ジクロルフェナミド
**ジクロルフェナミド**は全身性の**炭酸脱水酵素阻害薬（CAI）**であり、獣医眼科において**緑内障**の内科的治療に従来使用されてきました。 * **臨床のポイント**: 代謝性アシドーシスや低カリウム血症などの重大な全身性副作用と、商業的な入手の困難さから、全身性CAIは現在、**ドルゾラミド**や**ブリンゾラミド**などの局所点眼薬に大きく取って代わられています。 * 現在処方される場合、通常は調剤薬局（コンパウンディング薬局）を通じて入手する必要があります。 * 軽度の抗けいれん作用および利尿作用を持っていますが、現代の獣医学においてこれらの適応で使用されることは稀です。
作用機序: Dichlorphenamide exerts its effects via noncompetitive, reversible inhibition of the enzyme **carbonic anhydrase (CA)**. * **In the ciliary body**: Inhibition of **CA-II** → decreased formation of bicarbonate (HCO3-) and hydrogen (H+) ions from carbon dioxide and water → reduced active transport of sodium into the posterior chamber → decreased aqueous humor production → **lowered intraocular pressure (IOP)**. * **In the kidneys**: Inhibits CA in the proximal convoluted tubule → increased renal tubular secretion of Na+, K+, and HCO3- → alkaline diuresis and potential metabolic acidosis. * **In the CNS**: Exhibits mild anticonvulsant activity, likely secondary to localized metabolic acidosis or direct CA inhibition in the brain.
動物種別の用量
- Adjunctive treatment of glaucoma · 0.5-1.5 mg/kg PO two to three times daily · PO · q8-12h
- Adjunctive treatment of glaucoma · 1-2 mg/kg PO q8-12h · PO · q8-12h
- Adjunctive treatment of glaucoma · 2.2-4.4 mg/kg PO two to three times daily (q8-12h) · PO · q8-12h
- Adjunctive treatment of glaucoma · 10-15 mg/kg per day divided 2-3 times daily · PO · divided 2-3 times daily
- Adjunctive treatment of glaucoma · 2-5 mg/kg PO q8-12h · PO · q8-12h
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
- Significant hepatic disease (may precipitate hepatic coma)
- Renal or adrenocortical insufficiency
- Hyponatremia
- Hypokalemia
- Hyperchloremic acidosis
- Electrolyte imbalance
- Severe pulmonary obstruction (unable to increase alveolar ventilation)
- Hypersensitivity to carbonic anhydrase inhibitors
- Chronic, noncongestive, angle-closure glaucoma (long-term use)
有害事象
- Panting
- GI disturbances (inappetence, vomiting, diarrhea)
- CNS effects (sedation, depression, excitement)
- Hematologic effects (bone marrow depression)
- Renal effects (crystalluria, dysuria, renal colic, polyuria)
- Metabolic acidosis
- Hypokalemia
- Hyperglycemia
- Hyponatremia
- Hyperuricemia
- Hepatic insufficiency
- Dermatologic effects (rash)
- Hypersensitivity reactions
薬物相互作用
- Antidepressants, Tricyclic · Alkaline urine caused by dichlorphenamide may decrease excretion of tricyclic antidepressants.
- Aspirin (or other salicylates) · Increased risk of dichlorphenamide accumulation and toxicity; increased risk for metabolic acidosis; dichlorphenamide increases salicylate excretion.
- Digoxin · Dichlorphenamide may cause hypokalemia, leading to an increased risk for digoxin toxicity.
- Insulin · Rarely, carbonic anhydrase inhibitors interfere with the hypoglycemic effects of insulin.
- Methenamine compounds · Dichlorphenamide may negate the effects of methenamine in the urine due to alkalinization.
- Potassium-depleting drugs (corticosteroids, amphotericin B, corticotropin, diuretics) · Concomitant use may exacerbate potassium depletion.
- Phenobarbital · Increased urinary excretion, which may reduce phenobarbital levels.
- Primidone · Decreased primidone concentrations.
- Quinidine · Alkaline urine caused by dichlorphenamide may decrease quinidine excretion.
モニタリング
- Intraocular pressure (IOP) / tonometry
- Serum electrolytes (may need to supplement potassium)
- Baseline CBC with differential and periodic retests if using chronically
- Clinical signs of adverse effects (GI upset, panting, CNS changes)
過量投与
Information regarding acute toxicity of dichlorphenamide is limited. * **Clinical Signs**: Likely extensions of adverse effects, including severe electrolyte derangements (hypokalemia, hyponatremia), profound metabolic acidosis, CNS depression, and dehydration. * **Treatment**: * Monitor serum electrolytes, blood gases, volume status, and CNS status. * Provide aggressive supportive care, including IV fluid therapy to correct dehydration and acid-base/electrolyte imbalances (e.g., potassium supplementation). Treat symptomatically.
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。