Olmesartan Medoxomil
Olmesartan Medoxomil
Generic Name
Olmesartan Medoxomil
Mechanism
- Selective AT₁ receptor blockade – prevents angiotensin II from binding its receptor, inhibiting vasoconstriction, aldosterone secretion, and sympathetic activation.
- Pro‑drug conversion – *Olmesartan medoxomil* is hydrolyzed in the gut to the active drug Olmesartan, ensuring high systemic exposure.
- Blood pressure reduction – decreases systemic vascular resistance, leading to sustained lowering of systolic and diastolic pressure without reflex tachycardia.
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Pharmacokinetics
| Parameter | Value |
| Absorption | Oral; peak plasma concentration (Cₘₐₓ) ~4 h after a 40 mg dose |
| Bioavailability | ~23 % (after a 40 mg dose) |
| Distribution | 95 % protein‑bound |
| Metabolism | Minor hepatic metabolism (no major CYP450 involvement) |
| Elimination | Primarily renal (~95 % excreted unchanged) |
| Half‑life | ~13 h (allows once‑daily dosing) |
| Special populations | No dose adjustment needed for mild‑moderate liver impairment; renal impairment: reduce dose or discontinue if CrCl < 30 mL/min |
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Indications
- Primary (essential) hypertension – as monotherapy or with other antihypertensives.
- Diabetic nephropathy – to reduce intraglomerular pressure and preserve renal function in patients with albuminuria (type 1 or 2).
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Dosing
- Starting dose: 20 mg PO once daily.
- Titration: increase by 20 mg to a maximum of 40 mg daily.
- Maximum recommended dose: 40 mg/day for hypertension and 40 mg/day for renal protection.
- Form: tablets taken with or without food; ingestion with a full glass of water is preferred.
- Adjustment: reduce to 20 mg/day in patients with CrCl 15–30 mL/min; discontinue if CrCl ≤15 mL/min.
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Adverse Effects
- Common
- Dizziness, fatigue, syncope (especially post‑ural).
- Headache, dry cough (rare).
- Upper‑respiratory‑tract infections.
- Serious
- Severe hypotension (rare).
- Acute renal failure or worsening chronic renal disease.
- Hyperkalemia (serum K⁺ > 6 mmol/L).
- Angioedema (extremely rare).
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Monitoring
- Blood pressure – every visit until stable.
- Serum creatinine & eGFR – at baseline, 1 month, then every 3–6 months.
- Serum potassium – initially, then every 3–6 months.
- Liver function tests – if hepatic impairment suspected.
- Renal ultrasound – if renal artery stenosis suspected.
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Clinical Pearls
- Pro‑drug advantage: Olmesartan medoxomil offers superior oral bioavailability versus some other ARBs, making it preferable when maximal BP control is essential.
- Potassium caution: Avoid combining with potassium‑sparing diuretics (e.g., spironolactone, amiloride) unless serum potassium is strictly monitored.
- Diabetic patients: When used for diabetic nephropathy, pair with ACE inhibitors only after confirming no hyperkalemia and normal renal parameters.
- Elderly therapy: Start at the lowest dose (20 mg) as they are more prone to orthostatic hypotension and drug accumulation.
- Pregnancy screening: Always confirm pregnancy status before prescribing; a single dose during pregnancy can result in fetal renal dysgenesis.
- Drug interactions: Minimal CYP interactions; however, concomitant NSAID use may blunt antihypertensive effect and elevate creatinine.
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