Epidemiological and PK/PD cutoff values determination and PK/PD-based dose assessment of gamithromycin against Haemophilus parasuis in piglets.

Abstract

BACKGROUND:

Gamithromycin is a macrolide approved for the treatment of bovine and swine respiratory diseases. Our study aims to establish the clinical breakpoint and optimum dose regimen for gamithromycin against Haemophilus parasuis in piglets.

RESULTS:

Gamithromycin was well absorbed and fully bioavailable (87.2-101%) after intramuscular and subcutaneous administrations. The MICs of gamithromycin for 192 clinical H. parasuis isolates ranged from 0.008 to 128 mg/L and the epidemiological cutoff (ECOFF) was calculated as 1.0 mg/L. A large potentiation effect of serum on in vitro susceptibility of gamithromycin was observed for H. parasuis, with broth/serum ratios of 8.93 for MICs and 4.46 for MBCs, respectively. The postantibiotic effects were 1.5 h (1 × MIC) and 2.4 h (4 × MIC), and the postantibiotic sub-MIC effects ranged from 2.7 to 4.3 h. Gamithromycin had rapid and concentration-dependent killing against H. parasuis, and the AUC24h/MIC ratio correlated well with ex vivo efficacy (R2 = 0.97). The AUC24h/MIC targets in serum associated with bacteriostatic, bactericidal and eradication activities were 15.8, 30.3 and 41.2, respectively. The PK/PD-based population dose prediction indicated a probability of target attainment (PTA) for the current marketed dose (6 mg/kg) of 88.9% against H. parasuis. The calculated gamithromycin dose for a PTA ≥ 90% was 6.55 mg/kg. Based on Monte Carlo simulations, the PK/PD cutoff (COPD) was determined to be 0.25 mg/L.

CONCLUSION:

The determined cutoffs and PK/PD-based dose prediction will be of great importance in gamithromycin resistance surveillance and serve as an important step in the establishment of optimum dose regimen and clinical breakpoints.

• Authors: Yu-Feng Zhou, Ming-Xiao Bu, Ping Liu, Jian Sun, Ya-Hong Liu, Xiao-Ping Liao
• Journal: BMC veterinary research (BMC Vet Res) Vol. 16 Issue 1 Pg. 81 (Mar 05 2020) ISSN: 1746-6148 [Electronic] England
• PMID: 32138735 (Publication Type: Journal Article)

Chemical References

• Anti-Bacterial Agents
• Macrolides
• gamithromycin

Topics

• Animals
• Anti-Bacterial Agents (administration & dosage, pharmacokinetics, pharmacology)
• Area Under Curve
• Haemophilus Infections (drug therapy, veterinary)
• Haemophilus parasuis (drug effects)
• Injections, Intramuscular (veterinary)
• Injections, Subcutaneous (veterinary)
• Macrolides (administration & dosage, pharmacokinetics, pharmacology)
• Male
• Microbial Sensitivity Tests (veterinary)
• Sus scrofa
• Swine
• Swine Diseases (drug therapy)