Procaine penicillin G (procaine benzylpenicillin, CAS 54-35-3) is the workhorse long-acting injectable antibiotic in livestock medicine. Its sparing solubility keeps penicillin levels therapeutic for about 24-48 hours after one intramuscular injection. This guide explains how it is used in cattle, swine, sheep and poultry, and what the sterile micronized lecithin-coated grade adds in practice.
1. Why Procaine Penicillin Is Long-Acting
The procaine salt of benzylpenicillin dissolves slowly at the injection site, acting as a depot. Penicillin G is released gradually, maintaining effective blood levels against susceptible Gram-positive bacteria for roughly 24-48 hours – long enough for once-daily or single-dose protocols in many livestock infections.
2. Main Veterinary Indications
| Species | Typical indications |
|---|---|
| Cattle | Pneumonia/pasteurellosis, mastitis, foot infections, wound infections, erysipelas |
| Swine | Erysipelas, streptococcal infections, pneumonia, joint infections |
| Sheep & goats | Pneumonia, mastitis, abscesses, clostridial support |
| Poultry | Specific labelled Gram-positive infections (where licensed) |
3. Formulation: Why Micronized Lecithin-Coated Grade
- Micronization – narrow particle size (50% <8 μm) gives a uniform, slow-release suspension that does not settle hard or clog needles.
- Lecithin coating (~1%) – improves wettability and suspension stability, reduces caking on storage, and makes drawing and injection easier.
- Sterility – injectable products must be sterile with low endotoxins; the sterile grade is filled aseptically.
4. Handling and Withdrawal
- Shake suspension well before use; administer by deep intramuscular injection.
- Observe label withdrawal periods for meat and milk per local regulation.
- Watch for injection-site reactions; rotate sites for repeat dosing.
5. FAQ
Can procaine penicillin be used in dairy cattle?
Yes, but strict milk withdrawal times apply; follow the licensed label for the region.
Is it suitable for once-daily treatment?
Its 24-48 hour action supports once-daily or single-dose protocols in many infections; follow veterinary guidance and label directions.
6. References and Further Reading
- Ph. Eur. monograph for procaine benzylpenicillin; veterinary pharmacopoeia monographs.
- Supplier COA and sterility documentation for the specific grade.
This article is published for industrial and technical reference by PolyblueChem. Verify against the supplier’s COA and applicable regulations.
See our procaine benzylpenicillin chemistry and production guide. PolyblueChem supplies procaine benzylpenicillin (CAS 54-35-3) sterile micronized lecithin-coated grade – contact us for specifications and quotations.