Micro-scale analysis of aminoglycoside antibiotics in human plasma by capillary liquid chromatography and nanospray tandem mass spectrometry with column switching

A Status Update on Pharmaceutical Analytical Methods of Aminoglycoside Antibiotic: Amikacin

Amikacin (AMK) is one of the commonly used aminoglycoside antibiotics, introduced for clinical use in patients suffering from bacterial infections especially life-threatening gram-negative infections. Due to lack of chromophore in the molecule, the detection of AMK during analysis is a challenge. Thus, pre and post-column derivatization techniques are generally used for AMK estimation. This review focuses on different analytical methods used for detection and quantification of AMK in pure or fixed dose combination pharmaceutical formulations and biological samples. Various reported methods described in the literature include high-performance liquid chromatography techniques, pulsed electrochemical detection techniques, Chemiluminescence techniques, Capillary electrophoresis and immunological methods. High-performance-liquid-chromatography based methods with UV/Vis spectrophotometric, fluorescence and mass spectrometric detection are the most prevailing methods employed for the analysis of AMK. This review could be of significant importance in the area of future AMK analytical method development studies.

Ready for TDM: Simultaneous quantification of amikacin, vancomycin and creatinine in human plasma employing ultra-performance liquid chromatography-tandem mass spectrometry

BACKGROUND

Amikacin (AMI) and vancomycin (VAN) are antibiotics largely used in intensive care in the empiric treatment of severe infections by multi-resistant gram-negative and gram-positive bacteria. AMI and VAN are eliminated untransformed by glomerular filtration, showing depuration ratio highly correlated with creatinine (CRE) clearance. AMI, VAN and CRE are highly polar structures, presenting poor retention in reversed-phase liquid chromatography when using conventional stationary phases.

OBJECTIVE

This study aimed to develop and validate a simple UPLC-MS/MS method for simultaneous determination of AMI, VAN, and CRE in human plasma for therapeutic drug monitoring.

RESULTS

Samples were prepared by protein precipitation, followed by dilution. Heptafluorobutyric acid (HFBA) was added to the mobile phase at low concentration (0.01%), and separation was performed in an ultra-performance reversed-phase column (particle diameter of 1.8 μm). These conditions allowed retention times of 0.92, 0.93, 2.12, 2.17 and 2.27 min for CRE, CRE-D3, AMI, KAN and VAN, respectively. The assay was linear from 0.5 to 100 mg L^-1 for AMI and VAN and 5 to 100 mg L^-1. Precision, accuracy and stability assays were acceptable according to bioanalytical validation guidelines. Suitable results. Matrix effects were in the range of +10.5 to +11.6% for AMI, -4.3 to -4.5% for VAN, and - 1.7 to +0.7 for CRE.

CONCLUSION

The first assay for the simultaneous determination of AMI, VAN and CRE in plasma by liquid chromatography-tandem mass spectrometry was reported. This assay allows the obtention of the necessary analytical data for the clinical application of population pharmacokinetic methods for therapeutic drug monitoring of AMI and VAN.

Fit-for-purpose chromatographic method for the determination of amikacin in human plasma for the dosage control of patients

In this paper, a simple, rapid and sensitive method based on liquid chromatography with fluorimetric detection (HPLC-FLD) for the determination of amikacin (AMK) in human plasma is developed. Determination is performed by pre-column derivatization of AMK with ortho-phtalaldehyde (OPA) in presence of N-acetyl-L-cysteine (NAC) at pH 9.5 for 5 min at 80 °C. In our knowledge, this is the first time that NAC has been used in AMK derivatization. Derivatization conditions (pH, AMK/OPA/NAC molar ratios, temperature and reaction time) are optimized to obtain a single and stable, at room temperature, derivative. Separation of the derivative is achieved on a reversed phase LC column (Kromasil C18, 5 μm, 150 × 4.6 i.d. mm) with a mobile phase of 0.05 M phosphate buffer:acetonitrile (80:20, v/v) pumped at flow rate of 1.0 mL/min. Detection is performed using 337 and 439 nm for excitation and emission wavelengths, respectively. The method is fitted for the purpose of being a competitive alternative to the currently used method in many hospitals for AMK dosage control: fluorescence polarization immunoassay (FPIA). The method exhibits linearity in the 0.17-10 µg mL(-1) concentration range with a squared correlation coefficient higher than 0.995. Trueness and intermediate precision are estimated using spiked drug free plasma samples, which fulfill current UNE-EN ISO15189:2007 accreditation schemes. Finally, for the first time, statistical comparison against the FPIA method is demonstrated using plasma samples from 31 patients under treatment with AMK.

A simple quantitative method analysing amikacin, gentamicin, and vancomycin levels in human newborn plasma using ion-pair liquid chromatography/tandem mass spectrometry and its applicability to a clinical study

Neuroprotective controlled therapeutic hypothermia is the standard of care for newborns suffering perinatal asphyxia. Antibiotic drugs, such as amikacin, gentamicin, and vancomycin are frequently administered during controlled hypothermia, which possibly alters their pharmacokinetic (PK) and pharmacodynamic (PD) profiles. In order to examine this effect an LC-MS/MS method for the simultaneous quantification of amikacin, the major gentamicin components (gentamicin C, C1a and C2), and vancomycin in plasma was developed. In 25μL plasma proteins were precipitated with trichloroacetic acid (TCA) and detection of the components was achieved using ion-pair reversed phase chromatography coupled with electrospray ionization tandem mass spectrometry. The chromatographic runtime was 7.5min per sample. Calibration standards were prepared over a range of 0.3-50mgL(-1) for amikacin and gentamicin and 1.0-100mgL(-1) for vancomycin. At LLOQ accuracy was between 103 and 120% and imprecision was less than 19%. For concentrations above LLOQ accuracy ranged from 98% to 102% and imprecision was less than 6%. Process efficiency, ionization efficiency, and recovery were acceptable. Samples and stock solutions were stable during the time periods and at the different temperatures examined. The applicability of the method was shown by analysing plasma samples from 3 neonatal patients. The developed method allows accurate and precise simultaneous quantification of amikacin, gentamicin, and vancomycin in a small volume (25μL) of plasma.

Advances in antibiotic measurement

Antibiotics are most commonly prescribed drugs in clinical practice. Therapeutic drug monitoring of these medications is typically associated with a select group of antibiotics such as aminoglycosides and vancomycin. Outside this group, other antibiotics such as chloramphenicol and antituberculosis agents may also require monitoring. Due to their wide therapeutic index, other classes of antibiotics such as penicillins, cephalosporin, sulfonamides, quinolones, and macrolides do not generally require routine therapeutic drug monitoring. Determination of serum or plasma concentration of these drugs, however, may be beneficial in those patients with compromised renal function. As can be expected, immunoassays for routine monitoring of aminoglycosides and vancomycin have been developed and are widely commercially available. Tests for other antibiotics, due to their infrequent use and low clinical application, are generally limited to in-house developed methods.

Target-guided separation of Bougainvillea glabra betacyanins by direct coupling of preparative ion-pair high-speed countercurrent chromatography and electrospray ionization mass-spectrometry

In this study, preparative ion-pair high-speed countercurrent chromatography was directly coupled to an electrospray ionization mass-spectrometry device (IP-HSCCC/ESI-MS-MS) for target-guided fractionation of high molecular weight acyl-oligosaccharide linked betacyanins from purple bracts of Bougainvillea glabra (Nyctaginaceae). The direct identification of six principal acyl-oligosaccharide linked betacyanins in the mass range between m/z 859 and m/z 1359 was achieved by positive ESI-MS ionization and gave access to the genuine pigment profile already during the proceeding of the preparative separation. Inclusively, all MS/MS-fragmentation data were provided during the chromatographic run for a complete analysis of substitution pattern. On-line purity evaluation of the recovered fractions is of high value in target-guided screening procedures and for immediate decisions about suitable fractions used for further structural analysis. The applied preparative hyphenation was shown to be a versatile screening method for on-line monitoring of countercurrent chromatographic separations of polar crude pigment extracts and also traced some minor concentrated compounds. For the separation of 760mg crude pigment extract the biphasic solvent system tert.-butylmethylether/n-butanol/acetonitrile/water 2:2:1:5 (v/v/v/v) was used with addition of ion-pair forming reagent trifluoroacetic acid. The preparative HSCCC-eluate had to be modified by post-column addition of a make-up solvent stream containing formic acid to reduce ion-suppression caused by trifluoroacetic acid and later significantly maximized response of ESI-MS/MS detection of target substances. A variable low-pressure split-unit guided a micro-eluate to the ESI-MS-interface for sensitive and direct on-line detection, and the major volume of the effluent stream was directed to the fraction collector for preparative sample recovery. The applied make-up solvent mixture significantly improved smoothness of the continuously measured IP-HSCCC-ESI-MS base peak ion trace in the experimental range of m/z 50-2200 by masking stationary phase bleeding and generating a stable single solvent phase for ESI-MS/MS detection. Immediate structural data were retrieved throughout the countercurrent chromatography run containing complete MS/MS-fragmentation pattern of the separated acyl-substituted betanidin oligoglycosides. Single ion monitoring indicated clearly the base-line separation of higher concentrated acylated betacyanin components.