Esmolol

What is this medication for?

• Short-term SVT control (AF/flutter, sinus tach); test-dose to predict oral beta-blocker response (esp. feline HCM); intraoperative tachyarrhythmia/high blood pressure control

How is it given?

This medication is normally given by your veterinary team (in clinic or hospital).

• The "try before you commit" beta-blocker: esmolol's minutes-long half-life turns beta-blockade into a reversible experiment — if the SVT responds, an oral agent makes sense; if BP crashes, you just stop.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Hypotension, unusually slow heart rate (The expected dose-effects (stop = reverse))

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Bronchospasm (β2 at high dose), masked hypoglycemia (Class cautions)

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Overt CHF, 2nd/3rd-degree AV block, sinus unusually slow heart rate, cardiogenic shock
• has or has had: Compensated CHF, bronchoconstrictive disease, diabetes

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Digoxin, calcium blockers
  • Anesthetics (inhalants)

Storage and handling

into a vein only; concentrated vials require dilution per label.

Good to know

• The "try before you commit" beta-blocker: esmolol's minutes-long half-life turns beta-blockade into a reversible experiment — if the SVT responds, an oral agent makes sense; if BP crashes, you just stop.
• Found-drug contrast: propranolol (long, non-selective, oral) vs esmolol (minutes, β1, into a vein-only) — opposite ends of the beta-blocker clock.