Tilmicosin
Tilmicosin phosphate
Also known as: Micotil · Pulmotil · EL-870 · LY-177370 · Tilmicosin phosphate
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
Small Mammals
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections (Rabbits) - Regimen 1 | 25 mg/kg SC once; repeat in 3 days if necessary. | SC | Once, repeat in 3 days PRN | — | 🌎 NA |
| Susceptible infections (Rabbits) - Regimen 2 | 5 mg/kg SC on day 0, if no reaction, give 10 mg/kg SC on days 7 and 14. | SC | Days 0, 7, 14 | 14 days | 🌎 NA |
- Susceptible infections (Rabbits) - Regimen 1: Can cause weakness, pallor, tachypnea and sudden death. May cause acute death if given IV. SC injections can cause local swelling and necrosis.
- Susceptible infections (Rabbits) - Regimen 2: Can cause weakness, pallor, tachypnea and sudden death. May cause acute death if given IV. SC injections can cause local swelling and necrosis.
Cattle
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Treatment of pneumonic pasteurellosis | 10 mg/kg SC every 72 hours | SC | q72h | — | 🌎 NA |
| Susceptible infections | 10 mg/kg SC (not more than 15 mL per injection site) | SC | Single dose | — | 🌎 NA |
- Treatment of pneumonic pasteurellosis: Subcutaneous injection under the skin in the neck, or if not accessible, behind the shoulders and over the ribs is suggested.
Sheep
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 10 mg/kg SC (not more than 15 mL per injection site). | SC | Single dose | — | 🌎 NA |
- Susceptible infections: Subcutaneous injection under the skin in the neck, or if not accessible, behind the shoulders and over the ribs is suggested. Do not use in lambs less than 15 kg of body weight.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Tilmicosin is a semi-synthetic macrolide antibiotic synthesized from tylosin, primarily used in veterinary medicine for the treatment of bovine and ovine respiratory disease (BRD) associated with Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni.
- Key Features:
- Highly lipophilic, allowing for extensive tissue penetration. It actively concentrates in lung tissue and alveolar macrophages, providing targeted therapy for respiratory infections.
- Administered primarily via subcutaneous (SC) injection in ruminants or as a medicated feed additive in swine.
CRITICAL WARNING: Tilmicosin has a narrow margin of safety in many species. Accidental injection in humans, swine, horses, camelids, and non-human primates can be rapidly fatal due to severe cardiovascular toxicity.
Mechanism of action
Tilmicosin exerts its bacteriostatic effect by penetrating the bacterial cell membrane and reversibly binding to the 50S ribosomal subunit.
- Mechanism: Binds to the 50S subunit → blocks the exit tunnel for newly synthesized peptides → inhibits translocation of peptidyl-tRNA → premature termination of bacterial protein synthesis.
- It exhibits time-dependent antibacterial activity and has a prolonged post-antibiotic effect (PAE), especially against respiratory pathogens. Its accumulation in macrophages allows it to be delivered directly to the site of infection via chemotaxis.
Safety & warnings
Contraindications
- Intravenous (IV) administration (can be fatal)
- Use in automatically powered syringes
- Injection in swine, non-human primates, horses, and camelids
- Use in lactating ewes if milk is intended for human consumption
- Use in veal calves
- Use in female dairy cattle 20 months or older
Adverse effects
- Local tissue reaction and trim loss (if given IM)
- Edema at the site of subcutaneous injection
- Severe cardiovascular toxicity (fatalities) if given IV
- Fatalities in swine, non-human primates, and potentially horses if injected
- Severe reactions in camelids
Precautions
HUMAN SAFETY WARNING: Accidental self-injection can be fatal. Do not use automatically powered syringes. Avoid contact with eyes.
- Species Sensitivity: Highly toxic when injected in swine, equines, camelids, and primates.
- Pregnancy/Breeding: Safe use in pregnant animals or animals intended for breeding has not been demonstrated.
- Administration: Give strictly via subcutaneous injection in approved species. Intramuscular injection causes severe tissue reactions; intravenous injection is often fatal.
Drug interactions
Increased mortality associated with tilmicosin in swine.
Potential cross-resistance and competitive binding at the 50S ribosomal subunit (extrapolated from erythromycin).
Monitoring
- Clinical efficacy (resolution of respiratory signs)
- Injection site reactions
- Slaughter withdrawal times (28 days for cattle/sheep injection; 7 days for swine feed)
Pharmacokinetics
Absorption
Well absorbed following subcutaneous injection.
Distribution
Highly lipophilic; extensively distributes into tissues and concentrates heavily in lung tissue and alveolar macrophages. At 3 days post-injection, the lung:serum ratio is approximately 60:1.
Elimination
MIC95 concentrations (3.12 mcg/mL) for *P. haemolytica* persist in the lungs for a minimum of 3 days after a single SC injection.
Overdose
The cardiovascular system is the primary target of acute toxicity, likely due to calcium channel blockade leading to negative inotropic effects, tachycardia, and fatal arrhythmias.
- Cattle: Doses up to 50 mg/kg IM did not cause death, but SC doses of 150 mg/kg caused fatalities, as did IV doses of 5 mg/kg.
- Swine: Doses as low as 10 mg/kg caused increased respiration, emesis, and seizures; 20 mg/kg IM caused death in most animals tested.
- Monkeys: 10 mg/kg caused no signs of toxicity; 20 mg/kg caused vomiting; 30 mg/kg caused death.
HUMAN EXPOSURE: In cases of human injection, contact a physician immediately. Apply ice to the injection site. Emergency medical telephone numbers: 1-800-722-0987 or 1-317-276-2000.
Available products
Formulations
- Subcutaneous Injection: 300 mg/mL
- Feed Medication: 90.7 grams/lb
Veterinary
- Micotil 300 Injection (Elanco): 300 mg/mL in 50 mL, 100 mL, and 250 mL multi-dose vials (Rx)
- Pulmotil 90 Feed Medication (Elanco): 90.7 grams/lb (OTC)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store the injection at or below room temperature. Avoid exposure to direct sunlight.
Client information
CRITICAL SAFETY WARNING: Accidental self-injection of this medication can be FATAL to humans.
- Handling: Exercise extreme caution when handling syringes and needles. Never use automatically powered syringes.
- Accidental Exposure: If you accidentally prick or inject yourself, immediately apply ice to the site and seek emergency medical attention right away. Call 1-800-722-0987 or 1-317-276-2000 for emergency guidance.
- Administration: Only administer subcutaneously (under the skin) as directed by your veterinarian. Do not inject into muscle or veins, as this can be fatal to the animal.
- Species Warnings: Never use this injectable medication in pigs, horses, alpacas/llamas, or pets. It is highly toxic to these species.
- Storage: Keep securely away from children and avoid contact with eyes.
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.