Amoxicillin/Clavulanate Potassium
Amoxicillin/Clavulanate (commonly known by the veterinary trade name **Clavamox®**) is a highly effective, broad-spectrum **potentiated aminopenicillin** antibiotic. * **Broadened Spectrum:** The addition of clavulanic acid, a beta-lactamase inhibitor, protects amoxicillin from enzymatic degradation, significantly expanding its spectrum to include many beta-lactamase-producing bacteria (e.g., *Staphylococcus* spp., *E. coli*). * **Clinical Utility:** It is FDA-approved for use in dogs and cats for urinary tract infections (UTIs), skin and soft tissue infections, and periodontal disease. * **Empiric Choice:** It is considered an excellent first-line empiric choice for bacterial cystitis in female dogs and, when combined with a fluoroquinolone, for hepatobiliary infections. * **Limitations:** It is generally **not effective** against *Pseudomonas aeruginosa* or *Enterobacter* species, which often produce type I cephalosporinases that clavulanic acid cannot inhibit.
กลไกการออกฤทธิ์: **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.*
ขนาดยาตามชนิดสัตว์
- 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
วิธีการให้ยา
ข้อห้ามใช้
- 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)
อาการไม่พึงประสงค์
- 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)
อันตรกิริยาระหว่างยา
- 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.
การติดตาม
- Clinical efficacy (resolution of infection signs)
- Adverse gastrointestinal signs (vomiting, diarrhea, anorexia)
การได้รับยาเกินขนาด
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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