Bromide (Potassium / Sodium) — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	PO	Loading dose: 400-600 mg/kg/day divided q8-12h for 2-5 days; Maintenance: 30-40 mg/kg/day divided q12h or q24h	q12h or q24h	Duration: Long-term (lifelong for epilepsy) Notes: Therapeutic serum bromide concentration: 1-3 mg/mL (1000-3000 µg/mL). Adjust dose based on serum levels and clinical response. Monitor for bromide toxicity.
Cat	PO	Loading dose: 200-400 mg/kg/day divided q12h for 2-5 days; Maintenance: 20-30 mg/kg/day divided q12h or q24h	q12h or q24h	Duration: Long-term Notes: Cats have a shorter half-life and are more prone to bronchial irritation; use with caution. Therapeutic range: 1-2 mg/mL.
Horse	PO	30-50 mg/kg/day divided q12h or q24h	q12h or q24h	Duration: Long-term Notes: Limited data; monitor serum levels and clinical response.

Clinical Indications & Species Uses

General Indications

Anticonvulsant for seizure management in animals

Dog (Canine)

Adjunctive therapy for refractory epilepsy
Maintenance treatment for idiopathic epilepsy
Treatment of seizures not controlled by phenobarbital alone

Cat (Feline)

Adjunctive therapy for refractory epilepsy
Treatment of seizures associated with inflammatory brain disease

Horse (Equine)

Treatment of epilepsy or seizures (rarely used)
Adjunctive therapy for behavioral seizures

Pharmacology & Mechanism of Action

Drug Class: Anticonvulsant / Antiepileptic | Pharmacological Group: Halide salt

Mechanism of Action: Bromide is an inorganic halide that acts as an anticonvulsant by hyperpolarizing neuronal membranes. It competes with chloride ions for entry into neurons via GABA-A receptor chloride channels, enhancing GABA-mediated inhibitory neurotransmission. This results in an increased threshold for seizure activity and a reduction in the spread of epileptiform discharges. Bromide also affects the electrical activity of neurons by altering the resting membrane potential and reducing excitability.

Pharmacodynamics: Bromide produces a dose-dependent anticonvulsant effect. It has a wide therapeutic index and is effective in reducing the frequency and severity of seizures. The drug does not cause sedation at therapeutic doses, which is advantageous for long-term management. Its effects are primarily due to its action as a chloride mimetic, stabilizing neuronal membranes and enhancing inhibitory synaptic transmission.

⚡ Pharmacokinetics Summary

Absorption: Bromide is rapidly and completely absorbed from the gastrointestinal tract after oral administration. Peak plasma concentrations are reached within 1-2 hours in dogs. Food does not significantly affect absorption.

Distribution: Bromide distributes widely throughout the body, with a volume of distribution of approximately 0.4-0.5 L/kg in dogs. It crosses the blood-brain barrier and placenta, and is distributed into extracellular fluid. It does not bind significantly to plasma proteins.

Metabolism: Bromide is not metabolized in the body. It is excreted unchanged primarily by the kidneys.

Excretion: Bromide is eliminated primarily via renal excretion. It is reabsorbed by the renal tubules, and its excretion is inversely related to chloride intake. High chloride intake increases bromide excretion, while low chloride intake enhances bromide retention. The elimination half-life is long, ranging from 25 to 46 days in dogs, and approximately 11 days in cats.

Half-Life: Dogs: 25-46 days; Cats: ~11 days; Horses: ~72 hours

Bioavailability: Oral bioavailability is nearly 100%.

Protein Binding: Negligible (<5%)

Available Formulations & Strengths

Oral Solution Potassium bromide 250 mg/mL; Sodium bromide 250 mg/mL (PO)

Oral Tablet Potassium bromide 325 mg, 500 mg; Sodium bromide 500 mg (PO)

Oral Capsule Potassium bromide 100 mg, 200 mg, 400 mg (PO)

Injectable Solution Not commercially available; may be compounded (IV (rarely used))

Contraindications & Clinical Warnings

Contraindications:

Hypersensitivity to bromide
Severe renal impairment
Severe hepatic impairment (for potassium bromide, due to potassium load)
Concurrent use with other nephrotoxic drugs
Pregnancy (unless benefits outweigh risks)

Warnings & Clinical Precautions:

Use with caution in patients with renal disease, cardiac disease, or dehydration.
Monitor serum bromide levels regularly (target 1-3 mg/mL in dogs, 1-2 mg/mL in cats).
Bromide can cause gastrointestinal irritation; administer with food.
In cats, bronchial irritation and coughing may occur; use with caution.
Potassium bromide may cause hyperkalemia in patients with renal insufficiency.
Sodium bromide may exacerbate congestive heart failure or hypertension due to sodium load.
Abrupt withdrawal may precipitate seizures; taper dose gradually.
Use in pregnant animals only if clearly needed; bromide crosses the placenta and may cause fetal harm.

Adverse Effects & Reactions

Common:

Sedation (especially during loading)
Vomiting
Anorexia
Constipation
Polyuria
Polydipsia

Serious / Severe:

Bromide toxicity (bromism) with neurological signs (ataxia, tremors, paresis, coma)
Pancreatitis (rare)
Hyperkalemia (with potassium bromide)
Sodium overload (with sodium bromide)
Respiratory distress in cats (bronchial irritation)

Rare:

Dermatitis
Hepatotoxicity
Renal toxicity

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Phenobarbital	Additive anticonvulsant effects; may allow lower doses of each drug. Monitor serum levels of both.	Moderate
Chloride-containing drugs (e.g., potassium chloride, sodium chloride)	High chloride intake increases renal excretion of bromide, reducing its efficacy.	Moderate
Diuretics (e.g., furosemide)	May increase bromide excretion, reducing serum levels.	Moderate
ACE inhibitors (e.g., enalapril)	May increase risk of hyperkalemia when used with potassium bromide.	Moderate
NSAIDs	Potential for increased nephrotoxicity; monitor renal function.	Mild

Overdose & Toxicity Management

Signs of Toxicity:

Vomiting
Diarrhea
Ataxia
Tremors
Sedation
Coma
Respiratory depression
Cardiac arrhythmias (with potassium bromide)

Emergency Treatment Protocol: Discontinue drug. Administer intravenous fluids with sodium chloride to enhance bromide excretion. In severe cases, consider hemodialysis or peritoneal dialysis. Monitor serum electrolytes and neurological status. Supportive care including respiratory support if needed.

Food Animal Withdrawal Times

Not approved for use in food animals in the US. If used off-label, withdrawal times must be established by a veterinarian; due to long half-life, withdrawal may be prolonged (months).

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature (20-25°C, excursions 15-30°C).

Handling & Special Conditions: Keep container tightly closed. Protect from moisture. Compounded solutions should be stored according to pharmacy instructions.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; available as a compounded product or human-grade chemical.

Extra-Label (Off-Label) Use: Bromide is not FDA-approved for veterinary use; it is used extra-label under AMDUCA. For food animals, extra-label use is prohibited unless a valid VCPR and appropriate withdrawal times are established.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Bromide is a valuable anticonvulsant for dogs, particularly for refractory epilepsy. It is often used in combination with phenobarbital to achieve better seizure control with lower doses of each drug. The long half-life allows once-daily dosing after steady state is reached, but loading doses are necessary to achieve therapeutic levels quickly. Monitoring serum bromide concentrations is essential to avoid toxicity and ensure efficacy. Cats are more sensitive to bromide-induced bronchial irritation, so use with caution. In horses, bromide may be used for seizure management but data are limited. Due to its renal excretion, adequate hydration and chloride intake should be maintained. Gradual withdrawal is recommended to avoid rebound seizures.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)