METOPROLOL TARTRATE
Clinical safety rating: caution
Other drugs that lower heart rate or blood pressure can have additive effects Abrupt withdrawal may exacerbate angina pectoris or cause myocardial infarction.
Competitive beta-1 adrenergic receptor antagonist with weak beta-2 blocking activity; reduces heart rate, contractility, and AV conduction.
| Metabolism | Primarily CYP2D6; major metabolites include alpha-hydroxymetoprolol and O-demethylmetoprolol. |
| Excretion | Renal: 95% as metabolites, <5% unchanged. Fecal: negligible. |
| Half-life | 3–4 hours (terminal) in healthy adults; prolonged to 7–8 hours in severe hepatic impairment; no change in renal impairment. |
| Protein binding | ~12%, primarily to albumin. |
| Volume of Distribution | 4 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: ~50% (first-pass metabolism), range 40–70%. IV: 100%. |
| Onset of Action | IV: 5–10 minutes; oral: 1–2 hours. |
| Duration of Action | Oral: 6–12 hours (dose-dependent); IV: 5–8 hours. Clinical effects may persist longer due to active metabolites. |
Initial dose 100 mg daily in divided doses (e.g., 50 mg twice daily) orally; may increase weekly up to 200-450 mg daily in 2-3 divided doses.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for GFR >10 mL/min. For GFR <10 mL/min, reduce dose by 50% or extend dosing interval (e.g., 50 mg every 12-24 hours). |
| Liver impairment | Child-Pugh Class A: no adjustment. Class B: reduce dose by 50%. Class C: avoid use or use with extreme caution; dose reduction 75% if necessary. |
| Pediatric use | Oral: initial 1-2 mg/kg/day in 2-3 divided doses; maximum 6 mg/kg/day (up to 200 mg/day). IV: 0.1-0.2 mg/kg/dose slow IV bolus (max 5 mg/dose). |
| Geriatric use | Start at low end of dosing range (e.g., 25-50 mg daily in divided doses) based on increased sensitivity and risk of bradycardia; titrate slowly. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other drugs that lower heart rate or blood pressure can have additive effects Abrupt withdrawal may exacerbate angina pectoris or cause myocardial infarction.
| FDA category | Animal |
| Breastfeeding | Excreted into breast milk in low concentrations; M/P ratio approximately 2.5. Considered compatible with breastfeeding but monitor infant for bradycardia and hypotension. |
| Teratogenic Risk | First trimester: Limited data, no consistent evidence of major malformations; beta-blockers may cause fetal bradycardia and hypoglycemia. Second and third trimesters: Risk of fetal growth restriction, bradycardia, and hypoglycemia; use only if benefit outweighs risk. |
■ FDA Black Box Warning
None
| Common Effects | angina |
| Serious Effects |
["Cardiogenic shock","Sinus bradycardia (heart rate <45 bpm)","Second- or third-degree AV block (unless pacemaker)","Sick sinus syndrome","Decompensated heart failure","Hypersensitivity to metoprolol or any component"]
| Precautions | ["Abrupt withdrawal may exacerbate angina or precipitate myocardial infarction","May mask hypoglycemia in diabetic patients","May mask tachycardia in hyperthyroidism","Bronchospasm risk in patients with reactive airway disease","Heart failure exacerbation if not appropriately titrated","Bradycardia, hypotension, or AV block"] |
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| Fetal Monitoring | Maternal: Heart rate, blood pressure, signs of bronchospasm. Fetal: Heart rate, growth ultrasound, and amniotic fluid index; neonatal monitoring for bradycardia and hypoglycemia after delivery. |
| Fertility Effects | No known adverse effects on fertility in animal studies; limited human data. Beta-blockers may theoretically impair reproductive function via hemodynamic effects, but clinical significance unclear. |