西地那非
Sildenafil
Sildenafil citrate
別名: Viagra · Revatio · Aphrodil · UK 92480-10 · Sildenafil citrate
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
劑量為合格獸醫專業人員的臨床參考。請務必對照最新仿單及個別病患確認。
各物種劑量
🌎 NA — North America🌍 EU — Europe
狗
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Pulmonary hypertension | 1.9 mg/kg (range from 0.5-2.7 mg/kg) | PO | q8-24h | — | 🌎 NA |
| Pulmonary hypertension documented by Doppler, chronic pulmonary disease, right-sided heart failure (HW disease; congenital) | 0.5-1 mg/kg (higher dose of 2 -3 mg/kg three times a day may be tolerated and needed) | PO | two times daily | — | 🌎 NA |
| Moderate to severe PH secondary to either left heart disease or primary lung disease | 1 mg/kg | PO | q8h | — | 🌎 NA |
| Pulmonary hypertension | 1-2 mg/kg | PO | three times daily | — | 🌎 NA |
| Pulmonary arterial hypertension | 0.5-2.7 mg/kg (suggested median dose from clinical studies is 3 mg/kg/day) | PO | q8-24h | — | 🌍 EU |
- Pulmonary hypertension: Median dose from a retrospective study. Dogs may have been also treated with oxygen, ACE inhibitors, furosemide, amlodipine, diltiazem, theophylline, phenobarbital and/or antibiotics.
- Pulmonary arterial hypertension: Improves quality of life despite lack of significant echocardiographic reduction in pressures.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Moderate to severe PH secondary to either left heart disease or primary lung disease | 1 mg/kg | PO | q8h | — | 🌎 NA |
| Pulmonary arterial hypertension | 1.6 mg/kg | PO | q12h | — | 🌍 EU |
- Pulmonary arterial hypertension: Reported dose tolerated and clinically efficacious.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新仿單及個別病患確認。
概覽
西地那非是一種強效的 第5型磷酸二酯酶 (PDE5) 抑制劑。雖然在人類醫學中主要用於治療勃起功能障礙，但在獸醫藥理學中，它是治療 肺動脈高壓 (Pulmonary Hypertension, PH) 的基石藥物。
- 臨床要點：對於因慢性二尖瓣疾病、心絲蟲病或原發性肺部疾病（如肺纖維化）引起肺動脈高壓的犬貓特別有效。
- 透過選擇性擴張肺動脈血管床，它能顯著降低右心室後負荷，進而改善暈厥、運動不耐及右側充血性心衰竭等臨床症狀。
- 它對肺部血管具有高度專一性，這意味著除非與其他血管擴張劑併用，否則通常不會引起嚴重的全身性低血壓。
作用機轉
Sildenafil exerts its effects via the nitric oxide (NO) pathway in smooth muscle cells:
- Endothelial cells release Nitric Oxide (NO) → activates the enzyme guanylate cyclase → converts GTP to cyclic guanosine monophosphate (cGMP).
- cGMP acts as a secondary messenger causing smooth muscle relaxation and vasodilation.
- PDE5 is the enzyme responsible for degrading cGMP, and it is found in high concentrations in the pulmonary vasculature and corpus cavernosum.
- Mechanism: Sildenafil competitively inhibits PDE5 → prevents cGMP breakdown → intracellular cGMP accumulates → resulting in prolonged and enhanced NO-mediated pulmonary vasodilation.
安全性與警告
禁忌症
- Concurrent use with organic nitrates
- Known hypersensitivity to sildenafil
- Pulmonary veno-occlusive disease (PVOD)
- Systemic hypotension
- Significant hepatic impairment
- Significant renal impairment
- Bleeding disorders
- Concurrent use of nitrates
不良反應
- Cutaneous flushing of the inguinal region
- Gastrointestinal effects (possible)
- Headache, visual disturbances, dyspepsia, nasal congestion, myalgia, priapism, dizziness, and back pain (reported in humans)
- Vomiting
- Dizziness / weakness
- Raised intraocular pressure
- Systemic hypotension (especially if combined with other vasodilators)
注意事項
WARNING: Sildenafil should not be used concurrently with nitrates due to the risk of life-threatening hypotension.
- Pulmonary vasodilators may significantly worsen the cardiovascular status of patients with pulmonary veno-occlusive disease (PVOD).
- Use with extreme caution in patients with resting hypotension, fluid depletion, severe left ventricular outflow obstruction, or autonomic dysfunction.
藥物交互作用
May increase hypotensive effects
Potential to increase hypotensive effects
Potentially could increase hypotensive effects
May reduce sildenafil metabolism and increase AUC
May reduce sildenafil metabolism and increase AUC
May reduce sildenafil metabolism and increase AUC
May increase bleeding risks
Significant potentiation of vasodilatory effects; life-threatening hypotension possible
Significant potentiation of vasodilatory effects; life-threatening hypotension possible
May decrease sildenafil concentrations
May decrease sildenafil concentrations
Increases plasma sildenafil concentration
Increases plasma sildenafil concentration
Increased risk of systemic hypotension; should not be started at the same time
Significantly enhances hypotensive effect; concomitant use must be avoided
監測
- Clinical efficacy (improved syncope, cough, respiratory effort)
- Pulmonary artery pressure
- Systemic blood pressure
- Adverse effects
- Clinical signs of pulmonary hypertension (exercise tolerance, syncope, respiratory rate/effort)
- Echocardiography (to monitor right heart function and pulmonary pressures)
- Intraocular pressure (if pre-existing ocular disease)
藥物動力學
半衰期
吸收
Oral bioavailability is approximately 50% in dogs (higher than humans).
分佈
Volume of distribution is about 5.2 L/kg in dogs (versus 1.2 L/kg in humans).
代謝
Hepatic metabolism (implied by interactions with CYP inhibitors/inducers).
排除
Excreted primarily as metabolites.
過量
Little information is available in veterinary species. In humans, massive overdose (2000 mg) resulted in tachycardia, nonspecific ST-T changes on ECG, headache, dizziness, and flushing.
It is expected that overdoses in animals would mirror the drug's adverse effect profile (e.g., profound hypotension, tachycardia, cutaneous flushing). Treat supportively.
可用產品
劑型
- Oral tablets
- Injection solution
- 20 mg tablet
- 50 mg tablet
- 6.25 mg tablet (special reformulation)
- 10 mg tablet (special reformulation)
- 12.5 mg tablet (special reformulation)
- 10 mg/ml oral suspension
- 0.08 mg/ml injectable (IV)
獸醫用
- Special reformulations available: 6.25 mg, 10 mg and 12.5 mg tablets
人用標示
- Sildenafil Citrate Oral Tablets: 20 mg Revatio® (Pfizer); 25 mg, 50 mg & 100 mg Viagra® (Pfizer)
- Sildenafil Injection Solution: 10 mg/12.5 mL (dextrose 50.5 mg/mL) in 12.5 mL single-use vials; Revatio® (Pfizer)
- Revatio (20 mg tablets, 10 mg/ml oral suspension, 0.08 mg/ml IV)
- Viagra (25 mg, 50 mg tablets)
各地核准狀態
POM (Prescription Only Medicine). Used off-label under the cascade.
POM-V / POM. Used off-label under the prescribing cascade.
暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Sildenafil tablets should be stored at room temperature (25°C; 77°F); excursions permitted to 15-30°C (59-86°F).
飼主須知
重要提示：西地那非在獸醫學中常以「仿單標示外使用 (off-label)」的方式處方，用於治療肺部的高血壓（肺動脈高壓）。
- 預期效果：您可能會發現寵物的活力增加、咳嗽減少，且暈厥次數降低。
- 費用：由於這是人類藥物（常見商品名為 Viagra® 或 Revatio®），費用可能較高。如果預算有限，可與獸醫師討論使用學名藥或調劑藥品。
- 安全警告：在寵物服用西地那非期間，絕對不可給予其他心臟藥物，特別是硝酸鹽類（如硝酸甘油），因為這可能導致致命的血壓驟降。
- 副作用：請留意寵物腹部（鼠蹊部）是否出現發紅或腸胃不適。如果寵物出現頭暈、嗜睡或癱軟，請立即聯繫獸醫師。
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