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 Assoc 2002;221:1131–1135)
Animals—46 AED-naïve dogs with naturally occurring epilepsy.
Procedures—Study inclusion was based on age, history, findings on physical and neurologic examinations, and clinicopathologic test results. For either phenobarbital treatment (21 dogs) or bromide treatment (25), a 7-day loading dose period was initiated along with a maintenance dose, which was adjusted on the basis of monthly monitoring. Efficacy and safety outcomes were compared between times (baseline and study end [generally 6 months]) and between drugs.
Results—Phenobarbital treatment resulted in eradication of seizures (17/20 [85%]) significantly more often than did bromide (12/23 [52%]); phenobarbital treatment also resulted in a greater percentage decrease in seizure duration (88 ± 34%), compared with bromide (49 ± 75%). Seizure activity worsened in 3 bromide-treated dogs only. In dogs with seizure eradication, mean ± SD serum phenobarbital concentration was 25 ± 6 μg/mL (phenobarbital dosage, 4.1 ± 1.1 mg/kg [1.9 ± 0.5 mg/lb], PO, q 12 h) and mean serum bromide concentration was 1.8 ± 0.6 mg/mL (bromide dosage, 31 ± 11 mg/kg [14 ± 5 mg/lb], PO, q 12 h). Ataxia, lethargy, and polydipsia were greater at 1 month for phenobarbital-treated dogs; vomiting was greater for bromide-treated dogs at 1 month and study end.
Conclusions and Clinical Relevance—Both phenobarbital and bromide were reasonable first-choice AEDs for dogs, but phenobarbital was more effective and better tolerated during the first 6 months of treatment.