Quick Facts
| CAS Number | 137330-13-3 |
|---|---|
| Molecular Formula | C46H80N2O13·H3PO4 |
| Molecular Weight | 967.14 |
| Pharmacopoeia | IN HOUSE |
| Packaging | 25 KG/DRUM |
Product Overview
Tilmicosin was developed by Elanco Animal Health (a division of Eli Lilly) and first approved as Micotil 300 injectable solution in the United States in 1992. It represents a deliberate semi-synthetic modification of tylosin — a natural 16-membered macrolide — with the specific goal of creating a veterinary-only antibiotic optimized for respiratory disease. The key structural change is the substitution of a 3,5-dimethylpiperidine group for the mycarose sugar at position C-20 of the tylosin lactone ring. This modification alters the acid stability and tissue distribution profile, resulting in a compound that achieves lung tissue concentrations 60-70 times higher than plasma levels — the most extreme lung:plasma ratio of any commercially available veterinary macrolide.
Tilmicosin's pharmacokinetic profile is what defines its clinical role. After oral administration in feed or drinking water, approximately 85% of the drug is absorbed systemically, and it then undergoes preferential redistribution to lung tissue, alveolar macrophages, and bronchial epithelium. Therapeutic concentrations in lung parenchyma are maintained for 72 hours or longer after a single oral dose, while plasma levels become undetectable within 12-24 hours. This dissociation between lung and plasma concentrations means that tilmicosin continues working at the infection site long after the drug has cleared from circulation — a pharmacodynamic advantage that enables short-course (3-5 day) feed medication protocols for respiratory disease outbreaks. No other veterinary macrolide achieves this degree of pharmacokinetic selectivity for lung tissue.
The phosphate salt form (CAS 137330-13-3) is specifically designed for oral administration via feed and drinking water. Unlike the injectable tilmicosin base (Micotil 300), which requires extreme caution due to its cardiotoxicity risk to humans, the phosphate salt in feed premixes has a substantially wider safety margin in target species when administered orally at labeled doses. This is a critical practical distinction: the feed-grade tilmicosin phosphate represents the high-volume segment of the market, used for mass medication of entire groups of cattle, swine, and poultry, while the injectable formulation is restricted to individual animal treatment by veterinary professionals. The phosphate salt's water solubility also makes it suitable for drinking water administration in swine and poultry operations.
As of mid-2026, tilmicosin phosphate is one of the most prescribed macrolide antibiotics in global livestock production. Bovine respiratory disease (BRD) remains the single largest indication — the disease costs the global cattle industry an estimated USD 3 billion annually in mortality, reduced weight gain, and treatment costs. Tilmicosin's ability to be administered prophylactically via feed at feedlot arrival (metaphylaxis) has been demonstrated to reduce BRD morbidity by 30-50% compared to treatment-on-diagnosis approaches. China dominates global tilmicosin phosphate API production, with manufacturing concentrated in Shandong, Jiangsu, and Zhejiang provinces. KingWish supplies GMP-certified tilmicosin phosphate under IN HOUSE specifications, supporting feed premix and veterinary pharmaceutical manufacturers worldwide.
Quality Specifications
| Purity (HPLC) | ≥ 85.0% tilmicosin base equivalent, per IN HOUSE standard |
|---|---|
| Related Substances | Individual impurity ≤ 3.0%, total impurities ≤ 5.0% |
| Water Content | ≤ 5.0% (Karl Fischer) |
| Residual Solvents | Compliant with ICH Q3C; ethyl acetate typically the main process solvent |
| Heavy Metals | ≤ 20 ppm |
| GMP Status | Manufactured under ICH Q7 GMP conditions |
Veterinary Applications
Bovine Respiratory Disease (BRD)
Feed additive for control and metaphylaxis of BRD in feedlot cattle. Lung concentrations sustained for 72+ hours. Reduces morbidity by 30-50% in arrival metaphylaxis programs compared to treatment-on-diagnosis.
Swine Respiratory Disease Complex
Feed medication for PRDC, mycoplasmal pneumonia, and actinobacillus pleuropneumonia. Drinking water administration for outbreak control in grower-finisher pigs. 3-5 day course typical.
Therapeutic Areas
- Cattle (feedlot): BRD control and metaphylaxis, Pasteurella and Mannheimia infections, mycoplasmal pneumonia
- Cattle (injectable, vet-only): Individual treatment of BRD, foot rot, and respiratory infections
- Swine: Porcine respiratory disease complex (PRDC), mycoplasmal pneumonia, Actinobacillus pleuropneumoniae
- Sheep: Ovine respiratory infections, pasteurellosis, foot rot
- Poultry: Mycoplasma infections, chronic respiratory disease (CRD)
Sourcing Tilmicosin Phosphate: Key Checks
Documentation
Request CoA with HPLC purity (tilmicosin base equivalent), related substances profile, water content (Karl Fischer), residual solvent statement (ICH Q3C), heavy metals, and GMP certificate. Since tilmicosin phosphate has no official pharmacopoeia monograph, the supplier's IN HOUSE specification and validated analytical methods are critical.
Red Flags
Excessive related substances (particularly degradation products from the lactone ring opening), high water content above 5%, inconsistent potency between batches, and reluctance to share the IN HOUSE specification and validated test methods before order placement.
Packaging & Logistics
Standard: 25 KG/DRUM with PE liner. Store at room temperature in airtight containers, protected from moisture and light. The phosphate salt is hygroscopic — ensure drum integrity for sea freight. Verify import regulations: some countries classify tilmicosin as a prescription-only veterinary API.
Market Context
Tilmicosin is a high-volume veterinary macrolide driven by BRD metaphylaxis in feedlot cattle globally. The shift toward oral/feed-grade tilmicosin phosphate (away from injectable tilmicosin) is driven by safety and convenience. Patent expiry has enabled generic API production, with China dominating global supply. Tilmicosin competes with tulathromycin, gamithromycin, and tildipirosin in the premium macrolide segment for BRD.