Nurses Compass
Drug Guide
Telmisartan
Classification
Therapeutic: Antihypertensive
Pharmacological: Angiotensin II Receptor Blocker (ARB)
FDA Approved Indications
- Hypertension
- Reduction of cardiovascular risk in patients unable to tolerate ACE inhibitors
Mechanism of Action
Telmisartan selectively blocks the angiotensin II type 1 (AT1) receptor, preventing vasoconstriction and aldosterone-mediated volume expansion, thus lowering blood pressure.
Dosage and Administration
Adult: Initially 40 mg once daily; can be titrated up to 80 mg once daily based on response.
Pediatric: Not indicated for pediatric use.
Geriatric: Start at lower dose if necessary; monitor renal function and potassium.
Renal Impairment: Adjust dose cautiously; renal function should be monitored.
Hepatic Impairment: Use with caution; no specific dose adjustment recommended.
Pharmacokinetics
Absorption: Well absorbed, with a bioavailability of approximately 40-42%.
Distribution: Bound to plasma proteins (~99.5%).
Metabolism: Primarily metabolized via glucuronidation; minimal CYP450 involvement.
Excretion: Excreted mainly in feces (74%) and urine (13%).
Half Life: Approximately 24 hours, allowing for once-daily dosing.
Contraindications
- Pregnancy (Category D), especially in the second and third trimesters
- History of hypersensitivity to telmisartan or other ARBs
- Concomitant use with aliskiren in patients with diabetes
Precautions
- Monitor renal function and serum potassium periodically.
- Use cautiously in patients with bilateral renal artery stenosis or a single kidney.
Adverse Reactions - Common
- Dizziness (Common)
- Back pain (Less common)
- Upper respiratory tract infection (Common)
Adverse Reactions - Serious
- Angioedema (Rare)
- Hypotension (Rare)
- Elevated serum potassium (Less common)
- Renal dysfunction (Less common)
Drug-Drug Interactions
- NSAIDs (may reduce antihypertensive effect and increase risk of renal impairment)
- Other antihypertensives (additive effect)
- Potassium-sparing diuretics and potassium supplements (risk of hyperkalemia)
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure, renal function, and serum electrolytes regularly.
Diagnoses:
- Risk for impaired kidney function related to medication use
- Risk for hypotension in patients with dehydration or volume depletion
Implementation: Administer once daily, with or without food.
Evaluation: Assess blood pressure response and monitor for adverse effects.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Do not discontinue abruptly.
- Report signs of swelling, difficulty breathing, or hyperkalemia.
- Limit salt substitutes containing potassium.
Special Considerations
Black Box Warnings:
- Pregnancy category D; contraindicated in pregnancy.
Genetic Factors: Pharmacogenetic testing not typically required.
Lab Test Interference: May increase serum potassium and serum creatinine levels.
Overdose Management
Signs/Symptoms: Severe hypotension, tachycardia, dizziness.
Treatment: Supportive care, intravenous fluids, and monitoring. No specific antidote; consider activated charcoal if ingestion was recent.
Storage and Handling
Storage: Store at room temperature, 20-25°C (68-77°F).
Stability: Stable under recommended storage conditions.