Metoprolol Tartate (Lopressor)
Anesthesia Implications
Classification: Cardioselective Beta Blocker
Therapeutic Effects: Reduced heart rate, reduced blood pressure
Time to Onset: Immediate
Time to Peak: 20 min.
Duration: 5-8 hours
Contraindications
Significant hypovolemia
Hypotension
Acute hemorrhage causing anemia
Decompensated heart failure
Pulmonary Edema
Bradycardia,
second or third-degree heart block (in the absence of a pacemaker)
sick sinus syndrome (in absence of a pacemaker)
Acute or severe bronchospastic lung disease
Relative Contraindications:
Patients with cocaine intoxication – beta blockers may induce unopposed alpha-adrenergic stimulation. This may lead to hypertension and myocardial ischemia from coronary vasoconstriction.
Use caution in:
Hepatic or renal failure
Asthma
Diabetes Mellitus (masks signs of hypoglycemia)
Untreated Pheochromocytoma (use only after alpha blocker has been administered)
Parturient patients
Breastfeeding mothers
Geriatric patients (require lower doses)
Primary Considerations
Treatment – Metoprolol is a great choice for PERSISTENT hypertension with an elevated heart rate. This means you’ve already treated/ruled out other reasons for tachycardia (eg. pain, hypovolemia). For more acute episodes of hypertension along with an elevated heart rate, esmolol would likely be a better choice.
Benefits – metoprolol attenuates hemodynamic responses to intraoperative stimuli and reduces propofol dose requirements.
Hypovolemia – ALWAYS ensure that the patient is euvolemic before treating a tachycardic patient. Tachycardia may be resolved by treating hypovolemia (giving fluids).
Bronchospasm – This is a risk of metoprolol administration. The practitioner should be especially careful in patients that are high risk for this condition.
Geriatric patients – Older patients may have increased sensitivity to beta blockers, so it is recommended to reduce dosing and titrate to effect.
OB – Pregnancy risk factor Category C. Crosses the placenta AND breast milk. May cause fetal or neonatal bradycardia, hypoglycemia, and respiratory depression.
Hypoglycemia – Beta blockers like metoprolol may mask the signs of hypoglycemia.
Organ Impairment – Renal impairment does NOT affect dosing. Slow and careful titration should be used when the patient has hepatic impairment.
IV push dose
Hypertension: 1-5 mg.
Method of Action
Cardioselective beta-1-adrenergic receptor inhibitor. Cardiac output is reduced by negative inotropic (reduced contraction) and chronotropic (reduced heart rate) effects.
Metabolism
Hepatic
Elimination
Renal
Additional Notes
Side effects – fatigue, depression, bradycardia, heart block, hypotension, bronchospasm, cold extremities, dizziness, decreased libido, diarrhea, tinnitus, decreased exercise tolerance, glucose intolerance, masked hypoglycemia, and heart failure exacerbation.
London. Hemodynamic management during anesthesia in adults. Uptodate.com. 2022. web link
Morris. Metoprolol. StatPearls. 2022. web link
Ghosh. Both clonidine and metoprolol modify anesthetic depth indicators and reduce intraoperative propofol requirement. 2008.
