氟苯尼考
**氟苯尼考 (Florfenicol)** 是一種合成的**廣效性、抑菌性抗生素**，結構上與氯黴素 (chloramphenicol) 和甲碸黴素 (thiamphenicol) 相似。 **主要臨床特點：** * **安全性：** 與氯黴素不同，氟苯尼考缺乏會導致人類發生特異性、不可逆再生不良性貧血的對硝基 (p-nitro) 結構。這使其在經濟動物及接觸藥物的人員使用上更加安全。 * **獸醫核准用途：** FDA 主要核准用於牛隻（牛呼吸道疾病）、豬隻及水產養殖（魚類）。 * **標示外使用 (Off-label Use)：** 常被標示外用於小動物（犬貓）及特寵，治療具感受性的全身性細菌或立克次體感染，特別是在需要避免氯黴素骨髓毒性風險時。 * **抗菌譜：** 對溶血性曼海姆菌 (*Mannheimia haemolytica*)、多殺性巴斯德桿菌 (*Pasteurella multocida*)、睡眠組織嗜血桿菌 (*Histophilus somni*) 及牛黴漿菌 (*Mycoplasma bovis*)，以及多種革蘭氏陽性與陰性菌均具有高度療效。
作用機制: Florfenicol is a time-dependent, primarily bacteriostatic antibiotic (though it can be bactericidal against certain highly susceptible respiratory pathogens). * **Mechanism:** It readily penetrates bacterial cells and binds reversibly to the **50S ribosomal subunit**. * **Pathway:** Binding to the 50S subunit → inhibits the enzyme **peptidyl transferase** → prevents peptide bond formation → **inhibits bacterial protein synthesis**. * **Resistance:** Because it is fluorinated at the 3' position, it is resistant to inactivation by chloramphenicol acetyltransferase, an enzyme that confers resistance to chloramphenicol in many bacteria.
各物種劑量
- Susceptible systemic (bacterial or rickettsial) infections · 22 mg/kg · IM, PO · q12h · 3-5 days · Oral dosage form not available, but solution given orally to experimental cats was well absorbed.
- Swine respiratory disease · In water at a concentration of 400 mg/gallon (100 ppm) · PO · continuous · 5 days · Use as only source of drinking water.
- Respiratory disease complex in kids · 20 mg/kg a day · IM · q24h · 2 days · Route not specified; assume IM.
- Bovine respiratory disease (BRD) · 20 mg/kg · IM · repeat in 48 hours · 2 doses · In neck muscle only. Do not exceed 10 mL per injection site.
- Bovine respiratory disease (BRD) · 40 mg/kg · SC · once · Single dose · In neck only.
- Bovine respiratory disease (BRD) · 40 mg/kg (6 mL/100 lb B.W .) · SC · once · Single dose · Do not administer more than 15 mL at each site. Neck only.
- BRD and control of BRD-associated pyrexia · 40 mg/kg florfenicol/2.2 mg/kg flunixin (6 mL/100 lb. B.W .) · SC · once · Single dose · Do not administer more than 10 mL at each site. Neck only.
給藥途徑
禁忌症
- Intravenous (IV) administration
- Veal calves or preruminating calves
- Cattle or swine of breeding age (effects on reproduction unknown)
- Female dairy cattle 20 months of age or older
- Tympanic membrane rupture (perforated eardrum)
- Hypersensitivity to florfenicol, terbinafine, or betamethasone
- Dogs with generalized demodicosis (due to corticosteroid component)
不良反應
- Cattle: Anorexia, decreased water consumption, diarrhea
- Cattle: Injection site reactions (may result in trim loss)
- Cattle: Anaphylaxis and collapse (rare)
- Small Animals: Pain on IM injection
- Small Animals: Gastrointestinal effects, including severe diarrhea
- Mild application site erythema
- Head shaking
- Transient hearing loss (rare)
- Altered hearing or deafness in older dogs (rare)
藥物相互作用
- Penicillins · May antagonize the bactericidal activity of penicillins (theoretical, though often used together clinically).
- Aminoglycosides · May antagonize the bactericidal activity of aminoglycosides.
- Macrolides (e.g., erythromycin, tylosin) · May potentially antagonize activity due to competition for binding at the 50S ribosomal subunit.
- Lincosamides (e.g., clindamycin, lincomycin) · May potentially antagonize activity due to competition for binding at the 50S ribosomal subunit.
監測
- Clinical efficacy (resolution of infection/fever)
- Injection site reactions (swelling, pain, tissue necrosis)
- Gastrointestinal signs (appetite, stool consistency)
- Resolution of clinical signs of otitis externa
- Cytology to confirm clearance of bacteria and yeast
- Integrity of the tympanic membrane
過量
In toxicology studies, feeder calves injected with up to **10X the recommended dosage** exhibited transient adverse effects (anorexia, decreased water consumption, diarrhea) and increased serum enzymes. Long-term (43 day) standard dosage studies showed a transient decrease in feed consumption, but no long-term negative effects were noted. Treatment of acute overdose should be supportive and symptomatic.
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