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Functional Class
Class II Antidysrhythmic (Beta Blocker)
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Mechanism of Action
- Inhibits Beta-1 adrenergic receptors in cardiac muscle
- Little or no effect on Beta-2 in doses under 100 mg
- Reduces HR, cardiac output and BP at rest
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Indications
- CP associated with AMI, ACS
- Angina pectoris
- SVT
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Contraindications
- Hypersensitivity
- Sinus bradycardia
- HB greater than 1 degree (except in patients with artificial pacemaker)
- Cardiogenic shock (BP<100 systolic)
- Uncompensated cardiac failure
- Pregnancy (2nd, 3rd trimesters)
- Asthma
- COPD
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Precautions
- Impaired hepatic or renal function
- CHF controlled by digitalis or diuretics
- Do not mix with IV calcium channel blockers
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Side Effects
- Bronchospasm
- Bradycardia
- Palpitations
- Edema
- CHF
- Reduced peripheral circulations
- Drowsiness
- Insomnia
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Interactions
- Drugs whcih slow AV conduction such as digoxin as the effects may be cumulative
- Glucagon: Metoprolol may blunt the hyperglycemic effects
- Verapamil or diltiazem may have synergistic effects
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Dosage and Route
- 5 mg slow IVP (over 2-5 mins) q 5 mins max total 15 mg
- Acute MI: Maintain systolic BP> 100 and HR > 6o
- SVT: Maintain heart rate 90-100/minute
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