Immunoassay Analysis of Kanamycin in Serum Using the Tobramycin Kit.

Kanamycin is one of the aminoglycosides used in the treatment of multidrug-resistant tuberculosis. Blood concentrations of kanamycin are predictive for the treatment efficacy and the occurrence of side effects, and dose adjustments can be needed to optimize therapy. However, an immunoassay method for the quantification of kanamycin is not commercially available.

Quantification of co-trimoxazole in serum and plasma using MS/MS.

Background: Co-trimoxazole is frequently used in the prophylaxis and treatment of Pneumocystis carinii pneumonia. High plasma concentrations of sulfamethoxazole or trimethoprim are correlated with toxicity. There is, however, a large variation in PK observed which can lead to underexposure or toxicity.

The relation of the number of hydrogen-bond acceptors with recoveries of immunosuppressants in DBS analysis.

Background: We investigated the influence of the number of hydrogen-bond acceptors on the recovery of immunosuppressant drugs and their structural analogs. This hypothesis was tested by evaluation of the extraction recoveries of tacrolimus, ascomycin, sirolimus, everolimus and temsirolimus with 12, 12, 13, 14 and 16 hydrogen-bond acceptors, respectively.

Results: With an increasing number of hydrogen-bond acceptors of sirolimus, everolimus and temsirolimus, a decrease in recoveries was found while ascomycin showed recoveries corresponding to those of tacrolimus.

Determination of bedaquiline in human serum using liquid chromatography-tandem mass spectrometry.

Bedaquiline, a diarylquinoline for the treatment of multidrug-resistant tuberculosis (TB), relies on exposure-dependent killing. As data on drug exposure in specific populations are scarce, pharmacokinetic studies may be of interest. No simple and robust validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been reported to date.

The performance of five different dried blood spot cards for the analysis of six immunosuppressants.

Background: The relation between hematocrit, substance concentration, extraction recovery and spot formation of tacrolimus, sirolimus, everolimus, ascomycin, temsirolimus and cyclosporin A was investigated for Whatman 31 ET CHR, Whatman FTA DMPK-C, Whatman 903, Perkin Elmer 226 and Agilent Bond Elut DMS DBS cards.

Results & Discussion: We found that all DBS cards showed the same hematocrit and concentration-dependent recovery patterns for sirolimus, everolimus and temsirolimus. At high concentrations, the total hematocrit effects were much more pronounced than at low concentrations for tacrolimus, sirolimus, everolimus, ascomycin and temsirolimus.

What is the right blood hematocrit preparation procedure for standards and quality control samples for dried blood spot analysis?

Remco Koster is a research analyst and PhD candidate at the University Medical Center Groningen and University of Groningen. He has been working in the field of bioanalysis for over 13 years, where he has developed numerous analytical methods using LC-MS/MS. His main research focus is the influence of various matrices on the development and performance of analytical methods using LC-MS/MS.

Analysis of remifentanil with liquid chromatography-tandem mass spectrometry and an extensive stability investigation in EDTA whole blood and acidified EDTA plasma.

Background: Remifentanil is a μ-opioid receptor agonist that was developed as a synthetic opioid for use in anesthesia and intensive care medicine. Remifentanil is rapidly metabolized in both blood and tissues, which results in a very short duration of action. Even after blood sampling, remifentanil is unstable in whole blood and plasma through endogenous esterases and chemical hydrolysis.

The effect of acute alcohol intoxication on gut wall integrity in healthy male volunteers; a randomized controlled trial.

The aim of the study is to determine the effect of acute alcohol consumption on enterocytes. Chronic alcohol consumption has been known to induce a decrease in gut wall integrity in actively drinking alcoholics and patients with alcohol-induced liver disease. Data on the extent of the damage induced by acute alcohol consumption in healthy human beings is scarce.

Dried blood spot analysis of creatinine with LC-MS/MS in addition to immunosuppressants analysis.

In order to monitor creatinine levels or to adjust the dosage of renally excreted or nephrotoxic drugs, the analysis of creatinine in dried blood spots (DBS) could be a useful addition to DBS analysis. We developed a LC-MS/MS method for the analysis of creatinine in the same DBS extract that was used for the analysis of tacrolimus, sirolimus, everolimus, and cyclosporine A in transplant patients with the use of Whatman FTA DMPK-C cards. The method was validated using three different strategies: a seven-point calibration curve using the intercept of the calibration to correct for the natural presence of creatinine in reference samples, a one-point calibration curve at an extremely high concentration in order to diminish the contribution of the natural presence of creatinine, and the use of creatinine-[(2)H3] with an eight-point calibration curve.

Quantification of amikacin and kanamycin in serum using a simple and validated LC-MS/MS method.

Background: Amikacin and kanamycin are frequently used in the treatment of multidrug-resistant TB. The current commercially available immunoassay is unable to analyze kanamycin and trough levels of amikacin. The objective was therefore to develop a LC-MS/MS method for the quantification of amikacin and kanamycin in human serum.

Quantification and validation of ertapenem using a liquid chromatography-tandem mass spectrometry method.

Ertapenem, a carbapenem, relies on time-dependent killing. Therapeutic drug monitoring (TDM) should be considered, when ertapenem is used in specific populations, to achieve optimal bactericidal activity and optimize drug-dosing regimens. No validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been reported using deuterated ertapenem as the internal standard.

Simultaneous determination of rifampicin, clarithromycin and their metabolites in dried blood spots using LC-MS/MS.

Introduction: Rifampicin (RIF) and clarithromycin (CLR) are common drugs for the treatment of infections like Mycobacterium tuberculosis and Mycobacterium ulcerans. Treatment for these diseases are long-term and the individual pharmacokinetic variation, drug-drug interactions or non-adherence may introduce sub-therapeutic exposure or toxicity. The application of therapeutic drug monitoring (TDM) can be used to ensure efficacy and avoid toxicity.

Simultaneous quantification of anidulafungin and caspofungin in plasma by an accurate and simple liquid chromatography tandem mass-spectrometric method.

Introduction: Echinocandins are a valuable addition for the treatment of invasive fungal infections, as they are efficacious, demonstrate low toxicity, and have limited drug-drug interactions. In specific clinical situations when altered pharmacokinetics can be expected or dosing guidelines are conflicting, it may be useful to measure concentrations. For this purpose, a liquid chromatography tandem mass-spectrometric method to measure anidulafungin and caspofungin in ethylenediaminetetraacetic acid plasma was developed.

Fast and highly selective LC-MS/MS screening for THC and 16 other abused drugs and metabolites in human hair to monitor patients for drug abuse.

Background: To facilitate the monitoring of drug abuse by patients, a method was developed and validated for the analysis of amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, methylenedioxyamphetamine, methylenedioxyethylamphetamine, methylphenidate, cocaine, benzoylecgonine, morphine, codeine, heroin, 6-monoacteylmorphine, methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), delta-9-tetrahydrocannabinol (THC), nicotine, and cotinine in human hair.

Methods: The hair preparation method contains a 3-step wash procedure with dichloromethane followed by a simultaneous hair pulverization and extraction procedure with disposable metal balls. The developed liquid chromatography tandem mass spectrometry method uses a single injection to detect and confirm all 17 abused drugs, including THC, within 4.

Application of sweat patch screening for 16 drugs and metabolites using a fast and highly selective LC-MS/MS method.

Background: To facilitate the monitoring of drug abuse by patients, a method was developed and validated for fast and highly selective screening for amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, methylenedioxyamphetamine, methylenedioxyethylamphetamine, methylphenidate, cocaine, benzoylecgonine, morphine, codeine, heroin, 6-monoacteylmorphine, methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine, nicotine, and cotinine in PharmCheck sweat patches. The analysis of sweat patches would provide a noninvasive alternative matrix to urine or blood samples.

Methods: The sweat patches were extracted during vigorous shaking for 10 minutes with 1.

Fast LC-MS/MS analysis of tacrolimus, sirolimus, everolimus and cyclosporin A in dried blood spots and the influence of the hematocrit and immunosuppressant concentration on recovery.

We developed a method for the analysis of four immunosuppressants in dried blood spot (DBS) samples to facilitate therapeutic drug monitoring for transplant patients outside the hospital. An 8mm disc from the central part of the DBS was punched, extracted and followed by LC-MS/MS analysis. The method was validated with ranges from 1.

Dried blood spot analysis suitable for therapeutic drug monitoring of voriconazole, fluconazole, and posaconazole.

Invasive aspergillosis and candidemia are important causes of morbidity and mortality in immunocompromised and critically ill patients. The triazoles voriconazole, fluconazole, and posaconazole are widely used for the treatment and prophylaxis of these fungal infections. Due to the variability of the pharmacokinetics of the triazoles among and within individual patients, therapeutic drug monitoring is important for optimizing the efficacy and safety of antifungal treatment.

Clinical validation of the analysis of linezolid and clarithromycin in oral fluid of patients with multidrug-resistant tuberculosis.

Linezolid plays an increasingly important role in the treatment of multidrug-resistant tuberculosis (MDR-TB). However, patients should be carefully monitored due to time- and dose-dependent toxicity. Clarithromycin plays a more modest role.

Troubleshooting carry-over of LC-MS/MS method for rifampicin, clarithromycin and metabolites in human plasma.

Clarithromycin and rifampicin are used for the treatment of Mycobacteria. Pharmacokinetic drug interaction is possibly due to the influence of the two drugs on the liver enzymes. Using a Hypurity Aquastar C18 column (50mm×2.

Serum ibuprofen levels of extremely preterm infants treated prophylactically with oral ibuprofen to prevent patent ductus arteriosus.

Aim: The aim of this study was to explore the effects of early oral ibuprofen administration on the incidence of hemodynamically significant patent ductus arteriosus (hsPDA) and define the association between serum ibuprofen levels and ductal closure.

Method: Preterm infants with a gestational age of <28 weeks and/or birth weight of <1,000 g were randomized either to the intervention (ibuprofen prophylaxis) or control group. The intervention group received oral ibuprofen 10 mg/kg within 12-24 h after birth followed by 5 mg/kg at 24 and 48 h.

Dried blood spot analysis for therapeutic drug monitoring of linezolid in patients with multidrug-resistant tuberculosis.

Linezolid is a promising antimicrobial agent for the treatment of multidrug-resistant tuberculosis (MDR-TB), but its use is limited by toxicity. Therapeutic drug monitoring (TDM) may help to minimize toxicity while adequate drug exposure is maintained. Conventional plasma sampling and monitoring might be hindered in many parts of the world by logistical problems that may be solved by dried blood spot (DBS) sampling.

Determination of ribavirin in human serum using liquid chromatography tandem mass spectrometry.

A method has been developed for the determination of ribavirin in human serum for therapeutic drug monitoring purposes, using liquid chromatography electrospray ionization mass spectrometry. Separation was obtained with a mobile phase gradient starting and ending in 100% aqueous conditions using a Waters Atlantis® T3 column (100×2mm, 3μm). The entire sample preparation consisted of dilution, followed by ultrafiltration.

Determination of moxifloxacin in human plasma, plasma ultrafiltrate, and cerebrospinal fluid by a rapid and simple liquid chromatography- tandem mass spectrometry method.

Moxifloxacin (MFX) is a useful agent in the treatment of multi-drug-resistant tuberculosis (MDR-TB). At Tuberculosis Centre Beatrixoord, a referral center for tuberculosis in the Netherlands, approximately 36% of the patients have received MFX as treatment. Based on the variability of MFX AUC, the variability of in vitro susceptibility to MFX of M.

Method for therapeutic drug monitoring of azole antifungal drugs in human serum using LC/MS/MS.

Fungal infections occur in immunocompromised patients. Azole antifungal agents are used for the prophylaxis and treatment of these infections. The interest in therapeutic drug monitoring azole agents has increased over the last few years.