Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
APRESOLINE 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
Direct-acting arteriolar vasodilator that relaxes vascular smooth muscle, leading to decreased peripheral resistance and blood pressure. The exact molecular mechanism is unclear but may involve interference with calcium movement or inhibition of inositol trisphosphate-induced calcium release.
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 (oral, as adjunctive therapy),Severe hypertension or hypertensive emergency (parenteral)
Hypertension
Initial: 10 mg oral 4 times daily for 2-4 days; increase to 25 mg 4 times daily for the first week. Maintenance: 50 mg 4 times daily; maximum 300 mg/day. IV: 20-40 mg IM or slow IV push, repeat 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 3-7 hours in patients with normal renal function; prolonged to 7-16 hours in renal impairment. Acetylator phenotype affects half-life: in slow acetylators, half-life may be 4-5 hours; in fast acetylators, 1-2 hours, but clinical effect (antihypertensive) lasts longer due to persistent binding to vascular tissue.
Terminal half-life: 12–17 hours; clinical context: steady-state achieved within 2–3 days; effect persists 12–24 hours
Extensively metabolized in the liver via acetylation (N-acetyltransferase, NAT2) and oxidation (CYP450, primarily CYP3A4 and CYP2C19).
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; 86-90% of an oral dose is excreted in urine as metabolites (N-acetylhydralazine, hydralazine pyruvic acid hydrazone) and unchanged drug (<10% unchanged); biliary/fecal excretion is minimal (<10%).
Renal: ~70% unchanged; biliary/fecal: ~30% as metabolites
87-90% bound to plasma proteins, primarily albumin; binding is reduced in uremia.
~90%, primarily to albumin
1.5-1.8 L/kg; distributes widely into total body water, with high affinity for vascular smooth muscle, where it accumulates; Vd is larger in slow acetylators due to higher free drug levels.
2–4 L/kg; clinical meaning: extensive tissue distribution, concentrating in vascular smooth muscle
Oral immediate-release: 30-50% in fast acetylators; 50-75% in slow acetylators. Bioavailability is increased when taken with food (peak concentration enhanced 50-70%).
Oral: 50–60% (extensive first-pass metabolism)
Cr Cl 10-50 m L/min: administer every 8 hours. Cr Cl <10 m L/min: administer every 8 hours or reduce dose by 50%.
GFR 30-50 m L/min: maximum 1 tablet twice daily. GFR <30 m L/min: avoid use.
Child-Pugh Class B: reduce dose by 50%. Child-Pugh Class C: avoid use or reduce dose by 75%.
Child-Pugh A: caution, reduce dose. Child-Pugh B: avoid. Child-Pugh C: contraindicated.
Oral: 0.75-3 mg/kg/day in 2-4 divided doses, maximum 7.5 mg/kg/day or 200 mg/day. IV: 0.1-0.2 mg/kg/dose every 4-6 hours as needed.
Not recommended for pediatric use; safety in children under 12 years not established.
Start at 10 mg 2-3 times daily; increase gradually to avoid hypotension. Maximum 200 mg/day. Monitor for orthostatic hypotension and reflex tachycardia.
Start with 1 tablet once daily; monitor for hypotension and electrolyte imbalance. Reduce initial dose by 50%.
None.
None
May cause drug-induced lupus erythematosus, especially in slow acetylators; monitor for symptoms. Use cautiously in patients with coronary artery disease (may cause reflex tachycardia and exacerbate angina). Can cause peripheral neuritis (pyridoxine deficiency), alone with high doses. May cause sodium and water retention, requiring concomitant diuretic therapy.
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 any component of the formulation. Mitral valve rheumatic heart disease. Aortic aneurysm (theoretical contraindication due to increased cardiac output/loading conditions).
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)
Food may increase bioavailability of hydralazine; take with food to reduce peak concentrations and potential side effects. Avoid tyramine-rich foods (e.g., aged cheeses, cured meats) if taking MAOIs concurrently. No specific dietary restrictions otherwise.
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: Limited human data; animal studies show no teratogenicity at clinically relevant doses, but risk cannot be excluded. Second and third trimesters: May cause fetal tachycardia, neonatal hypotension, and ileus; associated with maternal hypotension and potential uteroplacental insufficiency. FDA Pregnancy 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: 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.
Minimal excretion into breast milk; M/P ratio approximately 1.0. Considered compatible with breastfeeding by the American Academy of Pediatrics; monitor infant for hypotension and feeding difficulties.
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.
No standard dose adjustment recommended; however, increased plasma volume may necessitate higher doses. Monitor response and titrate to effect; avoid severe hypotension to prevent uteroplacental hypoperfusion.
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 (Apresoline) is a direct-acting vasodilator primarily used for hypertension management, especially in preeclampsia and hypertensive emergencies. It can cause a lupus-like syndrome, especially in slow acetylators; testing for N-acetyltransferase 2 (NAT2) phenotype may be considered. Tachyphylaxis can occur; concomitant beta-blocker and diuretic therapy are often required. Onset of action is 10-20 minutes IV, 20-30 minutes IM. Avoid in patients with coronary artery disease due to reflex tachycardia.
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 stop suddenly as this can cause a rapid rise in blood pressure.,May cause dizziness or lightheadedness; avoid driving or operating machinery until you know how this medicine affects you.,Report any unexplained joint pain, fever, chest pain, or rash to your doctor immediately as these may be signs of a serious reaction (drug-induced lupus).,Avoid alcohol consumption as it can increase the blood pressure lowering effects and dizziness.,Do not take over-the-counter cold, sinus, or weight loss products without checking with your doctor, as many contain ingredients that can raise 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 vs ALDORIL 15, answered by our medical review team.
APRESOLINE is a Antihypertensive that works by Direct-acting arteriolar vasodilator that relaxes vascular smooth muscle, leading to decreased peripheral resistance and blood pressure. The exact molecular mechanism is unclear but may involve interference with calcium movement or inhibition of inositol trisphosphate-induced calcium release.. 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 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 is: Initial: 10 mg oral 4 times daily for 2-4 days; increase to 25 mg 4 times daily for the first week. Maintenance: 50 mg 4 times daily; maximum 300 mg/day. IV: 20-40 mg IM or slow IV push, repeat 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 APRESOLINE 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 is classified as Category C. First trimester: Limited human data; animal studies show no teratogenicity at clinically relevant doses, but risk cannot be excluded. Second and third trimesters: May cause fetal t. 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.