Chemistry - A semi-synthetic macrolide antibiotic, tilmicosin phosphate is commercially available in a 300 mg/ml (of tilmicosin base) injection with 25% propylene glycol.
Storage/Stability/Compatibility - Store the injection at or below room temperature. Avoid exposure to direct sunlight.
Pharmacology - Like other macrolides, tilmicosin has activity primarily against gram positive bacteria, although some gram negative bacteria are affected and the drug reportedly has some activity against mycoplasma. Preliminary studies have shown that 95% of studied isolates of Pasturella haemolytica are sensitive.
Uses/Indications - Tilmicosin is indicated fort the treatment of bovine respiratory diseases (BRD) caused by Pasturella haemolytica.
Pharmacokinetics - Tilmicosin apparently concentrates in lung tissue. At 3 days post injection, the lung:serum ratio is about 60:1. MIC95 concentrations (3.12 micrograms/ml) for P. Haemolytica persist for a minimum of 3 days after a single injection.
Contraindications/Precautions/Reproductive Safety - Not to be used in automatically powered syringes or to be given intravenously as fatalities may result. Tilmicosin has been shown to be fatal in swine, non-human primates and potentially fatal in horses.
Safe use in pregnant animals or in animals to be used for breeding purposes has not been demonstrated.
Adverse Effects/Warnings - If administered IM, a local tissue reaction may occur resulting in trim loss. Edema may be noted at the site of subcutaneous injection.
Avoid contact with eyes.
Overdosage/Acute Toxicity - The cardiovascular system is apparently the target of toxicity in animals. In cattle, doses up to 50 mg/kg did not cause death, but SQ doses of 150 mg/kg did cause fatalities. Doses as low as 10 mg/kg in swine caused increased respiration, emesis and seizures; 20 mg/kg caused deaths in most animals tested. In monkeys, 10 mg/kg administered once caused no signs of toxicity, but 20 mg/kg caused vomiting and 30 mg/kg caused death.
In cases of human injection, contact physician immediately. The manufacturer has emergency telephone numbers to assist in dealing with exposure: 1-800-722-0987 or 1-317-276-2000.
Drug Interactions - In swine, epinephrine increased the mortality associated with tilmicosin. No other specific information noted; refer to the erythromycin monograph for potential interactions.
For susceptible infections (subcutaneous injection behind the shoulders and over the ribs is suggested).
a) For treatment of pneumonic pasteurellosis in cattle: 10 mg/kg SQ every 72 hours. (Shewen and Bateman 1993)
b) Package insert (Micotil® 300; Elanco): 10 mg/kg SubQ (not more than 15 ml per injection site)
Monitoring Parameters - 1) Efficacy; 2) Withdrawal times
Client Information - If clients are administering the drug, they should be warned about the potential toxicity to humans, swine and horses if accidentally injected. They should also be carefully instructed in proper injection techniques. Avoid contact with eyes.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times -
Tilmicosin for Subcutaneous Injection 300 mg/ml in 100 ml and 250 ml multi-dose vials; Micotil® 300 Injection (Elanco); (Rx) Approved for use in cattle. Not approved for use in female dairy cattle 20 months or older. Do not use in veal calves. Slaughter withdrawal = 28 days.
Human-Approved Products: None
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