Disposition and clinical use of bromide in cats

Abstract
Objective—To establish a dosing regimen for potassium bromide and evaluate use of bromide to treat spontaneous seizures in cats.Design—Prospective and retrospective studies.Animals—7 healthy adult male cats and records of 17 cats with seizures.Procedure—Seven healthy cats were administered potassium bromide (15 mg/kg [6.8 mg/lb], PO, q 12 h) until steady-state concentrations were reached. Serum samples for pharmacokinetic analysis were obtained weekly until bromide concentrations were not detectable. Clinical data were obtained from records of 17 treated cats.Results—In the prospective study, maximum serum bromide concentration was 1.1 ± 0.2 mg/mL at 8 weeks. Mean disappearance half-life was 1.6 ± 0.2 weeks. Steady state was achieved at a mean of 5.3 ± 1.1 weeks. No adverse effects were detected and bromide was well tolerated. In the retrospective study, administration of bromide (n = 4) or bromide and phenobarbital (3) was associated with eradication of seizures in 7 of 15 cats (serum bromide concentration range, 1.0 to 1.6 mg/mL); however, bromide administration was associated with adverse effects in 8 of 16 cats. Coughing developed in 6 of these cats, leading to euthanasia in 1 cat and discontinuation of bromide administration in 2 cats.Conclusions and Clinical Relevance—Therapeutic concentrations of bromide are attained within 2 weeks in cats that receive 30 mg/kg/d (13.6 mg/lb/d) orally. Although somewhat effective in seizure control, the incidence of adverse effects may not warrant routine use of bromide for control of seizures in cats. (J Am Vet Med Assoc2002;221:1131–1135)