Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DEMI-REGROTON vs ALDORIL 25
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.
Combination of methyldopa, a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow, and hydrochlorothiazide, a thiazide diuretic that inhibits sodium reabsorption in the distal convoluted tubule, reducing plasma volume.
Hypertension (adjunctive therapy)
Hypertension
One tablet orally once daily, each tablet containing 25 mg chlorthalidone and 0.125 mg reserpine.
Oral: 1 tablet (hydrochlorothiazide 25 mg/methyldopa 250 mg) twice daily; increase as needed to max 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
7-16 hours (terminal). In renal impairment, half-life may exceed 24 hours, requiring dose adjustment.
Chlorothiazide: Not extensively metabolized; excreted unchanged in urine. Reserpine: Extensively metabolized in the liver via hydrolysis and glucuronidation; active metabolites.
Methyldopa is metabolized primarily via hepatic conjugation and renal excretion; hydrochlorothiazide is not significantly metabolized and is excreted unchanged in urine.
Renal: 70% as unchanged drug; biliary/fecal: 30% as metabolites
Renal: ~85% unchanged. Biliary/fecal: ~15% as metabolites.
90% bound to albumin and alpha-1-acid glycoprotein
Methyldopa: less than 10% bound to plasma proteins. Hydrochlorothiazide: ~70% bound to plasma proteins (primarily albumin).
3-5 L/kg, indicating extensive extravascular distribution
Methyldopa: 0.3-0.6 L/kg (distributes widely, including CNS). Hydrochlorothiazide: 0.8-1.5 L/kg (distributes into extracellular fluid).
Oral: 65-75% due to first-pass metabolism
Methyldopa: oral bioavailability ~25% (first-pass metabolism). Hydrochlorothiazide: oral bioavailability ~60-80%.
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: use with caution, reduce dose. GFR <30 m L/min: not recommended.
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: no adjustment; Child-Pugh B or C: contraindicated due to methyldopa hepatotoxicity risk.
Not recommended for pediatric use due to safety and efficacy data lacking. No established pediatric dosing guidelines.
Not established; avoid use in children.
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 at lowest dose (1 tablet daily); monitor for orthostatic hypotension, sedation, 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).
May cause sedation, depression, positive direct Coombs test, hemolytic anemia, hepatotoxicity, fluid/electrolyte imbalance, and sensitivity reactions; monitor liver function, CBC, and electrolytes.
Hypersensitivity to chlorothiazide, reserpine, or sulfonamides; anuria; history of depression (especially with suicidal tendencies); active peptic ulcer; ulcerative colitis; concurrent electroconvulsive therapy (ECT).
Hypersensitivity to methyldopa, hydrochlorothiazide, or sulfonamides; active hepatic disease; anuria; history of methyldopa-induced liver disorders.
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 to optimize antihypertensive effect. Limit alcohol intake. Do not consume large amounts of potassium-rich foods (e.g., bananas, oranges, spinach) unless advised by a healthcare provider, as hydrochlorothiazide can alter potassium levels.
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: Limited human data, but animal studies show no teratogenicity at therapeutic doses. Second and third trimesters: Associated with fetal hypotension, oligohydramnios, and renal dysfunction due to methyldopa component. Hydrochlorothiazide may cause fetal electrolyte imbalances.
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 is excreted in breast milk with M/P ratio of approximately 0.2-0.5; hydrochlorothiazide M/P ratio ~0.5-0.6. Considered compatible with breastfeeding by AAP, but monitor infant for hypotension and electrolyte disturbances.
No specific dose adjustment recommended; use lowest effective dose if necessary. Monitor closely for maternal hypotension and fetal effects.
No standard dose adjustment required, but increased plasma volume in pregnancy may necessitate higher doses of methyldopa. Monitor clinical response and adjust accordingly.
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 25 is a fixed-dose combination of methyldopa (250 mg) and hydrochlorothiazide (25 mg). Monitor for hypotension, especially during initial therapy or with volume depletion. Methyldopa may cause a positive direct Coombs test and hemolytic anemia; discontinue if anemia develops. Hydrochlorothiazide can cause electrolyte imbalances, hyperglycemia, and hyperuricemia. Avoid use in patients with pheochromocytoma or active liver 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 this medication exactly as prescribed, usually once or twice daily.,Rise slowly from sitting or lying to prevent dizziness from low blood pressure.,Avoid alcohol, which can increase dizziness and drowsiness.,Report any signs of infection, unusual tiredness, or yellowing of skin/eyes.,Use sun protection as hydrochlorothiazide may increase sun sensitivity.,Do not use potassium supplements or salt substitutes without consulting your doctor.
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 25, 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 25 is a Antihypertensive Combination that works by Combination of methyldopa, a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow, and hydrochlorothiazide, a thiazide diuretic that inhibits sodium reabsorption in the distal convoluted tubule, reducing plasma volume.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DEMI-REGROTON and ALDORIL 25 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 25 is: Oral: 1 tablet (hydrochlorothiazide 25 mg/methyldopa 250 mg) twice daily; increase as needed to max 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 25 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 25 is classified as Category C. First trimester: Limited human data, but animal studies show no teratogenicity at therapeutic doses. Second and third trimesters: Associated with fetal hypotension, oligohydramnios. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.