Cefazolin
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General
- Type: 1st generation Cephalosporin
- Dosage Forms: Intramammary suspension, Ophthalmic ointment
- Routes of Administration: Intramammary (IMM), Topical (Ophthalmic)
- Common Trade Names: Cepravin
- Note: Cefalonium is a semi-synthetic cephalosporin used almost exclusively in **veterinary medicine**. It is widely used for "Dry Cow" therapy to treat and prevent mastitis. It is not approved for human use in most jurisdictions.
Adult Dosing
General
- Human Systemic Dosing: Not established. Not indicated for human use.
- Veterinary (Bovine) - Dry Cow Therapy:
- Infuse one syringe (250 mg) into the teat canal of each quarter immediately after the last milking of the lactation.
- Massage udder upwards to distribute the suspension.
Ophthalmic (Veterinary)
- Apply a small amount (~1 cm) of ointment to the conjunctival sac q8–12h or as directed for infectious keratoconjunctivitis.
Pediatric Dosing
- Safety and Efficacy: Not applicable (Veterinary drug).
Special Populations
- Pregnancy/Lactation (Humans): No data available.
- Veterinary Lactation (Withdrawal Periods):
- Milk Withdrawal: Milk from treated cows must not be used for human consumption for a specific period post-calving (often 96 hours post-calving if the dry period was of sufficient length).
- Meat Withdrawal: Animals must not be slaughtered for human consumption during treatment or for a specified period (e.g., 21 days) after the last treatment.
Contraindications
- Known hypersensitivity to Cephalosporins.
- History of anaphylaxis to Penicillins (Risk of cross-reactivity).
- Veterinary: Do not use in lactating cows; intended for use during the dry period only.
Adverse Reactions
Serious
- Anaphylactic reactions (rare in animals).
- Superinfection (fungal or resistant bacterial growth).
Common
- Local irritation at the infusion site.
- Transient eye irritation (ophthalmic use).
Pharmacology
- Mechanism of Action: Bactericidal; inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), causing defects in the cell wall and leading to cell lysis.
- Absorption:
- Intramammary: Formulated for slow release to persist in the udder for prolonged periods (weeks) during the dry period. Systemic absorption is minimal.
- Ophthalmic: Penetrates the cornea efficiently.
- Chemical Class: Synthetic organic compound; contains Isonicotinamides, Thiophenes, and Pyridinium structures.
Antibiotic Sensitivities
- Note: As a 1st Generation Cephalosporin, the spectrum is primarily Gram-positive with modest Gram-negative coverage.
| Group | Organism | Sensitivity |
|---|---|---|
| Gram Positive | Streptococcus agalactiae | S |
| Streptococcus dysgalactiae | S | |
| Streptococcus uberis | S | |
| Streptococcus pyogenes | S | |
| Enterococcus spp. | R | |
| Staphylococcus aureus (MSSA) | S | |
| MRSA | R | |
| Corynebacterium pyogenes | S | |
| Gram Negatives | Escherichia coli | S/I |
| Klebsiella spp. | S | |
| Proteus mirabilis | S | |
| Enterobacter spp. | R | |
| Pseudomonas aeruginosa | R | |
| Pasteurella multocida | S | |
| Fusobacterium necrophorum | S | |
| Haemophilus influenzae | R |
Key: S = Susceptible, I = Intermediate, R = Resistant.