Gamithromycin

Gamithromycin (CAS No. 145435-72-9) is a 15-membered semi-synthetic macrolide antibiotic whose core biological activity is inhibition of bacterial protein synthesis, targeting the 50S subunit of the bacterial ribosome. It shows broad-spectrum antibacterial activity against respiratory pathogens in cattle, pigs, rabbits and other animals (such as Pasteurella multocida, Haemophilus parasuis, Mycoplasma hyopneumoniae, Streptococcus suis, etc.), and its in vitro potency can be significantly enhanced in serum (MIC values are 4~64-fold lower in serum than in culture medium). The MIC is pathogen-specific: for P. multocida the MIC in bovine serum is about 0.03~0.15 μg/mL and 0.5~0.71 μg/mL in culture medium; clinical isolates of H. parasuis have an MIC range of 0.008~128 mg/L (epidemiological cutoff is 1 mg/L); for M. hyopneumoniae strain B237 the MIC is 0.00012 μg/mL in serum and 0.016 μg/mL in culture medium; for S. suis the MIC90 is 0.125 μg/mL. Common application concentrations: in vitro experiments use gradient concentrations of 0.03~128 μg/mL (in culture medium or serum matrix); cell experiments (intracellular pathogens in macrophages) use 0.33~10 μg/mL; in animal experiments, commonly used doses in pigs, cattle, and rabbits are 6 mg/kg (subcutaneous or intramuscular injection). In foals, an intramuscular dose of 6 mg/kg can maintain pulmonary epithelial lining fluid concentrations above the MIC90 for up to 7 days. Clinically effective therapeutic concentrations correspond to treatment of bovine and porcine respiratory diseases, with a recommended dose of 6 mg/kg as a single subcutaneous/intramuscular injection. At steady state, concentrations in lung tissue and pulmonary epithelial lining fluid (PELF) are significantly higher than in plasma. The key PK/PD index is AUC24h/MIC, and the ratios required for bacteriostatic, bactericidal, and eradication effects are 15.4~56.77 h, 24.9~90.18 h, and 27.8~239.44 h, respectively (varying with animal species and pathogen). It is suitable for the treatment of bovine respiratory disease (P. multocida, Mannheimia haemolytica, etc.) and Gl?sser’s disease in pigs (H. parasuis infection), and is contraindicated in dairy cows producing milk for human consumption.

References:

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