Generic Name

Telmisartan

Mechanism

Telmisartan is a selective blocker of the angiotensin‑II type 1 (AT1) receptor.
• Competitive antagonist: It binds the AT1 receptor with high affinity, preventing angiotensin‑II from activating the receptor’s G‑protein signaling pathways.
• Resulting pharmacologic effects:
• Vasodilation → ↓ systemic vascular resistance
• Decreased aldosterone secretion → natriuresis & reduced sodium retention
• Inhibition of sympathetic activity and renin release

This blockade yields potent antihypertensive action and modest benefit in slowing progression of diabetic nephropathy.

Pharmacokinetics

• Absorption: Rapid, with peak plasma concentration (Tmax) at ~2 hrs. Oral bioavailability ~20 % (extensive first‑pass effect).
• Distribution: Highly protein‑bound (>99 % to albumin).
• Metabolism: Minimal hepatic metabolism (mostly unchanged).
• Excretion: Primarily biliary/fecal; ~30 % renal excretion.
• Half‑life: 24–45 hrs (long, allowing once‑daily dosing).
• Special Populations
• Renal impairment: Dose reduction (20 mg → 10 mg daily) recommended.
• Hepatic impairment: No dosage adjustment necessary.

Indications

• Primary:
• Essential hypertension (monotherapy or in combination).
• Adjunctive:
• Chronic heart failure (as part of triple therapy).
• Prevention of stroke and cardiovascular events in high‑risk patients.
• Management of diabetic nephropathy (slow progression of proteinuria).

Contraindications

• Contraindications
• Known hypersensitivity to telmisartan or any ARB component.
• Pregnancy (category X – risk of fetal renal dysgenesis).
• Active renal disease with serum creatinine >1.5 mg/dL (in non‑diabetic patients).
• Severe hepatic impairment (Child‑Pugh C).
• Warnings
• Hyperkalemia—especially in patients with renal insufficiency, CKD, diabetes, or those on potassium‑sparing diuretics or NSAIDs.
• Renal dysfunction—monitor serum creatinine and GFR; dose adjustment needed if decline >30 %.
• Hypotension—avoid in patients with severe hypotension or recent coronary events.

Dosing

• Start: 20 mg orally once daily (preferably in the evening).
• Maintenance: 40 mg once daily; maximum tolerated dose is 80 mg once daily.
• Titration: Increase by 20 mg increments every 4 weeks based on BP response.
• Combination: May be co‑administered with ACE inhibitors or diuretics; monitor for additive hypotensive effects.

Adverse Effects

*Note: Allergic reactions may manifest as rash, anaphylaxis. Discontinue therapy and seek urgent care if severe. *

Monitoring

• Baseline: Serum creatinine, eGFR, potassium, BP, basic metabolic panel.
• Follow‑up:
• BP: Twice weekly until stable, then monthly.
• Renal function: Every 2–4 weeks after initiation, then every 3–6 months.
• Serum potassium: Every 2–4 weeks initially, then every 3–6 months.
• Efficacy Assessment: 24‑hr ambulatory BP monitoring may be useful in resistant hypertension.

Clinical Pearls

• Longevity of action: Telmisartan’s half‑life (~24 hrs) is the longest among ARBs, supporting once‑daily dosing and stable BP control.
• Renal protection: In early diabetic nephropathy, telmisartan reduces albuminuria independent of BP lowering; ideal for high‑risk renal patients.
• Drug‑drug synergy: When paired with diuretics (especially potassium‑sparing ones), it can magnify antihypertensive effect—use caution for hyperkalemia.
• Pregnancy safety: A single‑dose exposure is sufficient to cause fetal toxicity; patients should discontinue immediately upon conception.
• Pediatric use: Not approved. Use is limited to adults; infant exposure is contraindicated due to potential for severe renal impairment.

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• *Prepared for medical students and clinicians seeking a quick reference to telmisartan's pharmacology and clinical use.*