普魯本辛 (溴丙胺太林)
**普魯本辛 (Propantheline bromide)** 是一種合成的四級銨抗毒蕈鹼（抗膽鹼）藥物。在獸醫學中主要利用其解痙和抗分泌的特性。 **主要臨床用途：** * **小動物：** 用於治療腹瀉、逼尿肌反射亢進（急迫性尿失禁）以及對抗膽鹼藥物有反應的心搏過緩。 * **馬匹：** 透過靜脈注射來減少結腸蠕動並放鬆直腸，使直腸檢查與手術更為安全順利。 **臨床要點：** 由於普魯本辛是一種四級銨化合物，它帶有永久的正電荷且具高度水溶性。這種結構特徵使其不易穿透血腦屏障 (BBB) 或進入眼部。因此，與阿托品 (atropine) 等三級胺相比，它能提供周邊抗膽鹼作用（如腸胃道放鬆和心率提升），同時大幅減少中樞神經系統 (CNS) 或眼部的副作用。
作用機制: **Propantheline** acts as a competitive antagonist at **muscarinic acetylcholine receptors** (primarily M1, M2, and M3 subtypes) located on smooth muscle, cardiac muscle, and exocrine glands. * **Gastrointestinal Tract:** Blockade of M3 receptors → decreased smooth muscle tone and peristalsis (antispasmodic effect) + reduced gastric acid secretion. * **Urinary Tract:** Blockade of M3 receptors on the detrusor muscle → relaxation of the bladder wall → increased bladder capacity and reduced urge incontinence. * **Cardiovascular System:** Blockade of M2 receptors on the sinoatrial (SA) node → vagolytic effect → increased heart rate. * **Exocrine Glands:** Blockade of muscarinic receptors → decreased salivation and respiratory secretions.
各物種劑量
- Detrusor hyperreflexia, urge incontinence · 0.25-0.5 mg/kg PO q12-24h · PO · q12-24h · Empirical dosage. Further studies required to substantiate beneficial effect.
- Detrusor hyperreflexia, urge incontinence · 5-7.5 mg (total dose) PO once a day to once every 3 days · PO · q24h to q72h
- Detrusor hyperreflexia, urge incontinence · 5-7.5 mg (total dose) PO q8h; 7.5 mg PO q72h · PO · q8h or q72h
- Sinus bradycardia, incomplete AV block, etc. · 0.8-1.6 mg/kg three times daily · PO · TID · Although generally ineffective, a trial may be attempted.
- Sinus bradycardia, incomplete AV block, etc. · 7.5 mg PO q8-12h · PO · q8-12h · Usually well tolerated, but improvement is usually partial and often temporary.
- Chronic colitis · 0.5 mg/kg two to three times daily · PO · BID-TID
- As an antiemetic/antidiarrheal · 0.25 mg/kg PO q8h · PO · q8h
- To reduce rectal contractions during oocyte collection · 0.04 mg/kg IV · IV · Once · Must be freshly prepared and filtered through a 0.22 micron-filter from oral tablets.
- To inhibit peristalsis for 2 hours during rectal surgery · 30 mg IV · IV · Once · Must be freshly prepared and filtered through a 0.22 micron-filter from oral tablets.
給藥途徑
禁忌症
- Hypersensitivity to anticholinergics
- Tachycardias secondary to thyrotoxicosis or cardiac insufficiency
- Myocardial ischemia
- Unstable cardiac status during acute hemorrhage
- Gastrointestinal obstructive disease
- Paralytic ileus
- Severe ulcerative colitis
- Obstructive uropathy
- Myasthenia gravis (unless used to reverse adverse muscarinic effects secondary to therapy)
不良反應
- Dry mouth (xerostomia)
- Dry eyes (keratoconjunctivitis sicca)
- Urinary hesitancy or retention
- Tachycardia
- Constipation
- Vomiting (especially in cats)
- Hypersalivation (especially in cats)
- Ileus (at high doses, potentially leading to bacterial overgrowth)
藥物相互作用
- Antihistamines · May enhance the anticholinergic activity of propantheline.
- Benzodiazepines · May enhance the activity of propantheline.
- Cimetidine · Propantheline may decrease the absorption of cimetidine.
- Corticosteroids · Long-term concurrent use may increase intraocular pressure.
- Meperidine · May enhance the activity of propantheline.
- Nitrates · May potentiate the adverse effects of propantheline.
- Nitrofurantoin · Propantheline may enhance the actions of nitrofurantoin.
- Phenothiazines · May enhance the anticholinergic activity of propantheline.
- Sympathomimetics · Propantheline may enhance their actions.
- Ranitidine · Propantheline delays absorption but increases peak serum levels of ranitidine; relative bioavailability of ranitidine may increase by 23%.
- Thiazide Diuretics · Propantheline may enhance their actions.
監測
- Clinical efficacy (resolution of diarrhea, incontinence, or bradycardia)
- Heart rate and rhythm (if indicated)
- Adverse effects (dry mouth, constipation, urinary retention)
過量
**Toxicity Profile:** Because of its quaternary structure, minimal CNS effects are expected following an overdose compared to tertiary amines like atropine. **Treatment:** * **Decontamination:** If recent oral ingestion, empty gut contents and administer activated charcoal and saline cathartics. * **Supportive Care:** Treat clinical signs symptomatically. Fluid therapy and standard treatments for shock may be instituted. **Do not use phenothiazines** as they may exacerbate anticholinergic effects. * **Antidote (Physostigmine):** Controversial. Reserve for extreme agitation/risk of injury, or severe/life-threatening supraventricular and sinus tachycardias. * *Human pediatric dose (reasonable for small animals):* 0.02 mg/kg slow IV; may repeat q10 minutes until reversal of toxic effects. * *Note:* Physostigmine adverse effects (bronchoconstriction, bradycardia, seizures) may be treated with small doses of IV atropine.
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