インスリン
インスリンは、ランゲルハンス島のβ細胞で産生される重要なペプチドホルモンです。獣医学における糖尿病および糖尿病性ケトアシドーシス（DKA）治療の基礎となります。 製剤は、作用発現と持続時間によって大まかに分類されます： * **短時間作用型（レギュラー、リスプロ）：** 主に病院内でDKAや重度の高カリウム血症の急性期安定化に使用されます。レギュラーインスリンは静脈内投与が可能な唯一の製剤です。 * **中間型（NPH、レンテ）：** 犬の維持療法に一般的に使用されます。豚インスリンは犬インスリンと構造的に同一であり、抗インスリン抗体形成のリスクを最小限に抑えます。 * **持続型（PZI、グラルギン、デテミル）：** 犬よりもインスリン代謝が速い猫の維持療法に頻繁に使用されます。 > **臨床のポイント：** 猫の糖尿病は人間の2型糖尿病に似ていることが多く、持続型インスリン（グラルギンなど）の早期かつ積極的な使用と低炭水化物食の組み合わせにより、寛解に至る可能性があります。犬の糖尿病は通常、人間の1型糖尿病に似ており、生涯にわたる外因性インスリン療法が必要です。
作用機序: Insulin initiates its action by binding to the **tyrosine kinase insulin receptor** on the cell membrane. **Mechanism Pathway:** Receptor binding → Autophosphorylation → Activation of **Insulin Receptor Substrates (IRS)** → Activation of the **PI3K/Akt pathway** → Translocation of **GLUT4** transport proteins to the cell surface → Rapid facilitated diffusion of glucose into skeletal muscle and adipose tissue. **Metabolic Effects:** * **Carbohydrate metabolism:** Promotes cellular glucose uptake and hepatic glycogenesis; inhibits glycogenolysis and gluconeogenesis. * **Lipid metabolism:** Stimulates lipogenesis and potently inhibits lipolysis and ketogenesis (crucial for resolving DKA). * **Protein metabolism:** Increases amino acid uptake and protein synthesis. * **Electrolyte shift:** Drives potassium and magnesium into the intracellular space (utilized therapeutically for life-threatening hyperkalemia).
動物種別の用量
- Diabetic ketoacidosis (Regular insulin) · Same protocol using regular insulin as described for dogs · IM, IV, SC · Varies · Until stabilized
- Diabetic ketoacidosis (Glargine) · 2 Units per cat SC and 1 Unit per cat IM (regardless of body weight) initially; repeat the IM dose 4 or more hours later if BG > 250-290 mg/dL; repeat the SC dose every 12 hours. · SC and IM · Initially, then q12h SC · Until stabilized
- Severe hyperkalemia · 0.5 to 1 Unit/kg IM regular insulin plus 2 grams dextrose per unit of insulin IV · IM · Once
- Uncomplicated diabetes mellitus (Glargine, Detemir, or PZI) · Blood glucose <360 mg/dL: 0.25 Units/kg of ideal body weight SC every 12 hours; Blood glucose >=360 mg/dL: 0.5 Units/kg of ideal body weight SC every 12 hours · SC · q12h · Lifelong · If no monitoring in first week, begin with 1 Unit per cat every 12 hours.
- Uncomplicated diabetes mellitus (ProZinc) · 0.2-0.7 Units/kg SC every 12 hours given concurrently with or right after a meal · SC · q12h · Lifelong · Goal: glucose nadir between 80 & 150 mg/dL.
- Uncomplicated diabetes mellitus (Vetsulin) · 0.5 Units/kg SC once daily · SC · q24h · Lifelong
- Uncomplicated diabetes mellitus (Lente) · 1 Unit per cat SC twice daily for cats <4kg & 1.5-2 Units/cat twice daily for cats >4kg. Alternatively: 0.25 Units/kg SC twice daily if BG 216-342 mg/dL; 0.5 Units/kg SC twice daily if BG>360mg/dL. · SC · q12h · Lifelong
- Diabetes mellitus · 0.5-1 Unit per ferret SC twice daily. Alternatively: 0.1-0.5 Units/kg IM or SC twice daily to start; adjust to optimal dose. · SC, IM · q12h · Lifelong · May require insulin to be diluted.
投与経路
禁忌
- Episodes of hypoglycemia (absolute contraindication)
- Systemic allergy to pork or pork products (specifically for Vetsulin/porcine lente)
有害事象
- Hypoglycemia (most common and potentially life-threatening)
- Insulin-induced hyperglycemia ('Somogyi effect' due to counter-regulatory hormone release following hypoglycemia)
- Insulin antagonism or resistance
- Rapid insulin metabolism
- Local hypersensitivity reactions to 'foreign' proteins
- Lipodystrophy at the injection site (if sites are not rotated)
薬物相互作用
- Beta-adrenergic blockers (e.g., propranolol) · Can have variable effects on glycemic control and can mask the clinical signs associated with hypoglycemia.
- Clonidine, Reserpine · Can mask the signs associated with hypoglycemia.
- Digoxin · Insulin alters serum potassium levels; concurrent use requires close monitoring for cardiac arrhythmias, especially with concurrent diuretics.
- Alcohol, Anabolic steroids, ACE inhibitors, Aspirin, Disopyramide, Fluoxetine, MAOIs, Somatostatin derivatives, Sulfonamides · May potentiate the hypoglycemic activity of insulin.
- Calcium channel blockers, Corticosteroids, Danazol, Diuretics, Isoniazid, Niacin, Phenothiazines, Thyroid hormones · May decrease the hypoglycemic activity of insulin (cause insulin resistance).
モニタリング
- Blood glucose (serial curves or continuous monitoring)
- Patient weight
- Appetite and water intake
- Urine output
- Blood or urine ketones (if DKA suspected)
- Fructosamine (goal <450 micromol/L) or glycosylated hemoglobin
過量投与
Overdosage of insulin leads to **hypoglycemia**, which can be rapidly fatal or cause permanent brain damage if untreated. **Clinical Signs:** * Weakness, lethargy, ataxia * Shaking, muscle fasciculations * Head tilting, bizarre behavior, blindness * Restlessness, extreme hunger * Seizures and coma **Treatment:** * **Mild:** Offer the animal its usual food. * **Severe (e.g., seizures):** Rub oral dextrose solutions (e.g., **Karo® syrup**) on the oral mucosa (do not pour down the throat to avoid aspiration). * **Veterinary Intervention:** Intravenous injections of 50% dextrose solutions (small amounts, slowly administered—usually 2-15 mL). * **Monitoring:** Once alleviated (usually within 1-2 minutes), monitor closely with serial blood glucose levels to prevent recurrence (especially with long-acting insulins) and adjust future doses.
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。