フルドロコルチゾン酢酸エステル
フルドロコルチゾンは、主に獣医療においてその強力な**鉱質コルチコイド**特性のために利用される、強力な経口**合成コルチコステロイド**です。 * **主な適応症：** 犬や猫の**副腎皮質機能低下症（アジソン病）**の主要な治療薬であり、注射用DOCPの経口代替薬として機能します。 * **二重作用：** 鉱質コルチコイド作用（ヒドロコルチゾンの125倍の効力）のために使用されますが、有意な**糖質コルチコイド活性**（ヒドロコルチゾンの10〜15倍）も有しています。 * **臨床的ポイント：** その固有の糖質コルチコイド活性のため、フルドロコルチゾンで管理されている犬の約50％は、DOCPで治療されている犬とは異なり、毎日のプレドニゾン/プレドニゾロンの追加補充を必要としません。ただし、高用量では、この同じ糖質コルチコイド活性が医原性副腎皮質機能亢進症の兆候（多飲多尿、多食）を引き起こす可能性があります。
作用機序: Fludrocortisone acts as a potent agonist at mineralocorticoid receptors. * Binds to **cytosolic mineralocorticoid receptors** in the principal cells of the **renal distal tubules** and **collecting ducts** → translocates to the nucleus. * Upregulates the transcription of **epithelial sodium channels (ENaC)** on the apical membrane and **Na+/K+-ATPase pumps** on the basolateral membrane. * This mechanism → promotes active **sodium reabsorption** (and obligate water retention) while accelerating the excretion of **potassium** and **hydrogen ions** into the tubular lumen. * Also binds to **glucocorticoid receptors**, contributing to anti-inflammatory and metabolic effects (gluconeogenesis, protein catabolism).
動物種別の用量
- Maintenance therapy of hypoadrenocorticism · 0.02 mg/kg PO once daily · PO · once daily · Prednisone or prednisolone (1.25 mg per cat PO once daily) can be used for glucocorticoid replacement.
- Maintenance therapy of hypoadrenocorticism · 0.1 mg total dose/cat PO once daily · PO · once daily · Administer with prednisolone (0.2 mg/kg PO once daily).
- Hypoadrenocorticism · 0.05-0.1 mg/kg PO q24h or divided q12h · PO · q24h or divided q12h · For those animals that still exhibit Addisonian signs even with prednisone therapy.
- Hypoadrenocorticism · Initial dose of 0.01 mg/kg PO twice daily · PO · twice daily · Adjust dose based on monitoring serum electrolyte concentrations every 1-2 weeks until stable. Once stable, recheck every 3-4 months. Addition of NaCl (0.1 g/kg/day) can be useful in reducing the dose of fludrocortisone and reducing PU/PD.
- Maintenance of hypoadrenocorticism · Initially, 0.01-0.02 mg/kg/day PO and adjusted by 0.05-0.1 mg (total dose) increments · PO · daily · Adjust based on serial electrolyte determinations. Most dogs will ultimately require 0.02-0.03 mg/kg/day.
- Hypoadrenocorticism · 0.01 mg/kg PO twice daily · PO · twice daily · Titrate dose to effect; typically dose needs to be increased over time. Only 50% of dogs on fludrocortisone require supplemental prednisone.
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
- Known hypersensitivity to fludrocortisone
有害事象
- Polyuria (PU)
- Polydipsia (PD)
- Hypertension
- Edema
- Hypokalemia
- Hypernatremia
- Signs of iatrogenic Cushing's syndrome (due to glucocorticoid effects)
薬物相互作用
- Amphotericin B · Patients may develop hypokalemia if administered concomitantly.
- Aspirin · Fludrocortisone may reduce salicylate levels.
- Potassium-depleting diuretics (e.g., thiazides, furosemide) · May cause hypokalemia; diuretics can cause sodium loss, counteracting the effects of fludrocortisone.
- Insulin · Potentially increases the insulin requirements of diabetic patients.
モニタリング
- Serum electrolytes (Sodium, Potassium)
- BUN and Creatinine
- Body weight
- Physical examination for signs of edema or hypertension
- Clinical signs of PU/PD
過量投与
Overdosage is typically characterized by excessive mineralocorticoid effects: * **Clinical Signs:** Hypertension, edema, severe hypokalemia, and hypernatremia. Excessive glucocorticoid signs (severe PU/PD, panting) may also occur. * **Management:** Discontinue the drug until clinical signs associated with overdosage have resolved. Electrolytes should be aggressively monitored. Potassium supplementation may be required. Once resolved, restart the drug at a lower dosage.
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。