奧昔布寧
奧昔布寧是一種泌尿生殖道平滑肌鬆弛劑和抗膽鹼藥物。在獸醫學中，主要作為輔助療法，用於治療犬隻的**逼尿肌反射亢進**（膀胱過動症或急迫性尿失禁），以及患有貓白血病病毒（FeLV）相關逼尿肌不穩定的貓咪。 主要臨床重點： * 作為泌尿道抗痙攣藥，可增加膀胱容量並減少不受抑制的收縮。 * 兼具直接平滑肌鬆弛特性與抗膽鹼作用。 * **臨床提示：** 由於其抗膽鹼特性，對於副交感神經張力降低會使病情惡化的患者（如青光眼、胃腸道停滯、心搏過速性心律不整），應極度謹慎使用。
作用機制: Oxybutynin exerts its effects via a dual mechanism of action on the lower urinary tract: 1. **Antimuscarinic (atropine-like) effect:** It competitively antagonizes acetylcholine at postganglionic muscarinic receptors. It has a high affinity for **M1, M2, and M3 receptors**, with M3 being the primary receptor mediating bladder detrusor contraction. 2. **Direct spasmolytic (papaverine-like) effect:** It directly relaxes smooth muscle independent of its anticholinergic activity. These combined actions → relaxation of the bladder detrusor muscle → **increased maximum bladder capacity** → **decreased frequency and amplitude of uninhibited detrusor contractions** → delayed initial desire to void.
各物種劑量
- To decrease bladder contractility (detrusor hyperreflexia) · 0.5-1 mg (total dose) · PO · q8-12h · Juvenile animals may require a prolonged dosing interval.
- To decrease bladder contractility (detrusor hyperreflexia) · 0.5-1.25 mg per cat · PO · q8-12h
- Detrusor hyperreflexia · 0.5-1.25 mg per cat · PO · q8-12h
- To decrease bladder contractility (detrusor hyperreflexia) · 0.2 mg/kg · PO · q8-12h · Most dogs are dosed at 1.25-3.75 mg (total dose) q12h. Juvenile animals may require a prolonged dosing interval.
- To decrease bladder contractility (detrusor hyperreflexia) · 1.25-5 mg (total dose) · PO · q8-12h
- To decrease bladder contractility (detrusor hyperreflexia) · 2-5 mg (total dose) · PO · q8-12h
- Detrusor hyperreflexia (refractory incontinence) · 0.2 mg/kg · PO · q8-12h
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- Obstructive GI tract disease
- Intestinal atony or paralytic ileus
- Angle closure glaucoma
- Hiatal hernia
- Cardiac disease (especially mitral stenosis, arrhythmias, tachycardia, CHF)
- Myasthenia gravis
- Hyperthyroidism
- Prostatic hypertrophy
- Severe ulcerative colitis
- Urinary retention or other obstructive uropathies
- Obstructive GI disease
- Ileus
- Gastrooesophageal reflux
- Glaucoma
- Cardiac disease
- Obstructive urinary disease
不良反應
- Diarrhea
- Constipation
- Urinary retention
- Hypersalivation
- Sedation
- Dry mouth (xerostomia)
- Dry eyes (keratoconjunctivitis sicca)
- Tachycardia
- Anorexia
- Vomiting
- Weakness
- Mydriasis (pupil dilation)
- Diarrhoea
- Dry mouth
- Dry eyes
- Skin reactions
- Palpitations
藥物相互作用
- Anticholinergic agents (e.g., atropine, propantheline, tricyclic antidepressants, antihistamines) · May intensify oxybutynin's anticholinergic adverse effects.
- Azole antifungals (e.g., ketoconazole) · May inhibit metabolism and increase oxybutynin systemic levels.
- CNS depressants · May exacerbate the sedating effects of oxybutynin. · moderate
- Macrolide antibiotics (e.g., erythromycin, clarithromycin) · May inhibit metabolism and increase oxybutynin systemic levels.
- Anticholinergic agents · Additive anticholinergic side effects (e.g., severe constipation, urinary retention, tachycardia) · major
- Azole antifungals · Potential CYP inhibition leading to increased oxybutynin plasma concentrations · moderate
- Macrolide antibiotics · Potential CYP inhibition leading to increased oxybutynin plasma concentrations · moderate
監測
- Clinical efficacy (reduction in urinary incontinence or frequency)
- Adverse effects (signs of anticholinergic toxicity such as dry mouth, tachycardia, constipation, or urinary retention)
- Urinary output and frequency
- Heart rate
- Bowel movements (monitor for constipation)
- Signs of excessive sedation
過量
Overdosage can lead to severe anticholinergic toxicity. * **CNS effects:** Restlessness, excitement, seizures. * **Cardiovascular effects:** Hypertension or hypotension, tachycardia, circulatory failure. * **Other signs:** Fever, nausea, vomiting. * **Massive overdose:** May lead to paralysis, coma, respiratory failure, and death. **Treatment:** Consists of general techniques to limit GI absorption (e.g., emesis, activated charcoal) and supportive care. Intravenous **physostigmine** may be useful to reverse severe anticholinergic signs.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。