阿莫西林/克拉維酸
阿莫西林/克拉維酸（獸醫界常用商品名為 **Clavamox®**）是一種高效、廣效的**增效氨基青黴素**抗生素。 * **擴大抗菌譜：** 添加了β-內醯胺酶抑制劑（克拉維酸），可保護阿莫西林免受酵素破壞，顯著擴大其抗菌範圍，涵蓋許多產生β-內醯胺酶的細菌（如葡萄球菌、大腸桿菌）。 * **臨床應用：** 獲 FDA 批准用於犬貓的泌尿道感染 (UTI)、皮膚與軟組織感染及牙周病。 * **經驗性首選：** 是治療母犬細菌性膀胱炎的極佳第一線經驗性用藥；若與氟喹諾酮類藥物併用，也適用於肝膽道感染。 * **限制：** 通常對**綠膿桿菌 (Pseudomonas aeruginosa)** 或**腸桿菌屬 (Enterobacter)** 無效，因為這些細菌常產生克拉維酸無法抑制的第一型頭孢菌素酶。
作用機制: **Amoxicillin** is a time-dependent, bactericidal antibiotic that binds to **Penicillin-Binding Proteins (PBPs)** → inhibits bacterial cell wall peptidoglycan cross-linking → compromises cell wall integrity → cell lysis and death. **Clavulanic acid** acts as a "suicide inhibitor" by competitively and irreversibly binding to **beta-lactamase enzymes** (types II, III, IV, V, and staphylococcal penicillinases) → prevents the enzymatic destruction of amoxicillin → restores and expands the antimicrobial spectrum against resistant organisms. *Note: There is little synergistic activity against organisms already susceptible to amoxicillin alone.*
各物種劑量
- Susceptible infections · 62.5 mg/cat · PO · twice daily · do not exceed 30 days
- Gram-positive infections · 10 mg/kg · PO · twice daily
- Gram-negative infections · 20 mg/kg · PO · three times daily
- Susceptible UTI's · 62.5 mg/cat (total dose) · PO · q12h · 10-30 days
- Susceptible skin, soft tissue infections · 62.5 mg/cat (total dose) or 10-20 mg/kg · PO · q12h · 5-7 days
- Susceptible sepsis, pneumonia · 10-20 mg/kg · PO · q8h · 7-10 days
- Susceptible infections · 10-20 mg/kg · PO · 2-3 times daily
- Susceptible infections · 50-100 mg/kg · PO · q6-8h
- Susceptible infections (Ratites) · 10-15 mg/kg · PO · twice daily
- Susceptible infections · 13.75 mg/kg · PO · twice daily · do not exceed 30 days
給藥途徑
禁忌症
- Patients with a history of hypersensitivity to penicillins
- Small hindgut fermenters (rabbits, guinea pigs, chinchillas, hamsters) due to risk of fatal clostridial enterotoxemia
- Oral administration in patients with septicemia, shock, or grave illness (due to delayed/diminished GI absorption)
不良反應
- Gastrointestinal upset (anorexia, vomiting, diarrhea)
- Hypersensitivity reactions (rashes, fever, eosinophilia, anaphylaxis)
- Antibiotic-associated diarrhea and superinfections (due to altered gut flora)
- Neurotoxicity (e.g., ataxia in dogs) at very high doses or prolonged use
- Elevated liver enzymes (rare)
- Tachypnea, dyspnea, edema, and tachycardia (rarely reported in dogs)
藥物相互作用
- Bacteriostatic Antimicrobials (e.g., chloramphenicol, macrolides, tetracyclines, sulfonamides) · Theoretical in vitro antagonism; clinical importance is currently in doubt but historically not recommended to combine.
- Methotrexate · Amoxicillin may decrease the renal excretion of methotrexate, causing increased levels and potential toxic effects.
- Probenecid · Competitively blocks the tubular secretion of most penicillins, thereby increasing serum levels and serum half-lives.
- Aminoglycosides · In vitro inactivation can occur if mixed together; serum concentrations of aminoglycosides may be falsely decreased if stored prior to analysis.
監測
- Clinical efficacy (resolution of infection signs)
- Adverse gastrointestinal signs (vomiting, diarrhea, anorexia)
過量
Acute oral penicillin overdoses are unlikely to cause significant problems other than **gastrointestinal distress** (vomiting, diarrhea, anorexia). In humans, very high dosages of parenteral penicillins, especially in patients with underlying renal disease, have induced Central Nervous System (CNS) effects. Treatment of oral overdose should be supportive and symptomatic.
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