Propranolol HCl

What is this medication for?

• Antiarrhythmic: atrial/ventricular premature complexes, SVT/V-tach (incl. digitalis-induced), WPW atrial unusually fast heart rate, AF (with digoxin); HCM performance; high blood pressure; thyrotoxicosis and pheochromocytoma sign control
• Arrhythmias; HCM; hyperthyroid sign control (feline)
• Serotonin syndrome unusually fast heart rate control (0.02 mg/kg slow into a vein)

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

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

• Bradycardia, AV-conduction impairment, low blood pressure, syncope (Core risks)
• CHF worsening / decompensation (The classic β-blocker trap)
• Bronchoconstriction (β2) (Asthmatic/bronchospastic cats)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

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

• Lethargy/depression, diarrhea, hypoglycemia (Additional)
• Masks hypoglycemia signs (and thyrotoxicosis signs) (Diagnostic masking)

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

• has or has had: CHF (unless tachyarrhythmia-driven), >1st-degree AV block, sinus unusually slow heart rate, bronchospastic disease, class hypersensitivity
• has or has had: Renal/hepatic insufficiency, sinus node dysfunction, labile diabetes (masks hypoglycemia), digitalized patients; gradual withdrawal (rebound tachyarrhythmia)

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Digoxin
  • Calcium-channel blockers (diltiazem/verapamil)
  • Insulin/antidiabetics
  • Phenothiazines, lidocaine (into a vein)
  • Thyroid hormone

Storage and handling

Room temperature; generic inexpensive.

Good to know

• The sign-controller, not the cure: propranolol blunts thyrotoxic and pheochromocytoma cardiovascular storms while definitive therapy (methimazole/surgery) takes hold — it does nothing to hormone levels.
• Its serotonin-syndrome role: the unusually fast heart rate/overheating adrenergic component (with cyproheptadine as the serotonin-side antidote).
• Start low (0.1 mg/kg), go slow, taper off — the beta-blocker trinity for avoiding decompensation and rebound.
• Feline asthma + propranolol = β2 breathing difficulty/airway tightening: choose cardioselective alternatives when airway disease coexists.