. No specific food restrictions, but limit alcohol as it may exacerbate hypotension.
Avoid high-sodium foods as they can reduce antihypertensive efficacy. Thiazides may cause hypokalemia; increase dietary potassium (bananas, orange juice) unless contraindicated. Alcohol may enhance orthostatic hypotension.
First trimester: No evidence of teratogenicity in human studies; animal studies show no fetal harm. Second and third trimesters: Associated with reduced placental perfusion and fetal growth restriction; risk of neonatal hypotension, hypoglycemia, and bradycardia if used near term.
First trimester: No increased risk of major malformations based on limited human data; animal studies show no teratogenicity at clinically relevant doses. Second/third trimesters: Fetal and neonatal adverse effects including oligohydramnios, fetal renal dysfunction, skull ossification delay, and hypotension in the neonate. Avoid use after 20 weeks gestation unless no alternative.
Excreted in breast milk in low concentrations; M/P ratio approximately 0.2. Considered compatible with breastfeeding; monitor infant for hypotension and drowsiness.
Methyldopa and hydrochlorothiazide are excreted into human milk. M/P ratio for methyldopa is approximately 0.5-1.0; for hydrochlorothiazide, M/P ratio ~2.0. Methyldopa is considered compatible with breastfeeding. Hydrochlorothiazide may suppress lactation and cause neonatal electrolyte disturbances. Use with caution; monitor infant for signs of diuresis or electrolyte imbalance.
Hypertension in pregnancy may require increased dosing due to increased volume of distribution and renal clearance; start with low doses and titrate based on blood pressure response; avoid severe hypotension to maintain placental perfusion.
Pharmacokinetic changes in pregnancy may include increased volume of distribution and enhanced renal clearance. No specific dose adjustment routine is recommended; dosing should be guided by clinical response. Methyldopa starting dose 250 mg twice daily, titrated to effect. Hydrochlorothiazide dose not typically adjusted, but caution due to potential volume depletion.
Hydralazine, the active component, is a direct-acting vasodilator used for hypertension. It can cause a lupus-like syndrome, especially in slow acetylators. Monitor for tachycardia and fluid retention; consider concomitant beta-blocker and diuretic. Do not use as monotherapy for long-term management. Onset of action is rapid (15-20 min) IV, but oral bioavailability is variable (30-50%). Dose adjustments needed in renal impairment.
Aldoril 15 (methyldopa 250mg + hydrochlorothiazide 15mg) is rarely used due to superior alternatives. Monitor for hepatotoxicity, hemolytic anemia, and lupus-like syndrome. Titrate slowly to avoid sedation. Contraindicated in active liver disease, pheochromocytoma, and anuria.
Take exactly as prescribed; do not skip doses or double up.,May cause dizziness or lightheadedness; rise slowly from sitting or lying down.,Report any joint pain, rash, fever, or unexplained bruising/bleeding.,May cause headaches or palpitations, especially early in therapy.,Avoid sudden discontinuation to prevent rebound hypertension.
May cause drowsiness; avoid driving until tolerance develops.,Report unexplained fever, jaundice, or dark urine immediately.,Take at bedtime to minimize sedation.,Avoid sudden discontinuation; follow prescribed tapering schedule.,Use sun protection; thiazides increase photosensitivity.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about HYDRAP-ES vs ALDORIL 15, answered by our medical review team.
HYDRAP-ES is a Antihypertensive Combination that works by Hydralazine is a direct-acting vasodilator that relaxes arteriolar smooth muscle, leading to decreased systemic vascular resistance and reduced blood pressure. The exact molecular mechanism involves inhibition of inositol trisphosphate (IP3)-induced calcium release from the sarcoplasmic reticulum and activation of guanylate cyclase, increasing c GMP levels.. ALDORIL 15 is a Antihypertensive Combination that works by Methyldopa is a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow from the brainstem, decreasing peripheral vascular resistance and blood pressure. Hydrochlorothiazide is a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule, reducing plasma volume and cardiac output.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between HYDRAP-ES and ALDORIL 15 depend on the specific clinical indication. These are both Antihypertensive Combination agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of HYDRAP-ES is: Oral: 25-50 mg twice daily, max 200 mg/day. IV: 10-20 mg every 4-6 hours as needed.. The standard adult dose of ALDORIL 15 is: 1 tablet (hydrochlorothiazide 15 mg, methyldopa 250 mg) orally twice daily; increase as needed up to 2 tablets twice daily.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between HYDRAP-ES and ALDORIL 15 in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. HYDRAP-ES is classified as Category C. First trimester: No evidence of teratogenicity in human studies; animal studies show no fetal harm. Second and third trimesters: Associated with reduced placental perfusion and fet. ALDORIL 15 is classified as Category C. First trimester: No increased risk of major malformations based on limited human data; animal studies show no teratogenicity at clinically relevant doses. Second/third trimesters: . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.