酚苄明
Phenoxybenzamine
Phenoxybenzamine HCl
別名: Dibenzyline · Dibenyline · SKF-688A · Dibenzyran · Fenoxene · Phenoxybenzaminum
由 VetSheet 獸醫團隊審訂更新於 2026年4月5日本內容以實證獸醫文獻為本
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
各物種劑量
🌎 NA — North America🌍 EU — Europe
狗
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Functional urethral obstruction | 0.25 mg/kg | PO | q12-24h | — | 🌎 NA |
| Functional urethral obstruction | 0.25 mg/kg | PO | q12h | — | 🌎 NA |
| Functional urethral obstruction | 0.25-0.5 mg/kg | PO | once or twice daily | — | 🌎 NA |
| Functional urethral obstruction | 5-15 mg (total dose) | PO | q12h | — | 🌎 NA |
| Hypertension associated with pheochromocytoma (pre-surgical) | Initially 0.5 mg/kg, gradually increase every few days until clinical signs of hypotension, adverse reactions, or max dosage of 2.5 mg/kg is attained | PO | twice daily | 1-2 weeks prior to surgery | 🌎 NA |
| Hypertension associated with pheochromocytoma (medical management) | Initial dose 0.25 mg/kg, gradually increase every few days until signs of hypotension, adverse reaction, or max dosage of 2.5 mg/kg is attained | PO | twice daily | Long-term | 🌎 NA |
| Adjunctive treatment of endotoxicosis | 0.25-0.5 mg/kg | PO | q6h | — | 🌎 NA |
- Functional urethral obstruction: Alternative dose: 2.5-20 mg (total dose) PO q12-24h
- Hypertension associated with pheochromocytoma (pre-surgical): Continue until the time of surgery. Close perioperative monitoring is critical.
- Hypertension associated with pheochromocytoma (medical management): Beta-blockers may be added for severe tachycardia, but NEVER without prior alpha-blockade to avoid severe hypertension.
- Adjunctive treatment of endotoxicosis: Use with appropriate antimicrobials, steroids, and supportive care.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Functional urethral obstruction | 2.5-7.5 mg/cat | PO | once to twice daily | — | 🌎 NA |
| Functional urethral obstruction | 1.25-7.5 mg (total dose) | PO | q12-24h | — | 🌎 NA |
| Functional urethral obstruction | 2.5-10 mg (total dose) | PO | q24h | — | 🌎 NA |
| Short-term treatment of hypertension | 0.5 mg/kg | PO | q12h | — | 🌎 NA |
| Short-term treatment of hypertension | 2.5 mg (total dose) increasing by 2.5 mg up to a maximum of 10 mg (total dose) | PO | q12h | — | 🌎 NA |
| Short-term treatment of hypertension | 2.5-7.5 mg per cat | PO | q8-12h | — | 🌎 NA |
馬
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Decrease urethral sphincter tone in bladder paresis | 0.7 mg/kg | PO | 4 times a day | — | 🌎 NA |
| Adjunctive treatment of laminitis (developmental phase) | 1 mg/kg | IV | q12h | for 2 doses | 🌎 NA |
| Treatment of profuse, watery diarrhea | 200-600 mg | — | q12h | — | 🌎 NA |
- Decrease urethral sphincter tone in bladder paresis: Used in combination with bethanechol at 0.25-0.75 mg/kg PO 2-4 times a day.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
概覽
酚苄明是一種長效、非競爭性的α-腎上腺素受體拮抗劑。
在獸醫學中，主要用於：
- 小動物：降低尿道內括約肌張力，以治療功能性尿道阻塞或逼尿肌無反射。它也是嗜鉻細胞瘤病患關鍵的術前藥物，用於預防手術操作腫瘤時引發致命的高血壓危象。
- 馬：特殊應用包括治療早期蹄葉炎、分泌性腹瀉和膀胱輕癱。
臨床要點：由於酚苄明與受體發生不可逆結合，其作用時間長，且必須等待身體合成新的受體才能恢復，此過程通常需要數天時間。
作用機制
Phenoxybenzamine covalently and irreversibly binds to alpha-1 and alpha-2 adrenergic receptors → non-competitive blockade of circulating epinephrine and norepinephrine → profound vasodilation and relaxation of smooth muscle.
- Urinary Tract: Blockade of alpha receptors in the trigone and internal urethral sphincter → decreased urethral resistance → facilitation of bladder emptying.
- Cardiovascular: Blockade of vascular alpha receptors → decreased peripheral vascular resistance → lowered blood pressure (often causing reflex tachycardia).
Because the binding is irreversible, the effect is often described as a 'chemical sympathectomy'. It has no effect on beta-adrenergic or parasympathetic receptors.
安全性與警告
禁忌症
- Conditions where hypotension is undesirable (e.g., shock, unless fluid replacement is adequate)
- Horses with clinical signs of colic
- Glaucoma (relative contraindication)
- Diabetes mellitus (relative contraindication)
不良反應
- Hypotension (postural/orthostatic)
- Hypertension (rebound)
- Miosis
- Increased intraocular pressure
- Tachycardia (reflex)
- Sodium retention
- Inhibition of ejaculation
- Nasal congestion
- Weakness or dizziness
- Gastrointestinal effects (nausea, vomiting)
- Constipation (specifically noted in horses)
注意事項
Use with extreme caution in patients with congestive heart failure (CHF) or other heart disease, as drug-induced tachycardia can occur. Use cautiously in patients with renal damage or cerebral/coronary arteriosclerosis.
Pregnancy: FDA Category C. Animal studies (guinea pigs) have shown abnormalities in the closure of the patent ductus. Use only if benefits outweigh risks.
藥物相互作用
Epinephrine reversal: If used with drugs that have both alpha- and beta-adrenergic effects, increased hypotension, vasodilation, or tachycardia may result due to unopposed beta effects.
Phenoxybenzamine will antagonize the effects of alpha-adrenergic sympathomimetic agents.
Phenoxybenzamine can antagonize the hypothermic effects of reserpine.
Increased risk of first dose hypotensive effect; if used for phaeochromocytoma, beta-blockers must only be started after alpha blockade is in place to avoid hypertensive crisis.
Increased risk of first dose hypotensive effect.
Phenoxybenzamine will antagonize the effects of these agents.
監測
- Clinical efficacy (e.g., adequate urination, ease of voiding)
- Blood pressure (monitor for hypotension)
- Heart rate (monitor for reflex tachycardia)
- Heart rate and rhythm
- Urine output and ease of urination
藥物動力學
吸收
Variably absorbed from the GI tract, with a bioavailability of 20-30% in humans. Onset of action is slow (several hours) and increases over several days after regular dosing. Effects persist for 3-4 days after discontinuation.
分佈
Highly lipid soluble and may accumulate in body fat. Unknown if it crosses the placenta or enters milk.
代謝
Metabolized (dealkylated) in the liver.
排除
Excreted in both the urine and bile.
過量
Overdosage may yield signs of postural hypotension (dizziness, syncope), tachycardia, vomiting, lethargy, or shock.
Treatment:
- Empty the gut if ingestion was recent and there are no contraindications.
- Treat hypotension with aggressive intravenous fluid support.
- DO NOT USE EPINEPHRINE (causes paradoxical further drop in blood pressure due to unopposed beta-adrenergic vasodilation).
- Most standard vasopressors are ineffective due to the alpha-blockade. Intravenous norepinephrine (levarterenol) may be beneficial if clinical signs are severe.
可用產品
劑型
- Capsules
- 10 mg oral capsule
- 50 mg/ml injectable solution
人用標示
- Phenoxybenzamine HCl Capsules: 10 mg (Dibenzyline)
- Dibenyline 10 mg capsules
- Phenoxybenzamine 50 mg/ml solution
各地核准狀態
POM (Prescription Only Medicine)
POM (Prescription Only Medicine)
暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Capsules should be stored at room temperature in well-closed containers.
飼主須知
酚苄明通常用於放鬆泌尿道肌肉以幫助您的寵物更順暢地排尿，或用於控制與某些腎上腺腫瘤相關的高血壓。
- 需要耐心：可能需要一週或更長時間才能看到對寵物排尿的完全效果。除非獸醫指示，否則請勿提早停藥。
- 隨餐服用：將此藥物與食物一起餵食有助於減少腸胃不適（噁心或嘔吐）。
- 注意低血壓：因為這種藥物會放鬆血管，可能會導致血壓下降。如果您的寵物出現虛弱、頭暈或在站立後倒下，請立即聯繫您的獸醫。
- 忘記服藥：如果您忘記餵藥，請在想起時盡快補餵，但絕對不要一次餵食兩劑。
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