LOPRESSOR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LOPRESSOR (LOPRESSOR).
Selective beta-1 adrenergic receptor antagonist; reduces heart rate, myocardial contractility, and blood pressure by blocking catecholamine effects at beta-1 receptors, predominantly in cardiac tissue.
| Metabolism | Primarily hepatic via CYP2D6; extensive first-pass metabolism; metabolites include alpha-hydroxymetoprolol and O-demethylmetoprolol. |
| Excretion | Renal: ~95% (primarily as metabolites, <5% unchanged); fecal: ~5% |
| Half-life | Terminal elimination half-life: 3-7 hours (mean 4.5 h); may be prolonged in hepatic impairment or elderly |
| Protein binding | ~12% (primarily to albumin) |
| Volume of Distribution | 3-4 L/kg; indicates extensive tissue distribution |
| Bioavailability | Oral: ~50% (first-pass effect; range 40-60%) |
| Onset of Action | Oral: 1-2 hours; Intravenous: 5-10 minutes |
| Duration of Action | Oral: 6-12 hours; Intravenous: 4-6 hours (dose-dependent) |
| Action Class | Beta blocker- Cardioselective |
| Brand Substitutes | Mprol 50mg Tablet, StayHappi Metoprolol Succinate 50mg Tablet, Opol 50mg Tablet, Metocare 50mg Tablet, Metopress 50mg Tablet, Mprol 25mg Tablet, Opol 25mg Tablet, Metoder 25mg Tablet, Mexcelol 25mg Tablet, Metosis 25mg Tablet, StayHappi Metoprolol Succinate 100mg Tablet, Embeta 100 Tablet, Opol 100mg Tablet, Evimeto 100mg Tablet, Metonce 100mg Tablet |
50 mg orally twice daily, titrate up to 100 mg twice daily as needed.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | eGFR <10 mL/min: reduce dose by 50% or use with caution; eGFR ≥10 mL/min: no adjustment required. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: contraindicated. |
| Pediatric use | 0.5-1 mg/kg/day orally divided every 12 hours, titrate to max 2 mg/kg/day; not recommended for children <6 years. |
| Geriatric use | Start at 25 mg orally twice daily, titrate slowly; monitor for bradycardia, hypotension, and CNS effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LOPRESSOR (LOPRESSOR).
| Breastfeeding | Excreted in breast milk in small amounts (M/P ratio approximately 1.3). Infant exposure estimated at 0.5-1% of maternal weight-adjusted dose. Not likely to cause adverse effects in term infants; monitor for bradycardia and hypotension in preterm or compromised infants. |
| Teratogenic Risk | First trimester: No increased risk of major malformations based on limited human data. Second and third trimesters: May cause fetal bradycardia, intrauterine growth restriction, and placental hypoperfusion. Avoid in preeclampsia due to risk of fetal harm. Crosses placenta. Neonatal effects include hypotension, bradycardia, and hypoglycemia. |
■ FDA Black Box Warning
Exacerbation of angina and myocardial infarction: Do not abruptly discontinue; taper gradually over 1-2 weeks.
| Serious Effects |
Sinus bradycardia, heart block greater than first degree, cardiogenic shock, decompensated heart failure, sick sinus syndrome (unless pacemaker present), severe peripheral arterial disease, hypersensitivity to metoprolol or any component.
| Precautions | May worsen heart failure; monitor heart failure patients. Can mask symptoms of hypoglycemia (e.g., tachycardia) and hyperthyroidism. Avoid abrupt withdrawal; may exacerbate angina or cause MI. May precipitate bradycardia or heart block; caution with conduction abnormalities. Use with caution in patients with bronchospastic disease; consider alternative if possible. May cause dizziness or fatigue; caution when driving or operating machinery. |
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| Fetal Monitoring | Maternal: Blood pressure, heart rate, and signs of bronchospasm. Fetal: Ultrasound for growth restriction and amniotic fluid index. Neonatal: Apgar scores, blood glucose, and heart rate monitoring for 24-48 hours after delivery. |
| Fertility Effects | No specific human data on fertility impairment. Animal studies show no adverse effects on fertility. Theoretical risk of reduced uteroplacental blood flow affecting implantation; clinical significance uncertain. |