Cefadroxil
Cefadroxil is a broad-spectrum, **first-generation cephalosporin** antibiotic used primarily in veterinary medicine to treat susceptible bacterial infections of the skin, soft tissue, and genitourinary tract. Structurally related to penicillins, cephalosporins contain a beta-lactam ring that confers their bactericidal activity. First-generation cephalosporins like cefadroxil are characterized by excellent activity against most **gram-positive pathogens** (including *Staphylococcus pseudintermedius*, *Staphylococcus aureus*, and *Streptococcus* spp.) and variable, limited activity against gram-negative organisms (such as *E. coli* and *Proteus mirabilis*). **Clinical Pearl:** Cefadroxil shares a nearly identical spectrum of activity with cephalexin, another common first-generation cephalosporin. However, cefadroxil has a slightly longer half-life in dogs and cats, which sometimes allows for less frequent dosing (e.g., twice daily instead of three times daily), though it is generally more expensive than generic cephalexin.
Mecanismo: Cefadroxil is a **time-dependent, bactericidal** antibiotic. It exerts its effect by binding to specific **Penicillin-Binding Proteins (PBPs)** located inside the bacterial cell wall. * Binding to PBPs → **Inhibition of peptidoglycan cross-linking** (the structural backbone of the bacterial cell wall) → Weakening of the cell wall → Activation of bacterial autolysins → **Cell lysis and death**. Because it is a time-dependent antibiotic, maintaining serum drug concentrations above the Minimum Inhibitory Concentration (MIC) for the majority of the dosing interval is critical for clinical efficacy.
Dosificación por especie
- UTI · 22 mg/kg PO once daily · PO · q24h · 21 days or less
- Skin, pyoderma · 22-35 mg/kg PO q12h · PO · q12h · 3-30 days
- Systemic, orthopedic infections · 22 mg/kg PO q8-12h · PO · q8-12h · 30 days
- Susceptible gram-positive infections · 10 mg/kg q12h · PO · q12h
- Susceptible gram-negative infections · 30 mg/kg q8h · PO · q8h
- Susceptible infections · 22 mg/kg PO q12h · PO · q12h
- Susceptible infections · 15-20 mg/kg PO twice daily · PO · q12h
- Susceptible infections (skin, soft tissue, GU) · 22 mg/kg PO twice daily · PO · q12h · Skin/soft tissue: at least 3 days. GU: at least 7 days. Max 30 days. · Treat for at least 48 hours after animal is afebrile and asymptomatic. Reevaluate if no response after 3 days.
- Susceptible Staph infections · 30 mg/kg PO q12h · PO · q12h · May not be adequate dose for non-UTI's caused by E. coli.
- UTI · 11-22 mg/kg PO q12h · PO · q12h · 7-30 days
Vías de administración
Contraindicaciones
- Known hypersensitivity to cephalosporins
- Septicemia, shock, or grave illness (oral absorption is unreliable; parenteral routes required)
Efectos adversos
- Anorexia
- Vomiting
- Diarrhea
- Hypersensitivity reactions (rash, fever, eosinophilia, anaphylaxis)
- Antibiotic-associated diarrhea/superinfections
- Tachypnea (rare)
- Neurotoxicity (at high doses)
- Neutropenia/thrombocytopenia (rare, prolonged use)
- Hepatitis (rare)
- Nephrotoxicity (rare)
Interacciones farmacológicas
- Probenecid · Competitively blocks the tubular secretion of most cephalosporins, thereby increasing serum levels and serum half-lives.
Monitorización
- Clinical efficacy (resolution of infection signs)
- Renal function (in patients with pre-existing diminished renal function)
Sobredosis
Acute oral cephalosporin overdoses are unlikely to cause significant problems other than **gastrointestinal distress** (vomiting, diarrhea, anorexia). Massive overdoses or prolonged use, particularly in patients with compromised kidney function, may theoretically lead to neurotoxicity, neutropenia, hepatitis, or nephrotoxicity. Treatment is generally supportive and symptomatic.
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