Potassium Bromide (KBr): veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

KBr, Bromide, Libromide, Potassium bromide

Species with doses

Dogs and Cats

General dose range

20–40 mg/kg PO q24h (or divided q12h) — check the species tables for the indication

Routes

PO, Rectal

Last reviewed

1 October 2026

Indications

• Canine idiopathic epilepsy — adjunct to phenobarbital for refractory seizures
• Monotherapy/first-line anticonvulsant in dogs with hepatic disease (no liver metabolism)
• Cluster-seizure / status management protocols (loading, with veterinary supervision)

Potassium Bromide (KBr) dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Adjunct anticonvulsant (with phenobarbital): Plumb’s p.159 (Thomas 2010; Munana): potassium bromide 20–30 mg/kg PO once daily with food (sodium bromide ~15% less). Steady state takes 4–5 months — check serum bromide at 3 months (target ≥1.5 mg/mL with phenobarbital); phenobarbital may then be tapered 25% every 2–4 weeks. Keep dietary chloride constant.
• Maintenance (higher starting dose): Plumb’s p.159 (Dewey 2005): a good starting dose is 35 mg/kg PO once daily. Titrate to serum bromide and seizure control; dogs on bromide alone often need concentrations at the higher end. Plumb’s also gives 30 mg/kg PO once daily as second-line therapy (Munana 2004).
• Loading (rapid control, supervised): Plumb’s p.159: 400 mg/kg divided into 8 doses over 48 h (50 mg/kg q6h) — giving it at once causes vomiting (Thomas 2010); 400–600 mg/kg/day divided with food over 1–5 days (Munana); 125 mg/kg/day divided q12h for 5 days (Dewey). Then start maintenance. Expect sedation/ataxia.
• Status epilepticus — rectal (no oral route): Plumb’s p.159 (Dewey 2005): 100 mg/kg per rectum every 4 hours for 6 total doses when oral dosing is not possible.

Cats

• Refractory seizures (last-line; high adverse-effect risk): Plumb’s p.159: 10–20 mg/kg/day PO as third-choice therapy (Quesnel 2000); 30 mg/kg once daily as second-line (Munana 2004). Bromide causes eosinophilic bronchitis/pneumonitis in a substantial proportion of cats — many clinicians avoid it; monitor for cough.

Contraindications

⚠ NEVER GIVE POTASSIUM BROMIDE INTRAVENOUSLY — an IV potassium load risks fatal hyperkalaemic cardiac arrest. Where an IV bromide load is indicated, Papich 5th ed specifies SODIUM bromide (800–1200 mg/kg infused over 8 hours) and states it is critical to use sodium bromide instead of potassium bromide for this use. CATS — contraindicated (severe, sometimes fatal eosinophilic bronchial disease). Significant renal impairment (renally excreted — accumulation/bromism). Avoid abrupt changes in dietary chloride/salt. Pre-existing severe sedation. Known hypersensitivity.

Species-specific warnings

Cats: CONTRAINDICATED — bromide causes a potentially fatal eosinophilic lower-airway (asthma-like) disease in cats. Use other anticonvulsants (e.g. phenobarbital, levetiracetam) instead.

Dogs: Avoid sudden dietary salt/chloride changes and chloride-rich IV fluids — both can swing bromide levels into toxicity or loss of seizure control.

Adverse effects

• Sedation, ataxia, hindlimb weakness (dose-related; worse early or in "bromism")
• Polyphagia, polydipsia/polyuria, weight gain
• GI irritation/vomiting (give with food)
• Pancreatitis (reported, especially combined with phenobarbital)
• Bromism (toxic accumulation): stupor, profound ataxia, muscle pain

Drug interactions

• Dietary chloride/salt: high chloride increases bromide excretion (lowers levels/effect); low chloride raises levels (toxicity) — keep diet consistent
• Loop/thiazide diuretics: increase bromide excretion (reduced effect)
• Phenobarbital / other CNS depressants: additive sedation (and combined pancreatitis risk)
• IV chloride-rich fluids (0.9 % saline): can rapidly lower bromide levels

Pregnancy and lactation

Crosses the placenta; data limited. Uncontrolled epilepsy is itself dangerous — if needed, continue with monitoring rather than risk status epilepticus.

Monitoring

• Serum bromide concentration (steady state ~3 months; check ~6–12 weeks after starting/changing, then periodically)
• Seizure frequency/severity (efficacy)
• Sedation/ataxia and signs of bromism
• Consistent dietary chloride/salt intake (avoid abrupt diet changes)
• Renal function; consider pancreatic monitoring if combined with phenobarbital

Toxicity and overdose

"Bromism" is the cardinal toxicity — accumulation causing profound sedation, marked ataxia/paresis, stupor, muscle pain and inappetence; it develops with overdose, renal impairment or a sudden fall in dietary chloride. Reversible by lowering the level. In cats, bromide causes a distinct, potentially fatal eosinophilic bronchial disease (hence the contraindication).

Management: For bromism: stop or reduce bromide and promote excretion by giving chloride — IV 0.9 % sodium chloride (saline) diuresis and increased dietary salt accelerate bromide elimination. Provide supportive/nursing care for sedation and ataxia; signs improve as levels fall. Recheck serum bromide and re-titrate.

Clinical pearls

• The classic add-on to phenobarbital — and the anticonvulsant of choice when the liver can't tolerate phenobarbital (bromide isn't liver-metabolised)
• Be patient: with a half-life of weeks, it takes ~3 months to reach steady state — use a loading protocol if you need control sooner
• Diet matters: keep salt/chloride intake constant, and remember IV saline can rapidly drop bromide levels and trigger seizures
• Treat bromism by giving chloride (saline diuresis + dietary salt) to flush bromide out — and re-titrate
• NEVER use in cats — it causes a serious, sometimes fatal asthma-like bronchial disease

Mechanism of action

Bromide ions substitute for chloride at neuronal membranes and pass more readily through GABA-gated chloride channels, hyperpolarising neurons and raising the threshold for seizure generation — a membrane-stabilising, GABA-facilitating anticonvulsant effect. Because bromide and chloride compete for renal reabsorption and channel flux, dietary chloride intake directly and substantially alters bromide levels and effect.

Formulations and products

• Oral solution 250 mg/mL (compounded)
• 325 mg tablet (Libromide)
• Libromide (Dechra) — 325 mg tablet, Tablet
• Potassium bromide (compounded) (Compounding pharmacy) — Custom solution (e.g. 250 mg/mL), Oral solution

Storage

Solution/tablets: 15–30 °C, dry, protected from light; keep tightly closed (solutions can crystallise — redissolve gently).

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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• Prazosin
• Prednisone
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Frequently asked questions