The European Agency for the Evaluation of Medicinal Products Veterinary Medicines Evaluation Unit

1. Tylosin is a macrolide antibiotic that is active mostly against Gram-positive bacteria and mycoplasmas. It is ineffective against Enterobacteriacea. It consists predominantly of tylosin A (factor A), but varying amounts of tylosin factor B (desmycosin), tylosin factor C (macrosin) and tylosin factor D (relomycin) may also be present, depending on the manufacturing source. Most of the microbiological activity resides with tylosin A. Tylosin factors B, C and D and dihydroxydesmycosin (metabolite) have around 50%, 70%, 30% and 15% of the activity of tylosin A respectively. The safety studies were carried out using tylosin from a commercial source with a specification of tylosin A being at least 80% and the sum of tylosin A, B, C and D : being at least 95%. Tylosin and its phosphate and tartrate salts are used in pigs, cattle and poultry for the treatment of conditions caused by sensitive organisms. It may be administered to calves, orally in the milk replacer, at a dose of 40 mg/kg bw and to cattle by intramuscular injection at a dose of 4-10 mg/kg bw. In pigs, tylosin may be administered in the drinking water at a dose of 25 mg/kg bw, in the feed at a dose of 3-7 mg/kg bw, or by intramuscular injection at a dose of 2-10 mg/kg bw for the prevention and control of diseases such as swine dysentery and enzootic pneumonia. Tylosin is administered to poultry in the drinking water at a dose equivalent to 35 mg/kg bw. Tylosin is also authorised as a feed additive in accordance with Council Directive 70/524/EEC; the substance may be incorporated into pig feed at concentrations in the range of 5-20 mg/kg feed for animals up to 6 months of age and 10-40 mg/kg feed for animals up to 4 months of age.