Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
AZOR vs ALDORIL 25
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Amlodipine is a dihydropyridine calcium channel blocker that inhibits calcium ion influx across cardiac and vascular smooth muscle cells, causing vasodilation and reduced peripheral vascular resistance. Olmesartan is an angiotensin II receptor blocker (ARB) that selectively blocks AT1 receptors, inhibiting vasoconstriction and aldosterone secretion.
Combination of methyldopa, a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow, and hydrochlorothiazide, a thiazide diuretic that inhibits sodium reabsorption in the distal convoluted tubule, reducing plasma volume.
Treatment of hypertension, alone or with other antihypertensive agents
Hypertension
AZOR is a combination of amlodipine and olmesartan. Typical adult dose: one tablet orally once daily. Available strengths: amlodipine/olmesartan 5mg/20mg, 5mg/40mg, 10mg/20mg, 10mg/40mg. Dose can be titrated based on blood pressure response.
Oral: 1 tablet (hydrochlorothiazide 25 mg/methyldopa 250 mg) twice daily; increase as needed to max 2 tablets twice daily.
Amlodipine: 30-50 h (terminal); supports once-daily dosing. Olmesartan: 10-15 h (terminal); once-daily dosing effective
7-16 hours (terminal). In renal impairment, half-life may exceed 24 hours, requiring dose adjustment.
Amlodipine is extensively metabolized in the liver via CYP3A4 to inactive metabolites. Olmesartan is metabolized by the liver to a minor extent; it undergoes glucuronidation and some oxidation by CYP2C9.
Methyldopa is metabolized primarily via hepatic conjugation and renal excretion; hydrochlorothiazide is not significantly metabolized and is excreted unchanged in urine.
Renal: 90% (amlodipine: 60% as metabolites, 10% as parent; olmesartan: 35-50% as parent via urine, rest in feces via bile). Fecal: 10%
Renal: ~85% unchanged. Biliary/fecal: ~15% as metabolites.
Amlodipine: ~93% bound to plasma proteins. Olmesartan: >99% bound to albumin
Methyldopa: less than 10% bound to plasma proteins. Hydrochlorothiazide: ~70% bound to plasma proteins (primarily albumin).
Amlodipine: 21 L/kg (large, extensive tissue distribution). Olmesartan: 17-30 L (approximate, Vd not typically reported per kg); distribution into tissues
Methyldopa: 0.3-0.6 L/kg (distributes widely, including CNS). Hydrochlorothiazide: 0.8-1.5 L/kg (distributes into extracellular fluid).
Oral: amlodipine 64-90% (high, first-pass ~10%); olmesartan 26% (oral, complete absorption reduced by first-pass ester hydrolysis)
Methyldopa: oral bioavailability ~25% (first-pass metabolism). Hydrochlorothiazide: oral bioavailability ~60-80%.
No dose adjustment is required for mild to moderate renal impairment (Cr Cl ≥30 m L/min). For severe renal impairment (Cr Cl <30 m L/min), use with caution; maximum dose of olmesartan is 20 mg once daily. Monitor serum potassium and creatinine.
GFR 30-50 m L/min: use with caution, reduce dose. GFR <30 m L/min: not recommended.
No dose adjustment for mild hepatic impairment (Child-Pugh A). For moderate to severe hepatic impairment (Child-Pugh B or C), amlodipine half-life is prolonged; initiate with amlodipine 2.5 mg and olmesartan 10 mg, and titrate slowly. Use caution; contraindicated in severe hepatic impairment with cholestasis? Not specifically contraindicated but not recommended.
Child-Pugh A: no adjustment; Child-Pugh B or C: contraindicated due to methyldopa hepatotoxicity risk.
Safety and efficacy in pediatric patients <18 years have not been established. Not recommended for use in children.
Not established; avoid use in children.
In elderly patients (≥65 years), start with the lowest available dose (amlodipine/olmesartan 5/20 mg daily) and titrate slowly due to increased sensitivity and potential for hypotension. Monitor renal function and electrolytes closely in geriatric patients.
Start at lowest dose (1 tablet daily); monitor for orthostatic hypotension, sedation, and electrolyte imbalance.
None
None
Fetal toxicity (detectable in second and third trimesters): drugs acting on the renin-angiotensin system can cause oligohydramnios, fetal renal dysfunction, and death,Avoid concomitant use with aliskiren in patients with diabetes,Hypotension in volume/depleted patients,Increased angina or myocardial infarction with calcium channel blockers, particularly with severe obstructive coronary artery disease,Peripheral edema is dose-dependent and more common with amlodipine,Hepatic impairment: lower starting dose,Renal artery stenosis,Electrolyte imbalances
May cause sedation, depression, positive direct Coombs test, hemolytic anemia, hepatotoxicity, fluid/electrolyte imbalance, and sensitivity reactions; monitor liver function, CBC, and electrolytes.
Hypersensitivity to any component,Do not use with aliskiren in patients with diabetes
Hypersensitivity to methyldopa, hydrochlorothiazide, or sulfonamides; active hepatic disease; anuria; history of methyldopa-induced liver disorders.
Avoid grapefruit and grapefruit juice due to CYP3A4 inhibition increasing amlodipine levels. No other significant food interactions.
Avoid high-sodium foods to optimize antihypertensive effect. Limit alcohol intake. Do not consume large amounts of potassium-rich foods (e.g., bananas, oranges, spinach) unless advised by a healthcare provider, as hydrochlorothiazide can alter potassium levels.
Pregnancy Category D. First trimester: Potential for fetal toxicity (oligohydramnios, fetal/neonatal renal dysfunction, skull hypoplasia) due to olmesartan action on renin-angiotensin system; avoid use. Second trimester: Continued risk of fetal renal impairment and oligohydramnios. Third trimester: High risk of fetal/neonatal renal failure, hypotension, hyperkalemia, and skull ossification defects; contraindicated.
First trimester: Limited human data, but animal studies show no teratogenicity at therapeutic doses. Second and third trimesters: Associated with fetal hypotension, oligohydramnios, and renal dysfunction due to methyldopa component. Hydrochlorothiazide may cause fetal electrolyte imbalances.
No human data on olmesartan or amlodipine excretion in breast milk. Amlodipine transfers into human milk with M/P ratio approximately 0.5-1.5; risk to infant unknown. Due to potential for adverse effects (hypotension, renal impairment), use is not recommended. Alternative antihypertensives with more safety data should be considered.
Methyldopa is excreted in breast milk with M/P ratio of approximately 0.2-0.5; hydrochlorothiazide M/P ratio ~0.5-0.6. Considered compatible with breastfeeding by AAP, but monitor infant for hypotension and electrolyte disturbances.
Not applicable; use is contraindicated in pregnancy. No dose adjustment can mitigate fetal risk; alternative agents (e.g., labetalol, nifedipine) are preferred. If inadvertently used, discontinue as soon as pregnancy is detected.
No standard dose adjustment required, but increased plasma volume in pregnancy may necessitate higher doses of methyldopa. Monitor clinical response and adjust accordingly.
AZOR is a fixed-dose combination of amlodipine (calcium channel blocker) and olmesartan (angiotensin II receptor blocker). Monitor serum potassium and creatinine, especially in renal impairment or concomitant ACE inhibitor use. Avoid in pregnancy (use effective contraception). May cause dizziness or peripheral edema, often dose-related.
ALDORIL 25 is a fixed-dose combination of methyldopa (250 mg) and hydrochlorothiazide (25 mg). Monitor for hypotension, especially during initial therapy or with volume depletion. Methyldopa may cause a positive direct Coombs test and hemolytic anemia; discontinue if anemia develops. Hydrochlorothiazide can cause electrolyte imbalances, hyperglycemia, and hyperuricemia. Avoid use in patients with pheochromocytoma or active liver disease.
Take exactly as prescribed, usually once daily, with or without food.,Avoid grapefruit or grapefruit juice as it can increase amlodipine levels.,Notify your doctor if you become pregnant or plan to become pregnant.,Do not stop taking suddenly; consult your doctor before discontinuing.,Report lightheadedness, fainting, or significant swelling in your ankles or feet.,Use caution when driving or operating machinery until you know how this medication affects you.
Take this medication exactly as prescribed, usually once or twice daily.,Rise slowly from sitting or lying to prevent dizziness from low blood pressure.,Avoid alcohol, which can increase dizziness and drowsiness.,Report any signs of infection, unusual tiredness, or yellowing of skin/eyes.,Use sun protection as hydrochlorothiazide may increase sun sensitivity.,Do not use potassium supplements or salt substitutes 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 AZOR vs ALDORIL 25, answered by our medical review team.
AZOR is a Antihypertensive Combination that works by Amlodipine is a dihydropyridine calcium channel blocker that inhibits calcium ion influx across cardiac and vascular smooth muscle cells, causing vasodilation and reduced peripheral vascular resistance. Olmesartan is an angiotensin II receptor blocker (ARB) that selectively blocks AT1 receptors, inhibiting vasoconstriction and aldosterone secretion.. ALDORIL 25 is a Antihypertensive Combination that works by Combination of methyldopa, a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow, and hydrochlorothiazide, a thiazide diuretic that inhibits sodium reabsorption in the distal convoluted tubule, reducing plasma volume.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between AZOR and ALDORIL 25 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 AZOR is: AZOR is a combination of amlodipine and olmesartan. Typical adult dose: one tablet orally once daily. Available strengths: amlodipine/olmesartan 5mg/20mg, 5mg/40mg, 10mg/20mg, 10mg/40mg. Dose can be titrated based on blood pressure response.. The standard adult dose of ALDORIL 25 is: Oral: 1 tablet (hydrochlorothiazide 25 mg/methyldopa 250 mg) twice daily; increase as needed to max 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 AZOR and ALDORIL 25 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. AZOR is classified as Category C. Pregnancy Category D. First trimester: Potential for fetal toxicity (oligohydramnios, fetal/neonatal renal dysfunction, skull hypoplasia) due to olmesartan action on renin-angioten. ALDORIL 25 is classified as Category C. First trimester: Limited human data, but animal studies show no teratogenicity at therapeutic doses. Second and third trimesters: Associated with fetal hypotension, oligohydramnios. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.