TENORETIC 100
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TENORETIC 100 (TENORETIC 100).
Tenoretic 100 is a combination of atenolol (a cardioselective beta-1 adrenergic receptor antagonist) and chlorthalidone (a thiazide-like diuretic that inhibits sodium reabsorption in the distal convoluted tubule). Atenolol reduces heart rate, cardiac output, and blood pressure by blocking beta-1 receptors; chlorthalidone reduces plasma volume and peripheral resistance.
| Metabolism | Atenolol: Minimal hepatic metabolism; primarily excreted unchanged by kidneys. Chlorthalidone: Not metabolized; excreted unchanged in urine. |
| Excretion | Tenoretic 100 (atenolol 100 mg + chlorthalidone 25 mg): Atenolol: ~85% renal unchanged, <10% fecal; Chlorthalidone: ~65% renal unchanged, remainder biliary/fecal. |
| Half-life | Atenolol: terminal half-life 6-7 h (up to 14 h in severe renal impairment); Chlorthalidone: 40-60 h (long-acting diuretic). |
| Protein binding | Atenolol: <5% bound to albumin; Chlorthalidone: ~75% bound to albumin and erythrocytes. |
| Volume of Distribution | Atenolol: 0.7-1.2 L/kg (moderate tissue distribution); Chlorthalidone: 3-4 L/kg (extensive tissue binding). |
| Bioavailability | Oral: Atenolol ~50% (first-pass); Chlorthalidone ~65%. |
| Onset of Action | Oral: atenolol antihypertensive effect 1-2 h; chlorthalidone diuresis 2 h, peak 4-6 h. |
| Duration of Action | Atenolol: 24 h (once-daily dosing); Chlorthalidone: 24-72 h (long duration permits QD/BID dosing). |
One tablet orally once daily, each tablet containing atenolol 100 mg and chlorthalidone 25 mg. May be increased to 2 tablets once daily if needed.
| Dosage form | TABLET |
| Renal impairment | For CrCl 30-59 mL/min: maximum atenolol 50 mg/day; for CrCl <30 mL/min: maximum atenolol 25 mg/day. Chlorthalidone is ineffective if CrCl <30 mL/min. No adjustment for CrCl >60 mL/min. |
| Liver impairment | No specific Child-Pugh based adjustments are established; use with caution in severe hepatic impairment due to potential for electrolyte imbalance and altered drug metabolism. |
| Pediatric use | Not recommended for pediatric use; safety and efficacy not established. If used, atenolol dose: 0.5-1 mg/kg/day orally; chlorthalidone: 0.5-1 mg/kg/day orally. Adjust based on response and renal function. |
| Geriatric use | Start at lowest possible dose (e.g., atenolol 25-50 mg once daily) and titrate slowly due to increased risk of bradycardia, hypotension, and electrolyte disturbances. Monitor renal function closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TENORETIC 100 (TENORETIC 100).
| Breastfeeding | Atenolol: Concentrated in breast milk (M/P ratio ~3.6); may cause bradycardia and hypoglycemia in nursing infants. Chlorthalidone: Excreted in small amounts (M/P ratio unknown); may suppress lactation. Not recommended during breastfeeding. |
| Teratogenic Risk | First trimester: Risk of congenital malformations not established; animal studies show some fetal toxicity at high doses. Second and third trimesters: Associated with fetal growth restriction, oligohydramnios, neonatal bradycardia, and hypotension due to maternal beta-blockade and ACE inhibition (atenolol component). ACE inhibitor (chlorthalidone component not teratogenic but causes fetal nephrotoxicity and oligohydramnios). Avoid in pregnancy. |
■ FDA Black Box Warning
Warning: Avoid abrupt discontinuation in patients with coronary artery disease; may exacerbate angina or precipitate myocardial infarction.
| Serious Effects |
["Sinus bradycardia","Heart block greater than first degree","Cardiogenic shock","Decompensated heart failure","Severe renal impairment (CrCl <30 mL/min)","Anuria","Hypersensitivity to atenolol, chlorthalidone, or other sulfonamide-derived drugs","Untreated pheochromocytoma (relative)","Bronchial asthma (relative)"]
| Precautions | ["Bradycardia or heart block","Exacerbation of peripheral arterial disease","Mask symptoms of hyperthyroidism","Electrolyte imbalances (hypokalemia, hyponatremia) due to chlorthalidone","Acute myopia and secondary angle-closure glaucoma","Renal impairment","Worsening of renal function","Hypotension or syncope"] |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, renal function, and electrolytes (potassium). In fetus: serial growth scans, amniotic fluid index (oligohydramnios risk), and fetal heart rate monitoring for bradycardia. Neonatal monitoring for hypotension, bradycardia, and hypoglycemia after delivery. |
| Fertility Effects | Beta-blockers (atenolol) may reduce libido and cause erectile dysfunction in males; no proven direct effect on female fertility. Thiazide diuretics may affect electrolyte balance and ovulation; data limited. Not associated with permanent infertility. |