糖質コルチコイド
糖質コルチコイドは、哺乳類のほぼすべての細胞型およびシステムに深い影響を与えるステロイドホルモンの広範なクラスです。獣医学では、主に以下の4つの幅広い用量範囲と適応症で使用されます： * **生理的補充療法：** 副腎皮質機能低下症（アジソン病など）の患者向け。 * **抗炎症：** アレルギー状態、呼吸器疾患（喘息）、皮膚疾患、変形性関節症の管理。 * **免疫抑制：** 免疫介在性溶血性貧血（IMHA）、血小板減少症、天疱瘡、全身性エリテマトーデスなどの自己免疫疾患向け。 * **抗腫瘍：** 特定の腫瘍（リンパ腫など）における細胞毒性薬として。 **臨床のポイント：** 猫は通常、犬よりも高い用量を必要としますが、副作用に対する耐性が強い傾向があります。逆に、犬は糖質コルチコイドに非常に敏感であり、長期使用により医原性副腎皮質機能亢進症（クッシング症候群）を容易に発症します。
作用機序: Glucocorticoids exert their effects primarily by binding to cytosolic **glucocorticoid receptors (GR)**. The receptor-ligand complex translocates to the nucleus, where it binds to glucocorticoid response elements (GREs) on DNA, altering gene transcription (transactivation and transrepression). * **Anti-inflammatory Pathway:** They induce the production of **lipocortin (annexin-1)**, which inhibits **phospholipase A2**. This blocks the release of **arachidonic acid** from cell membranes → dramatically decreasing the synthesis of both **prostaglandins** and **leukotrienes**. * **Immune Suppression:** They inhibit macrophage function, decrease circulating T-lymphocytes, suppress inflammatory cytokines (IL-1, IL-6, TNF-alpha), and inhibit the complement cascade. * **Metabolic Effects:** Stimulate gluconeogenesis, mobilize amino acids, and redistribute adipose tissue, which can lead to insulin resistance.
動物種別の用量
- Anti-inflammatory (Prednisolone equivalent) · 1.0-2.0 mg/kg · PO · q12h to q24h · Taper to lowest effective alternate-day dose · Cats require higher doses than dogs and should receive prednisolone, not prednisone.
- Immunosuppressive (Prednisolone equivalent) · 2.0-4.0 mg/kg · PO · q12h to q24h · Taper slowly over weeks to months · Monitor for signs of diabetes mellitus.
- Anti-inflammatory (Prednisolone equivalent) · 0.5-1.0 mg/kg · PO · q12h to q24h · Taper to lowest effective alternate-day dose · Doses are highly variable depending on the specific glucocorticoid used.
- Immunosuppressive (Prednisolone equivalent) · 2.0-4.0 mg/kg · PO · q24h (divided q12h initially) · Taper slowly over weeks to months · Monitor closely for severe adverse effects at these doses.
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
- Systemic fungal infections (unless used for physiologic replacement)
- Intramuscular administration in patients with idiopathic thrombocytopenia
- Known hypersensitivity to the specific compound
- Chronic use of sustained-release injectables for systemic diseases
- Concurrent use with NSAIDs (relative contraindication due to severe GI ulcer risk)
- Pregnant animals
- Renal disease (systemic use)
- Diabetes mellitus (systemic use)
- Systemic fungal infections
- Corneal ulcers
- Concurrent use of NSAIDs
- Uncontrolled diabetes mellitus
- Late pregnancy (may induce abortion or parturition)
有害事象
- Polyuria (PU), polydipsia (PD), and polyphagia (PP)
- Weight gain and fat redistribution
- Panting (especially in dogs)
- Dull, dry haircoat and alopecia
- Vomiting and diarrhea
- Gastrointestinal ulceration
- Elevated liver enzymes (ALP > ALT) and vacuolar hepatopathy (dogs)
- Pancreatitis
- Insulin resistance leading to or worsening diabetes mellitus
- Muscle wasting and weakness
- Behavioral changes (depression, lethargy, viciousness)
- Iatrogenic hyperadrenocorticism (Cushing's syndrome) with chronic use
- Laminitis (horses)
- Hypothalamic-pituitary axis (HPA) suppression
- Adrenal atrophy
薬物相互作用
- Amphotericin B · May cause hypokalemia when administered concomitantly
- Anticholinesterase agents (e.g., pyridostigmine) · May lead to profound muscle weakness in myasthenia gravis patients; discontinue 24h prior if possible
- Aspirin (salicylates) · Glucocorticoids may reduce salicylate blood levels; increased risk of GI ulceration
- Cyclophosphamide · Glucocorticoids may inhibit hepatic metabolism of cyclophosphamide
- Cyclosporine · May mutually inhibit hepatic metabolism, increasing blood levels of both drugs
- Digoxin · Increased risk for arrhythmias secondary to glucocorticoid-induced hypokalemia
- Diuretics (potassium-depleting, e.g., furosemide) · May cause additive hypokalemia
- Ephedrine · May increase glucocorticoid metabolism
- Estrogens · May potentiate the effects of hydrocortisone and possibly other glucocorticoids
- Insulin · Insulin requirements may increase due to glucocorticoid-induced insulin resistance · moderate
- Ketoconazole · May decrease glucocorticoid metabolism
- Mitotane · May alter steroid metabolism; higher steroid doses may be necessary to treat mitotane-induced adrenal insufficiency
モニタリング
- Weight, appetite, and signs of edema
- Serum and/or urine electrolytes (potassium, calcium, sodium)
- Total plasma proteins and albumin
- Blood glucose
- Liver enzymes (ALP, ALT, GGT)
- Growth and development in young animals
- ACTH stimulation test (if assessing adrenal recovery or iatrogenic Cushing's)
- Clinical signs of hyperadrenocorticism
- Blood glucose (especially in diabetics)
- Electrolytes (potassium)
- Thyroid panel (T3/T4 may decrease)
- Clinical signs of PU/PD and weight gain
- Blood glucose (due to diabetes mellitus risk)
- ACTH stimulation test (to monitor HPA axis suppression)
- Water intake and urine output
過量投与
Short-term massive overdoses are unlikely to cause acute harmful effects, though one case of acute CNS effects in a dog has been reported (treat supportively). Chronic overdosage leads to serious adverse effects manifesting as iatrogenic hyperadrenocorticism (Cushing's syndrome).
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。