A rapid, simple, high-performance liquid chromatography method for the clinical measurement of beta-lactam antibiotics in serum and interstitial fluid

Selection of a new aptamer targeting amoxicillin for utilization in a label-free electrochemical biosensor

Pharmaceutical pollution has received considerable attention because of the harmful effects of pharmaceutical compounds on human health, even in trace amounts. Amoxicillin is one of the frequently used antibiotics that was included in the list of emerging water pollutants. Therefore, a highly selective and rapid technique for amoxicillin detection is required. In this work, a new aptamer was selected for amoxicillin and utilized for the development of a label-free electrochemical aptasensor. Aptamer selection was performed using the systematic evolution of ligands by exponential enrichment. The selected aptamer showed good specificity against other antibiotics, including the structurally related antibiotics: ampicillin and ciprofloxacin. Among the selected aptamers, Amx3 exhibited the lowest dissociation constant value of 112.9 nM. An aptasensor was developed by immobilization of thiolated Amx3 aptamer onto gold screen-printed electrodes via self-assembly, which was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The detection was realized by monitoring the change in the differential pulse voltammetry peak current in the ferro/ferricyanide redox couple upon binding of the aptasensor to amoxicillin. The aptasensor showed very good sensitivity with an ultralow limit of detection of 0.097 nM. When the aptasensor was tested using actual spiked milk samples, excellent recovery percentages were observed. The label-free electrochemical aptasensor developed herein is a promising tool for the selective and sensitive detection of amoxicillin in environmental samples.

Towards pharmacokinetic boosting of phenoxymethylpenicillin (penicillin-V) using probenecid for the treatment of bacterial infections

In the face of increasing antimicrobial tolerance and resistance there is a global obligation to optimise oral antimicrobial dosing strategies including narrow spectrum penicillins, such as penicillin-V. We conducted a randomised, crossover study in healthy volunteers to characterise the influence of probenecid on penicillin-V pharmacokinetics and estimate the pharmacodynamics against Streptococcus pneumoniae. Twenty participants took six doses of penicillin-V (250 mg, 500 mg or 750 mg four times daily) with and without probenecid. Total and free concentrations of penicillin-V and probenecid were measured at two timepoints. A pharmacokinetic model was developed, and the probability of target attainment (PTA) calculated. The mean difference (95% CI) between penicillin-V alone and in combination with probenecid for serum total and free penicillin-V concentrations was significantly different at both timepoints (total: 45 min 4.32 (3.20-5.32) mg/L p < 0.001, 180 min 2.2 (1.58-3.25) mg/L p < 0.001; free: 45 min 1.15 (0.88-1.42) mg/L p < 0.001, 180 min 0.5 (0.35-0.76) mg/L p < 0.001). There was no difference between the timepoints in probenecid concentrations. PTA analysis shows probenecid allows a fourfold increase in MIC cover. Addition of probenecid was safe and well tolerated. The data support further research into improved dosing structures for complex outpatient therapy and might also be used to address penicillin supply shortages.

Search for Biomarkers for the LC-ESI-QqQ Determination of Phenoxymethylpenicillin Treatment in Raw or Cooked Chicken Meat Samples

The high standards required for food safety make it necessary to trace unambiguously raw or cooked food products coming from medicated animals. Nevertheless, considering the lability of β-lactams and their degradation, the detection of the presence of antibiotics in meat either raw or submitted to a cooking process is not easily affordable. To achieve this goal, an evaluation of the effect of common domestic cooking procedures, such as boiling and grilling, on the fate of phenoxymethylpenicillin (PENV) residues was performed. Finally, in this work, the penilloic acid from PENV (MET02) and the corresponding penicilloic acid (PENV-HYDRO) are suggested as biomarkers. These compounds present the highest relative abundances 5 days after the treatment was stopped (5PT) and show enough thermal stability to be considered suitable biomarker candidates for the pharmacological treatment instead of the parent compound. Nevertheless, the peaks corresponding to MET02 are significantly more intense than those for PENV-HYDRO, which makes preferential the use of MET02 to perform the control of samples.

Solid phase extraction technology combined with UPLC-MS/MS: a method for detecting 20 β-lactamase antibiotics traces in goat's milk

We develop and validate a method for the rapid determination and identification of 20 β-lactamase antibiotics traces in goat's milk by combining the solid phase extraction technology with ultra-high performance liquid chromatography-tandem mass spectrometry. Goat milk samples were extracted with acetonitrile twice. The supernatant was then extracted and cleaned by solid-phase extraction using divinylbenzene and N-vinylpyrrolidone copolymer. The method was validated, with limits of quantification (LOQs) of 0.3 μg kg-1, specificities of 1/3 LOQ, linearities (R2) > 0.99, recoveries of 80-110%, repeatabilities <10.0%, and intermediate precisions <10.0%. The developed method was suitable for the routine analysis of β-lactamase antibiotics residues in goat's milk and was used to test 76 goat milk samples produced in China.

A low-volume LC/MS method for highly sensitive monitoring of phenoxymethylpenicillin, benzylpenicillin, and probenecid in human serum

Background: The optimization of antimicrobial dosing plays a crucial role in improving the likelihood of achieving therapeutic success while reducing the risks associated with toxicity and antimicrobial resistance. Probenecid has shown significant potential in enhancing the serum exposure of phenoxymethylpenicillin, thereby allowing for lower doses of phenoxymethylpenicillin to achieve similar pharmacokinetic/pharmacodynamic (PK/PD) targets. We developed a triple quadrupole liquid chromatography mass spectrometry (TQ LC/MS) analysis of, phenoxymethylpenicillin, benzylpenicillin and probenecid using benzylpenicillin-d7 and probenecid-d14 as IS in single low-volumes of human serum, with improved limit of quantification to support therapeutic drug monitoring. Methods: Sample clean-up was performed by protein precipitation using acetonitrile. Reverse phase chromatography was performed using TQ LC/MS. The mobile phase consisted of 55% methanol in water + 0.1% formic acid, with a flow rate of 0.4 mL min-1. Antibiotic stability was assessed at different temperatures. Results: Chromatographic separation was achieved within 2 minutes, allowing simultaneous measurement of phenoxymethylpenicillin, benzylpenicillin and probenecid in a single 15 μL blood sample. Validation indicated linearity over the range 0.0015-10 mg L-1, with accuracy of 96-102% and a LLOQ of 0.01 mg L-1. All drugs demonstrated good stability under different storage conditions. Conclusion: The developed method is simple, rapid, accurate and clinically applicable for the quantification of phenoxymethylpenicillin, benzylpenicillin and probenecid in tandem.