Tylosin is a macrolide antibiotic produced by a strain of Streptomyces fradiae.it exerts its antimicrobial effect by inhibiting protein synthesis of susceptible micro- organisms.

The tylosin spectrum of activity includes amongst others Gram +ve bacteria, some Gram –ve strains such as pasteurella, and mycoplasma spp.

In most species peak plasma concentrations have been attained 1 to 2 hours after administration of tylosin.com-pared to plasma levels clearly higher tissue concentrations have been observed. Tylosin was extensively metabolized.

Most of the residues are excreted in faces predominantly consisting of tylosin (factor A), relomycin (factor D) and di hydrodesmycosin.