Penicillin G potassium (Benzylpenicillin potassium), the potassium salt form of Penicillin G, is a narrow-spectrum β-lactam antibiotic with potent antimicrobial activity that exerts its bactericidal effect by inhibiting bacterial cell wall synthesis[1,2]. Penicillin G potassium is primarily active against Gram-positive bacteria (such as Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus spp.) and certain Gram-negative bacteria (Neisseria meningitidis), and is commonly used for the treatment and research of diseases caused by bacterial infections[3,4].
In vitro, Penicillin G potassium (0.8mg/mL) significantly increases the relative electrical conductivity of Agrobacterium tumefaciens T-37 after 5h of co-incubation, indicating altered membrane structure and enhanced permeability. Furthermore, after 18h of treatment, increases in nucleic acid (OD260) and protein (OD280) absorbance values demonstrate disruption of membrane integrity and leakage of cellular contents. SDS-PAGE analysis confirmed a time-dependent decrease in total intracellular protein levels over 4-16h of exposure, consistent with membrane damage and subsequent protein leakage[5].
In vivo, following a single intramuscular injection (38mg/kg) in the gluteal muscle of six-month-old New Zealand White rabbits, Penicillin G potassium reached a mean peak plasma concentration of 9.5μg/mL within 36min. The plasma concentration declined to 0.32μg/mL and 0.13μg/mL at 9 and 12h post-administration, respectively, indicating a relatively short elimination half-life[6]. In a murine model of pneumonia, intranasal administration of Penicillin G potassium (40μL; 1μg/μL; once daily for 3 days), initiated 4h after intranasal inoculation with Staphylococcus aureus (8.3×109CFU/mL; 50μL), significantly reduced bacterial loads in the lungs and preserved alveolar structure in BALB/c mice[7].
References:
[1] Bush K. Beta-lactam antibiotics: Penicillins[J]. Antibiotic and chemotherapy, 2010: 200-225.
[2] Prescott J F. Beta-lactam antibiotics: penam penicillins[J]. Antimicrobial therapy in veterinary medicine, 2013: 133-152.
[3] Nathwani D, Wood M J. Penicillins: a current review of their clinical pharmacology and therapeutic use[J]. Drugs, 1993, 45(6): 866-894.
[4] COCCI A G P. Benzylpenicillin (Penicillin G)[J]. Kucers' The Use of Antibiotics: A Clinical Review of Antibacterial, Antifungal, Antiparasitic, and Antiviral Drugs, -Three Volume Set, 2017: 23.
[5] Guo K, Zhang Q, Zhao J, et al. Antibacterial mechanism of Aspergillus niger xj spore powder crude extract B10 against Agrobacterium tumefaciens T-37[J]. Biotechnology & Biotechnological Equipment, 2021, 35(1): 162-169.
[6] Jekl V, Hauptman K, Minarikova A, et al. Pharmacokinetic study of benzylpenicillin potassium after intramuscular administration in rabbits[J]. Vet Rec, 2016, 179(1): 18.
[7] Liu Y, Li S, Shen T, et al. N-terminal myristoylation enhanced the antimicrobial activity of antimicrobial peptide PMAP-36PW[J]. Frontiers in Cellular and Infection Microbiology, 2020, 10: 450.
Penicillin G potassium (Benzylpenicillin potassium)是青霉素G的钾盐形式，是一种具有高效抗菌活性，通过抑制细菌细胞壁合成发挥杀菌作用的窄谱β-内酰胺类抗生素[1,2]。Penicillin G potassium主要对革兰氏阳性菌（如金黄色葡萄球菌、肺炎球菌、链球菌）及部分革兰氏阴性菌（脑膜炎双球菌）具有活性，常用于细菌感染所引起的相关疾病治疗与研究[3,4]。
在体外，Penicillin G potassium（0.8mg/mL）与T-37菌液混合培养5h后，能引起相对电导率的显著升高，表明细胞膜的基本结构发生了变化，提高了膜的通透性。Penicillin G potassium（0.8mg/mL）与T-37菌液混合培养18h，导致核酸吸光度（OD260）和蛋白质吸光度（OD280）增加，表明可以破坏细胞膜的完整性，使内容物泄露。Penicillin G potassium（0.8mg/mL）与T-37菌液混合培养4-16h，菌体内总蛋白含量随时间延长而降低，与细胞膜被破坏导致蛋白泄露的结果相互印证[5]。
在体内，Penicillin G potassium（38mg/kg）通过单次臀部肌肉注射给药6月龄的新西兰白兔，在给药前0h和给药后0.25-24h进行药代动力学测定，Penicillin G potassium平均血浆浓度在36min内达到峰值9.5μg/mL，在9h和12h平均血浆药物浓度分别下降至0.32μg/mL和0.13μg/mL，半衰期较短[6]。鼻内接种金黄色葡萄球菌感染BALB/c小鼠（8.3×109CFU/mL; 50μL），4h后鼻腔给药Penicillin G potassium（40μL; 1μg/μL; qd）治疗小鼠3天，能显著降低肺部细菌数量并保证小鼠肺泡结构完整[7]。