法莫替丁
Famotidine
3-[({2-[(diaminomethylidene)amino]-1,3-thiazol-4-yl}methyl)sulfanyl]-N'-sulfamoylpropanimidamide
別名: Pepcid AC · Pepcid RPD · famotidinum · L-643341 · MK-208 · YM-11170 · Famotidina
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 |
|---|---|---|---|---|---|
| To reduce gastric acid production | 0.1-0.2 mg/kg | PO, SC, IM, IV | q12h | — | 🌎 NA |
| To reduce gastric acid production | 0.5 mg/kg | PO, SC, IM, IV | q12-24h | — | 🌎 NA |
| For esophagitis | 0.5-1 mg/kg | PO | q12h | — | 🌎 NA |
| For acute reflex esophagitis | 0.55-1.1 mg/kg | PO | q24h (or q12h if severe) | 2-3 weeks | 🌎 NA |
| Adjunctive treatment (prevent/treat gastric ulcers) of mast cell tumors | 0.5 mg/kg | Not specified | q24h | — | 🌎 NA |
| Adjunctive treatment of GI effects associated with chronic kidney disease | 0.5 mg/kg | PO | q24h | — | 🌎 NA |
| All uses (ulcers, gastritis, oesophagitis, hypersecretory conditions) | 0.5-1.0 mg/kg | PO | q12-24h | — | 🌍 EU |
- Adjunctive treatment of GI effects associated with chronic kidney disease: Effective evidence grade: 3
- All uses (ulcers, gastritis, oesophagitis, hypersecretory conditions): Effect on gastric pH diminishes with time when given daily.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| To reduce gastric acid production | 0.2 mg/kg | PO, SC, IM, IV | q24h | — | 🌎 NA |
| To reduce gastric acid production | 0.5 mg/kg | PO, SC, IM, IV | q12-24h | — | 🌎 NA |
| For esophagitis | 0.5 mg/kg | PO | q12h | — | 🌎 NA |
| For acute reflex esophagitis | 0.55-1.1 mg/kg | PO | q24h (or q12h if severe) | 2-3 weeks | 🌎 NA |
| Adjunctive treatment of GI effects associated with chronic progressive renal disease | 1 mg/kg | PO | q24h | — | 🌎 NA |
| Adjunctive treatment of GI effects associated with chronic progressive renal disease | 0.5-1 mg/kg | PO | q12-24h | — | 🌎 NA |
| All uses (ulcers, gastritis, oesophagitis, hypersecretory conditions) | 0.5-1.0 mg/kg | PO | q12-24h | — | 🌍 EU |
- To reduce gastric acid production: See warning about IV use in cats
- All uses (ulcers, gastritis, oesophagitis, hypersecretory conditions): Effect on gastric pH diminishes with time when given daily.
小型哺乳類
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Rabbits: For stress induced ulcer prevention once critically ill animal has stabilized | 1 mg/kg | IV | q24h | — | 🌎 NA |
雪貂
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| For stress induced ulcers | 0.25-0.5 mg/kg | PO, IV | q24h | — | 🌎 NA |
| In combination with antibiotics for Helicobacter treatment | 0.25-0.5 mg/kg | PO, IV | q24h | — | 🌎 NA |
馬
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| As an adjunct in ulcer treatment | 0.23 mg/kg or 0.35 mg/kg | IV | q8h (for 0.23 mg/kg) or q12h (for 0.35 mg/kg) | — | 🌎 NA |
| As an adjunct in ulcer treatment | 1.88 mg/kg or 2.8 mg/kg | PO | q8h (for 1.88 mg/kg) or q12h (for 2.8 mg/kg) | — | 🌎 NA |
- As an adjunct in ulcer treatment: ARCI UCGFS Class 5 Drug
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
法莫替丁（Famotidine）是一種強效、長效的組織胺H2受體拮抗劑，在獸醫學中廣泛用於抑制胃酸分泌，並治療或預防胃/十二指腸潰瘍、胃炎和食道炎。
與西咪替丁（Cimetidine）相比，法莫替丁的效力顯著更強，給藥頻率較低，且最重要的是它不會抑制肝臟細胞色素P450酵素系統，因此幾乎沒有常見的藥物交互作用。
臨床要點：雖然對輕度胃酸抑制或常規預防有效，但質子幫浦抑制劑（PPIs，如奧美拉唑 Omeprazole）在治療活動性潰瘍、預防運動誘發性胃炎或處理嚴重食道炎方面通常被認為效果更好。此外，在犬貓連續使用3至14天後，法莫替丁容易產生藥理耐受性（Tachyphylaxis），使其抑制胃酸的效力隨時間減弱。
作用機制
Famotidine acts as a competitive, reversible antagonist at the H2 receptors located on the basolateral membrane of gastric parietal cells.
By blocking histamine binding, it prevents the activation of adenylate cyclase → decreases intracellular cAMP levels → reduces the activation of the H+/K+-ATPase proton pump. This effectively blunts both basal gastric acid secretion and secretion stimulated by food, pentagastrin, or insulin. By decreasing the total volume of gastric juice produced, H2-blockers also indirectly decrease the amount of pepsin secreted. It does not alter gastric emptying time, biliary secretion, or lower esophageal sphincter pressure.
安全性與警告
禁忌症
- Known hypersensitivity to H2 blockers
- Known hypersensitivity to famotidine or other H2 receptor antagonists
不良反應
- Bradycardia (if infused too rapidly IV)
- GI effects (anorexia, vomiting, diarrhea)
- Headache
- Dry mouth or skin
- Intravascular hemolysis (rare, anecdotally reported in cats given IV)
- Transient increase in serum gastrin (returns to baseline by 14 days)
- Generally has a very good safety profile with fewer side effects than cimetidine
注意事項
Use cautiously in geriatric patients and those with significantly impaired hepatic or renal function; consider dosage reduction in patients with significant renal dysfunction. Famotidine may have negative inotropic effects and some cardioarrhythmogenic properties; use with caution in patients with cardiac disease. When administering IV to cats, infuse slowly (over 5 minutes) to minimize the rare risk of intravascular hemolysis.
藥物相互作用
Famotidine raises gastric pH, which may decrease the absorption of these agents. Administer the azole one hour prior to famotidine.
Famotidine may decrease the absorption of these cephalosporins. Taking with food may alleviate this effect.
Famotidine may decrease the absorption of oral iron. Administer iron at least one hour prior to famotidine.
監測
- Clinical efficacy (decrease in symptomatology, endoscopic examination, resolution of blood in feces)
- Adverse effects
- Clinical signs of GI ulceration or bleeding (vomiting, melena, anorexia)
- Gastric pH (if clinically indicated and feasible)
藥物動力學
半衰期
吸收
Incompletely absorbed after oral administration with minimal first-pass metabolism. Systemic bioavailability is ~40-50% in humans. Bioavailability is low in horses (13%).
分佈
Concentrates in the liver, pancreas, kidney, and submandibular gland (in rats). Only ~15-20% is bound to plasma proteins. Does not cross the blood-brain barrier or placenta in rats. Distributed into milk. Volume of distribution in horses is 4.28 L/kg.
代謝
Primarily metabolized in the liver.
排除
Excreted in the urine. After oral dosing, ~1/3 is excreted unchanged; after IV dosing, ~2/3 is excreted unchanged.
過量
Famotidine has a wide margin of safety. The minimum acute lethal dose in dogs is reported to be >2 grams/kg for oral doses and approximately 300 mg/kg for intravenous doses.
IV doses in dogs ranging from 5-200 mg/kg caused vomiting, restlessness, mucous membrane pallor, and redness of the mouth and ears. Higher doses caused hypotension, tachycardia, and collapse.
Most overdoses require only monitoring. In massive oral overdoses, gut-emptying protocols should be considered and supportive therapy initiated when warranted.
可用產品
劑型
- Oral tablets (plain, film-coated, chewable, orally disintegrating)
- Powder for oral suspension
- Injection
- 20 mg tablets
- 40 mg tablets
人用標示
- Famotidine Oral Tablets (plain, film-coated, chewable & orally disintegrating) & Gelcaps: 10 mg, 20 mg, & 40 mg (Pepcid®, Pepcid AC®, generic)
- Famotidine Powder for Oral Suspension: 8 mg/mL when reconstituted (Pepcid®)
- Famotidine Injection: 10 mg/mL in vials; 20 mg/50 mL premixed containers (generic)
- 20 mg tablets
- 40 mg tablets
各地核准狀態
Human authorized product used off-label under the cascade. Cimetidine is the only H2 antagonist with veterinary authorization.
Human authorized product used off-label under the cascade (POM).
暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Tablets should be stored in well-closed, light-resistant containers at room temperature. Powder for oral suspension should be stored <40°C; after reconstitution, it is stable for 30 days when stored <30°C (do not freeze). Injection should be stored in the refrigerator (2-8°C).
飼主須知
- 給藥方式：請嚴格按照獸醫師的指示給藥。為了達到最大的阻斷胃酸效果，通常最好在空腹時（飯前30至60分鐘）給予。
- 規律服藥：請勿漏掉劑量。若漏吃藥物，胃酸逆流或潰瘍的臨床症狀可能會復發。
- 液體製劑：如果使用配製的口服懸浮液，請在每次使用前充分搖勻，並存放在冰箱中。超過30天未用完的部分請丟棄。
- 藥物交互作用：如果您的寵物正在服用其他藥物或保健品，請告知您的獸醫師。如果您的寵物有服用口服鐵劑或某些抗黴菌藥物，應與法莫替丁錯開至少一小時服用。
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