Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DEMI-REGROTON vs ALDORIL D50
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.
Aldoril D50 is a combination of methyldopa and hydrochlorothiazide. 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 reabsorption in the distal convoluted tubule, reducing plasma volume and further lowering blood pressure.
Hypertension (adjunctive therapy)
Hypertension (first-line or second-line therapy),Hypertensive urgency (off-label)
One tablet orally once daily, each tablet containing 25 mg chlorthalidone and 0.125 mg reserpine.
1 tablet (hydrochlorothiazide 25 mg + methyldopa 250 mg) orally twice daily; maximum dose: 2 tablets (50 mg + 500 mg) twice daily.
Terminal elimination half-life is 40-60 hours (mean 48 h), allowing once-daily dosing; steady state reached in 5-7 days
3–6 hours (terminal elimination half-life); clinical context: requires twice-daily dosing for sustained blood pressure control; prolonged in renal impairment.
Chlorothiazide: Not extensively metabolized; excreted unchanged in urine. Reserpine: Extensively metabolized in the liver via hydrolysis and glucuronidation; active metabolites.
Methyldopa is extensively metabolized in the liver via conjugation and O-methylation, with involvement of catechol-O-methyltransferase (COMT). Hydrochlorothiazide is not extensively metabolized; it is eliminated largely unchanged by the kidneys.
Renal: 70% as unchanged drug; biliary/fecal: 30% as metabolites
Renal: 50% as unchanged drug and 20% as metabolites; biliary/fecal: ~25% (as metabolites); total renal clearance accounts for ~70% of elimination.
90% bound to albumin and alpha-1-acid glycoprotein
~20% bound to albumin; minimal binding to other plasma proteins.
3-5 L/kg, indicating extensive extravascular distribution
0.2–0.3 L/kg (moderately low Vd, indicating limited extravascular distribution and predominantly plasma water distribution).
Oral: 65-75% due to first-pass metabolism
Oral: 30–40% (due to extensive first-pass metabolism); IV: 100%.
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.
Contraindicated if GFR < 30 m L/min; for GFR 30-50 m L/min: reduce dose and monitor electrolytes.
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 Class A: no adjustment; Class B: reduce dose by 50% and monitor; Class C: contraindicated.
Not recommended for pediatric use due to safety and efficacy data lacking. No established pediatric dosing guidelines.
Not recommended; inadequate safety data.
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 (hydrochlorothiazide 12.5 mg + methyldopa 125 mg) once daily; increase slowly; monitor for hypotension and electrolyte imbalance.
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 and drowsiness common; avoid driving or hazardous activities. Risk of Coombs-positive hemolytic anemia with methyldopa (discontinue if anemia develops). Hepatotoxicity and liver function abnormalities (discontinue if jaundice occurs). Orthostatic hypotension; caution in volume-depleted patients. Electrolyte imbalances (particularly hypokalemia, hyponatremia) with hydrochlorothiazide; monitor serum electrolytes. Sulfonamide cross-sensitivity possible. Exacerbation of systemic lupus erythematosus. Avoid abrupt withdrawal of methyldopa (may cause rebound hypertension).
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 (cirrhosis, hepatitis) associated with methyldopa therapy; previous methyldopa-induced liver disorders. Anuria or hypersensitivity to thiazide diuretics or sulfonamide-derived drugs. Concomitant use with MAO inhibitors. Severe renal impairment (creatinine clearance <30 m L/min) or electrolyte depletion due to hydrochlorothiazide. Concurrent lithium therapy (risk of lithium toxicity).
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 potassium supplements or salt substitutes containing potassium without consulting doctor. Limit alcohol intake. Avoid excessive grapefruit juice. Maintain adequate potassium intake through diet to prevent hypokalemia.
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.
Hydrochlorothiazide (HCTZ) is Pregnancy Category B in first trimester and Category D in second/third trimesters. Methyldopa (M) is Category B. HCTZ use in second/third trimester may cause fetal/neonatal effects including electrolyte disturbances, jaundice, thrombocytopenia, and possible fetal growth restriction. Methyldopa has not shown teratogenicity. Aldoril D50 (M 500mg/HCTZ 50mg) is not recommended during pregnancy, especially after first trimester.
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.
Both methyldopa and HCTZ are excreted in breast milk. Methyldopa M/P ratio approximately 1.0; HCTZ M/P ratio variable, small amounts. Use during breastfeeding may suppress lactation due to HCTZ diuretic effect. Monitor infant for signs of hypotension, electrolyte imbalance. Caution recommended; use only if clearly needed.
No specific dose adjustment recommended; use lowest effective dose if necessary. Monitor closely for maternal hypotension and fetal effects.
Pregnancy-induced increase in plasma volume may reduce effectiveness of HCTZ, requiring dose adjustment. Methyldopa pharmacokinetics not significantly altered; however, increased clearance in pregnancy may require higher doses. In preeclampsia, dose adjustments may be needed. Avoid HCTZ in pregnancy if possible.
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 D50 combines methyldopa and hydrochlorothiazide. Monitor for orthostatic hypotension, especially in volume-depleted patients. May cause positive Coombs test, hemolytic anemia, and lupus-like syndrome. Avoid in pheochromocytoma. Use caution in hepatic disease.
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.
Take exactly as prescribed; do not skip doses or double up.,May cause dizziness or drowsiness; avoid driving until you know how it affects you.,Report unexplained fever, jaundice, or dark urine immediately.,Avoid sudden discontinuation; may cause rapid increase in blood pressure.,Stay hydrated but do not overhydrate; monitor for signs of electrolyte imbalance.
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 D50, 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 D50 is a Antihypertensive Combination that works by Aldoril D50 is a combination of methyldopa and hydrochlorothiazide. 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 reabsorption in the distal convoluted tubule, reducing plasma volume and further lowering blood pressure.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DEMI-REGROTON and ALDORIL D50 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 D50 is: 1 tablet (hydrochlorothiazide 25 mg + methyldopa 250 mg) orally twice daily; maximum dose: 2 tablets (50 mg + 500 mg) 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 D50 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 D50 is classified as Category C. Hydrochlorothiazide (HCTZ) is Pregnancy Category B in first trimester and Category D in second/third trimesters. Methyldopa (M) is Category B. HCTZ use in second/third trimester ma. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.