Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DEMI-REGROTON 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
DEMI-REGROTON is a fixed-dose combination of chlorothiazide (a thiazide diuretic) and reserpine (a Rauwolfia alkaloid). Chlorothiazide inhibits the Na+-Cl- symporter in the distal convoluted tubule, reducing sodium and water reabsorption. Reserpine depletes catecholamines (norepinephrine, dopamine, serotonin) from central and peripheral nerve endings by inhibiting vesicular monoamine transporter 2 (VMAT2), leading to reduced sympathetic outflow and vasodilation.
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 (adjunctive therapy)
Hypertension
One tablet orally once daily, each tablet containing 25 mg chlorthalidone and 0.125 mg reserpine.
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 40-60 hours (mean 48 h), allowing once-daily dosing; steady state reached in 5-7 days
Terminal half-life: 12–17 hours; clinical context: steady-state achieved within 2–3 days; effect persists 12–24 hours
Chlorothiazide: Not extensively metabolized; excreted unchanged in urine. Reserpine: Extensively metabolized in the liver via hydrolysis and glucuronidation; active metabolites.
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: 70% as unchanged drug; biliary/fecal: 30% as metabolites
Renal: ~70% unchanged; biliary/fecal: ~30% as metabolites
90% bound to albumin and alpha-1-acid glycoprotein
~90%, primarily to albumin
3-5 L/kg, indicating extensive extravascular distribution
2–4 L/kg; clinical meaning: extensive tissue distribution, concentrating in vascular smooth muscle
Oral: 65-75% due to first-pass metabolism
Oral: 50–60% (extensive first-pass metabolism)
Contraindicated if GFR <30 m L/min. For GFR 30-60 m L/min, reduce dose to half tablet daily and monitor electrolytes. No adjustment needed if GFR >60 m L/min.
GFR 30-50 m L/min: maximum 1 tablet twice daily. GFR <30 m L/min: avoid use.
Contraindicated in severe hepatic impairment (Child-Pugh class C). For Child-Pugh class B, use half the initial dose and titrate cautiously. No adjustment for Child-Pugh class A.
Child-Pugh A: caution, reduce dose. Child-Pugh B: avoid. Child-Pugh C: contraindicated.
Not recommended for pediatric use due to safety and efficacy data lacking. No established pediatric dosing guidelines.
Not recommended for pediatric use; safety in children under 12 years not established.
Initiate at half tablet (12.5 mg chlorthalidone/0.0625 mg reserpine) daily. Monitor for orthostatic hypotension, electrolyte imbalance, and CNS depression. Titrate slowly based on response and tolerability.
Start with 1 tablet once daily; monitor for hypotension and electrolyte imbalance. Reduce initial dose by 50%.
Reserpine: Risk of mental depression and suicidal tendencies. Treatment should be discontinued at the first sign of depression.
None
Hypotension, electrolyte imbalance (especially hypokalemia), depression (with reserpine), peptic ulcer disease (reserpine may increase gastric acid secretion), and sensitivity reactions (chlorothiazide, sulfonamide derivative).
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 chlorothiazide, reserpine, or sulfonamides; anuria; history of depression (especially with suicidal tendencies); active peptic ulcer; ulcerative colitis; concurrent electroconvulsive therapy (ECT).
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 excessive potassium intake (bananas, oranges, salt substitutes) due to risk of hyperkalemia from chlorthalidone. Limit sodium to enhance antihypertensive effect. Grapefruit juice may alter drug metabolism; avoid large quantities.
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.
FDA Pregnancy Category C. First trimester: potential risk of neural tube defects and cardiovascular anomalies based on animal studies; human data limited. Second and third trimesters: risk of fetal growth restriction, oligohydramnios, and neonatal hypotension due to renin-angiotensin system interference. Avoid in pregnancy unless no alternative.
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 amounts; M/P ratio not established. Potential for adverse effects in nursing infant such as hypotension. Use caution; consider alternative agent.
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 specific dose adjustment recommended; use lowest effective dose if necessary. Monitor closely for maternal hypotension and fetal effects.
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.
DEMI-REGROTON (chlorthalidone 15 mg + reserpine 0.125 mg) is indicated for hypertension. Monitor for hypokalemia and hyperuricemia. Reserpine may cause depression; avoid in patients with history of depressive disorders. Chlorthalidone may exacerbate gout. Use cautiously 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 double doses if missed.,May cause dizziness or drowsiness; avoid driving until effects known.,Report symptoms of depression, slow heart rate, or unusual bleeding.,Avoid alcohol and NSAIDs (ibuprofen, naproxen) unless approved by doctor.,Monitor for signs of low potassium: muscle cramps, weakness, irregular heartbeat.,Rise slowly from sitting or lying to prevent dizziness.
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 DEMI-REGROTON vs ALDORIL 15, answered by our medical review team.
DEMI-REGROTON is a Antihypertensive Combination that works by DEMI-REGROTON is a fixed-dose combination of chlorothiazide (a thiazide diuretic) and reserpine (a Rauwolfia alkaloid). Chlorothiazide inhibits the Na+-Cl- symporter in the distal convoluted tubule, reducing sodium and water reabsorption. Reserpine depletes catecholamines (norepinephrine, dopamine, serotonin) from central and peripheral nerve endings by inhibiting vesicular monoamine transporter 2 (VMAT2), leading to reduced sympathetic outflow and vasodilation.. 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 DEMI-REGROTON 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 DEMI-REGROTON is: One tablet orally once daily, each tablet containing 25 mg chlorthalidone and 0.125 mg reserpine.. 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 DEMI-REGROTON 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. DEMI-REGROTON is classified as Category C. FDA Pregnancy Category C. First trimester: potential risk of neural tube defects and cardiovascular anomalies based on animal studies; human data limited. Second and third trimeste. 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.