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.

A brief review on critical analytical aspects for quantification of ambroxol in biological samples

Ambroxol (AMB) is a member of the expectorant class, widely used as a secreolytic agent in patients to break up secretions. AMB is rapidly and effectively distributed from blood to tissue. The lungs have the highest concentration of AMB; accumulation of AMB in human lung tissue was detected at concentrations 15- to 20-fold greater than those reported in the circulation. Because of its wide range of actions and therapeutic applications may be worth looking into, particularly for respiratory symptoms, antioxidant, anti-inflammatory, influenza, and rhinovirus infections. Though several analytical methodologies have been established and confirmed for the AMB analysis in matrices of pharmaceutical and biological origins, novel sustainable, and economical methods are still to be choice of protocol to increase its sensitivity, reliability, and repeatability. Therefore, the present review offers an overview of critical analytical aspects regarding the HPLC, LC-MS/MS, HPTLC, capillary electrophoresis, spectrophotometry, and electrochemical methods for quantifying AMB in pharmaceutical and biological samples. Furthermore, this review will thoroughly discuss the physicochemical properties, stability, extraction conditions, instrumentation, and operational parameters of the targeted analyte. As a result, for the first time, this review complies with vital background information and an up-to-date interpretation of research undertaken by anticipated methodologies examined and implemented for the pharmaceutical analysis AMB.

A Suitable Therapeutic Drug Monitoring Method for Amoxicillin in Plasma by High Performance Liquid Chromatography–UV (HPLC–UV) in Neonates

Amoxicillin, a broad-spectrum β-lactam antibiotic, is widely used for treatment of neonatal infections. Despite the unmet need in neonates, an adapted analytical method is still missing in clinical practice. The purpose of this study was to develop and test an easy and credible high performance liquid chromatography–UV (HPLC–UV) method to determine amoxicillin in small volumes of human plasma and use it in routine therapeutic drug monitoring (TDM) of neonates. After a protein precipitation, amoxicillin for standards, quality control samples, and patient samples were separated by LC and measured by UV detection, and tinidazole was used as the internal standard. The calibration range was 0.50–20.0 μg/mL. Intra- and inter-day precisions were less than 4.7%. The acceptance criteria of accuracy (between 85–115%) were met in all cases. A plasma volume of 50 μL was required to achieve the limit of quantification of 0.50 μg/mL. Thus, a simple, rapid, and accurate HPLC–UV method has been developed to detect the concentration of amoxicillin in human plasma. This method was adapted to do TDM of amoxicillin in neonates.

Protein unbound pharmacokinetics of ambroxol in the blood and brains of rats and the interaction of ambroxol with Polygala tenuifolia by multiple microdialysis

ETHNOPHARMACOLOGICAL RELEVANCE

Ambroxol elevates glucocerebrosidase (GCase) activity and reduces nigrostriatal alpha-synuclein burden to better ameliorate motor function in Parkinson's disease (PD). Polygala tenuifolia is a potential alternative botanical medicine for the treatment of many nonmotor symptoms of PD commonly used in Taiwanese patients. Co-administration of these two medicines pose potential herb-drug interaction.

AIM OF THE STUDY

Our hypothesis is that ambroxol and P. tenuifolia may potentially possess herbal drug synergetic effects in the blood and brain.

MATERIALS AND METHODS

To investigate this hypothesis, a multiple microdialysis system coupled with validated ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for rat blood and brain samples. Experimental rats were divided into three groups: low-dose and high-dose ambroxol alone (10 mg/kg, i.v. and 30 mg/kg, i.v., respectively) and ambroxol (10 mg/kg, i.v.) pretreated with P. tenuifolia extract (1 g/kg, p.o. for 5 consecutive days).

RESULTS

Ambroxol easily penetrated into the brain and reached a maximum concentration in the striatum at approximately 60 min after low- and high-dose treatment. The area under the concentration curve (AUC) ratio increased proportionally at the doses of 10 and 30 mg/kg, which suggested a linear pharmacokinetic manner of ambroxol. The brain penetration of ambroxol was approximately 30-34%, which was defined as the ambroxol AUC blood-to-brain distribution ratio (AUCbrain/AUCblood). The P. tenuifolia extract did not significantly alter the pharmacokinetics of ambroxol in the blood and brain of rats.

CONCLUSION

The present study suggests that it is safety without pharmacokinetic interactions for this dosing regimen to use P. tenuifolia extract and ambroxol together.

Rapid Raman Spectroscopic Analysis of Stress Induced Degradation of the Pharmaceutical Drug Tetracycline

Stress factors caused by inadequate storage can induce the unwanted degradation of active compounds in pharmaceutical formulations. Resonance Raman spectroscopy is presented as an analytical tool for rapid monitoring of small concentration changes of tetracycline and the metabolite 4˗epianhydrotetracycline. These degradation processes were experimentally induced by changes in temperature, humidity, and irradiation with visible light over a time period of up to 23 days. The excitation wavelength λ_exc = 413 nm was proven to provide short acquisition times for the simultaneous Raman spectroscopic detection of the degradation of tetracycline and production of its impurity in small sample volumes. Small concentration changes could be detected (down to 1.4% for tetracycline and 0.3% for 4-epianhydrotetracycline), which shows the potential of resonance Raman spectroscopy for analyzing the decomposition of pharmaceutical products.

Pharmacokinetic profiles of amoxicillin trihydrate in freshwater crocodiles (Crocodylus siamensis) after intramuscular administration at two doses

The aim of the present study was to elucidate the pharmacokinetic profiles of amoxicillin trihydrate (AMX) in Siamese freshwater crocodiles (Crocodylus siamensis). Crocodiles were administered a single intramuscular injection of AMX, at a dose of either 5 or 10 mg/kg body weight (b.w.). Blood samples were collected at preassigned times up to 120 hr. The plasma concentrations of AMX were measured using a validated liquid chromatography tandem-mass spectrometry method. AMX plasma concentrations were quantifiable for up to 72 hr (5 mg/kg b.w.) and 96 hr (10 mg/kg b.w.). The elimination half-life (t_{1/2λ z} ) of AMX following dosing at 5 mg/kg b.w. (8.72 ± 0.61 hr) was almost identical to that following administration at 10 mg/kg b.w (8.98 ± 1.13 hr). The maximum concentration and area under the curve from zero to the last values of AMX increased in a dose-dependent fashion. The average binding percentage of AMX to plasma protein was 21.24%. Based on the pharmacokinetic data, susceptibility break point, and the surrogate PK-PD index (T > MIC, 0.25 μg/ml), intramuscular administration of AMX at dose of 5 mg/kg b.w. every 4 days might be appropriate for the treatment of susceptible bacterial infections in freshwater crocodiles.

A 2D HPLC-MS/MS method for several antibiotics in blood plasma, plasma water, and diverse tissue samples

An analytical method using 2D high-performance liquid chromatography followed by tandem mass spectrometry for the quantification of the beta-lactam antibiotics amoxicillin, flucloxacillin, piperacillin, benzylpenicillin, the beta-lactamase inhibitors clavulanic acid, and tazobactam, as well as the macrolide antibiotic clindamycin, is presented. All analytes were measured in human plasma, while amoxicillin, clavulanic acid, flucloxacillin, and clindamycin were also analyzed in human tissue samples. Because of its high-protein binding, additionally, the free fraction of flucloxacillin was measured after ultrafiltration. As internal standards, deuterated forms of the beta-lactams were used. Sample preparation for all matrices was protein precipitation followed by online extraction on a TurboFlow MAX column, while sample separation was performed on an Accucore XL C18 column. Calibration curves were linear over 0.2-25 mg/kg for the tissue samples and 0.05-20 mg/l for the free fraction of flucloxacillin. In plasma, the calibration curves for amoxicillin and piperacillin were linear over 3.125-125 mg/l, for clavulanic acid and tazobactam over 1-40 mg/l, for benzylpenicillin 0.25-40 mg/l, and for flucloxacillin and clindamycin over 1.5-60 mg/l and 0.05-8 mg/l respectively. In plasma and plasma ultrafiltrate, inaccuracy and imprecision for any analyte were always less than 15%. In tissue, the accuracy and precision varied up to 16%, respectively, 20%, when various tissues were analyzed using a calibration in water. Graphical abstract.

Reduced bioavailability of oral amoxicillin tablets compared to suspensions in Roux-en-Y gastric bypass bariatric subjects

AIMS

To evaluate the relative bioavailability of oral amoxicillin (AMX) tablets in comparison to AMX suspension in Roux-en-Y gastric bypass bariatric subjects.

METHODS

A randomized, double-blind, cross-over study was performed on the bioavailability of oral AMX tablets and suspension in Roux-en-Y gastric bypass subjects operated at least 3 months previously . Doses of 875 mg of the AMX tablet or 800 mg of the AMX suspension were given to all the subjects, allowing a washout of 7 days between the periods. Blood samples were collected at 0, 0.25, 0.5, 1, 1.5, 2, 4, 6 and 8 hours after drug administration and the AMX levels were quantified by liquid chromatography coupled with triple quadrupole tandem mass spectrometry. The pharmacokinetic parameters were calculated by noncompartmental analysis, normalized to an 875 mg dose and the bioavailability of the AMX from the tablets was compared to that from the suspension formulation.

RESULTS

Twenty subjects aged 42.65 ± 7.21 years and with a body mass index of 29.88 ± 4.36 kg/m² were enrolled in the study. The maximum AMX plasma concentration of the tablets and the suspension (normalized to 875 mg) were 7.42 ± 2.99 mg/L and 8.73 ± 3.26 mg/L (90% confidence interval of 70.71-99.11), and the total area under the curve from time zero to infinity were 23.10 ± 7.41 mg.h/L and 27.59 ± 8.32 mg.h/L (90% confidence interval of 71.25-97.32), respectively.

CONCLUSION

The tablets presented a lower bioavailability than the suspension formulation and the total absorbed amount of AMX in these subjects was lower in comparison to the standard AMX absorption rates in nonbariatric subjects, regardless of the formulation.

Development of a LC-MS method for simultaneous determination of amoxicillin and metronidazole in human serum using hydrophilic interaction chromatography (HILIC)

A method was developed for the determination of amoxicillin and metronidazole in human serum. The procedure used was hydrophilic interaction chromatography (HILIC) followed by mass spectrometric (MS) detection. Chromatographic separation was achieved on a ZIC-HILIC column and the mobile phase consisted of a mixture of 0.1% (v/v) formic acid in water and 0.1% (v/v) formic acid in acetonitrile. The method was validated with regard to selectivity, accuracy, precision, calibration, lower limit of quantification (LOQ), extraction recovery and matrix effect. The LOQs were 0.0138 and 0.008 μg/ml for amoxicillin and metronidazole respectively, while for quantification purposes linearity was achieved in the range of 0.1 μg/ml to 6.4 μg/ml for both drugs with correlation coefficients >0.9990. The intraday precision (expressed as %RSD) and the accuracy (expressed as the % deviation from the nominal value) was <15% for both antibiotics at all QC levels. Extraction recoveries for both drugs and internal standards were >80%, while a considerable matrix effect (<60%) was observed for amoxicillin. Finally, the method was applied to the determination of amoxicillin and metronidazole concentrations in serum for 20 patients.

Validated electrochemical and chromatographic quantifications of some antibiotic residues in pharmaceutical industrial waste water

Realistic implementation of ion selective electrodes (ISEs) into environmental monitoring programs has always been a challenging task. This could be largely attributed to difficulties in validation of ISE assay results. In this study, the electrochemical response of amoxicillin trihydrate (AMX), ciprofloxacin hydrochloride (CPLX), trimethoprim (TMP), and norfloxacin (NFLX) was studied by the fabrication of sensitive membrane electrodes belonging to two types of ISEs, which are polyvinyl chloride (PVC) membrane electrodes and glassy carbon (GC) electrodes. Linear response for the membrane electrodes was in the concentration range of 10^-5-10^-2 mol/L. For the PVC membrane electrodes, Nernstian slopes of 55.1, 56.5, 56.5, and 54.0 mV/decade were achieved over a pH 4-8 for AMX, CPLX, and NFLX, respectively, and pH 3-6 for TMP. On the other hand, for GC electrodes, Nernstian slopes of 59.1, 58.2, 57.0, and 58.2 mV/decade were achieved over pH 4-8 for AMX, CPLX, and NFLX, respectively, and pH 3-6 for TMP. In addition to assay validation to international industry standards, the fabricated electrodes were also cross-validated relative to conventional separation techniques; high performance liquid chromatography (HPLC), and thin layer chromatography (TLC)-densitometry. The HPLC assay was applied in concentration range of 0.5-10.0 μg/mL, for all target analytes. The TLC-densitometry was adopted over a concentration range of 0.3-1.0 μg/band, for AMX, and 0.1-0.9 μg/band, for CPLX, NFLX, and TMP. The proposed techniques were successfully applied for quantification of the selected drugs either in pure form or waste water samples obtained from pharmaceutical plants. The actual waste water samples were subjected to solid phase extraction (SPE) for pretreatment prior to the application of chromatographic techniques (HPLC and TLC-densitometry). On the other hand, the fabricated electrodes were successfully applied for quantification of the antibiotic residues in actual waste water samples without any pretreatment. This finding assures the suitability of the fabricated ISEs for environmental analysis.

A turn-on FRET sensor based on dichlorofluorescein and AuNPs for rapid and ultrasensitive detection of ambroxol hydrochloride in urine

Schematic illustration for the detection of ambroxol based on FRET between the AuNPs and DCF.

Pharmacokinetics of amoxicillin trihydrate in Thai swamp buffaloes (Bubalus bubalis): a pilot study

This study aimed to investigate the pharmacokinetic characteristics of amoxicillin (AMX) in Thai swamp buffaloes, Bubalus bubalis, following single intramuscular administration at two dosages of 10 and 20 mg/kg body weight (b.w.). Blood samples were collected at assigned times up to 48 h. The plasma concentrations of AMX were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The concentrations of AMX in the plasma were determined up to 24 h after i.m. administration at both dosages. The C_max values of AMX were 3.39 ± 0.18 μg/mL and 6.16 ± 0.18 μg/mL at doses of 10 and 20 mg/kg, respectively. The AUC_last values increased in a dose-dependent fashion. The half-life values were 5.56 ± 0.40 h and 4.37 ± 0.23 h at doses of 10 and 20 mg/kg b.w, respectively. Based on the pharmacokinetic data and PK-PD index (T > MIC), i.m. administration of AMX at a dose of 20 mg/kg b.w might be appropriate for the treatment of susceptible Mannheimia haemolytica infection in Thai swamp buffaloes.

Development of an Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Amoxicillin in Broth Medium and its Application to an In Vitro Pharmacokinetic and Pharmacodynamic Model

A simple, rapid and highly sensitive liquid chromatographic-tandem mass spectrometry (LC-MS-MS) method has been developed and validated for the quantification of amoxicillin in broth-a liquid bacterial culture medium. After appropriate dilution with ultrapure water, broth samples containing amoxicillin and an internal standard (IS) were extracted by acetonitrile and dichloromethane. The extract was injected into the system. The analyte and the IS were separated by a prepacked Atlantis C18 column using acetonitrile-0.1% formic acid as a mobile phase and detected by selected reaction monitoring in electrospray ionization positive ion mode. The calibration curve of amoxicillin was linear over the concentration range of 0.05-20.00 µg/mL. The mean recovery of amoxicillin from broth was 71.7%, and the intra- and interday precision and accuracies of the assay were within 10%. Amoxicillin was stable in broth for 12 h at room temperature (24°C), for 6.5 months at -80°C and for 24 h after preparation in an autosampler at room temperature. It has been successfully applied to an in vitro pharmacokinetic (PK) and pharmacodynamic (PD) model in which the broth is used for bacterial growth. The method provides high-throughput biological analysis to facilitate the in vitro PK and PD model of amoxicillin.

A practical and novel “standard addition” strategy to screen pharmacodynamic components in traditional Chinese medicine using Heishunpian as an example

The standard addition strategy allows accurate pharmacodynamic compounds screening and embodies the systematic nature of TCM.

Electrospray ionization collision-induced dissociation tandem mass spectrometry of amoxicillin and ampicillin and their degradation products

RATIONALE

Detailed analysis of the literature results on the electrospray ionization mass spectrometry (ESI-MS) fragmentation of amoxicillin and ampicillin, and their comparison with our results, have revealed some incorrect suggestions or incomplete interpretations of mass spectra of these compounds. Therefore, this paper contains a comprehensive discussion devoted to the ESI-MS/MS of ampicillin and amoxicillin as well as their degradation products, namely products of hydrolysis and methanolysis.

METHODS

Electrospray ionization collision-induced dissociation tandem mass (ESI-CID-MS/MS) spectra and accurate mass measurements were made on a quadrupole time-of-flight (Q-tof) mass spectrometer. Hydrolysis of the antibiotics was performed by heating, for a few hours, their aqueous solutions adjusted to pH 10. Methanolysis of the antibiotics was performed by heating their methanol solutions for a few minutes. Additionally, mass spectra of isotope-labeled compounds were also obtained.

RESULTS

A number of fragment ions, previously wrongly interpreted or not interpreted, have been rationalized. For example, formation of an abundant fragment at m/z 208 originating from the protonated amoxicillin molecule (ion [Amox + H](+)) was previously rationalized as a result of breaking of two bonds of the β-lactam ring. We found that this fragment ion had to be formed by the loss of ammonia and breaking of three bonds of the bicyclic system.

CONCLUSIONS

The discussion presented enables a better understanding of the MS decompositions of amoxicillin and ampicillin as well as their degradation products. MS decomposition is used for the determinations of these compounds, when the so-called multiple-reaction monitoring is applied during liquid chromatography (LC)/ESI-MS analysis. Thus, better understanding of MS decompositions of the above compounds seems to be important.