ATC Vet Code: QJ01XQ01
Pharmacotherapeutic group: Antibacterials for systemic use, Other antibacterials, Pleuromutilins
Pharmacodynamic properties
Tiamulin hydrogen fumarate is a semi-synthetic derivative of the diterpene antibiotic pleuromutilin, produced by Pleurotus mutilis later renamed Clitopilus scyphoides. Tiamulin is active against pathogenic mycoplasmas, against most Grampositive organisms and anaerobes. Tiamulin is bacteriostatic at therapeutic concentrations and has been shown to act at the ribosome level and the primary binding site is on the 50S subunit and possibly a secondary site where the 50S and 30S subunits join. It appears to inhibit microbial protein production by producing biochemical inactive initiation complexes, which prevent elongation of the polypeptide chain.
Research has shown that resistant bacterial mutants can be created through multi step resistance. Horizontal transferable resistance has also been described (e.g. vga genes & cfr gene). In practice, resistance in mycoplasmas has been reported rarely. Resistance against B. hyodysenteriae has been seen and can vary geographically. If response to treatment of dysentery with the product is poor, then the possibility of resistance must be considered. Cross resistance between tiamulin and tylosin tartrate has been reported: micro-organisms that are resistant for tiamulin, are also resistant for tylosin tartrate, but not vice versa. Transferable resistance mechanism (cfr) can cause cross-resistance to lincosamides, streptogramins (A) and phenicols (florfenicol). Resistance in Brachyspira hyodysenteriae can be caused by a point mutation in the 23S rRNA gene and/or the ribosomal protein L3 gene.
Pharmacokinetic properties
Following a single intramuscular administration at a dose rate of approximately 14 mg tiamulin per kg bodyweight, mean maximum tiamulin concentration (approximately 350ng/ml) was reached after approximately 3 hours. The mean terminal half-life is approximately 12 hours.