Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
METATENSIN #2 vs ALDOCLOR-250
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.
Aldoclor-250 is a combination of methyldopa and chlorothiazide. Methyldopa is a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow from the brain, decreasing peripheral vascular resistance and blood pressure. Chlorothiazide is a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule, increasing urinary output and reducing plasma volume.
Hypertension
Hypertension (first-line or adjunctive therapy),Off-label: Management of hypertensive crisis (as part of combination therapy)
1-2 tablets orally every 12 hours; each tablet contains reserpine 0.1 mg, hydralazine 25 mg, hydrochlorothiazide 15 mg.
250 mg orally twice daily
12 hours (terminal); clinical context: twice-daily dosing maintains stable plasma levels
1.5-3 hours; prolonged in renal impairment (up to 20 hours with Cr Cl <10 m L/min).
Reserpine: primarily metabolized by CYP3A4; methyclothiazide: not extensively metabolized, excreted unchanged in urine.
Methyldopa: Primarily hepatic metabolism via catecholamine pathways; conjugated to sulfate and other metabolites. Chlorothiazide: Not extensively metabolized; excreted unchanged in urine.
Renal (80% unchanged, 15% as glucuronide metabolite); biliary/fecal (5%)
Renal (70-80% unchanged), biliary/fecal (15-25% as metabolites); total clearance ~250 m L/min.
85% bound to albumin and alpha-1-acid glycoprotein
25-40% bound primarily to albumin and alpha-1-acid glycoprotein.
2.5 L/kg; indicates extensive tissue distribution
0.6-1.0 L/kg; indicates distribution into total body water and some tissue binding.
Oral: 60% (first-pass metabolism reduces bioavailability)
70-90% (oral); 100% (IV).
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.
Cr Cl >50 m L/min: no adjustment; Cr Cl 10-50 m L/min: 250 mg once daily; Cr Cl <10 m L/min: 250 mg every 48 hours
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 A: no adjustment; Child-Pugh B: use with caution, reduce dose by 50%; Child-Pugh C: avoid use
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 at lower end of dosing range; monitor renal function closely; adjust dose based on Cr Cl
No FDA black box warning.
None explicitly listed. However, methyldopa carries a warning for hepatotoxicity and hemolytic anemia; chlorothiazide carries a warning for electrolyte disturbances and hypersensitivity reactions.
Mental depression,Electrolyte imbalance (hypokalemia, hyponatremia),Orthostatic hypotension,Increased gastric acid secretion,Pancreatitis,Exacerbation of systemic lupus erythematosus
Hepatotoxicity (methyldopa), hemolytic anemia, positive direct Coombs test, sedation, depression, bradycardia, orthostatic hypotension, electrolyte imbalance (hypokalemia, hyponatremia, hypomagnesemia), hyperuricemia, hyperglycemia, photosensitivity, lupus-like syndrome, and hypersensitivity reactions.
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-induced liver dysfunction, hemolytic anemia associated with methyldopa, anuria, hypersensitivity to methyldopa, chlorothiazide, or sulfonamide-derived drugs, severe renal impairment (Cr Cl <30 m L/min), and concomitant therapy with MAO inhibitors.
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.
Avoid high-potassium foods (bananas, oranges, spinach) unless specifically advised; chlorothiazide may cause potassium loss, but methyldopa can cause potassium retention. Avoid excessive alcohol intake as it may potentiate hypotension. Take with food to reduce gastrointestinal upset. May decrease glucose tolerance; monitor in diabetic patients.
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.
FDA Pregnancy Category D. First trimester: Associated with cardiovascular defects (e.g., VSD), neural tube defects, and oral clefts. Second and third trimesters: Fetal nephrotoxicity (oligohydramnios, renal failure), premature closure of ductus arteriosus, pulmonary hypertension, and intracranial hemorrhage. Avoid in third trimester.
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.
Chlorothiazide is excreted in breast milk; M/P ratio unknown. Can suppress lactation. Use only if maternal benefit outweighs potential infant risks (e.g., electrolyte disturbances, thrombocytopenia).
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.
Increased volume of distribution and GFR in pregnancy may necessitate higher doses for equivalent effect. Start at lowest effective dose; titrate based on BP response. Monitor for hypokalemia and metabolic alkalosis.
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.
Aldoclor-250 is a combination of methyldopa (250mg) and chlorothiazide. Methyldopa can cause a positive direct Coombs test (10-20% of patients) which may interfere with blood cross-matching; obtain a hematocrit and Coombs test before therapy and at 6 and 12 months. Chlorothiazide may cause hypokalemia; monitor potassium and consider potassium supplementation. Onset of methyldopa is 3-6 hours; delay full effect for 48-72 hours. Avoid use in patients with active liver disease or history of previous methyldopa-induced liver dysfunction.
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; do not skip doses or stop suddenly.,May cause drowsiness or dizziness; avoid driving or operating machinery until you know how it affects you.,Rise slowly from sitting or lying to prevent lightheadedness.,Report any unexplained fever, jaundice, or dark urine immediately.,Use sun protection; this drug may increase sensitivity to sunlight.,Do not use potassium supplements or salt substitutes without consulting your doctor.,If you miss a dose, take it as soon as you remember unless it's near the next dose; do not double.
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 ALDOCLOR-250, 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.. ALDOCLOR-250 is a Antihypertensive Combination (Central Alpha Agonist and Thiazide Diuretic) that works by Aldoclor-250 is a combination of methyldopa and chlorothiazide. Methyldopa is a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow from the brain, decreasing peripheral vascular resistance and blood pressure. Chlorothiazide is a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule, increasing urinary output and reducing plasma volume.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between METATENSIN #2 and ALDOCLOR-250 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 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 ALDOCLOR-250 is: 250 mg orally 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 ALDOCLOR-250 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. ALDOCLOR-250 is classified as Category C. FDA Pregnancy Category D. First trimester: Associated with cardiovascular defects (e.g., VSD), neural tube defects, and oral clefts. Second and third trimesters: Fetal nephrotoxici. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.