Cloxacillin
- **Class:** Narrow-spectrum, penicillinase-resistant penicillin (isoxazolyl-penicillin). - **Spectrum:** Highly effective against penicillinase-producing gram-positive cocci, particularly **Staphylococcus** species. - **Limitations:** Inactive against *Rickettsia*, mycobacteria, fungi, *Mycoplasma*, and viruses. Methicillin-resistant staphylococci (MRSA/MRSP) are inherently resistant. - **Availability:** In the USA, only intramammary infusion products are currently marketed for veterinary use (dairy cattle). Oral formulations are no longer commercially available in the US, though they may be compounded or available internationally.
Mecanismo: Cloxacillin is a bactericidal beta-lactam antibiotic. Binds to **Penicillin-Binding Proteins (PBPs)** → inhibits peptidoglycan cross-linking → disrupts bacterial cell wall synthesis → cell lysis and death. **Mechanistic Pearl:** The bulky isoxazolyl side chain sterically hinders staphylococcal **beta-lactamases**, preventing the enzymatic hydrolysis of the beta-lactam ring that normally inactivates natural penicillins.
Dosificación por especie
- Susceptible infections · 20-40 mg/kg PO or IM q6-8h · PO/IM · q6-8h
- Staph. pyoderma, diskospondylitis, osteoarthritis or skin infections · 10-15 mg/kg PO q6h for 14-84 days · PO · q6h · 14-84 days
- Systemic infections, bacteremia · 10-40 mg/kg PO q6-8h for 7-14 days · PO · q6-8h · 7-14 days
- Ocular infections · Apply 1/10 of a tube (0.3 g) · topical · q24h · Specifically for beta-lactamase-producing Staphylococcus
- Mastitis (treatment or prophylaxis) caused by susceptible organisms - Lactating cow · After milking out and disinfecting teat, instill contents of syringe; massage. · Intramammary · q12h · 3 total doses · Using lactating cow formula (Dari-Clox)
- Mastitis (treatment or prophylaxis) caused by susceptible organisms - Dry (non-lactating) cows · After last milking (or early in the dry period), instill contents of syringe and massage into each quarter. · Intramammary · Once · Using dry cow formula (benzathine)
- Susceptible infections · 20-40 mg/kg PO q8h · PO · q8h · Oral dosage forms are no longer available commercially in the USA
- Staph. pyoderma, diskospondylitis, osteoarthritis or skin infections · 10-15 mg/kg PO q6h for 14-84 days · PO · q6h · 14-84 days
Vías de administración
Contraindicaciones
- Known hypersensitivity to penicillins
- Known hypersensitivity to penicillins or cephalosporins
Efectos adversos
- Hypersensitivity reactions (rashes, fever, anaphylaxis)
- Eosinophilia
- Neutropenia
- Agranulocytosis
- Thrombocytopenia
- Leukopenia
- Anemias
- Lymphadenopathy
- Hypersensitivity reactions
- Local irritation (ophthalmic)
Monitoreo
- Clinical efficacy (resolution of infection/mastitis)
- Signs of hypersensitivity or toxicity
- Resolution of clinical signs of ocular infection
- Signs of local irritation or hypersensitivity
Sobredosis
Overdosage of intramammary infusions is unlikely to pose much systemic risk to the patient. > **Note:** Excessive dosing may prolong required withdrawal times for milk and meat in food-producing animals.
La referencia de fármacos de VetSheet está destinada a médicos veterinarios como apoyo a la decisión clínica; no sustituye el juicio profesional ni la información vigente del fabricante.