Comparison of phenobarbital with bromide as a first-choice antiepileptic drug for treatment of epilepsy in dogs

Objective-To compare efficacy and safety of treatment with phenobarbital or bromide as the first-choice antiepileptic drug (AED) in dogs. Design-Double-blinded, randomized, parallel, clinical trial. Animals-46 AED-naive 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 mu g/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. (J Am Vet Med Assoc 2012;240:1073-1083)