Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
HYDRA-ZIDE 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
Hydra-Zide is a combination of hydrochlorothiazide (thiazide diuretic) and hydralazine (direct vasodilator). Hydrochlorothiazide inhibits the sodium-chloride symporter in the distal convoluted tubule, reducing electrolyte reabsorption and increasing urine output. Hydralazine relaxes arteriolar smooth muscle, decreasing systemic vascular resistance and afterload.
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.
Treatment of hypertension
Hypertension
Oral, 1 tablet (25 mg hydrochlorothiazide / 50 mg hydralazine) twice daily, titrated up to maximum of 2 tablets twice daily based on blood pressure response.
Oral: 1 tablet (hydrochlorothiazide 30 mg / methyldopa 500 mg) twice daily; maximum dose: 2 tablets twice daily.
Hydralazine: 2-4 hours (fast acetylators), 4-8 hours (slow acetylators); thiazide: 6-15 hours.
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.
Hydrochlorothiazide is not extensively metabolized; eliminated unchanged primarily by renal tubular secretion. Hydralazine undergoes extensive hepatic metabolism via acetylation (N-acetyltransferase) and hydroxylation, with glucuronidation and sulfation.
Methyldopa is metabolized by conjugation (catechol-O-methyltransferase) and hepatic sulfation; hydrochlorothiazide is not extensively metabolized and is excreted unchanged by the kidney.
Renal: 50-70% of hydralazine as metabolites, 30-40% as parent drug; thiazide: 95% renal as unchanged drug.
Renal: approximately 50% as parent drug and metabolites; biliary/fecal: minimal, less than 5%.
Hydralazine: 85-90% bound to albumin; thiazide: 40-70% bound to albumin.
Methyldopa: <10% bound to plasma proteins; hydrochlorothiazide: 40-68% bound to albumin.
Hydralazine: 1.5-2.5 L/kg (distributes extensively into tissues); thiazide: 0.2-0.5 L/kg (primarily extracellular fluid).
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).
Hydralazine: 30-50% (oral, variable due to first-pass metabolism); thiazide: 60-80% (oral).
Oral bioavailability of methyldopa is approximately 25% (variable, influenced by gut metabolism); hydrochlorothiazide bioavailability is 65-75%.
GFR >30 m L/min: No adjustment. GFR 10-30 m L/min: Use with caution, consider reducing dose (e.g., 1 tablet once daily) or extending interval; avoid if possible. GFR <10 m L/min: Not recommended due to thiazide ineffectiveness.
GFR 30-60 m L/min: reduce dose by 50%; GFR <30 m L/min: not recommended.
Child-Pugh A: No adjustment. Child-Pugh B: Consider 50% dose reduction (e.g., 1 tablet once daily) and monitor liver function. Child-Pugh C: Contraindicated due to risk of hepatic encephalopathy and hydralazine accumulation.
Child-Pugh Class B or C: contraindicated; use not recommended.
Not approved for pediatric use; safety and efficacy not established. Alternative antihypertensives preferred.
Not recommended for use in pediatric patients due to lack of safety and efficacy data.
Start at 0.5 tablet (12.5 mg hydrochlorothiazide / 25 mg hydralazine) once or twice daily; titrate slowly. Monitor for hypotension, electrolyte disturbances, and renal function. Maximum dose 2 tablets daily.
Start with lowest dose; monitor for hypotension, electrolyte imbalance, and CNS effects; consider reduced initial dose.
There is no FDA black box warning for Hydra-Zide.
None
May cause a lupus-like syndrome, especially in slow acetylators; discontinue if symptoms appear.,Risk of hypotension, especially with high doses or volume depletion.,Can cause electrolyte imbalances (hypokalemia, hyponatremia, hypercalcemia), monitor serum electrolytes.,May exacerbate renal impairment; use with caution in renal disease.,Possible hypersensitivity reactions including rash, urticaria, and angioedema.
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.
Anuria,Hypersensitivity to hydrochlorothiazide, hydralazine, or sulfonamide-derived drugs,Severe renal impairment (Cr Cl <30 m L/min),Use with MAO inhibitors (monoamine oxidase inhibitors),Pregnancy (especially second and third trimester) due to hydralazine
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, tomatoes, spinach, salt substitutes) unless directed. Take with food to reduce gastrointestinal upset. Grapefruit juice may increase drug levels; avoid consumption.
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: Hydralazine (component of HYDRA-ZIDE) not associated with major malformations; thiazide diuretics (hydrochlorothiazide) have equivocal risk, some studies suggest increased risk of congenital anomalies, but confounded by underlying disease. Second and third trimesters: Thiazides may cause fetal/neonatal electrolyte disturbances, thrombocytopenia, and jaundice; hydralazine may cause neonatal lupus-like syndrome, thrombocytopenia, and hypotension. Use only if clearly needed.
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.
Hydralazine and hydrochlorothiazide are excreted into breast milk in low amounts. M/P ratio not established. Hydrochlorothiazide may suppress lactation and cause neonatal electrolyte disturbances. Caution advised; monitor infant for jaundice, electrolyte imbalance, and dehydration.
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.
Pregnancy-induced increased plasma volume and renal clearance may necessitate dose escalation. Start at lowest effective dose; titrate to blood pressure control. Hydrochlorothiazide is generally avoided as a first-line agent due to volume depletion risks. Hydralazine often used as add-on therapy; dose adjustments based on clinical response.
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.
Monitor serum potassium and creatinine before initiation and periodically; hypokalemia common early, but may cause hyperkalemia in renal impairment. Avoid use in pregnancy (category D). Titrate dose slowly to minimize orthostatic hypotension. Add-on therapy often requires lower doses of each component.
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; do not skip doses or stop without consulting your doctor.,This drug contains two medicines; your doctor may adjust other medications accordingly.,Stand up slowly to prevent dizziness or fainting.,Report symptoms of electrolyte imbalance: muscle cramps, weakness, irregular heartbeat, or excessive thirst.,Avoid alcohol and NSAIDs (ibuprofen, naproxen) unless approved by your doctor.
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 HYDRA-ZIDE vs ALDORIL D30, answered by our medical review team.
HYDRA-ZIDE is a Antihypertensive Combination that works by Hydra-Zide is a combination of hydrochlorothiazide (thiazide diuretic) and hydralazine (direct vasodilator). Hydrochlorothiazide inhibits the sodium-chloride symporter in the distal convoluted tubule, reducing electrolyte reabsorption and increasing urine output. Hydralazine relaxes arteriolar smooth muscle, decreasing systemic vascular resistance and afterload.. 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 HYDRA-ZIDE 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 HYDRA-ZIDE is: Oral, 1 tablet (25 mg hydrochlorothiazide / 50 mg hydralazine) twice daily, titrated up to maximum of 2 tablets twice daily based on blood pressure response.. 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 HYDRA-ZIDE 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. HYDRA-ZIDE is classified as Category C. First trimester: Hydralazine (component of HYDRA-ZIDE) not associated with major malformations; thiazide diuretics (hydrochlorothiazide) have equivocal risk, some studies suggest i. 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.