Paul J. Jannetto

Retrospective Comparison of Posaconazole Levels in Patients Taking the Delayed-Release Tablet versus the Oral Suspension

ABSTRACT While posaconazole prophylaxis decreases the risk of invasive fungal infection compared to fluconazole, low bioavailability of the oral-suspension formulation limits its efficacy. A new delayed-release tablet formulation demonstrated an improved pharmacokinetic profile in healthy volunteers. However, serum levels for the two formulations have not been compared in clinical practice. This study compared achievement of therapeutic posaconazole levels in patients taking the delayed-release tablet to those taking the oral suspension. This retrospective cohort study included 93 patients initiated on posaconazole between 2012 and 2014 and had at least one serum posaconazole level measured. The primary measure was the proportion of patients achieving an initial therapeutic level (>700 ng/ml). An initial therapeutic posaconazole level was seen in 29 of 32 (91%) patients receiving tablets and 37 of 61 (61%) patients receiving suspension (P = 0.003). Among patients with a steady-state level measured 5 to 14 days after initiation, a therapeutic level was observed in 18 of 20 (90%) patients receiving tablets and 25 of 43 (58%) patients receiving suspension (P = 0.01). In these patients, the median posaconazole level of the tablet cohort (1655 ng/ml) was twice that of the suspension cohort (798 ng/ml) (P = 0.004). In this cohort study, the improved bioavailability of delayed-release posaconazole tablets translates into a significantly higher proportion of patients achieving therapeutic serum levels than in the cohort receiving the oral suspension. The results of this study strongly support the use of delayed-release tablets over suspension in patients at risk for invasive fungal infection.

Effective Use of Mass Spectrometry in the Clinical Laboratory

BACKGROUND Historically the success of mass spectrometry in the clinical laboratory has focused on drugs of abuse confirmations, newborn screening, and steroid analysis. Clinical applications of mass spectrometry continue to expand, and mass spectrometry is now being used in almost all areas of laboratory medicine. CONTENT A brief background of the evolution of mass spectrometry in the clinical laboratory is provided with a discussion of future applications. Prominent examples of mass spectrometry are covered to illustrate how it has improved the practice of medicine and enabled physicians to provide better patient care. With increasing economic pressures and decreasing laboratory test reimbursement, mass spectrometry testing has been shown to provide cost-effective solutions. In addition to pointing out the numerous benefits, the challenges of implementing mass spectrometry in the clinical laboratory are also covered. SUMMARY Mass spectrometry continues to play a prominent role in the field of laboratory medicine. The advancement of this technology along with the development of new applications will only accelerate the incorporation of mass spectrometry into more areas of medicine.

Hydroxychloroquine Serum Concentrations and Flares of Systemic Lupus Erythematosus: A Longitudinal Cohort Analysis.

To study the relationship between serum hydroxychloroquine (HCQ) concentrations and flares of systemic lupus erythematosus (SLE) in a longitudinal cohort of patients.

Antibacterial and Biocompatible Titanium-Copper Oxide Coating May Be a Potential Strategy to Reduce Periprosthetic Infection: An In Vitro Study

BackgroundPeriprosthetic infections are devastating for patients and more efficacious preventive strategies are needed. Surface-modified implants using antibacterial coatings represent an option to cope with this problem; however, manufacturing limitations and cytotoxicity have curbed clinical translation. Among metals with antibacterial properties, copper has shown superior in vitro antibacterial performance while maintaining an acceptable cytotoxicity profile. A thin film containing copper could prevent early biofilm formation to limit periprosthetic infections. This pilot study presents the in vitro antibacterial effect, cytotoxicity, and copper ion elution pattern of a thin film of titanium-copper oxide (TiCuO).Questions/purposes(1) Do titanium alloy (Ti6Al4V) discs coated with a thin film of TiCuO reduce Staphylococcus epidermidis biofilm and planktonic cell density compared with uncoated discs? (2) Do Ti6Al4V discs coated with a thin film of TiCuO affect normal human osteoblast viability compared with untreated cells? (3) Is copper ion concentration generated by coated discs lower than previously published copper ion concentrations that cause 50% toxicity in similar human cell lines in vitro (TC50)?MethodsNinety Ti6Al4V discs (12.5 mm diameter; 1.25 mm thick) were used in this study. Seventy-two Ti6Al4V discs were coated with a thin film of either titanium oxide (TiO) or TiCuO containing 20%, 40%, or 80% copper using high-power impulse magnetron sputtering (HiPIMS). Eighteen Ti6Al4V discs remained uncoated for control purposes. We tested antibacterial properties of S epidermidis grown on discs in wells containing growth medium. After 24 hours, planktonic bacteria as well as biofilms removed by sonication were quantitatively cultured. Annexin/Pi staining was used to quantify in vitro normal human osteoblast cell viability at 24 hours and Day 7, respectively. Copper elution was measured at Days 1, 2, 3, 7, 14, and 28 using an inductively coupled plasma mass spectrometer to analyze aliquots of culture medium. Copper ion concentration achieved at 24 hours was compared with previously published TC50 for gingival fibroblast, a phenotypically similar cell line with available data regarding copper ion exposure.ResultsDiscs coated with TiCuO 80% copper showed greater biofilm and planktonic cell density reduction when compared with other tested compositions (analysis of variance [ANOVA]; p < 0.001). Discs coated with TiCuO 80% copper showed mean biofilm and planktonic cell density of 4.0 log10 (SD = 0.4) and 5.7 log10 (SD = 0.2). Discs coated with TiCuO 80% showed a mean difference in biofilm and planktonic cell density of 2.5 log10 (95% confidence interval [CI], 1.9–3.1 log10; p < 0.001) and 1.2 (95% CI, 0.6–1.8; p < 0.001), respectively, when compared with uncoated discs. Normal human osteoblast viability did not differ among all groups at 24 hours (ANOVA; p = 0.2) and Day 7 (ANOVA; p = 0.7). Discs coated with TiCuO 80% copper showed a mean difference (95% CI) in relative cell viability (%) at 24 hours and Day 7 of 31.1 (95% CI, −19.4 to 81.7; p = 0.4) and −5.0 (95% CI, −7.8 to 17.9; p = 0.9), respectively, when compared with untreated cells. For all TiCuO-coated discs, copper ion elution peaked at 24 hours and slowly decreased in a curvilinear fashion to nearly undetectable levels by Day 28. Discs coated with TiCuO 80% copper showed mean copper ion concentration at 24 hours of 269.4 µmol/L (SD = 25.2 µmol/L) and this concentration was lower than previously published TC50 for similar human cell lines at 24 hours (344 µmol/L, SEM = 44 µmol/L).ConclusionsThis pilot study demonstrates a proof of concept that a thin-film implant coating with TiCuO can provide a potent local antibacterial environment while remaining relatively nontoxic to a human osteoblast cell line. Further research in an animal model will be necessary to establish efficacy and safety of this technique and whether it might be useful in the design of implants.Clinical RelevanceA thin film coating with TiCuO demonstrates high antibacterial activity and low cellular cytotoxicity to human osteoblasts in vitro. Taken together, these properties represent a potential strategy for preventing periprosthetic infection if further work in animal models can confirm these results in vivo.

The development and validation of a turbulent flow-liquid chromatography–tandem mass spectrometric method for the simultaneous quantification of citalopram, sertraline, bupropion and hydroxybupropion in serum

OBJECTIVES Depression is a rapidly growing issue in the United States. There are many drug classes that may be used to treat depression, including the selective serotonin-reuptake inhibitors (SSRIs) citalopram (Celexa®) and sertraline (Zoloft®), as well as the aminoketone bupropion (Wellbutrin®). However, therapeutic efficacy and treatment success is often variable, requiring changes in dosing regimens or drug selection. Methods for drug quantification can become important tools in the assessment of drug efficacy to optimize treatment regimens. Here, we present a turbulent flow-liquid chromatography-tandem mass spectrometric (TFC-MS/MS) method for the robust, simultaneous quantification of citalopram, sertraline, bupropion and its active metabolite, hydroxybupropion (OH-bupropion). DESIGN AND METHODS Serum spiked with the aforementioned antidepressants, along with their corresponding isotopically labeled internal standards was subjected to protein precipitation. Samples were injected onto a TFC column for on-line solid phase extraction and a Hypersil Gold C18 column for chromatographic separation. Detection was achieved using a TSQ Vantage mass spectrometer. Assay validation followed FDA bioanalytical guidelines. RESULTS The analytical measuring range for all analytes spanned from 5 to 1000ng/mL. Intra- and inter-assay precision across four quality control levels were ≤9.2% and ≤14.8%, respectively. A comparison to other LC-MS/MS methods resulted in a strong correlation with correlation coefficients ranging from 0.9929 to 0.9971. Carryover, stability, recovery, matrix effects, extraction and processing efficiency were also deemed acceptable in accordance with FDA recommendations. CONCLUSIONS The development and validation of this TFC-MS/MS method allow for the robust and high-throughput quantification of commonly prescribed antidepressants.

High-Throughput Quantitation of Busulfan in Plasma Using Ultrafast Solid-Phase Extraction Tandem Mass Spectrometry (SPE-MS/MS).

Busulfan is a commonly used antineoplastic agent to condition/ablate bone marrow cells before hematopoietic stem cell transplant. While intravenous (IV) formulations of busulfan are now available and have lower incidences of toxicity and treatment related mortality compared to oral dosing, it still displays large pharmacokinetic variability. As a result, studies have shown that therapeutic drug monitoring is clinically useful to minimize graft failure, disease reoccurrence, and toxicities like veno-occlusive disease and neurologic toxicity. Current methods for assaying busulfan include the use of GC/MS, HPLC, and LC-MS/MS. The clinical need for faster turnaround times and increased testing volumes has required laboratories to develop faster methods of analysis for higher throughput of samples. Therefore, we present a method for the quantification of busulfan in plasma using an ultrafast SPE-MS/MS which has much faster sample cycle times (<20 s per sample) and comparable analytical results to GC/MS.

Fecal electrolyte testing for evaluation of unexplained diarrhea: Validation of body fluid test accuracy in the absence of a reference method

BACKGROUND Validation of tests performed on body fluids other than blood or urine can be challenging due to the lack of a reference method to confirm accuracy. The aim of this study was to evaluate alternate assessments of accuracy that laboratories can rely on to validate body fluid tests in the absence of a reference method using the example of sodium (Na(+)), potassium (K(+)), and magnesium (Mg(2+)) testing in stool fluid. METHODS Validations of fecal Na(+), K(+), and Mg(2+) were performed on the Roche cobas 6000 c501 (Roche Diagnostics) using residual stool specimens submitted for clinical testing. Spiked recovery, mixing studies, and serial dilutions were performed and % recovery of each analyte was calculated to assess accuracy. Results were confirmed by comparison to a reference method (ICP-OES, PerkinElmer). RESULTS Mean recoveries for fecal electrolytes were Na(+) upon spiking=92%, mixing=104%, and dilution=105%; K(+) upon spiking=94%, mixing=96%, and dilution=100%; and Mg(2+) upon spiking=93%, mixing=98%, and dilution=100%. When autoanalyzer results were compared to reference ICP-OES results, Na(+) had a slope=0.94, intercept=4.1, and R(2)=0.99; K(+) had a slope=0.99, intercept=0.7, and R(2)=0.99; and Mg(2+) had a slope=0.91, intercept=-4.6, and R(2)=0.91. Calculated osmotic gap using both methods were highly correlated with slope=0.95, intercept=4.5, and R(2)=0.97. Acid pretreatment increased magnesium recovery from a subset of clinical specimens. CONCLUSIONS A combination of mixing, spiking, and dilution recovery experiments are an acceptable surrogate for assessing accuracy in body fluid validations in the absence of a reference method.

High-throughput online solid-phase extraction tandem mass spectrometry: Is it right for your clinical laboratory?

With increasing patient volumes and growing demands for rapid turnaround on many clinical tests, there is a demand for high-throughput technologies. High-Throughput Online Solid-Phase Extraction Tandem Mass Spectrometry is an example of one technology that can achieve these desired results and the RapidFire 365 Mass Spectrometry system from Agilent Technologies is one vendors solution. The key advantage of the RapidFire system is its speed of analysis and throughput. While the Agilent RapidFire system cannot be utilized for every clinical analyte, it does work well for several classes of medications including immunosuppressants, anticonvulsants and antineoplastic agents where dosage adjustments are made to maximize efficacy and minimize toxicity once results are available. In the end, high throughput tandem mass spectrometry has numerous benefits and limitations which must be weighed for each clinical analyte to determine if its the right solution for your lab. This article will specifically discuss the Agilent RapidFire system.

Accumulation of Gadolinium in Human Cerebrospinal Fluid after Gadobutrol-enhanced MR Imaging: A Prospective Observational Cohort Study

Purpose To determine whether gadolinium accumulates within cerebrospinal fluid (CSF) in patients recently exposed to the macrocyclic agent gadobutrol and identify factors that may affect this accumulation. Materials and Methods In this prospective observational cohort study, gadolinium was quantified by using inductively coupled plasma mass spectrometry of CSF samples from patients who underwent gadobutrol-enhanced magnetic resonance (MR) imaging followed by lumbar puncture within 30 days (gadobutrol group) or patients who underwent lumbar puncture without history of gadolinium-enhanced MR imaging (control group). CSF total protein level of 35 mg/dL or lower was used as a surrogate marker of an intact blood-brain barrier (BBB). Associations between gadolinium CSF concentration and patient characteristics were examined by using log (e)-linear regression models. Results A total of 82 patients (68 in gadobutrol group, 14 in control group; 42 male and 40 female patients; median age, 47 years [interquartile range, 25-65 years]) were included in this study. Gadolinium was detected in the CSF of all 68 patients in the gadobutrol group (100% [95% confidence interval: 94.7, 100]; range, 0.2-1494 ng/mL). CSF total protein level higher than 35 mg/dL and patient age of at least 18 years were associated with higher gadolinium concentrations (estimate: 1.1, with standard error [SE] of 0.26 [P < .001] and 0.91, with SE of 0.37 [P = .02], respectively). Conclusion Intravenous administration of the macrocyclic agent gadobutrol results in gadolinium accumulation within the CSF, even in the setting of normal renal function and no BBB dysfunction.

Debates in pain management testing

The annual healthcare costs associated with chronic pain are significant. Chronic pain also has important societal implications including the increasing availability of prescription narcotics. Recent literature and several professional societies have recommended urine drug testing to monitor adherence to prescription medications and to detect drug abuse and/or misuse. The technical benefits of urine drug testing using definitive testing methods such as LC-MS/MS are well documented. However, the guidelines, literature, and expert consensus on other aspects of pain management testing are sparse and/or more controversial. While many institutions and laboratories perform some form of validity and adulterant testing, the extent and utility of testing in pain management is not standardized. The benefits of point-of-care testing and the resources required to maintain a robust testing program are also not well studied. Furthermore, while urine testing is currently the gold standard in pain management, recent literature has shown some benefits of testing oral fluid and other matrices. There continue to be analytical and billing challenges with pain management testing. The utility of quantitative, definitive testing is controversial. Some laboratories only report qualitative results, while others find value in reporting some or all results quantitatively. Furthermore, the practice of laboratory professionals providing formal consultations for pain management testing and/or billing for interpretations is variable. Finally, pharmacogenomic testing is not routinely done in pain management, but some studies suggest it may be beneficial. Here we ask 7 individuals their expert opinion on different aspects of drug testing to assess compliance in pain management. Which validity and adulterant testing (e.g., observation of specimen collection, recording urine temperature immediately after collection, chain of custody, creatinine, specific gravity, pH, oxidants, nitrites) should be required? William Clarke: If there is a low suspicion for adulteration, measuring temperature, specific gravity, and creatinine should be sufficient. If tampering with the specimen …