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). |
| Molecular Weight | Amlodipine besylate: 567.05 Da; Olmesartan medoxomil: 558.59 Da; Twynsta is a combination, typical molecular weight of active components. |
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 | Avoid during first trimester due to risk of teratogenicity (olmesartan medoxomil is an ARB, and amlodipine is a CCB; ARBs are contraindicated in pregnancy). |
| 2nd trimester | Contraindicated in second trimester due to fetal renal toxicity and oligohydramnios from ARB component. |
| 3rd trimester | Contraindicated in third trimester due to fetal renal toxicity, oligohydramnios, and neonatal hypotension from ARB component. |
Clinical note
Comprehensive clinical and safety monograph for TWYNSTA (TWYNSTA).
| Placental transfer | Amlodipine crosses placenta; olmesartan crosses placenta (limited data). ARBs are known to cross and cause fetal harm. |
| Breastfeeding | Amlodipine is excreted in breast milk at low levels; olmesartan is not detected in breast milk. Compatible with breastfeeding, but monitor infant for hypotension and renal effects. Use with caution in preterm or low-birth-weight infants. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
PregnancyHypersensitivity to any component (amlodipine, olmesartan, or any dihydropyridine calcium channel blocker)Breastfeeding (relative, but absolute in some guidelines)
| 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. |
| Food/Dietary | Avoid grapefruit and grapefruit juice. May take with or without food. Avoid potassium-containing salt substitutes unless cleared by doctor. |
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| Lactation Rating | L2 - Safer |
| 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. |
| 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. |
| Clinical Pearls | Twynsta (telmisartan/amlodipine) is a fixed-dose combination for hypertension not controlled on monotherapy. Avoid use with aliskiren in patients with diabetes or renal impairment (GFR < 60 mL/min). Monitor serum potassium and renal function periodically. Amlodipine component may cause peripheral edema, which is lessened by the ARB component. Telmisartan has a long half-life (~24 h) allowing once-daily dosing. Use caution in patients with aortic stenosis or hypertrophic cardiomyopathy due to amlodipine's vasodilatory effects. |
| Patient Advice | Take exactly as prescribed, usually once daily. Do not skip doses or stop without consulting your doctor. · This medication does not cure high blood pressure but helps control it; continue taking even if you feel well. · Avoid grapefruit or grapefruit juice while taking this medication as it can affect drug levels and increase side effects. · Report symptoms of low blood pressure (dizziness, fainting) or allergic reactions (swelling of face/lips/tongue). · Use caution when rising from sitting or lying down to prevent falls. Notify your doctor if you experience severe swelling in your ankles or feet. · Do not use potassium supplements or salt substitutes without consulting your doctor. · If you are pregnant or planning to become pregnant, inform your doctor immediately; this medication can cause harm to the unborn baby. · Keep all appointments for blood pressure checks and lab tests. |