Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
APRESOLINE-ESIDRIX 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
Apresoline (hydralazine) is a direct-acting vasodilator that relaxes arteriolar smooth muscle via unknown mechanism; Esidrix (hydrochlorothiazide) is a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule.
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
Hypertension
Hydralazine (Apresoline): Oral, initial 10 mg 4 times daily for first 2-4 days, then increase to 25 mg 4 times daily for first week, then 50 mg 4 times daily thereafter. Maximum daily dose: 300 mg. Hydrochlorothiazide (Esidrix): Oral, initial 12.5-25 mg once daily, may increase to 50 mg once daily if needed.
1 tablet (hydrochlorothiazide 15 mg, methyldopa 250 mg) orally twice daily; increase as needed up to 2 tablets twice daily.
Hydralazine: 2-8 h (prolonged in renal impairment); Hydrochlorothiazide: 6-15 h (mean 10 h, increased in renal failure).
Terminal half-life: 12–17 hours; clinical context: steady-state achieved within 2–3 days; effect persists 12–24 hours
Hydralazine undergoes N-acetylation (polymorphic, NAT2) and CYP450; hydrochlorothiazide is not extensively metabolized (excreted unchanged in urine).
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.
Renal: Hydralazine 85-90% as metabolites, 5-10% unchanged; Hydrochlorothiazide 95% as unchanged drug. Biliary/fecal: Hydralazine <10%.
Renal: ~70% unchanged; biliary/fecal: ~30% as metabolites
Hydralazine: 85-90% (primarily albumin); Hydrochlorothiazide: 40-68% (albumin).
~90%, primarily to albumin
Hydralazine: 1.5-1.8 L/kg (extensive tissue distribution); Hydrochlorothiazide: 0.83-1.2 L/kg.
2–4 L/kg; clinical meaning: extensive tissue distribution, concentrating in vascular smooth muscle
Hydralazine: 30-50% (oral, extensive first-pass metabolism; slower in slow acetylators); Hydrochlorothiazide: 65-75% (oral).
Oral: 50–60% (extensive first-pass metabolism)
Hydralazine: No adjustment for GFR >10 m L/min; for GFR <10 m L/min, reduce dose to 30-50% of normal. Hydrochlorothiazide: Not effective if GFR <30 m L/min; use alternative diuretic. For Cr Cl 30-50 m L/min, reduce dose or interval.
GFR 30-50 m L/min: maximum 1 tablet twice daily. GFR <30 m L/min: avoid use.
Hydralazine: Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated. Hydrochlorothiazide: Caution in severe liver disease due to electrolyte imbalances; no specific dose adjustment defined; use with monitoring.
Child-Pugh A: caution, reduce dose. Child-Pugh B: avoid. Child-Pugh C: contraindicated.
Hydralazine: Oral, initial 0.75-1 mg/kg/day in 2-4 divided doses, increase over 3-4 weeks to maximum 7.5 mg/kg/day or 200 mg/day. Hydrochlorothiazide: Oral, 1-2 mg/kg/day in 2 divided doses; maximum 6 mg/kg/day or 50 mg/day.
Not recommended for pediatric use; safety in children under 12 years not established.
Hydralazine: Start at lower end of dosing range (10 mg 4 times daily) and titrate slowly due to increased sensitivity and risk of hypotension. Hydrochlorothiazide: Start at 12.5 mg once daily, monitor renal function and electrolytes more frequently.
Start with 1 tablet once daily; monitor for hypotension and electrolyte imbalance. Reduce initial dose by 50%.
No black box warning specifically for the combination; hydralazine carries a warning for drug-induced lupus erythematosus.
None
Lupus erythematosus-like syndrome (hydralazine),Hypotension,Myocardial infarction (exacerbation due to reflex tachycardia),Electrolyte imbalances (hypokalemia, hyponatremia) from thiazide,Hyperuricemia,Sulfonamide allergy cross-reactivity (thiazide)
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 or hydrochlorothiazide,Anuria,Concomitant use with MAO inhibitors,Rheumatic mitral valve disease (hydralazine)
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)
Avoid natural licorice (glycyrrhizin) as it can worsen hypokalemia and reduce antihypertensive effect. High-sodium foods should be limited as they can counteract the blood pressure-lowering effect. Grapefruit juice may enhance hydralazine absorption; consistent consumption is advised if intake is routine. Alcohol may potentiate orthostatic hypotension and dizziness.
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.
APRESOLINE-ESIDRIX (hydralazine/hydrochlorothiazide). First trimester: Hydrochlorothiazide (HCTZ) may cause fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse reactions. Hydralazine has been associated with minor anomalies in animal studies but no well-controlled human studies; risk cannot be ruled out. Second/third trimester: Maternal hypotension may reduce uterine blood flow; HCTZ may cause fetal electrolyte disturbances, thrombocytopenia, and jaundice. Avoid use for edema in pregnancy; use only if clearly needed.
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.
Hydralazine: M/P ratio unknown; excreted in breast milk in small amounts; unlikely to cause adverse effects in infant. Hydrochlorothiazide: M/P ratio ~0.3; excreted in breast milk; may suppress lactation; use caution, especially if high doses or dehydration.
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.
Dose adjustments not typically required; however, pregnancy may alter pharmacokinetics (increased volume of distribution, increased renal clearance). Use lowest effective dose; monitor response. Avoid HCTZ for routine edema; use only if other diuretics contraindicated. Start with low doses and titrate slowly.
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.
APRESOLINE-ESIDRIX is a fixed-dose combination of hydralazine (vasodilator) and hydrochlorothiazide (thiazide diuretic). Monitor for reflex tachycardia and fluid retention with hydralazine; hypokalemia, hyponatremia, and hyperuricemia with hydrochlorothiazide. Use with caution in severe renal impairment (Cr Cl <30 m L/min) and coronary artery disease. May cause lupus-like syndrome with prolonged high-dose hydralazine (usually >200 mg/day). Administer with food to reduce GI upset.
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 this medication exactly as prescribed, usually once daily in the morning to avoid nighttime urination.,You may experience dizziness or lightheadedness, especially when standing up quickly; rise slowly from sitting or lying down.,Report any unexplained joint pain, rash, fever, or fatigue, as these may be signs of a lupus-like reaction.,Avoid alcohol, which can increase blood pressure-lowering effects and dizziness.,Drink adequate fluids unless otherwise advised by your doctor, but do not increase salt intake without consulting your healthcare provider.,Do not stop taking this medication abruptly, as sudden withdrawal may cause a rapid increase in blood pressure.
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 APRESOLINE-ESIDRIX vs ALDORIL 15, answered by our medical review team.
APRESOLINE-ESIDRIX is a Antihypertensive that works by Apresoline (hydralazine) is a direct-acting vasodilator that relaxes arteriolar smooth muscle via unknown mechanism; Esidrix (hydrochlorothiazide) is a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule.. 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 APRESOLINE-ESIDRIX and ALDORIL 15 depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of APRESOLINE-ESIDRIX is: Hydralazine (Apresoline): Oral, initial 10 mg 4 times daily for first 2-4 days, then increase to 25 mg 4 times daily for first week, then 50 mg 4 times daily thereafter. Maximum daily dose: 300 mg. Hydrochlorothiazide (Esidrix): Oral, initial 12.5-25 mg once daily, may increase to 50 mg once daily if 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 APRESOLINE-ESIDRIX 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. APRESOLINE-ESIDRIX is classified as Category C. APRESOLINE-ESIDRIX (hydralazine/hydrochlorothiazide). First trimester: Hydrochlorothiazide (HCTZ) may cause fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse. 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.