プロプラノロール
プロプラノロールは**非選択的βアドレナリン受容体拮抗薬**（β遮断薬）であり、獣医学では主に**抗不整脈薬**として使用されます。クラスII抗不整脈薬に分類されます。 * **主な用途：** 上室性および心室性頻脈性不整脈（APC、VPC、心房細動など）、肥大型心筋症（HCM）、および全身性高血圧の管理。 * **内分泌疾患での用途：** **猫の甲状腺機能亢進症**や褐色細胞腫における交感神経過剰刺激による心血管系および神経筋肉系の症状を制御するために頻繁に使用されます。 * **行動学的な用途：** 犬の状況不安や大きな音に対する恐怖症に対して適応外使用されることがあります。 > **臨床上のポイント：** プロプラノロールは非選択的であるため、心臓と肺の両方の受容体を遮断します。猫喘息やその他の気管支痙攣性気道疾患を持つ患者には、極めて慎重に使用するか、使用を避けるべきです。
作用機序: Propranolol acts via **competitive blockade of both $\beta_1$ and $\beta_2$ adrenergic receptors**. * **$\beta_1$ Blockade (Cardiac):** $\rightarrow$ Decreases sinus heart rate (negative chronotropy) $\rightarrow$ Depresses AV node conduction (negative dromotropy) $\rightarrow$ Decreases myocardial contractility (negative inotropy) $\rightarrow$ Ultimately reduces cardiac output and myocardial oxygen demand. * **$\beta_2$ Blockade (Pulmonary/Vascular):** $\rightarrow$ Can cause bronchoconstriction and peripheral vasoconstriction. * **Additional Effects:** Possesses **membrane-stabilizing (quinidine-like) effects** at higher doses, which alters the cardiac action potential. It lacks intrinsic sympathomimetic activity (ISA) and inhibits glycogenolysis.
動物種別の用量
- Susceptible cardiac arrhythmias · 0.02 mg/kg IV slowly (up to a maximum of 1 mg/kg) · IV · As needed
- Susceptible cardiac arrhythmias · 2.5 mg (up to 10 mg) total dose per cat q 8-12h. · PO · q8-12h
- Susceptible cardiac arrhythmias · 0.02 mg/kg IV over one minute; can repeat up to a maximum of four times as needed based upon response · IV · As needed
- Adjunctive therapy in heart failure · 2.5-10 mg (total dose) PO q8h (start low and titrate) · PO · q8h
- Adjunctive therapy of hypertension · 2.5-5 mg (total dose) PO q8-12h · PO · q8-12h
- Adjunctive therapy in feline hyperthyroidism · 2 mg/kg (6.25 mg per cat) once daily · PO · q24h · To control neuromuscular and cardiovascular effects
- Hypertrophic cardiomyopathy · 0.5-2 mg/kg PO or SC once a day to twice a day · PO/SC · q12-24h
- Hypertrophic cardiomyopathy · 0.2-2 mg/kg PO q8-12h. · PO · q8-12h
- V-Tach · 0.05-0.16 mg/kg IV · IV · Single dose · Negative inotropic and chronotropic effects may be undesirable.
- V-Tach · 0.03-0.15 mg/kg IV · IV · Single dose · Considered not as effective as lidocaine; decreases ventricular rate even if it does not restore sinus rhythm. Use with caution in animals with airway disease.
投与経路
禁忌
- Overt heart failure
- Hypersensitivity to beta-blockers
- Greater than 1st degree heart block
- Sinus bradycardia
- Congestive heart failure (unless secondary to a tachyarrhythmia responsive to beta-blockers)
- Bronchospastic lung disease (e.g., feline asthma)
- Bradyarrhythmias
- Acute or decompensated congestive heart failure
- Concurrent administration with alpha-adrenergic agonists (e.g., adrenaline)
有害事象
- Bradycardia
- Lethargy and depression
- Impaired AV conduction
- Congestive heart failure (CHF) or worsening of heart failure
- Hypotension
- Syncope
- Diarrhea
- Hypoglycemia
- Bronchoconstriction
- AV block
- Myocardial depression
- Heart failure
- Hypoglycaemia
- Bronchospasm
- Diarrhoea
- Peripheral vasoconstriction
- Depression
薬物相互作用
- Antacids · May reduce oral propranolol absorption; separate doses by at least one hour
- Anesthetics, General · Additive myocardial depression may occur
- Anticholinergics · May negate cardiac effects of beta-blockers
- Calcium Channel Blockers · Concurrent use should be done with caution due to additive negative inotropic effects, particularly in patients with cardiomyopathy or CHF
- Cimetidine · May decrease the metabolism of propranolol and increase blood levels · moderate
- Diuretics · May increase risk for hypotension · moderate
- Epinephrine · Unopposed alpha effects of epinephrine may lead to rapid increases in blood pressure and decrease in heart rate
- Fluoxetine · May decrease propranolol metabolism; complete heart block reported in one human
- Insulin and Antidiabetic Drugs · Propranolol may prolong the hypoglycemic effects of insulin therapy
- Lidocaine · Clearance may be impaired by propranolol · major
- Methimazole, Propylthiouracil · Propranolol doses may need to be decreased when initiating therapy
- Phenobarbital · May increase the metabolism of propranolol · moderate
モニタリング
- ECG (Electrocardiogram)
- Signs of toxicity (bradycardia, hypotension, lethargy)
- Blood pressure (especially if administering IV)
- Heart rate and rhythm (ECG)
- Blood pressure
- Signs of congestive heart failure (e.g., respiratory rate/effort)
- Blood glucose (especially in diabetic patients receiving insulin)
過量投与
**Clinical Signs:** The most predominant expected signs are **hypotension** and **bradycardia**. Other possible effects include CNS depression (ranging from depressed consciousness to seizures), bronchospasm, hypoglycemia, hyperkalemia, respiratory depression, pulmonary edema, AV block, or asystole. **Treatment:** * **Decontamination:** If recent oral ingestion, consider emptying the gut and administering activated charcoal. * **Monitoring:** Monitor ECG, blood glucose, potassium, and blood pressure. * **Cardiovascular Support:** Use IV fluids and pressor agents for hypotension. Treat bradycardia with **atropine**; if atropine fails, cautiously administer **isoproterenol**. A transvenous pacemaker may be necessary. * **Heart Failure:** Treat with digoxin, diuretics, oxygen, and IV aminophylline if necessary. * **Antidotal Therapy:** **Glucagon** (5-10 mg IV; human dose) may increase heart rate and blood pressure, reducing the cardiodepressant effects of propranolol. * **Seizures:** Generally respond to IV diazepam.
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。