Potassium Bromide / Sodium Bromide
Potassium bromide (KBr), Sodium bromide (NaBr)
Also known as: KBr · NaBr · Bromide
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Seizures (Maintenance) | 20-30 mg/kg PO once daily, with food | PO | q24h | — | 🌎 NA |
| Seizures (Rapid Loading Dose) | 400 mg/kg PO divided into 8 doses given over a 48-hour period (i.e., 50 mg/kg every 6 hours for 2 days) | PO | q6h | 2 days | 🌎 NA |
| Seizures (Alternative Loading Dose) | 400-600 mg/kg/day divided and given with food | PO | divided | 1 to 5 days | 🌎 NA |
| Seizures (Alternative Loading Dose 2) | 125 mg/kg/day for 5 days PO divided q12h | PO | q12h | 5 days | 🌎 NA |
| Status epilepticus / NPO | 100 mg/kg body weight every 4 hours for 6 total doses | Rectal | q4h | 24 hours | 🌎 NA |
| Seizures (IV Loading - Sodium Bromide) | 600-1200 mg/kg, diluted in a solution and administered over eight hours | IV | once | 8 hours | 🌎 NA |
- Seizures (Maintenance): Dose is for potassium bromide. If sodium bromide is used, decrease dose by 15% (i.e., 17-26 mg/kg).
- Seizures (Rapid Loading Dose): Giving entire loading dose at once will usually cause vomiting. Start maintenance dose after loading.
- Seizures (Alternative Loading Dose): May be given over 24 hours or more gradually over 5 days. Then go to initial maintenance dose.
- Seizures (Alternative Loading Dose 2): Resume at 35 mg/kg PO once daily after loading.
- Seizures (IV Loading - Sodium Bromide): Sodium bromide only. If target serum bromide concentrations are not reached, additional IV NaBr may be administered. Use with caution.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Refractory seizures (3rd choice therapy) | 10-20 mg/kg/day PO | PO | q24h | — | 🌎 NA |
| Epilepsy (2nd line therapy) | 30 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
- Refractory seizures (3rd choice therapy): Follow same guidelines as dogs. Use with extreme caution.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Bromides are among the oldest anticonvulsant medications, having been used in human and veterinary medicine since the 19th century. They are halide salts utilized primarily as a first-line or adjunctive therapy for the management of refractory seizure disorders in dogs, particularly when phenobarbital alone is insufficient or contraindicated due to hepatotoxicity.
Key Clinical Features:
- Hepatic Sparing: Unlike phenobarbital, bromides are not metabolized by the liver and are excreted entirely by the kidneys, making them the drug of choice for epileptic dogs with concurrent hepatic dysfunction.
- Extremely Long Half-Life: The half-life in dogs is roughly 16-25 days. Consequently, it takes 3 to 4 months to reach steady-state serum concentrations. Loading doses are frequently required to achieve rapid seizure control.
- Dietary Sensitivity: Bromide competes with chloride for renal reabsorption. Changes in dietary salt (chloride) intake will directly and inversely affect serum bromide levels.
- Feline Contraindication: Bromides are generally avoided in cats due to a high risk of developing severe, asthma-like lower respiratory tract disease (feline pneumonitis), which can be fatal.
Mechanism of action
Bromide's anti-seizure activity stems from its generalized depressant effect on neuronal excitability.
- Mechanism: The bromide ion (Br⁻) is a halide that closely mimics the chloride ion (Cl⁻) in the body. It competes with chloride for transport across cell membranes, particularly at the GABA_A receptor chloride channels.
- Pathway: GABA binds to the receptor → channel opens → Bromide traverses the channel more readily than chloride → membrane hyperpolarization.
- Result: This hyperpolarization lowers the resting membrane potential, making it significantly harder for the neuron to depolarize. This effectively raises the seizure threshold and limits the spread of epileptic electrical discharges across the brain.
Safety & warnings
Contraindications
- Cats (relative to absolute contraindication due to severe pulmonary effects)
- Patients with severe renal dysfunction (requires extreme caution and dose adjustment)
- Pregnant or lactating animals (crosses placenta and enters milk, causing fetal growth retardation/intoxication)
Adverse effects
- Profound sedation (especially transiently during loading or when combined with phenobarbital)
- Polyphagia (increased appetite) and subsequent weight gain
- Polydipsia and polyuria (increased thirst and urination)
- Ataxia and hind limb paresis (signs of toxicity)
- Gastrointestinal upset (vomiting, anorexia, constipation)
- Pancreatitis (reported in combination with phenobarbital/primidone)
- Pruritic dermatitis (rare)
- Paradoxical hyperactivity (rare)
- Cats: Severe lower respiratory effects (cough, dyspnea, peribronchial infiltrates)
Precautions
Dietary Warning: Chloride intake must remain strictly consistent. Sudden increases in dietary salt (e.g., salty treats, switching to a high-chloride prescription diet) will cause rapid excretion of bromide and potential seizure breakthrough.
- Renal Impairment: Use with caution in older animals or those with renal disease, as decreased GFR will lead to bromide accumulation and toxicity.
- Feline Patients: Use with extreme caution, if at all, in cats due to the risk of fatal peribronchial infiltrates and dyspnea.
- GI Irritation: Potassium bromide is a gastric irritant. Giving the medication with food or dividing the dose can help mitigate vomiting. If vomiting persists, switching to sodium bromide may be beneficial.
Drug interactions
Additive sedation and CNS depression.
May enhance the renal excretion of bromides, lowering serum levels and potentially causing seizure breakthrough.
Increases renal excretion of bromide, reducing serum bromide levels and affecting seizure control.
Decreases renal excretion of bromide, increasing serum bromide levels and risking bromide toxicity.
May potentially reduce the efficacy of antiseizure medications.
Monitoring
- Serum bromide concentrations (Therapeutic range in dogs: 1-3 mg/mL)
- Seizure frequency and severity
- Signs of toxicity (sedation, ataxia, weakness)
- Renal function (BUN, Creatinine, USG)
- Body weight (due to polyphagia)
Pharmacokinetics
Half-life
Absorption
Well absorbed after oral administration, primarily in the small intestine. Also well absorbed rectally in dogs (bioavailability 60-100%).
Distribution
Distributed in the extracellular fluid and mimics the volume of distribution of chloride (0.2-0.4 L/kg). Not bound to plasma proteins. Readily enters the CSF (87% of serum concentration in dogs). Enters maternal milk.
Metabolism
Not metabolized by the liver. Excreted unchanged.
Elimination
Principally excreted by the kidneys. Competes with chloride for renal tubular reabsorption.
Overdose
Toxicity (bromism) is more likely with chronic overdoses, but acute overdoses can occur.
Clinical Signs of Bromism:
- Profound sedation to stupor
- Ataxia, tremors, and hind limb paresis
- Muscle pain
- Conscious proprioceptive deficits
- Anisocoria and hyporeflexia
Treatment:
- Acute Ingestion: Standard gut removal techniques (emesis, gastric lavage). Death from acute oral ingestion is rare as spontaneous vomiting usually occurs.
- Enhancing Excretion: Administration of parenteral 0.9% sodium chloride (NaCl) or oral sodium chloride, parenteral glucose, and loop diuretics (e.g., furosemide) are highly effective in promoting renal excretion and reducing bromide loads in intoxicated patients.
Available products
Formulations
- Compounded oral solution (typically 250 mg/mL)
- Compounded oral capsules
- Chemical powder/crystals (Reagent or ACS grade)
Veterinary
- Compounded oral solutions (e.g., 250 mg/mL)
- Compounded oral capsules
Human-labeled
- None (Not FDA-approved)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store in tight containers. Solutions may be stored for up to one year in clear or brown, glass or plastic containers at room temperature. Refrigerating the solution may help reduce microbial growth but may cause crystals to form. If precipitation occurs, warming the solution will resolubilize the bromide.
Client information
Important Guidance for Pet Owners:
- Consistency is Key: Anti-seizure medications must be given on a strict, regular schedule. Missed doses are a major cause of treatment failure. If you miss a dose, give it when you remember, but space it out from the next dose to avoid stomach upset.
- Dietary Strictness: Bromide levels are directly affected by the amount of salt (chloride) in your dog's diet. Do not change your dog's diet without consulting your veterinarian. Avoid giving salty treats like pig ears, cheese, or hot dogs, as this can cause the drug to be flushed from the body, leading to seizures.
- Patience is Required: Because this drug stays in the body for a very long time, it can take several months to see its full effect unless your veterinarian prescribes a high "loading dose" initially.
- Side Effects to Expect: Increased thirst, urination, and appetite are common. Your dog may also seem very sleepy or wobbly (ataxic) for the first few weeks. If the wobbliness is severe or your dog seems stuporous, contact your vet immediately.
- Administration: Liquid doses should be measured carefully with a syringe. It can be mixed with food to help prevent stomach upset and vomiting.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.