Tiamulin

Tiamulin (CAS No. 55297-95-5) is a semi-synthetic pleuromutilin derivative whose core biological activities are antibacterial and anti-inflammatory. Its targets include the peptidyl transferase center of the 50S subunit of the bacterial ribosome (binding to 23S rRNA at A2058, A2059, G2505, and U2506 to inhibit protein synthesis) and TNF-α-mediated inflammatory pathways (NF-κB, MAPK, JAK/STAT3 pathways). MIC values are strain-specific: 0.03 μg/mL for Mycoplasma gallisepticum strain S6 in chickens; 100-125 μg/mL for wild-type Escherichia coli (CN2476); 350-400 μg/mL for L3 mutant strain (JB5). Actinobacillus pleuropneumoniae and other Gram-positive bacteria, as well as some mycoplasmas, are sensitive. Regarding IC50, inhibition of TNF-α-mediated cytotoxicity is 23 μM, and in vitro inhibition of inflammatory pathways requires 50-100 μM. Common working concentrations: cell experiments (anti-inflammatory/antibacterial) 10-200 μM; animal experiments (intramuscular injection in chickens) 5-80 mg/kg, oral 20 mg/kg; for treatment of Mycoplasma gallisepticum infection in chickens, 45 mg/kg/day is recommended (for 3 consecutive days). Clinically effective therapeutic concentrations correspond to veterinary use: 30-60 mg/kg via drinking water in pigs and poultry, 10-20 mg/kg intramuscular injection in pigs. A steady-state peak serum concentration above 8.8 μg/mL (at a 40 mg/kg dose) is required, and an AUC24h/MIC ≥ 382.58 h can achieve a 2 log10 reduction in pathogen load. In addition, a 5% topical cream can alleviate psoriasis-like dermatitis, and its anti-inflammatory potential in humans is still under investigation. Veterinary clinical MRLs are 100 μg/kg for muscle and 500 μg/kg for liver.

References:

[1] Long KS, Hansen LH, Jakobsen L, Vester B. Interaction of pleuromutilin derivatives with the ribosomal peptidyl transferase center. Antimicrob Agents Chemother. 2006 Apr;50(4):1458-62. doi: 10.1128/AAC.50.4.1458-1462.2006. PMID: 16569865; PMCID: PMC1426994.

[2] Xiao X, Sun J, Yang T, Fang X, Cheng J, Xiong YQ, Liu YH. Pharmacokinetic/Pharmacodynamic Profiles of Tiamulin in an Experimental Intratracheal Infection Model of Mycoplasma gallisepticum. Front Vet Sci. 2016 Sep 6;3:75. doi: 10.3389/fvets.2016.00075. PMID: 27656647; PMCID: PMC5012102.

[3] Sun F, Yang S, Zhang H, Zhou J, Li Y, Zhang J, Jin Y, Wang Z, Li Y, Shen J, Zhang S, Cao X. Comprehensive Analysis of Tiamulin Metabolites in Various Species of Farm Animals Using Ultra-High-Performance Liquid Chromatography Coupled to Quadrupole/Time-of-Flight. J Agric Food Chem. 2017 Jan 11;65(1):199-207. doi: 10.1021/acs.jafc.6b04377. Epub 2016 Dec 27. PMID: 28026174.

[4] Xiang R, Hu L, Li S, Wei Z, Song Z, Chen Z, Liu Y, Liu J, Lei X, Yang Y. Tiamulin inhibits TNF-α and alleviates psoriasis-like dermatitis. J Dermatol Sci. 2022 Jul;107(1):32-40. doi: 10.1016/j.jdermsci.2022.05.006. Epub 2022 May 21. PMID: 35718680.

[5] Ekinci ?B, Ch?odowska A, Olejnik M. Ionophore Toxicity in Animals: A Review of Clinical and Molecular Aspects. Int J Mol Sci. 2023 Jan 15;24(2):1696. doi: 10.3390/ijms24021696. PMID: 36675211; PMCID: PMC9863538.