臭化カリウム
**臭化カリウム (KBr)** は、主にフェノバルビタール単独では不十分な場合や禁忌となる場合に、犬の難治性てんかんをコントロールするための補助療法または代替療法として使用される抗てんかん薬です。半減期が非常に長いため、初期に負荷用量（ローディングドーズ）を投与しない限り、定常状態の治療濃度に達するまでに数ヶ月を要します。 > **重大な警告**: 猫への投与は、重篤で致命的な好酸球性気管支炎を発症するリスクが高いため、絶対禁忌です。 **臨床のポイント:** 標準的な検査機器では臭化物イオンが塩化物イオンとして測定されるため、KBrを服用している患者では偽性高クロール血症（血清クロール値の偽性上昇）が認められます。
作用機序: 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).
動物種別の用量
- 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.
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Cats (causes severe, potentially fatal eosinophilic bronchitis)
- Dogs with a history of, or predisposition to, pancreatitis
有害事象
- 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)
薬物相互作用
- 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
モニタリング
- 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
過量投与
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.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。