본 연구는 겐타마이신(GEN)을 돼지에 경구 투여한 다 음, 돼지 식용조직 내 GEN의 잔류농도를 조사하였으며, 돼지 식용조직에서 GEN의 적정 휴약기간을 설정하였다. 총 42마리의 건강한 돼지에게 체중 kg 당 1 . 1 mg (GEN- 1, n=20)과 2.2 mg (GEN-2, n=20)의 GEN을 하루에 한 번씩 3일 동안 연속적으로 경구투여하였다. 약물 투여 후, 1, 3, 5, 7, 14일째에 각각 돼지 4마리로부터 조직 시료를 채취하였다. 돼지 조직 내 GEN 잔류농도는 액체크로마토 그래피-질량분석법(LC-MS/MS)을 사용하여 측정하였다. 본 연구에, 확립한 LC-MS/MS의 상관계수는 0.9961에서 0.9996 사이였으며, 검출한계(LOD)와 정량한계(LOQ)는 각 각 0.003-0.008 mg/kg과 0.01-0.025 mg/kg이었다. 근육, 간, 신 장 및 지방 조직에서의 회수율은 각각 55.51-73.15%, 69.65- 78.21%, 66.56-83.29%, 96.76-107.74%였으며, 변이계수는 모두 11.16% 이하였다. GEN-1과 GEN-2 모두에서 근육, 간, 지방 시료 내 GEN 농도는 약제 투여 종료 후 1일째 에 LOQ 이하로 나타났다. 그러나 두 그룹 모두에서 신장 시료에서는 약제 투여 종료 후 7일째까지 LOQ 이상으로 GEN이 검출되었다. 유럽의약청(EMA)의 식용조직에 대한 휴약기간 설정 지침에 따라서, GEN-1과 GEN-2의 돼지 조 직 내 휴약기간은 각각 2일 및 9일로 설정되었다. 이상의 결과로부터, 본 연구에서 확립된 분석법은 돼지 조직 내 GEN 검출에 적합하며, 설정된 GEN의 휴약기간은 돼지 식용조직 제품의 안전성 확보에 기여할 것으로 판단된다.

Gentamicin is an aminoglycoside antibiotic effective against aerobic gram-negative bacteria and is also used in veterinary medicine, particularly in the swine and bovine industries. However, no gentamicin product is currently approved for treating equine diseases in Korea. The present study aims to examine the time-dependent residue of gentamicin in horses after intravenous injection (IV) via jugular vein. The test product was injected at 6.6 mg/kg BW via jugular vein in nine horses. Blood was collected from the horse's jugular vein at 15 minutes, 30 minutes, 1, 4, 8, 12, 24 and 48 hours after injection. To purify the gentamicin in serum, 100μL of 20 mM HFBA in DW, 100 μL of 30% trichloroacetic acid and 300 μL of 20 mM heptafluorobutyric acid (HFBA) in acetonitrile (ACN) were added to 500 μL of serum and supernatant was applied to LC-MS/MS after centrifugation. LC-MS/MS-8050 analyzed the level of gentamicin in serum with Electrospray ionization (ESI) and multiple reaction monitoring (MRM) positive mode. Gentamicin C1 was 478 m/z and product ions were 322, 157 m/z. Precursor ion of Gentamicin C1a was 450 m/z and product ions were 322, 160 m/z. Precursor ion of Gentamicin C2 and C2a was 464 m/z and product ions were 322, 160 m/z. The LC column was a C18 and mobile phase composed of 20 mM HFBA in 5% ACN and 20 mM HFBA in 50% ACN. The amount of gentamicin was calculated by adding four components of gentamicin (C1, C1a, C2 and C2a). The pharmacokinetic parameters of gentamicin were calculated by the WinNonlin program. The Cmax of gentamicin in horse serum was 93 ± 17 μg/kg and the Tmax was 0.25 ± 0 hours. The T1/2 was 6.41 ± 2.32 hours and the CLt was 0.05 ± 0.01L/hr/kg. The Vd was shown as 0.44 ± 0.13 L/kg and the MRT was 1.98 ± 0.55 hours. In conclusion, our data provides useful pharmacokinetic parameters for gentamicin in horses following IV injection.

This paper presents the characteristics of gentamicin-loaded into cetyl trimethyl ammonium intercalated montmorillonite (GtM/CTMA/Mt) as a hybrid composite for a slow-released antibacterial delivery systems. The work describes the successful immobilization of gentamicin into the interlayers of surfactant-modified montmorillonite. Physicochemical characterization of the material is carried out by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The kinetics of the gentamicin release is investigated by in vitro study and analyzed based on UV–Vis spectrometry. In addition, antibacterial study is performed towards Klebsiella pneumoniae Staphylococcus aureus, Escherichia coli, and Streptococcus pyogenes. The results show that the gentamicin loading into CTMA/ Mt increases the effectiveness of the antibacterial activity, as shown by the higher inhibition zone for all tested bacteria, compared to gentamicin as a positive control. The kinetics study suggests that the gentamicin release obeys the modified Korsmeyer–Peppas model. The physicochemical study and activity test demonstrate the feasibility of the GtM/CTMA/Mt for practical applications.

This study investigated the synergistic effects of a combination of cephalexin and gentamicin (CCG) against Streptococcus spp. isolated from bovine milk. Minimum inhibitory concentrations (MICs) and fractional inhibitory concentration (FIC) index were determined for 12 bacteria isolated from 12 bovine farms in Gyeongnam province. The MIC ranges of cephalexin, gentamicin and CCG were 0.25-0.5, 0.5-2.0 and 0.06-0.125 μg/mL, respectively. In addition, the FIC index range of CCG against the isolates was 0.32-0.34, showing a synergistic effect in the checkboard assay. In conclusion, CCG has a high antibacterial activity against Streptococcus isolates and may be utilized in the treatment of bovine streptococcal mastitis.