Esmolol?

Esmolol is an ultra-short-acting, cardioselective beta-1 blocker used intravenously to rapidly slow the heart rate.

Key points:
- Mechanism: Blocks beta-1 receptors in the heart, reducing heart rate and myocardial oxygen demand. It has minimal beta-2 effects in the lungs at typical doses.
- Pharmacokinetics: Very quick onset (within 1–2 minutes) and a short half-life (~9 minutes) because it’s rapidly metabolized by esterases in red blood cells.
- Typical uses: Acute management of tachyarrhythmias (e.g., atrial fibrillation/flutter with rapid ventricular response, other SVTs) and perioperative control of heart rate and hemodynamics. Often used in the ICU or operating room.
- Dosing (general reference):
- Loading (bolus): 500 mcg/kg IV over ~30 seconds.
- Infusion: 50–300 mcg/kg/min, titrating to desired heart rate and blood pressure targets (often to achieve a target HR around 60–100 bpm or stable hemodynamics).
- Some protocols use different starting boluses; follow your institution’s guidelines.
- Adverse effects: Bradycardia, hypotension, dizziness, fatigue, potential AV block or heart failure in susceptible patients. Bronchospasm is less likely but possible at higher doses (beta-2 effects are minimal at usual doses).
- Contraindications/precautions:
- Absolute: second- or third-degree AV block (unless there’s a functioning pacemaker), symptomatic bradycardia, decompensated heart failure or cardiogenic shock.
- Relative: asthma/COPD with asthma risk, severe hypotension, significant bradyarrhythmias, or concurrent use of other agents that depress conduction or contractility (e.g., non-dihydropyridine calcium channel blockers).
- Caution in pregnancy/lactation; use only if benefits justify risks.
- Pharmacokinetic note: Since it’s rapidly cleared, if side effects occur they typically improve quickly after stopping the infusion.
- Monitoring: Continuous ECG, blood pressure, and heart rate during infusion; monitor for signs of bradycardia or hypotension.

If you have a specific scenario (e.g., perioperative use, a particular tachyarrhythmia, or patient with comorbidities), tell me more and I can tailor dosing ranges and considerations.