Potassium bromide
**Potassium bromide (KBr)** is an anticonvulsant medication primarily used as an adjunct or alternative therapy for the control of refractory seizures in dogs, particularly when phenobarbital alone is insufficient or contraindicated. It has a very long half-life, meaning steady-state therapeutic levels take months to achieve unless a loading dose is utilized. > **CRITICAL WARNING**: Potassium bromide is strictly contraindicated in cats due to the high risk of developing severe, potentially fatal eosinophilic bronchitis. **Clinical Pearl:** Because bromide is measured by standard laboratory analyzers as chloride, patients on KBr will exhibit a pseudohyperchloremia (falsely elevated serum chloride levels).
Mecanismo: Within the central nervous system, bromide competes with transmembrane **chloride** transport and inhibits **sodium** transport → resulting in membrane hyperpolarization and elevation of the seizure threshold. Bromide also competes with chloride in post-synaptic anion channels following activation by inhibitory neurotransmitters → potentiates the effect of **GABA**. It acts synergistically with other GABA-ergic therapeutic agents (such as phenobarbital).
Dosificación por especie
- Control of seizures (Maintenance) · 20-40 mg/kg · PO · q24h · Long-term · Initial daily maintenance dose. More frequent dosing is not detrimental but not necessary.
- Control of seizures (5-day Loading Dose) · 200 mg/kg/day divided into 4-6 hour doses · PO · Divided q4-6h · 5 days · After 5 days, decrease to maintenance dose (20-40 mg/kg p.o. q24h). If seizures resolve sooner, decrease to maintenance earlier to reduce adverse effects.
- Control of seizures (Single Loading Dose) · 600-1000 mg/kg · PO · Single dose · Once · Likely to result in excessive sedation, ataxia, and potentially vomiting.
- Control of seizures (Intrarectal Loading) · 100 mg/kg · PR · q4h · 6 doses (over 24 hours) · Total 600 mg/kg over 24 hours. Use liquid bromide (250 mg/ml). Useful if animal is not conscious enough for oral medication.
- Contraindicated · Do not use · PO · N/A · N/A · Causes severe coughing due to eosinophilic bronchitis, which may be fatal.
Las dosis son una referencia clínica para veterinarios colegiados. Confirme siempre con la ficha técnica vigente y el paciente individual.
Vías de administración
Contraindicaciones
- Cats (causes severe, potentially fatal eosinophilic bronchitis)
- Dogs with a history of, or predisposition to, pancreatitis
Efectos adversos
- Ataxia
- Sedation
- Somnolence
- Vomiting (especially with high concentration solutions >250 mg/ml)
- Polyphagia
- Polydipsia
- Pancreatitis
- Skin reactions (in animals with pre-existing skin diseases)
- Behavioural changes (irritability, restlessness)
- Transient diarrhoea (with intrarectal loading)
Interacciones farmacológicas
- Dietary salt (Sodium chloride) · Increased dietary salt increases renal elimination of bromide, decreasing serum bromide concentrations. · major
- Chloride-containing IV fluids · Increases bromide excretion and lowers serum bromide levels. · major
- Loop diuretics (e.g., furosemide) · Increases bromide excretion and decreases serum bromide concentrations. · moderate
- Phenobarbital · Synergistic GABA-ergic anticonvulsant effects. · minor
Monitorización
- Serum KBr concentrations (Therapeutic range: 0.8-1.5 mg/ml)
- Serum chloride (Note: KBr causes falsely elevated chloride readings on standard chemistry panels)
- Renal function (BUN, Creatinine, USG)
- Signs of excessive sedation, ataxia, or vomiting
- Pancreatic enzymes if clinical signs of pancreatitis develop
Sobredosis
Acute bromide toxicity (bromism) presents with profound sedation, ataxia, somnolence, and potentially vomiting. **Treatment of choice:** Intravenous administration of **0.9% NaCl (normal saline)**. The chloride in the saline competes with bromide for renal reabsorption, rapidly accelerating the renal excretion of bromide.
La referencia de fármacos de VetSheet está destinada a veterinarios colegiados como apoyo a la decisión clínica, no sustituye el juicio profesional ni la ficha técnica vigente del fabricante.