呋喃妥因
Nitrofurantoin
Synthetic nitrofuran antibacterial
別名: Macrodantin · Macrobid · Furadantin · furadoninum · nitrofurantoinum · Nitrofurantoine
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 |
|---|---|---|---|---|---|
| Prevention of re-infections with gram-negative organisms | 4 mg/kg | PO | q24h | Long-term | 🌎 NA |
| Recurrent UTI (Conventional dose) | 4 mg/kg | PO | q8h | — | 🌎 NA |
| Recurrent UTI (Prophylactic dose) | 3-4 mg/kg | PO | q24h | — | 🌎 NA |
| Susceptible bacterial urinary tract infections | 4 mg/kg | PO | q6-8h | — | 🌎 NA |
| Susceptible bacterial urinary tract infections | 5 mg/kg | PO | q8h | — | 🌎 NA |
| Susceptible bacterial urinary tract infections | 4.4 mg/kg | PO | q8h | — | 🌎 NA |
| Urinary tract infections (lower UTI only) | 4.4-5 mg/kg | PO | q8h | As directed by culture and sensitivity | 🌍 EU |
- Prevention of re-infections with gram-negative organisms: Give once a day immediately before bedtime after the dog has urinated. Only use after extensive search for underlying cause and after effective treatment of existing UTI.
- Recurrent UTI (Prophylactic dose): Should be given at night after micturition and immediately before bedtime.
- Susceptible bacterial urinary tract infections: Listed as three times daily.
- Urinary tract infections (lower UTI only): For urinary tract infections only. Not for pyelonephritis.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Susceptible bacterial urinary tract infections | 5 mg/kg | PO | q8h | — | 🌎 NA |
| Recurrent UTI (Conventional dose) | 4 mg/kg | PO | q8h | — | 🌎 NA |
| Recurrent UTI (Prophylactic dose) | 3-4 mg/kg | PO | q24h | — | 🌎 NA |
| Susceptible bacterial urinary tract infections | 4 mg/kg | PO | q6-8h | — | 🌎 NA |
| Urinary tract infections (lower UTI only) | 4.4-5 mg/kg | PO | q8h | As directed by culture and sensitivity | 🌍 EU |
- Recurrent UTI (Prophylactic dose): Should be given at night after micturition and immediately before bedtime.
- Urinary tract infections (lower UTI only): For urinary tract infections only. Not for pyelonephritis.
馬
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Susceptible urinary tract infections | 2.5-4.5 mg/kg | PO | q8h | — | 🌎 NA |
| Susceptible urinary tract infections | 10 mg/kg | PO | q24h | — | 🌎 NA |
- Susceptible urinary tract infections: Listed as three times daily.
- Susceptible urinary tract infections: Listed as daily.
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
呋喃妥因 (Nitrofurantoin) 是一種合成的呋喃類抗菌藥物，主要用作泌尿道防腐劑/抗菌劑。
- 部位特異性療效：由於它會迅速排泄到尿液中，因此在下泌尿道能達到高濃度，但無法在全身血液循環或組織中達到治療濃度。因此，它對下泌尿道感染 (UTIs) 非常有效，但對全身性感染、腎盂腎炎（腎臟感染）或腎周圍膿腫無效。
- 抗菌譜：對多種革蘭氏陰性菌和革蘭氏陽性菌有效，包括大腸桿菌 (E. coli)、克雷伯氏菌 (Klebsiella)、葡萄球菌 (Staphylococcus) 和腸球菌 (Enterococcus)。值得注意的是，它對假單胞菌 (Pseudomonas spp.) 和大多數變形桿菌 (Proteus) 無效。
- 臨床要點：由於對第一線抗生素的抗藥性日益增加，呋喃妥因通常被保留用於治療多重抗藥性的下泌尿道感染，特別是由具抗藥性的大腸桿菌或腸球菌引起的感染。
作用機轉
Nitrofurantoin can be bacteriostatic or bactericidal depending on the concentration and organism susceptibility.
- Mechanism: Inside the bacterial cell, nitrofurantoin is reduced by bacterial flavoproteins to highly reactive intermediate compounds.
- Pathway: Reactive intermediates → attack bacterial ribosomal proteins and other macromolecules → inhibit protein synthesis, aerobic energy metabolism (specifically acetyl coenzyme A), DNA synthesis, RNA synthesis, and cell wall synthesis.
- Environmental Factor: It exhibits significantly greater antibacterial activity in acidic environments.
安全性與警告
禁忌症
- Renal impairment (decreased efficacy and increased risk of systemic toxicity)
- Known hypersensitivity to nitrofurantoin
- Pregnant patients at term (risk of hemolytic anemia in neonates)
- Rats (high risk of neurotoxicity)
- Significant renal impairment (decreased excretion leads to toxic serum levels)
- Pregnancy (mutagenic properties)
- Pyelonephritis
- Systemic infections outside the urinary tract
- Food-producing animals
不良反應
- Gastrointestinal disturbances (vomiting, nausea, diarrhea)
- Hepatopathy (can be severe or chronic)
- Myasthenic-like effects (rare, reversible in dogs)
- Infertility in male dogs
- Peripheral neuropathy (rare)
- Hemolytic anemia (rare)
- Pneumonitis (rare)
- Emesis
- Diarrhoea
- Gastrointestinal bleeding
- Hepatotoxicity
- Peripheral neuritis (rare)
- Pulmonary complications (rare)
- Thrombocytopenia (at high doses)
- Anaemia (at high doses)
- Leucopenia (at high doses)
- Prolonged bleeding times (at high doses)
注意事項
Renal Function Warning: Do not use in patients with compromised renal function. The drug relies on renal excretion to reach the site of infection (the bladder); poor kidney function means the drug won't work for the UTI and will accumulate in the blood, causing toxicity.
- Hepatotoxicity: Can cause drug-induced hepatopathy. Monitor liver enzymes if adverse effects are suspected, especially during long-term prophylactic use.
- Reproductive Warning: May cause infertility in male dogs. Use with caution in breeding animals.
- Lab Interference: May cause false-positive urine glucose results if using cupric-sulfate solutions (e.g., Clinitest). May also cause decreases in blood glucose and increases in serum creatinine, bilirubin, and ALP.
藥物交互作用
Nitrofurantoin may antagonize the antimicrobial activity of fluoroquinolones; concomitant use should be avoided.
May increase the oral bioavailability and absorption of nitrofurantoin.
May inhibit the oral absorption of nitrofurantoin.
May inhibit the renal excretion of nitrofurantoin, potentially increasing systemic toxicity and reducing its effectiveness in the urinary tract.
Delays gastric emptying time and increases absorption/bioavailability of nitrofurantoin
Delays gastric emptying time and increases absorption/bioavailability of nitrofurantoin
Antagonism of antibacterial efficacy
May increase the hyperkalaemic effects of spironolactone
Significantly decreases the antibacterial activity of nitrofurantoin
監測
- Clinical efficacy (resolution of UTI symptoms, negative urine cultures)
- Adverse effects (especially GI upset)
- Periodic liver function tests (especially with chronic/prophylactic therapy)
- Resolution of clinical signs of UTI
- Urine culture and sensitivity
- Renal function (BUN, Creatinine)
- Complete Blood Count (CBC) if used long-term or at high doses
- Liver enzymes
藥物動力學
半衰期
吸收
Rapidly absorbed from the GI tract. Presence of food enhances absorption. Macrocrystalline forms are absorbed more slowly, resulting in less GI upset and prolonged urine levels.
分佈
Therapeutic levels in systemic circulation are not maintained due to rapid elimination. Approximately 20-60% is bound to serum proteins. Crosses the placenta; minimal quantities found in milk.
代謝
Some of the drug is metabolized, primarily in the liver.
排除
Rapidly eliminated. Approximately 40-50% is excreted into urine unchanged via both glomerular filtration and tubular secretion. Peak urine levels occur within 30 minutes of dosing.
過量
Because the drug is rapidly absorbed and excreted, patients with normal renal function usually require little therapy for mild overdoses.
- Massive Overdose: If ingestion was recent, empty the gut using standard protocols (emesis/gastric lavage).
- Monitoring: Monitor closely for gastrointestinal distress, hepatotoxicity, and neurologic signs. Provide supportive care as needed.
可用產品
劑型
- Oral capsules (macrocrystals)
- Oral capsules (monohydrate/macrocrystals)
- 50 mg tablet
- 100 mg tablet
- 25 mg/5 ml oral suspension
人用標示
- Nitrofurantoin Macrocrystals Oral Capsules: 25 mg, 50 mg & 100 mg (Macrodantin, generic)
- Nitrofurantoin Monohydrate/Macrocrystals Oral Capsules: 100 mg (Macrobid, generic)
- Nitrofurantoin Oral Suspension: 25 mg/5 mL (5 mg/mL) (Furadantin)
- Nitrofurantoin 50 mg tablets
- Nitrofurantoin 100 mg tablets
- Nitrofurantoin 25 mg/5 ml oral suspension
各地核准狀態
Banned for use in food-producing animals (Annex IV / Table 2 substance).
Human POM used under the prescribing cascade. Banned in food-producing animals.
暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Store in tight containers at room temperature and protect from light. Do not freeze the oral suspension. Nitrofurantoin will decompose if it comes into contact with metals other than aluminum or stainless steel.
飼主須知
呋喃妥因是一種專門用於治療膀胱感染的抗生素。它會集中在尿液中以殺死細菌，但對身體其他部位的感染無效。
- 與食物一起餵食：請務必將此藥物與正餐或零食一起餵食。這能顯著減少胃部不適（嘔吐），並幫助身體更好地吸收藥物。
- 給藥時機很關鍵：如果您的寵物每天服用一次作為預防劑量，請在睡前，也就是牠們晚上最後一次排尿之後立即給藥。這樣可以讓藥物在膀胱中停留一整夜來對抗細菌。
- 注意副作用：最常見的副作用是嘔吐。如果嘔吐嚴重或持續，請聯繫您的獸醫師。
- 肝臟警告：在極少數情況下，此藥物可能會影響肝臟。如果您發現寵物的眼睛或牙齦變黃、嚴重嗜睡或食慾不振，請立即聯繫您的獸醫。
- 完成整個療程：即使您的寵物看起來已經好轉，也請務必完成整個抗生素療程，以防止感染復發或產生抗藥性。
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