硝唑尼特
**硝唑尼特 (Nitazoxanide)** 是一種廣效的噻唑類抗寄生蟲與抗菌藥物。 臨床重點： * **廣效性**：對多種原蟲（包括肉孢子蟲、梨形鞭毛蟲、隱孢子蟲）、線蟲、吸蟲及厭氧菌（如幽門螺旋桿菌）具有活性。 * **馬匹用途**：過去曾獲 FDA 批准作為口服糊劑 (Navigator®) 用於治療馬原蟲性脊髓腦炎 (EPM)，但該產品已退出美國市場。 * **小動物用途**：臨床上對於犬貓難治性隱孢子蟲和梨形鞭毛蟲感染的標示外使用有相當大的興趣。然而，其在小動物的臨床應用常因明顯的胃腸道副作用（尤其是犬隻）而受限。 * **人類用途**：獲 FDA 批准用於治療人類由微小隱孢子蟲和梨形鞭毛蟲引起的腹瀉，且耐受性通常非常良好。
作用機制: **Nitazoxanide** acts as a prodrug and is rapidly converted into its active metabolites, **tizoxanide** and **tizoxanide glucuronide**. * **Mechanism**: It inhibits the **pyruvate:ferredoxin oxidoreductase (PFOR)** enzyme-dependent electron transfer reactions. * **Pathway**: Inhibition of PFOR → disruption of essential anaerobic energy metabolism → death of susceptible protozoa and anaerobic bacteria. * Unlike nitroimidazoles (e.g., metronidazole), nitazoxanide does not appear to cause DNA damage, reducing its mutagenic potential.
各物種劑量
- Cryptosporidia-associated diarrhea · 25 mg/kg PO q12-24h · PO · q12-24h · No drug is consistently effective. Diarrhea sometimes resolves after administration.
- Equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona · Days 1-5: 25 mg/kg (11.36 mg/lb) PO once daily; Days 6-28: 50 mg/kg (22.72 mg/lb) PO once daily · PO · once daily · 28 days · Product has been withdrawn from the US market.
- Relapsing EPM · Extend the treatment regimen from 28 to 56 days · PO · once daily · 56 days · Potentially effective therapy for relapsing cases.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- Horses less than 1 year of age
- Horses that are sick or debilitated for reasons other than EPM
- Use with extreme caution in stallions and horses predisposed to laminitis
- Animals with compromised renal or hepatic function (safety not established)
不良反應
- Horses: Fever, anorexia, lethargy/depression, decreased gut sounds, diarrhea/enterocolitis, colic, laminitis, head/limb edema
- Horses: 'Treatment crisis' (CNS inflammation secondary to dying protozoa)
- Dogs: Excessive salivation, vomiting, diarrhea (often therapy-limiting)
- Humans: Yellow discoloration of sclera (rare, reversible)
藥物相互作用
- Highly protein-bound drugs with narrow therapeutic index · Use with caution; tizoxanide is >99% protein bound and may displace or be displaced by other highly bound drugs, potentially altering free drug concentrations.
監測
- Clinical efficacy (resolution of diarrhea or neurological signs)
- Weekly body weight
- Adverse reactions (GI upset, hypersalivation)
- If adverse reactions occur: Physical exam, CBC, serum albumin, total serum protein
過量
Information on acute toxicity is limited. * **Horses**: Overdoses of 2.5X have been associated with fatalities. Doses of ~5X labeled dose caused anorexia, diarrhea, and lethargy within 4 days. * **Dogs/Cats**: Oral LD50 is > 10 g/kg. * **Rats**: Repeated doses of 450 mg/kg caused intense salivation and increased liver/spleen weights. * **Humans**: Doses up to 4 grams have been taken without significant adverse effects. > **Treatment**: In the event of an overdose, observe the patient closely and provide supportive care.
VetSheet 藥物參考供持牌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方最新藥品說明書。