TELMISARTAN
Clinical safety rating: avoid
Contraindicated (not allowed)
Angiotensin II receptor antagonist; selectively blocks the binding of angiotensin II to AT1 receptors, leading to vasodilation, reduced aldosterone secretion, and decreased blood pressure.
| Metabolism | Primarily metabolized by glucuronidation (via UGT1A3 and UGT2B7); minor CYP2C9 metabolism; excreted mainly in feces as unchanged drug. |
| Excretion | Primarily biliary-fecal (approximately 97% unchanged in feces); renal excretion accounts for <1% of the dose. |
| Half-life | Terminal half-life is approximately 24 hours (range 20–30 hours), supporting once-daily dosing without significant accumulation. |
| Protein binding | >99.5% bound, primarily to albumin and alpha-1 acid glycoprotein. |
| Volume of Distribution | Approximately 500 L (7 L/kg for a 70 kg adult), indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is 42–58% (mean ~50%), unaffected by food. |
| Onset of Action | Oral: antihypertensive effect begins within 3 hours, with peak effect at 4–8 hours. |
| Duration of Action | Duration of antihypertensive effect is at least 24 hours, maintaining efficacy over the dosing interval with trough-to-peak ratio >80%. |
| Molecular Weight | 514.6 |
40 mg orally once daily; range 20-80 mg/day
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for GFR ≥30 mL/min. Safety/efficacy not established in GFR <30 mL/min; use not recommended. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh C). For mild-moderate (Child-Pugh A/B): maximum dose 40 mg once daily. |
| Pediatric use | Not approved for use in pediatric patients; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment required; consider lower starting dose (20 mg) due to potential greater sensitivity and decreased renal function. |
| 1st trimester | Contraindicated due to risk of teratogenicity (oligohydramnios, fetal renal dysfunction, skull ossification defects). Avoid use. |
| 2nd trimester | Contraindicated. Angiotensin II receptor antagonist: fetal renal hypoperfusion, oligohydramnios, anuria, and neonatal renal failure. |
| 3rd trimester | Contraindicated. Risk of fetal and neonatal morbidity (hypotension, renal failure, hyperkalemia). |
Clinical note
NSAIDs may diminish the antihypertensive effect Lithium levels may be increased Use in pregnancy can cause injury and death to the developing fetus.
| Placental transfer | Crosses placenta in animals; human data limited but presumed transfer due to molecular size and pharmacological effects. Documented fetal toxicity suggests significant placental passage. |
| Breastfeeding | Present in animal milk; unknown in humans. Due to potential adverse effects on infant renal function and hypotension, use during breastfeeding is not recommended. Alternative antihypertensives preferred. |
■ FDA Black Box Warning
None.
| Common Effects | Hyperkalemia |
| Serious Effects |
Pregnancy (particularly second and third trimesters)History of angioedema with ACE inhibitors or ARBsHereditary or idiopathic angioedemaConcomitant use with aliskiren in patients with diabetes
| Precautions | Fetal toxicity: Can cause fetal harm if used during pregnancy; discontinue as soon as possible., Avoid use with aliskiren in patients with diabetes or renal impairment (eGFR <60 mL/min)., May cause symptomatic hypotension, especially in volume-depleted patients., Monitor renal function and potassium levels; risk of hyperkalemia., May cause angioedema, though rare. |
| Food/Dietary | No significant food interactions. However, high-potassium foods (e.g., bananas, oranges, spinach) should be consumed in moderation to avoid hyperkalemia, especially in patients with renal impairment or those taking potassium supplements. |
Loading safety data…
| Lactation Rating | L4 |
| Teratogenic Risk | First trimester: Potential risk based on renin-angiotensin system blockade; second and third trimesters: Oligohydramnios, fetal renal dysfunction, skull ossification defects, hypotension, anuria, renal failure, and death. Angiotensin II receptor antagonists are not recommended in pregnancy. |
| Fetal Monitoring | Monitor fetal ultrasound for amniotic fluid volume and renal function; maternal blood pressure and renal function regularly; fetal heart rate monitoring if used inadvertently in later pregnancy. |
| Fertility Effects | No human data; animal studies show no impairment of fertility. Theoretical effect on renin-angiotensin system may impact sperm function; clinical significance unknown. |
| Clinical Pearls | Telmisartan is a long-acting angiotensin II receptor blocker (ARB) with a half-life of approximately 24 hours, allowing once-daily dosing. It has the strongest PPAR-γ agonist activity among ARBs, potentially improving insulin sensitivity. Avoid in pregnancy (category D) and in patients with bilateral renal artery stenosis. Monitor renal function and serum potassium periodically. |
| Patient Advice | Take once daily at the same time each day, with or without food. · Avoid salt substitutes containing potassium unless approved by your doctor. · Do not use during pregnancy; use effective contraception. · May cause dizziness; avoid driving until you know how the drug affects you. · Do not stop taking without consulting your doctor. · Report symptoms of angioedema (swelling of face, lips, tongue) immediately. |