Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ARALEN HYDROCHLORIDE 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
Chloroquine, a 4-aminoquinoline, accumulates in acidic organelles such as lysosomes and food vacuoles of malaria parasites, raising p H and inhibiting hemozoin polymerization, which leads to toxic heme accumulation and parasite death. It also has anti-inflammatory and immunomodulatory effects by inhibiting TLR signaling and cytokine production.
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.
Treatment of uncomplicated malaria due to chloroquine-sensitive Plasmodium species,Prophylaxis of malaria in areas with chloroquine-sensitive parasites,Extraintestinal amebiasis,Treatment of discoid lupus erythematosus (off-label),Treatment of rheumatoid arthritis (off-label)
Hypertension (first-line or adjunctive therapy),Off-label: Management of hypertensive crisis (as part of combination therapy)
Chloroquine phosphate 500 mg (300 mg base) orally once weekly for prophylaxis; 600 mg base (1 g phosphate) orally initially, followed by 300 mg base (500 mg phosphate) at 6, 24, and 48 hours for treatment of malaria.
250 mg orally twice daily
48-72 hours (terminal elimination half-life); prolonged to weeks with chronic dosing due to extensive tissue accumulation, especially in the liver, spleen, and melanin-containing tissues.
1.5-3 hours; prolonged in renal impairment (up to 20 hours with Cr Cl <10 m L/min).
Hepatic metabolism via CYP2C8, CYP3A4, and CYP2D6 to desethylchloroquine and other metabolites.
Methyldopa: Primarily hepatic metabolism via catecholamine pathways; conjugated to sulfate and other metabolites. Chlorothiazide: Not extensively metabolized; excreted unchanged in urine.
Renal (~70% unchanged), with 10-20% in feces; biliary elimination is minor.
Renal (70-80% unchanged), biliary/fecal (15-25% as metabolites); total clearance ~250 m L/min.
50-60%, primarily to albumin and α1-acid glycoprotein.
25-40% bound primarily to albumin and alpha-1-acid glycoprotein.
50-100 L/kg; extensive tissue sequestration including erythrocytes, liver, spleen, and melanin-containing tissues like skin and retina.
0.6-1.0 L/kg; indicates distribution into total body water and some tissue binding.
Oral: ~70-80% (variable due to first-pass metabolism); intravenous: 100%.
70-90% (oral); 100% (IV).
Severe renal impairment (GFR <10 m L/min): reduce dose by 50% or increase dosing interval.
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
Use with caution in patients with hepatic impairment; no specific dose adjustment guidelines available; contraindicated in severe hepatic disease or porphyria.
Child-Pugh A: no adjustment; Child-Pugh B: use with caution, reduce dose by 50%; Child-Pugh C: avoid use
Prophylaxis: 5 mg base/kg orally once weekly (max 300 mg base). Treatment: 10 mg base/kg orally initially, then 5 mg base/kg at 6, 24, and 48 hours (max 600 mg base total).
Not recommended for use in pediatric patients due to lack of safety and efficacy data
Start at lower end of dosing range due to increased risk of adverse effects (e.g., QT prolongation, retinal toxicity); monitor renal function.
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.
Retinopathy and irreversible retinal damage with prolonged use or high doses; requires baseline and periodic ophthalmologic exams,QT prolongation and ventricular arrhythmias, especially with concomitant QT-prolonging drugs or electrolyte abnormalities,Severe hypoglycemia including loss of consciousness,Neuropsychiatric effects including psychosis and suicidal ideation,Hemolysis in glucose-6-phosphate dehydrogenase (G6PD) deficiency
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.
Hypersensitivity to chloroquine or any 4-aminoquinoline,Pre-existing retinopathy or known maculopathy,Known G6PD deficiency (relative, use with caution),Concomitant use with strong QT-prolonging drugs (e.g., quinidine, procainamide)
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 grapefruit and grapefruit juice as they may increase drug levels and toxicity. Limit alcohol intake to reduce risk of liver toxicity. Administer with food to decrease gastrointestinal irritation. Avoid antacids containing aluminum or magnesium; separate by at least 4 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.
Chloroquine hydrochloride crosses the placenta. First trimester: associated with increased risk of spontaneous abortion and congenital abnormalities (cochleovestibular and ocular) at high doses. Second and third trimesters: possible ototoxicity and retinal toxicity; use only for malaria prophylaxis or treatment when benefit outweighs risk.
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.
Chloroquine is excreted into breast milk in low concentrations (M/P ratio approximately 0.1-0.3). Amounts are unlikely to cause adverse effects in nursing infants. The American Academy of Pediatrics considers chloroquine compatible with breastfeeding. Monitor infant for potential ocular effects.
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 clearance during pregnancy may require higher doses for malaria prophylaxis (e.g., 400 mg base weekly) and treatment; therapeutic drug monitoring recommended for optimal dosing. No standard dose adjustment established; base dose on indication and clinical response.
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.
ARALEN HYDROCHLORIDE (chloroquine hydrochloride) is used for malaria prophylaxis and treatment, and for amebiasis. Monitor for retinal toxicity with long-term use; baseline and periodic ophthalmologic exams recommended. Caution in patients with hepatic disease, G6PD deficiency, or porphyria. May exacerbate psoriasis and myasthenia gravis. QT prolongation possible; avoid with other QT-prolonging drugs. Administer with food to reduce GI upset. For acute malaria, dose may be divided to improve tolerance. In severe malaria, use parenteral form with cardiac monitoring.
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 this medication exactly as prescribed; do not skip doses for malaria prophylaxis.,If vomiting occurs within 1 hour of a dose, contact your healthcare provider for instructions.,Report any vision changes, such as blurred vision or difficulty focusing, immediately.,Avoid alcohol and limit caffeine intake as they may increase gastrointestinal side effects.,Use effective contraception during treatment if you are of childbearing potential.,Do not take antacids or kaolin within 4 hours of this medication.,Seek medical attention if you experience signs of allergic reaction: rash, hives, swelling, or difficulty breathing.
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 ARALEN HYDROCHLORIDE vs ALDOCLOR-250, answered by our medical review team.
ARALEN HYDROCHLORIDE is a Antimalarial that works by Chloroquine, a 4-aminoquinoline, accumulates in acidic organelles such as lysosomes and food vacuoles of malaria parasites, raising p H and inhibiting hemozoin polymerization, which leads to toxic heme accumulation and parasite death. It also has anti-inflammatory and immunomodulatory effects by inhibiting TLR signaling and cytokine production.. 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 ARALEN HYDROCHLORIDE 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 ARALEN HYDROCHLORIDE is: Chloroquine phosphate 500 mg (300 mg base) orally once weekly for prophylaxis; 600 mg base (1 g phosphate) orally initially, followed by 300 mg base (500 mg phosphate) at 6, 24, and 48 hours for treatment of malaria.. 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 ARALEN HYDROCHLORIDE 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. ARALEN HYDROCHLORIDE is classified as Category C. Chloroquine hydrochloride crosses the placenta. First trimester: associated with increased risk of spontaneous abortion and congenital abnormalities (cochleovestibular and ocular) . 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.