Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
METATENSIN #2 vs ALDORIL D30
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
METATENSIN #2 contains reserpine and methyclothiazide. Reserpine inhibits vesicular monoamine transporter (VMAT), depleting catecholamines from peripheral neurons. Methyclothiazide inhibits sodium-chloride symporter in distal convoluted tubule, reducing fluid volume.
Aldoril D30 is a combination of methyldopa, a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow, and hydrochlorothiazide, a thiazide diuretic that inhibits the sodium-chloride symporter in the distal convoluted tubule, decreasing plasma volume and peripheral resistance.
Hypertension
Hypertension
1-2 tablets orally every 12 hours; each tablet contains reserpine 0.1 mg, hydralazine 25 mg, hydrochlorothiazide 15 mg.
Oral: 1 tablet (hydrochlorothiazide 30 mg / methyldopa 500 mg) twice daily; maximum dose: 2 tablets twice daily.
12 hours (terminal); clinical context: twice-daily dosing maintains stable plasma levels
Terminal elimination half-life of hydrochlorothiazide is 6-15 hours; methyldopa half-life is 1.8 hours (normal renal function). In renal impairment, half-life of both components is prolonged.
Reserpine: primarily metabolized by CYP3A4; methyclothiazide: not extensively metabolized, excreted unchanged in urine.
Methyldopa is metabolized by conjugation (catechol-O-methyltransferase) and hepatic sulfation; hydrochlorothiazide is not extensively metabolized and is excreted unchanged by the kidney.
Renal (80% unchanged, 15% as glucuronide metabolite); biliary/fecal (5%)
Renal: approximately 50% as parent drug and metabolites; biliary/fecal: minimal, less than 5%.
85% bound to albumin and alpha-1-acid glycoprotein
Methyldopa: <10% bound to plasma proteins; hydrochlorothiazide: 40-68% bound to albumin.
2.5 L/kg; indicates extensive tissue distribution
Methyldopa: Vd 0.2-0.3 L/kg (distributes into tissues, crosses placenta); hydrochlorothiazide: Vd 0.75-1.5 L/kg (extensively distributed, does not cross blood-brain barrier significantly).
Oral: 60% (first-pass metabolism reduces bioavailability)
Oral bioavailability of methyldopa is approximately 25% (variable, influenced by gut metabolism); hydrochlorothiazide bioavailability is 65-75%.
Contraindicated if Cr Cl <30 m L/min. For Cr Cl 30-60 m L/min, reduce dose by 50%; avoid if possible. Monitor potassium and creatinine.
GFR 30-60 m L/min: reduce dose by 50%; GFR <30 m L/min: not recommended.
Contraindicated in severe hepatic impairment (Child-Pugh class C). For Child-Pugh class A or B, use with caution; reduce dose by 50% and monitor liver function.
Child-Pugh Class B or C: contraindicated; use not recommended.
Not recommended for children; safety and efficacy not established. Use alternative antihypertensives.
Not recommended for use in pediatric patients due to lack of safety and efficacy data.
Start at half the standard dose (0.5-1 tablet every 12 hours). Monitor for hypotension, electrolyte imbalance, and CNS effects (depression, sedation). Avoid in frail elderly.
Start with lowest dose; monitor for hypotension, electrolyte imbalance, and CNS effects; consider reduced initial dose.
No FDA black box warning.
None
Mental depression,Electrolyte imbalance (hypokalemia, hyponatremia),Orthostatic hypotension,Increased gastric acid secretion,Pancreatitis,Exacerbation of systemic lupus erythematosus
May cause hemolytic anemia, liver disorders, positive Coombs test, sedation, depression, and hypersensitivity reactions. Hydrochlorothiazide may cause electrolyte imbalance, hyperuricemia, photosensitivity, and exacerbation of systemic lupus erythematosus. Use with caution in renal impairment, hepatic disease, and in patients with a history of drug-induced hemolytic anemia.
History of mental depression (especially with suicidal tendencies),Active peptic ulcer,Ulcerative colitis,Electroshock therapy,Hypersensitivity to reserpine, methyclothiazide, or sulfonamides,Anuria
Active hepatic disease, history of previous methyldopa therapy-associated liver disorders; anuria; hypersensitivity to methyldopa, hydrochlorothiazide, or sulfonamide-derived drugs.
Avoid high-potassium foods (bananas, oranges, leafy greens) as hydrochlorothiazide can cause hypokalemia; monitor potassium levels. Use salt substitutes cautiously due to potassium content. Avoid excessive sodium intake which may counteract antihypertensive effects. Grapefruit juice may reduce methyldopa absorption; separate by 2 hours.
Food may decrease absorption of methyldopa. Avoid excessive intake of high-potassium foods (e.g., bananas, oranges) unless directed. Hydrochlorothiazide may cause potassium depletion; maintain adequate dietary potassium. Avoid natural licorice as it can worsen hypokalemia.
First trimester: Increased risk of cardiovascular and neural tube defects due to inhibition of folate-dependent enzymes. Second and third trimesters: Fetal bradycardia, oligohydramnios, intrauterine growth restriction, and neonatal hypotension. Avoid throughout pregnancy unless maternal benefit outweighs risks.
First trimester: Limited data; no clear evidence of major malformations but methyldopa crosses placenta. Second and third trimesters: Associated with reduced placental perfusion; possible fetal bradycardia and neonatal hypotension. Hydrochlorothiazide may cause fetal/neonatal jaundice, thrombocytopenia, and electrolyte disturbances.
Excreted into breast milk; M/P ratio approximately 0.8. Potential for neonatal cardiovascular effects such as bradycardia and hypotension. Caution advised; monitor infant for signs of β-blockade.
Methyldopa is excreted in breast milk in low concentrations; M/P ratio approximately 0.2. Hydrochlorothiazide is excreted in minimal amounts; may suppress lactation. Consider risks versus benefits.
Increased volume of distribution and renal clearance in pregnancy may necessitate dose escalation. Start at lowest effective dose, titrate based on blood pressure response. Monitor for hypotension and adjust accordingly.
Methyldopa: Pregnancy-induced plasma volume expansion may require dose titration; monitor blood pressure and adjust accordingly. Hydrochlorothiazide: Often avoided in pregnancy due to volume depletion risks; if used, monitor electrolytes and renal function, no pharmacokinetic data necessitate routine dose adjustment.
METATENSIN #2 is a fixed-dose combination of methyldopa and hydrochlorothiazide. Monitor for hypotension, especially during initial dosing. LFTs and CBC at baseline and periodically due to methyldopa's risk of hepatotoxicity and hemolytic anemia. Use with caution in renal impairment (Cr Cl <30 m L/min). Discontinue if jaundice occurs. Adjust dose in hepatic disease.
ALDORIL D30 combines methyldopa (central alpha-2 agonist) and hydrochlorothiazide (thiazide diuretic). Monitor for orthostatic hypotension, especially at initiation. Taper not needed for methyldopa but discontinue if fever or liver dysfunction occurs. Interferes with urinary catecholamine measurements (false elevation). Hydrochlorothiazide may cause hyponatremia, hypokalemia, and hyperglycemia; check electrolytes and glucose periodically.
Take exactly as prescribed at the same time each day.,May cause dizziness or drowsiness; avoid driving until effects are known.,Rise slowly from sitting or lying to prevent lightheadedness.,Report jaundice, fever, unexplained bruising/bleeding, or severe fatigue.,Use sun protection; hydrochlorothiazide increases photosensitivity.,Avoid alcohol, as it may worsen hypotension.,Do not stop abruptly; withdrawal can cause severe hypertension.
Take exactly as prescribed, preferably with food to reduce stomach upset.,Rise slowly from sitting or lying down to prevent dizziness.,This drug may make you drowsy; avoid driving or operating machinery until you know how it affects you.,Report fever, unexplained fatigue, jaundice, or dark urine immediately.,Weigh yourself daily and report rapid weight gain or swelling.,Limit alcohol intake as it can increase side effects.,Do not use salt substitutes containing potassium 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 METATENSIN #2 vs ALDORIL D30, answered by our medical review team.
METATENSIN #2 is a Antihypertensive Combination that works by METATENSIN #2 contains reserpine and methyclothiazide. Reserpine inhibits vesicular monoamine transporter (VMAT), depleting catecholamines from peripheral neurons. Methyclothiazide inhibits sodium-chloride symporter in distal convoluted tubule, reducing fluid volume.. ALDORIL D30 is a Antihypertensive Combination that works by Aldoril D30 is a combination of methyldopa, a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow, and hydrochlorothiazide, a thiazide diuretic that inhibits the sodium-chloride symporter in the distal convoluted tubule, decreasing plasma volume and peripheral resistance.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between METATENSIN #2 and ALDORIL D30 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 METATENSIN #2 is: 1-2 tablets orally every 12 hours; each tablet contains reserpine 0.1 mg, hydralazine 25 mg, hydrochlorothiazide 15 mg.. The standard adult dose of ALDORIL D30 is: Oral: 1 tablet (hydrochlorothiazide 30 mg / methyldopa 500 mg) twice daily; maximum dose: 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 METATENSIN #2 and ALDORIL D30 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. METATENSIN #2 is classified as Category C. First trimester: Increased risk of cardiovascular and neural tube defects due to inhibition of folate-dependent enzymes. Second and third trimesters: Fetal bradycardia, oligohydram. ALDORIL D30 is classified as Category C. First trimester: Limited data; no clear evidence of major malformations but methyldopa crosses placenta. Second and third trimesters: Associated with reduced placental perfusion; p. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.