Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
APRESAZIDE vs ALDOCLOR-150
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Apresazide is a combination of hydralazine, a direct-acting vasodilator that relaxes arteriolar smooth muscle, and hydrochlorothiazide, a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule.
Aldoclor-150 is a combination of methyldopa and chlorothiazide. Methyldopa is a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow, decreasing peripheral vascular resistance and blood pressure. Chlorothiazide is a thiazide diuretic that inhibits sodium reabsorption in the distal convoluted tubule, leading to increased excretion of sodium and water, reducing plasma volume and blood pressure.
Hypertension
Hypertension
1 capsule (hydralazine 25 mg / hydrochlorothiazide 25 mg) orally twice daily; may increase to 2 capsules twice daily if needed. Maximum: 4 capsules daily.
ALDOCLOR-150 is a combination product containing 150 mcg of clonidine and 25 mg of chlorthalidone. The typical adult dose is one tablet orally once daily.
Hydralazine: 2-4 hours (fast acetylators), 4-8 hours (slow acetylators); Hydrochlorothiazide: 6-15 hours. Clinical context: Dosing interval typically 12 hours for hydralazine component.
Terminal elimination half-life is approximately 6-8 hours in patients with normal renal function. In patients with creatinine clearance <30 m L/min, half-life may be prolonged to 15-20 hours, necessitating dose adjustment.
Hydralazine: primarily hepatic acetylation by N-acetyltransferase; Hydrochlorothiazide: not extensively metabolized, eliminated renally.
Methyldopa is metabolized primarily via conjugation and decarboxylation; chlorothiazide is not extensively metabolized and is excreted unchanged in urine.
Hydralazine: ~75% renal (metabolites), <10% unchanged; Hydrochlorothiazide: >95% renal (unchanged).
Renal excretion of unchanged drug accounts for approximately 50-60% of the administered dose; hepatic metabolism contributes the remainder, with metabolites excreted via bile and feces. Less than 2% is excreted unchanged in feces.
Hydralazine: 85-90% (plasma proteins); Hydrochlorothiazide: 40-68% (albumin).
Approximately 70-80% bound to plasma proteins, primarily albumin.
Hydralazine: 1.5 L/kg; Hydrochlorothiazide: 3-4 L/kg. Clinical meaning: Hydralazine distributes widely; Hydrochlorothiazide distributes into extracellular fluid.
Vd is approximately 0.3-0.5 L/kg, indicating distribution primarily in extracellular fluid and limited tissue binding.
Hydralazine: 26-50% (oral, first-pass metabolism); Hydrochlorothiazide: 65-70% (oral).
Oral bioavailability is approximately 70-80%; food does not significantly alter absorption.
Contraindicated in anuria. For GFR 30-50 m L/min: reduce dose to 1 capsule daily. For GFR <30 m L/min: avoid use due to thiazide inefficacy.
Contraindicated in patients with GFR <30 m L/min. For GFR 30-50 m L/min, reduce frequency to every other day. For GFR >50 m L/min, no adjustment necessary.
Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50% (start with 1 capsule daily). Child-Pugh C: contraindicated.
Child-Pugh Class A: No adjustment necessary. Child-Pugh Class B: Reduce dose by 50% or extend dosing interval. Child-Pugh Class C: Use is not recommended due to risk of hepatic encephalopathy and fluid retention.
Weight-based: hydralazine 0.75-1 mg/kg/dose every 6-12 hours (max 50 mg/dose); hydrochlorothiazide 1-2 mg/kg/day divided every 12 hours. Combination not recommended; adjust individual components.
Not recommended for pediatric use due to lack of safety and efficacy data in patients under 18 years of age.
Start with 1 capsule daily; titrate slowly due to increased risk of hypotension and electrolyte imbalance. Monitor renal function and serum potassium.
Initiate at lower dose (e.g., half tablet) due to increased sensitivity to antihypertensive effects, risk of orthostatic hypotension, and impaired renal function. Monitor blood pressure and electrolytes closely.
None
None.
May cause drug-induced lupus erythematosus (hydralazine),Peripheral neuritis (hydralazine),Electrolyte imbalances (hypokalemia, hyponatremia) due to hydrochlorothiazide,Sulfonamide hypersensitivity cross-reaction,Exacerbation or activation of systemic lupus erythematosus,Possible myocardial infarction or angina pectoris in patients with coronary artery disease
May cause sedation, dizziness, and orthostatic hypotension. Avoid abrupt discontinuation. Use with caution in patients with impaired renal function, liver disease, or history of depression. Monitor for electrolyte imbalance, especially hypokalemia, due to chlorothiazide component.,Methyldopa may cause positive direct Coombs test, hemolytic anemia, and liver disorders. Discontinue if jaundice or liver abnormalities occur.
Hypersensitivity to hydralazine, hydrochlorothiazide, or sulfonamides,Anuria,Acute myocardial infarction,Dissecting aortic aneurysm,Severe renal impairment (creatinine clearance <30 m L/min)
Hypersensitivity to methyldopa, chlorothiazide, or sulfonamide-derived drugs.,Active liver disease or previous methyldopa-induced liver disorders.,Anuria or severe renal impairment (creatinine clearance <30 m L/min).
Avoid high-potassium foods if potassium-sparing effect is not desired (but hydrochlorothiazide causes potassium loss; monitor accordingly). Take with food to reduce GI upset. Avoid natural licorice as it may enhance potassium loss and worsen hypertension.
Avoid excessive potassium-rich foods (bananas, oranges, spinach) unless directed, as thiazide can cause potassium loss; however, monitor for hypokalemia. Limit sodium intake to enhance antihypertensive effect. Methyldopa absorption is not significantly affected by food.
Apresazide is a fixed-dose combination of hydralazine and hydrochlorothiazide. Hydralazine: First trimester: limited data, no clear evidence of major malformations; second and third trimesters: risk of neonatal thrombocytopenia, lupus-like syndrome, and hypotension. Hydrochlorothiazide: First trimester: possible association with neural tube defects and oral clefts (weak); second and third trimesters: fetal or neonatal jaundice, thrombocytopenia, electrolyte imbalance, and possible growth restriction. Overall, use only if benefit outweighs risk.
First trimester: Increased risk of neural tube defects (spina bifida) and other major congenital malformations (e.g., cardiovascular, orofacial clefts) due to folate antagonism. Second and third trimesters: Risk of intrauterine growth restriction (IUGR), oligohydramnios, and renal dysplasia. Neonatal: Folate deficiency, megaloblastic anemia, and potential for methotrexate-like toxicity if used near term.
Hydralazine: excreted in breast milk in low amounts; M/P ratio not well established; considered compatible with caution. Hydrochlorothiazide: excreted in breast milk; may suppress lactation; risk of neonatal electrolyte disturbances. Avoid use during breastfeeding, especially with high doses.
Pyrimethamine (component of ALDOCLOR-150) is excreted into breast milk in small amounts; the M/P ratio is not well established. Sulfadoxine (component) is also excreted. Theoretical risk of kernicterus in jaundiced infants due to sulfonamide displacement of bilirubin. Use with caution, especially in preterm or G6PD-deficient infants. The benefits of breastfeeding should outweigh potential risks; alternative antimalarials are preferred.
Hydralazine: dose may need downward adjustment in later pregnancy due to altered volume of distribution and increased clearance. Hydrochlorothiazide: avoid use in pregnancy; consider alternative diuretics. If used, dose adjustment not well defined but start at lowest effective dose. No standard pharmacokinetic-based adjustments.
No standard dose adjustment required, but consider increased folic acid supplementation (5 mg daily) to reduce teratogenic risk. Due to increased glomerular filtration rate (GFR) in pregnancy, renal clearance may be enhanced; however, ALDOCLOR-150 is typically used as a single dose and pharmacokinetic data do not support routine dose adjustment. Individualize based on clinical response and toxicity monitoring.
Combination product of hydralazine and hydrochlorothiazide. Monitor for lupus-like syndrome (especially with high hydralazine doses). Check electrolytes and renal function regularly. Use with caution in patients with coronary artery disease or high-output heart failure.
ALDOCLOR-150 combines chlorothiazide (a thiazide diuretic) and methyldopa (a central alpha-2 agonist). Monitor for hypokalemia and hyponatremia due to thiazide; methyldopa may cause positive Coombs test (hemolytic anemia risk) and hepatotoxicity. Titrate methyldopa slowly to avoid sedation. Use with caution in renal impairment (Cr Cl <30 m L/min reduces thiazide efficacy).
Take exactly as prescribed, do not skip doses.,May cause dizziness or faintness, especially when rising from sitting or lying position.,Avoid sudden discontinuation; taper under medical supervision.,Report symptoms like joint pain, fever, chest pain, or rash immediately.,Limit alcohol intake as it can exacerbate hypotension.
Take medication exactly as prescribed, usually once or twice daily.,May cause dizziness or drowsiness; avoid driving until effects are known.,Stand up slowly to prevent falls from low blood pressure.,Report unexplained fever, fatigue, or jaundice (signs of liver issues).,Avoid alcohol, which enhances sedative effects.,Do not stop abruptly (risk of rebound hypertension).
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 APRESAZIDE vs ALDOCLOR-150, answered by our medical review team.
APRESAZIDE is a Antihypertensive that works by Apresazide is a combination of hydralazine, a direct-acting vasodilator that relaxes arteriolar smooth muscle, and hydrochlorothiazide, a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule.. ALDOCLOR-150 is a Antihypertensive Combination (Central Alpha Agonist and Thiazide Diuretic) that works by Aldoclor-150 is a combination of methyldopa and chlorothiazide. Methyldopa is a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow, decreasing peripheral vascular resistance and blood pressure. Chlorothiazide is a thiazide diuretic that inhibits sodium reabsorption in the distal convoluted tubule, leading to increased excretion of sodium and water, reducing plasma volume and blood pressure.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between APRESAZIDE and ALDOCLOR-150 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 APRESAZIDE is: 1 capsule (hydralazine 25 mg / hydrochlorothiazide 25 mg) orally twice daily; may increase to 2 capsules twice daily if needed. Maximum: 4 capsules daily.. The standard adult dose of ALDOCLOR-150 is: ALDOCLOR-150 is a combination product containing 150 mcg of clonidine and 25 mg of chlorthalidone. The typical adult dose is one tablet orally once 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 APRESAZIDE and ALDOCLOR-150 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. APRESAZIDE is classified as Category C. Apresazide is a fixed-dose combination of hydralazine and hydrochlorothiazide. Hydralazine: First trimester: limited data, no clear evidence of major malformations; second and thir. ALDOCLOR-150 is classified as Category C. First trimester: Increased risk of neural tube defects (spina bifida) and other major congenital malformations (e.g., cardiovascular, orofacial clefts) due to folate antagonism. Se. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.