Cephapirin
Cephapirin sodium, Cephapirin benzathine
Also known as: Cefa-Lak · Cefa-Dri · ToDAY · ToMORROW · Metricure · BL-P-1322 · cefapirinum natricum · Brisfirina · Cefaloject · Cefatrex · Lopitrex · Piricef
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Cattle
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Mastitis (Lactating cow) | After milking out udder, clean and dry teat area. Swab teat tip with alcohol wipe and allow to dry. Insert tip of syringe into teat canal; push plunger to instill entire contents. Massage quarter and do not milk out for 12 hours. | Intramammary | q12h | May repeat dose | 🌎 NA |
| Mastitis (Dry Cow) | Same basic directions as above, but should be done at the time of drying off and not later than 30 days prior to calving. | Intramammary | Once at drying off | Single treatment | 🌎 NA |
| Subacute and chronic endometritis (at least 14 days after parturition) | Contents of syringe (500 mg) instilled through the cervix into the lumen of the uterus; depending on response may re-treat in 7-14 days if signs persist. | Intrauterine | Once, may repeat in 7-14 days | 1-2 treatments | 🌎 NA |
- Mastitis (Lactating cow): Milk withdrawal = 96 hours; Slaughter withdrawal = 4 days.
- Mastitis (Dry Cow): Milk withdrawal = 72 hours after calving; Slaughter withdrawal = 42 days.
- Subacute and chronic endometritis (at least 14 days after parturition): May be used one day after insemination. If pyometra, pretreatment with a prostaglandin recommended.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Cephapirin is a first-generation cephalosporin antibiotic primarily utilized in veterinary medicine for the treatment of bovine mastitis and endometritis.
- Spectrum of Activity: Effective against many Gram-positive organisms (e.g., Staphylococcus and Streptococcus spp.) commonly implicated in mastitis, as well as some Gram-negative bacteria.
- Clinical Use: Administered locally via intramammary or intrauterine routes. Systemic parenteral formulations are largely obsolete in veterinary practice.
- Key Consideration: Strict adherence to milk and meat withdrawal times is essential for food-producing animals to prevent illegal residues.
Mechanism of action
Cephapirin is a time-dependent, bactericidal beta-lactam antibiotic.
- Binds to specific penicillin-binding proteins (PBPs) (such as transpeptidases, carboxypeptidases, and endopeptidases) located inside the bacterial cytoplasmic membrane.
- Inhibition of these enzymes → blocks the final stages of mucopeptide (peptidoglycan) synthesis in the bacterial cell wall.
- Defective cell wall formation → creates an osmotically unstable spheroplast → cell lysis and death.
- Note: Like other beta-lactams, it is most effective against actively growing and dividing bacteria.
Safety & warnings
Contraindications
- Patients with a known history of hypersensitivity to cephalosporins
Adverse effects
- Hypersensitivity reactions (rashes, fever, eosinophilia, lymphadenopathy)
- Anaphylaxis (rare but possible)
Precautions
Cross-Reactivity: Use cautiously in patients with documented hypersensitivity to other beta-lactam antibiotics (e.g., penicillins, cefamycins, carbapenems) due to potential cross-reactivity.
- Pregnancy: Cephalosporins cross the placenta. Safe use during pregnancy has not been firmly established, though no teratogenic problems have been documented.
- Withdrawal Times: Extended withdrawal times may be prudent in cows with very low milk production (<25 kg/day) as they appear to absorb more drug systemically.
Monitoring
- Clinical efficacy (resolution of mastitis or endometritis)
- Renal function (in patients with diminished renal capacity, though primarily a concern for systemic use)
Pharmacokinetics
Half-life
Absorption
When administered via intramammary infusion, it is rapidly metabolized to the active metabolite desacetylcephaprin in milk. Cows with low daily milk production (<25kg) appear to absorb more cephalothin systemically.
Distribution
Apparent volume of distribution (systemic) in cattle is 0.335-0.399 L/kg.
Metabolism
Rapidly metabolized to the active metabolite desacetylcephaprin in milk.
Elimination
Total body clearance is 12.66 mL/min/kg in cattle.
Overdose
No significant clinical adverse effects are expected with acute overdosage. However, if used at doses or rates higher than labeled, withdrawal times for milk and meat may be significantly prolonged.
Available products
Formulations
- Intramammary suspension/syringe
- Intrauterine suspension/syringe
Veterinary
- Cephapirin Sodium Mastitis Tube; 200 mg cephapirin per 10 mL tube (ToDAY, Cefa-Lak)
- Cephapirin Benzathine Mastitis Tube; 300 mg cephapirin per 10 mL tube (ToMORROW, Cefa-Dri)
- Cephapirin Benzathine Intrauterine Infusion Syringe; 500 mg (Metricure)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store intramammary syringes at controlled room temperature (15-30°C); avoid excessive heat.
Client information
Important Note for Producers: This medication is primarily used in dairy and beef cattle for localized infections.
- Administration Technique: Ensure the teat end or vulva is thoroughly cleaned and disinfected with alcohol before infusion to prevent introducing new environmental bacteria.
- Withdrawal Times: Strictly follow the prescribed milk discard and slaughter withdrawal times to prevent illegal drug residues in the food supply. Note that low-producing cows may require extended withdrawal periods.
- Allergic Reactions: Watch for signs of hypersensitivity, such as hives, swelling, or sudden breathing difficulty. Contact your veterinarian immediately if these occur.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.