TWYNSTA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TWYNSTA (TWYNSTA).
Twynsta (telmisartan/amlodipine) is a combination of an angiotensin II receptor blocker (ARB) and a dihydropyridine calcium channel blocker (CCB). Telmisartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively antagonizing AT1 receptors, reducing peripheral resistance. Amlodipine inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle, causing vasodilation and reduced blood pressure.
| Metabolism | Telmisartan is primarily metabolized by glucuronidation via UGT1A3 and to a lesser extent by CYP2C9. Amlodipine is extensively metabolized by CYP3A4 to inactive metabolites. |
| Excretion | Telmisartan: predominantly biliary/fecal (≥97% unchanged), renal <1%. Amlodipine: renal (60% as metabolites), fecal (20-25%). |
| Half-life | Telmisartan: terminal half-life ~24 h (allows once-daily dosing). Amlodipine: terminal half-life 30-50 h (provides smooth 24-h coverage). |
| Protein binding | Telmisartan: >99.5% bound to albumin and α1-acid glycoprotein. Amlodipine: ~93% bound to albumin. |
| Volume of Distribution | Telmisartan: ~500 L (500 L/70 kg ≈ 7.1 L/kg), extensive tissue distribution. Amlodipine: ~21 L/kg (21 L/kg × 70 kg = 1470 L), large Vd due to lipophilicity. |
| Bioavailability | Telmisartan: 42-58% (oral). Amlodipine: 64-90% (oral). |
| Onset of Action | Amlodipine: gradual onset, 2-6 h to peak effect; Telmisartan: onset within 1-2 h, peak at 3-4 h. |
| Duration of Action | Amlodipine: ≥24 h (effective once-daily). Telmisartan: ≥24 h (sustained BP reduction). |
Twynsta (telmisartan/amlodipine) is available as 40/5 mg, 40/10 mg, 80/5 mg, and 80/10 mg tablets. Recommended starting dose is 40/5 mg once daily. Titrate based on blood pressure response to a maximum of 80/10 mg once daily. Administered orally.
| Dosage form | TABLET |
| Renal impairment | For GFR <30 mL/min/1.73 m²: contraindicated for telmisartan component; thus avoid use. For GFR 30-60 mL/min/1.73 m²: no dose adjustment required, but monitor serum potassium and creatinine. For GFR ≥60 mL/min/1.73 m²: no dose adjustment. |
| Liver impairment | Child-Pugh A (mild): No dose adjustment. Child-Pugh B (moderate): Telmisartan is contraindicated; amlodipine half-life prolonged, use with caution and consider lower starting doses (e.g., 2.5 mg amlodipine component). Child-Pugh C (severe): Contraindicated due to telmisartan and limited amlodipine data. |
| Pediatric use | Safety and efficacy not established in pediatric patients under 18 years; no dose recommendations. |
| Geriatric use | Patients ≥65 years: Start at 40/2.5 mg if available (or 40/5 mg with caution), titrate slowly due to increased risk of hypotension, syncope, and electrolyte disturbances. Avoid use in elderly with significant renal or hepatic impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TWYNSTA (TWYNSTA).
| Breastfeeding | Both telmisartan and amlodipine are excreted in breast milk. The M/P ratio for telmisartan is unknown; for amlodipine, the M/P ratio is approximately 1. Given the potential for adverse effects in the nursing infant, particularly on the RAS, breastfeeding is not recommended during therapy. |
| Teratogenic Risk | FDA Pregnancy Category D. Drugs acting directly on the renin-angiotensin system (RAS) can cause fetal and neonatal morbidity and death when used in pregnancy. First trimester exposure: no increased risk of major malformations. Second and third trimester exposure: oligohydramnios, fetal renal dysfunction, skull ossification defects, hypotension, and anuria. Monitor fetal renal function and amniotic fluid volume if exposure occurs after first trimester. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Pregnancy (especially second and third trimesters)","Hypersensitivity to telmisartan, amlodipine, or any component of the formulation","Concomitant use with aliskiren in patients with diabetes mellitus","Severe hypotension","Shock (including cardiogenic shock)","Obstruction of the outflow tract (e.g., aortic stenosis)"]
| Precautions | ["Fetal toxicity: Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. Discontinue as soon as possible once pregnancy is detected.","Hypotension in volume- or salt-depleted patients: Correct volume depletion before initiation.","Increased angina or myocardial infarction: Particularly in patients with severe obstructive coronary artery disease upon starting or increasing dose of amlodipine.","Hepatic impairment: Use caution in patients with severe hepatic impairment.","Renal impairment: Monitor renal function periodically.","Hyperkalemia: Monitor serum potassium levels, especially in patients with risk factors."] |
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| Fetal Monitoring | Monitor maternal blood pressure, serum potassium, and renal function. In pregnancy, if exposure occurs in second or third trimester, perform serial ultrasound assessments of amniotic fluid volume and fetal renal function. Monitor neonatal blood pressure and renal function after delivery. |
| Fertility Effects | No human data on effects on fertility. In animal studies, telmisartan and amlodipine did not impair fertility. However, drugs affecting the RAS may alter reproductive function; clinical significance unknown. |