甲硝唑 / 滅滴靈
Metronidazole
2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethanol; Metronidazole benzoate
別名: Flagyl · Metrobactin · Stomorgyl · Metronidazole benzoate · Bayer-5360 · metronidazolum · SC-32642 · NSC-50364 · RP-8823 · SC-10295
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
經審核的 v13 劑量證據
結構化劑量計算證據Anaerobic infections (extra-label) — less severe anaerobic infections
- q8-12h
NA
必須一併考量的臨床脈絡 (6)
- 1. Dosages are for metronidazole base unless otherwise noted. If metronidazole benzoate is being used, dosages should be adjusted unless provided by pharmacy as “mg/mL of the base.”
- One mg of metronidazole base = 1.6 mg of metronidazole benzoate. For example, if the calculated metronidazole dose is 200 mg (of the base), the corresponding dose using metronidazole benzoate would be 320 mg (metronidazole benzoate).
- 2. Because of the drug’s extreme bitterness, using a flavored, compounded metronidazole benzoate or putting quartered tablets in an empty gelatin capsule may be considered.
- Anaerobic infections (extra-label):
- ■ Give this medication with food.
- Metronidazole tablets and solution for injection should be stored at temperatures less than 30°C (86°F) and protected from light. The shelf life of divided tablets is 3 days. 5
Hepatic encephalopathy (extra-label)
- q8-12h
NA
必須一併考量的臨床脈絡 (5)
- 1. Dosages are for metronidazole base unless otherwise noted. If metronidazole benzoate is being used, dosages should be adjusted unless provided by pharmacy as “mg/mL of the base.”
- One mg of metronidazole base = 1.6 mg of metronidazole benzoate. For example, if the calculated metronidazole dose is 200 mg (of the base), the corresponding dose using metronidazole benzoate would be 320 mg (metronidazole benzoate).
- 2. Because of the drug’s extreme bitterness, using a flavored, compounded metronidazole benzoate or putting quartered tablets in an empty gelatin capsule may be considered.
- ■ Give this medication with food.
- Metronidazole tablets and solution for injection should be stored at temperatures less than 30°C (86°F) and protected from light. The shelf life of divided tablets is 3 days. 5
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
甲硝唑是一種合成的硝基咪唑類抗菌及抗原蟲藥物，在獸醫學中被廣泛使用。
主要臨床應用：
- 抗原蟲： 對梨形鞭毛蟲 (Giardia)、滴蟲 (Trichomonas)、溶組織內阿米巴 (Entamoeba histolytica) 和結腸小袋纖毛蟲 (Balantidium coli) 具有高度療效。
- 抗厭氧菌： 對絕對厭氧菌（如擬桿菌屬、梭狀芽孢桿菌屬、梭桿菌屬）具有極佳的抗菌效果。常被用於治療腸道及全身性厭氧菌感染，包括敗血症、腹膜炎和深層咬傷。
- 胃腸道調節： 經常被用於控制炎症性腸病 (IBD) 和慢性結腸炎。臨床要點： 除了抗菌特性外，甲硝唑被認為在胃腸道中具有局部免疫調節和抗發炎作用，特別是透過抑制細胞介導的免疫反應。
重要注意事項：
- FDA 嚴格禁止用於產食動物。
- 以其極度苦澀的金屬味而聞名，這會導致嚴重的流涎和拒絕服藥，特別是在貓身上。對於貓科病患，通常首選調配的苯甲酸甲硝唑 (metronidazole benzoate)，因為它在唾液中的溶解度較低，因此苦味較輕。
作用機轉
Metronidazole is a concentration-dependent bactericidal agent.
Mechanism Pathway:
- Entry: The drug enters the cell of the organism via passive diffusion.
- Activation: In obligate anaerobes and certain protozoa, the nitro group of metronidazole is reduced by electron-transport proteins (such as ferredoxin).
- DNA Disruption: This reduction process creates highly reactive, short-lived cytotoxic intermediate compounds (free radicals) → These radicals bind to and disrupt DNA and nucleic acid synthesis → leading to rapid cell death.
Because aerobic bacteria lack the specific electron-transport proteins required to reduce and activate the drug, metronidazole is virtually inactive against obligate aerobes.
安全性與警告
禁忌症
- Hypersensitivity to metronidazole or other nitroimidazole derivatives
- Food-producing animals (FDA prohibited)
- Pregnancy (potential teratogen, especially in early pregnancy)
- Severe hepatic disease (requires dose reduction)
不良反應
- Neurologic disorders (ataxia, nystagmus, seizures, head-tilt)
- Lethargy and weakness
- Neutropenia
- Hepatotoxicity
- Hematuria
- Anorexia, nausea, vomiting, and diarrhea
- Hypersalivation (especially in cats due to bitter taste)
- CNS toxicity (nystagmus, ataxia, knuckling, head tilt, seizures)
- Haematuria
- Excessive salivation/foaming (especially in cats)
- Impaired sense of smell (reported in explosive detection dogs)
注意事項
Neurotoxicity Warning: In dogs, total daily doses should not exceed 65 mg/kg/day to minimize the risk of central vestibular and cerebellar toxicity. Toxicity can occur with acute high doses or chronic moderate-to-high dose therapy.
- Hepatic Impairment: Use with caution in animals with hepatic dysfunction. Consider reducing the dose to 25-50% of the usual dose in significant liver impairment.
- Pregnancy: Potential teratogen. Avoid use during pregnancy, particularly during the first 3 weeks of gestation, unless benefits clearly outweigh risks.
- Nursing: Consider alternative therapy or switching to milk replacer due to potential tumorigenicity.
- Debilitated Patients: Use with extreme caution in severely debilitated animals.
藥物交互作用
May induce a disulfiram-like reaction (nausea, vomiting, cramps).
May decrease the metabolism of metronidazole, increasing the likelihood of dose-related side effects.
May increase the metabolism of metronidazole, thereby decreasing blood levels.
May increase the metabolism of metronidazole, thereby decreasing blood levels.
May prolong the prothrombin time (PT). Avoid concurrent use or intensify monitoring.
Should not be used concurrently with Spiramycin (in combination products) as the combination may be antagonistic.
監測
- Clinical efficacy (resolution of diarrhea, negative fecal tests)
- Adverse effects (especially neurologic signs like ataxia or nystagmus)
- Neurological signs (for early detection of CNS toxicity)
- Liver function tests (ALT, AST, Bilirubin) in patients with pre-existing hepatic disease
- Complete Blood Count (for neutropenia)
藥物動力學
半衰期
吸收
Relatively well absorbed after oral administration. Oral bioavailability in dogs is high (50-100%) and enhanced with food. In cats, bioavailability averages ~65%. In horses, oral bioavailability averages ~80% (decreased by 50% if given rectally).
分佈
Highly lipophilic and widely distributed to most body tissues and fluids, including bone, abscesses, the CNS, and seminal fluid. Less than 20% bound to plasma proteins.
代謝
Primarily metabolized in the liver via several pathways, including glucuronidation.
排除
Both metabolites and unchanged drug are eliminated in the urine and feces.
過量
Signs of intoxication in dogs and cats are primarily neurologic and include:
- Anorexia and/or vomiting
- Depression
- Mydriasis (dilated pupils)
- Nystagmus (rapid eye flicking, very common in dogs)
- Ataxia (stumbling, uncoordinated gait)
- Head-tilt, proprioceptive deficits, joint knuckling
- Tremors, seizures, rigidity, and stiffness
These effects may be seen with acute massive overdoses, or more commonly with chronic therapy at doses >60 mg/kg/day (though sometimes seen at 'recommended' doses like 30 mg/kg/day).
Treatment:
- Discontinue metronidazole immediately. Most dogs with mild to moderate signs improve rapidly within 1-2 days of stopping the drug.
- Diazepam has been used successfully to rapidly decrease the CNS effects associated with metronidazole toxicity.
- For acute massive ingestions, standard decontamination protocols (emesis, activated charcoal) apply, but use extreme caution before inducing vomiting if the patient is already showing CNS signs, due to aspiration risk.
可用產品
劑型
- Oral capsules
- Extended-release oral tablets
- Injection (IV)
- Compounded oral suspensions (often using metronidazole benzoate)
- 5 mg/ml i.v. infusion
- 250 mg tablet
- 500 mg tablet
- 25 mg metronidazole + 46.9 mg spiramycin tablet (Stomorgyl 2)
- 125 mg metronidazole + 234.4 mg spiramycin tablet (Stomorgyl 10)
- 250 mg metronidazole + 469 mg spiramycin tablet (Stomorgyl 20)
- 40 mg/ml oral solution
獸醫用
- None (Prohibited for use in food animals by the FDA)
- Metrobactin 250 mg, 500 mg tablets
- Stomorgyl 2, 10, 20 tablets (combination with spiramycin)
人用標示
- Metronidazole Oral Tablets: 250 mg & 500 mg (Flagyl, generic)
- Metronidazole Oral Capsules: 375 mg (Flagyl 375, generic)
- Metronidazole Extended-Release Oral Tablets: 750 mg (Flagyl ER)
- Metronidazole Injection: 5 mg/mL in 100 mL vials
- Bismuth Subsalicylate, Metronidazole & Tetracycline HCl Combination (Helidac)
- Flagyl 200 mg, 400 mg tablets
- Metronidazole 5 mg/ml IV infusion
各地核准狀態
POM-V classification. Prohibited for use in food-producing animals.
POM-V classification.
暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Tablets and HCl powder for injection should be stored at temperatures less than 30°C and protected from light. The injection should be protected from light and freezing and stored at room temperature. Compounded metronidazole benzoate suspensions can be stable for up to 90 days or longer depending on the specific vehicle used.
飼主須知
寵物主人重要指引：
- 極度苦味： 甲硝唑藥錠對動物來說味道極差。除非絕對必要，否則請勿壓碎藥錠，因為苦味會導致您的寵物（尤其是貓）過度流口水或拒絕進食。如果您在餵藥時遇到困難，請向您的獸醫詢問是否可以使用調配的液體版本（苯甲酸甲硝唑），它能更好地掩蓋味道。
- 隨餐服用： 將此藥物與食物一起餵食有助於提高其吸收率並減少胃部不適。
- 注意神經系統症狀： 如果您的寵物出現任何神經毒性跡象，請立即聯繫您的獸醫。請注意觀察：步態蹣跚或「醉酒」狀行走（共濟失調）、眼球快速來回跳動（眼球震顫）、頭部傾斜、極度嗜睡、發抖或癲癇發作。
- 完成療程： 即使您的寵物的腹瀉或症狀有所改善，也請務必完成整個處方療程，以確保感染或寄生蟲被完全清除。
VetSheet 藥物參考供合格獸醫專業人員作臨床決策輔助之用，不能取代專業判斷或廠商最新仿單。