Serum and Urine Quantification of Delta-8 and Delta-9 Tetrahydrocannabinol Carboxylic Acid Using Gas Chromatography-Mass Spectrometry

Marijuana is one of the most frequently used drugs in the United States. The major psychoactive ingredient of the marijuana plant is delta-9-tetrahydrocannabinol (Δ9-THC) with delta-8-tetrahydrocannabinol (Δ8-THC) also being a minor psychoactive ingredient. Marijuana has several clinical applications, but it is more notably used for recreational purposes. Δ8-THC elicits similar but diminished psychotropic effects to Δ9-THC, and the popularity of consuming synthetically produced Δ8-THC is on the rise. The use of Δ9-THC and Δ8-THC has varying degrees of legality depending on one's location; thus it is important to distinguish between the two isomers. Both compounds are metabolized in humans to their corresponding carboxylic acids and then undergo glucuronidation. This method describes how to separate and quantify Δ9-THC-COOH and Δ8-THC-COOH in serum or urine using gas chromatography-mass spectrometry (GC-MS) and a deuterated internal standard.

Quantification of Phencyclidine (PCP) in Urine, Serum, or Plasma by Gas Chromatography-Mass Spectrometry (GC-MS)

Phencyclidine (PCP), a dissociative anesthetic, is a commonly abused recreational drug. In the 1950s, initially tested as an intravenous anesthetic, PCP was discontinued for clinical use due to its severe adverse effects. Since then, it has gained popularity as a recreational drug due to its ability to induce hallucinations and alter perception. PCP can be detected in urine, serum, or plasma by immunoassays and quantified and its presence confirmed by gas or liquid chromatography-mass spectrometry. In the method described here, a deuterated internal standard is added to the sample and the drug is extracted under alkaline conditions. Analysis is conducted using gas chromatography-mass spectrometry (GC-MS). Selected ion monitoring is used for quantitation of PCP.

Quantification of Fentanyl and Norfentanyl in Whole Blood Using Liquid Chromatography-Tandem Mass Spectrometry

Fentanyl is a synthetic opioid used in pain management with a potency 50-100 times that of morphine. Due to fentanyl's high potency, very low dosages are needed to elicit the desired response. Fentanyl is gaining popularity as a drug of abuse. Overdose of fentanyl causes respiratory depression that can lead to death. Fentanyl undergoes N-dealkylation in the liver to its inactive metabolite norfentanyl. Quantitation of fentanyl and its metabolite norfentanyl in whole blood can be performed using liquid chromatography-mass spectrometry. In this method, whole blood samples are spiked with deuterated internal standards for fentanyl and norfentanyl. The samples are alkalized with potassium hydroxide and the drugs are extracted with an organic solvent. Extracts are dried and reconstituted, then injected on LC-MS/MS. They are quantitated using positive ion multiple reaction monitoring (MRM) mode.

Comprehensive Urine Drug Screen by Gas Chromatography-Mass Spectrometry (GC-MS)

Drug screening is an important diagnostic tool in patient management and is an indispensable part of clinical toxicology laboratory services. While some laboratories employ automated chemistry analyzers for limited screening of drugs of abuse and a few common over-the-counter drugs, more comprehensive and detailed drug screening is needed for better patient care. Comprehensive drug screening generally involves immunoassays, colorimetric tests, and gas or liquid chromatography-mass spectrometry. Mass spectrometry is widely regarded as the gold standard for comprehensive drug screening due to its ability to detect hundreds of drugs. In this chapter, we present an efficient and rapid gas chromatography-mass spectrometry (GC-MS) method for comprehensive drug screening of urine samples. This method involves a liquid-liquid sample extraction, sample concentration, and subsequent analysis using GC-MS.

Liquid Chromatography-Tandem Mass Spectrometry Method for the Quantification of Plasma Busulfan

Busulfan is an alkylating agent and functions as a myeloablative and anti-leukemic chemotherapy drug. It is widely used with cyclophosphamide for conditioning patients undergoing bone marrow transplantation for myeloid leukemia. Studies have shown that the busulfan plasma concentration correlates better with clinical efficacy and toxicity than the patient's administered dosage. Low concentrations predispose to disease recurrence and even graft rejection, and higher concentrations can increase the risk of hepatic toxicity. As a result, dosing levels can vary significantly from patient to patient. Therapeutic drug monitoring (TDM) of busulfan plasma concentration guides the dosage adjustment to optimally achieve complete bone marrow ablation while minimizing the dosage-dependent toxicity. The quick and precise (precision <10%) UPLC-MS/MS method described here for monitoring plasma busulfan levels between 50 ng/mL and 5000 ng/mL involves the addition of an organic solvent and deuterated internal standard (busulfan d-8) followed by a liquid-liquid extraction, injection of the extract onto a C18 column, and analysis by multiple reaction monitoring (MRM) in ESI-positive mode.

Mass Spectrometry in Clinical Laboratory: Applications in Therapeutic Drug Monitoring and Toxicology

Mass spectrometry (MS) coupled with liquid chromatography (LC) or gas chromatography (GC) has been proven to be a powerful platform in research and specialized clinical laboratories for decades. In clinical laboratories, it is used for compound identification and quantification. Due to the ability to provide specific identification, high sensitivity, and simultaneous analysis of multiple analytes (>100) in recent years, application of MS in routine clinical laboratories has increased significantly. Although MS is used in many laboratory areas, therapeutic drug monitoring, drugs of abuse, and clinical toxicology remain the primary focuses of the field. Due to rapid increase in the number of prescription drugs and drugs of abuse (e.g., novel psychoactive substances), clinical laboratories are challenged with developing new MS assays to meet the clinical needs of the patients. We are here to present "off-the-shelf" and "ready-to-use" protocols of recent developments in new assays to help the clinical laboratory community adopt the technology and analysis for the betterment of patient care.

Evaluation of a Delta-9-Tetrahydrocannabinol Carboxylic Acid (Δ9-THC-COOH) Immunoassay and a Gas Chromatography-Mass Spectrometry (GC-MS) Method for the Detection of Delta-8-Tetrahydrocannabinol Carboxylic Acid (Δ8-THC-COOH)

BACKGROUND

Delta-8 tetrahydrocannabinol (Δ8-THC) is a naturally occurring or synthetically prepared cannabinoid that elicits psychological and physiological experiences commonly reported for its more infamous isomer, delta-9 tetrahydrocannabinol (Δ9-THC). Unlike Δ9-THC, Δ8-THC products are generally legal under federal law and there has been a rise in their usage. One of the main targets for detection and quantitation of Δ9-THC is its inactive metabolite, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (Δ9-THC-COOH).

METHODS

This study evaluated the ability of the currently used Δ9-THC-COOH immunoassay and gas chromatography-mass spectrometry (GC-MS) methods to detect 11-nor-9-carboxy-Δ8-tetrahydrocannabinol (Δ8-THC-COOH) and distinguish it from Δ9-THC-COOH.

RESULTS

The EMIT II Plus® Cannabinoid immunoassay for Δ9-THC-COOH with a cutoff of 20 ng/mL showed positive results for Δ8-THC-COOH with concentrations of 30 ng/mL or higher. Although many of the ion fragments generated by mass spectrometry were found to overlap between the 2 compounds, the GC-MS method presently used to quantify Δ9-THC-COOH separated the 2 compounds sufficiently to identify them independently by relative retention time.

CONCLUSION

Current immunoassays and GC-MS methods should be evaluated for the ability to detect and distinguish the presence of Δ8-THC-COOH.

Quantitation of Mycophenolic Acid and Mycophenolic Acid Glucuronide in Serum or Plasma by LC-MS/MS

Mycophenolic acid (MPA) is an immunosuppressant that is used as an adjunct therapy in renal, liver, and heart transplantation. Due to its narrow therapeutic range, monitoring MPA levels is essential to avoid toxicity and organ rejection. Although immunoassays are available for the determination of MPA, mass spectrometry methods are preferred due to their higher specificity. Herein, we describe a liquid chromatography tandem mass spectrometry (LC-MS/MS) method utilizing positive ionization electrospray and multiple reaction monitoring (MRM) for the quantification of MPA levels and its conjugate, MPA glucuronide (MPAG). Blood collected in a plain, EDTA, or heparin-containing tube is centrifuged to separate the serum or plasma. Proteins are precipitated using a zinc sulfate solution and acetonitrile containing deuterated internal standards (MPA-d3 and MPAG-d3). The resulting protein-free supernatant is injected into the LC-MS/MS system for analysis. The chromatography involves the use of a C18 column and ammonium acetate/water/formic acid and ammonium acetate/methanol/formic acid mobile phases. Quantification of MPA and MPAG levels is achieved by comparing the MRM peak area ratios of analytes and internal standards, consisting of specific precursor/product pairs, with those of calibrators at various concentrations. Calibration curves are constructed from the MRM peak area ratios of calibrators and internal standards versus concentration. © 2023 Wiley Periodicals LLC. Basic Protocol: Quantitation of mycophenolic acid and mycophenolic acid glucuronide in serum or plasma by LC-MS/MS.

Accuracy of Three Commercial Home-Use Hemoglobin A1c Tests

Background: The COVID-19 pandemic and the rapid expansion of telemedicine have increased the need for accurate and reliable capillary hemoglobin A1c (HbA1c) testing. Nevertheless, validation studies of commercially available products suitable for home use have been in short supply. Methods: Three commercial home-use capillary blood sample HbA1c tests (Home Access, CoreMedica, and A1cNow+) were evaluated in 219 participants with type 1 or type 2 diabetes (4-80 years years of age, HbA1c 5.1%-13.4% [32-123 mmol/mol]) at four clinical sites. Comparisons were made between HbA1c measurements from the commercial tests and paired venous samples for which HbA1c was measured at two central reference laboratories. The primary outcome was percentage of commercial HbA1c values within 5% of the corresponding reference values. Results: HbA1c values were within 5% (relative difference) of paired reference values for 82% of Home Access samples, 29% of CoreMedica samples, and 46% of A1cNow+ samples. Absolute differences were within 0.3% of the reference value for 75% of Home Access samples, 28% of CoreMedica samples, and 44% of A1cNow+ samples and exceeded 0.5% for 8%, 55%, and 37%, respectively. Conclusions: None of the commercial home-use HbA1c tests produced the National Glycohemoglobin Standardization Program goal of ≥90% measurements within 5% of a DCCT venous reference. However, the Home Access product performed substantially better than the CoreMedica or A1cNow+ products. Telemedicine is likely to persist as a mainstay of diabetes care well after the COVID-19 era. As such, accurate home-based HbA1c assessment represents an urgent need for the diabetes community.

The effect of burosumab on intact and C-terminal FGF23 measurements

OBJECTIVE

To investigate the effect of CRYSVITA® (burosumab-twza) on FGF23 measurements in an intact and a C-terminal immunoassay.

METHODS

An intact serum FGF23 (MedFrontier) and a C-terminal plasma FGF23 assay (Immutopics) were used. Serum/plasma pools were spiked to span the burosumab therapeutic range (1.4-11.3 μg/ml) and FGF23 recovery was assessed. Patient serum and plasma samples obtained pre and post-burosumab treatment were evaluated on both assays and compared with corresponding phosphorus measurements RESULTS: Spiking burosumab (1.4-11.3 μg/ml) into sample pools resulted in a dose-dependent negative analytical interference on intact FGF23 measurements and no significant interference for C-terminal FGF23 measurements. However, more than a 500-fold median increase (post- vs. pre-burosumab administration) in in vivo FGF23 concentrations were observed by both assays.

CONCLUSIONS

Therapeutic concentrations of burosumab result in a negative analytical interference of the intact, but not the C-terminal FGF23 immunoassay. Despite this in vitro analytical interference in the intact assay, relatively large elevations of both intact FGF23 and C-terminal FGF23 measurements were observed in vivo following burosumab administration. Following burosumab administration, FGF23 measurements must be interpreted within the clinical context of the patient and other relevant biomarker results.

SUMMARY

This article describes a negative analytical interference by burosumab in an intact FGF23 immunoassay. The recovery of C-terminal FGF23 is not significantly affected by the presence of burosumab. In vivo, both assays demonstrate extreme FGF23 elevations in the presence of the drug. Furthermore, the measurement of FGF23 blocked by burosumab is not clinically useful regarding hypophosphataemia.

Quantification of Tryptophan, Indole, and Indoxyl Sulfate in Urine Using Liquid Chromatography-Tandem Mass Spectrometry

Having a diverse gut microbiota has been correlated with the short- and long-term success of allogeneic stem cell transplantation. Intestinal bacteria metabolize the amino acid tryptophan to indole. Indole is further oxidized and sulfonated in the liver to 3-indoxyl sulfate (3-IS), which is then excreted in urine. Urinary 3-IS is a potential biomarker for intestinal health and an early predictor of successful stem cell transplantation. We describe a rapid method for quantifying tryptophan, indole, and 3-indoxyl sulfate in urine specimens, in which urine samples are diluted with a formic acid solution and deuterated internal standards, and then injected on LC-MS/MS for analysis.

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Method for the Quantification of Steroids Androstenedione, Dehydroepiandrosterone, 11-Deoxycortisol, 17-Hydroxyprogesterone, and Testosterone

Congenital adrenal hyperplasia (CAH) is a group of autosomal-recessive disorders due to deficiency of 11- or 21-hydroxylase. The analysis of cortisol, androstenedione, 17-hydroxyprogesterone (OHPG), dehydroepiandrosterone (DHEA), 11-deoxycortisol, and testosterone is generally performed in the diagnosis and/or follow-up of CAH. Analysis of specific steroids is also performed in other disorders such as evaluation of hirsutism or infertility in females and hypogonadism in males. Cortisol is generally analyzed by immunoassays, whereas other hormones are preferably assayed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A multiple reaction monitoring, positive mode atmospheric pressure chemical ionization, LC-MS/MS method is described for the simultaneous quantification of androstenedione, 17-hydroxyprogesterone, DHEA, 11-deoxycortisol and testosterone. The method involves addition of labeled internal standards to serum samples and extraction of steroids in methyl tert-butyl ether. The extract is evaporated under stream of nitrogen, and the residue is reconstituted in methanol and analyzed by LC-MS/MS.

Quantitation of Phenylalanine in Dried Blood Spot Using Liquid Chromatography Tandem Mass Spectrometry for Monitoring of Patients with Phenylketonuria (PKU)

Newborn screening for phenylketonuria (PKU) is performed by analysis of phenylalanine in dried blood spot (DBS). Once diagnosed by a definitive method, a patient's dietary control is performed by repeated analysis of phenylalanine in venous blood or DBS. Since venipuncture is time consuming, painful, and may often be difficult to achieve in newborns, the use of DBS for analysis of phenylalanine is becoming a preferred method for dietary monitoring of patients with PKU. Using a lancet, patients or their guardians collect finger capillary blood on an approved filter paper. Once collected, the filter paper with DBS is sent to the laboratory for phenylalanine analysis. In the laboratory, phenylalanine is extracted from the DBS using organic solvents. Here, we describe an LC-MS/MS method for the analysis of phenylalanine from DBS with an approximation to serum levels.

Quantification of Free and Total Carnitine in Serum Using Liquid Chromatography Tandem Mass Spectrometry

L-carnitine is a crucial component for transporting long-chained fatty acids from the cytosol into the mitochondrial matrix for fatty acid oxidation. During this process, carnitine forms numerous acylcarnitines before being recycled into the cytosol. Abnormal levels of free carnitine, total carnitine, and acylcarnitines in serum can be indicative of a metabolic disorder before symptoms are present. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method is described for the determination of free and total carnitine in serum. To measure total carnitine, samples are spiked with deuterated carnitine (internal standard) and hydrolyzed with potassium hydroxide to convert acylcarnitines to carnitine. The reaction is quenched by the addition of hydrochloric acid. Carnitine is extracted via a methanolic protein precipitation. The solution is then injected on LC-MS/MS for analysis to determine the carnitine concentration using multiple-reaction monitoring.

Quantification of 25-Hydroxyvitamin D2 and D3 Using Liquid Chromatography-Tandem Mass Spectrometry

Vitamin D plays an important role not only in bone health but also in many other body functions. Vitamin D deficiency is very common in the general population. Measurement of blood 25-hydroxyvitamin D is a common practice to evaluate vitamin D deficiency. Immunoassays and liquid chromatography tandem mass spectrometry (LC-MS/MS) are the most commonly used methods for the measurement of 25-hydroxyvitamin D. Immunoassays suffer from specificity issues and do not distinguish between 25-hydroxyvitamin D2 and D3. Therefore, LC-MS/MS is a preferred method for quantification of 25-hydroxyvitamin. We describe an LC-MS/MS method, which involves protein precipitation and analysis of the extract using atmospheric pressure chemical ionization and multiple reaction monitoring. 25-hydroxyvitamin D3-d6 is used as an internal standard. The method is linear from 1-100 ng/mL for both 25-hydroxyvitamin D2 and D3 and has imprecision of <10%.

Peppermint oil effects on the gut microbiome in children with functional abdominal pain

Peppermint oil (PMO) is effective in the treatment of functional abdominal pain disorders, but its mechanism of action is unclear. Evidence suggests PMO has microbicidal activity. We investigated the effect of three different doses of PMO on gut microbiome composition. Thirty children (7-12 years of age) with functional abdominal pain provided a baseline stool sample prior to randomization to 180, 360, or 540 mg of enteric coated PMO (10 participants per dose). They took their respective dose of PMO (180 mg once, 180 mg twice, or 180 mg thrice daily) for 1 week, after which the stool collection was repeated. Baseline and post-PMO stools were analyzed for microbiome composition. There was no difference in alpha diversity of the gut microbiome between the baseline and post-PMO treatment. Principal coordinate analysis revealed no significant difference in overall bacterial composition between baseline and post-PMO samples, as well as between the PMO dose groups. However, the very low abundant Collinsella genus and three operational taxonomic units (one belonging to Collinsella) were significantly different in samples before and after PMO treatment. The Firmicutes/Bacteroidetes ratio was lower in children who received 540 mg of PMO compared to the 180 mg and 360 mg dose groups (p = 0.04). Network analysis revealed separation between pre- and post-PMO fecal samples with the genus Collinsella driving the post-PMO clusters. PMO administration appeared to impact only low abundance bacteria. The 540 mg PMO dose differentially impacted the Firmicutes/Bacteroidetes ratio. A higher dose and/or longer duration of treatment might yield different results.

Randomised trial: Peppermint oil (menthol) pharmacokinetics in children and effects on gut motility in children with functional abdominal pain

AIMS

Little is known regarding the pharmacokinetics and pharmacodynamics of menthol, the active ingredient in peppermint oil (PMO). Our aim was to investigate the pharmacokinetics of menthol at 3 dose levels in children and determine their effects on gut motility and transit.

METHODS

Thirty children ages 7-12 years with functional abdominal pain underwent wireless motility capsule (WMC) testing. Approximately 1 week later they were randomized to 180, 360 or 540 mg of enteric coated PMO (10 participants per dose). Menthol pharmacokinetics were determined via blood sampling over 24 hours. They then took their respective dose of PMO (180 mg once, 180 mg twice or 180 mg thrice daily) for 1 week during which time the WMC test was repeated.

RESULTS

Evaluable area under the plasma concentration vs. time curve (AUC_last ) data were available in 29 of 30 participants. A direct linear relationship (apparent dose-proportionality for systemic menthol exposure) was observed between PMO dose and menthol systemic exposure with mean elimination half-life 2.1, 3.5 and 4.6 hours for the 180, 360 and 540 mg doses, respectively. WMC technical issues precluded complete motility data in all participants. Colonic transit time was inversely related to AUC_last (P = .003); transit time in other regions was not affected. In contrast, stomach, small bowel and whole gut (but not colonic) contractility positively correlated with menthol AUC_last (P < .05).

CONCLUSION

Pharmacokinetics and pharmacodynamics of menthol derived from PMO demonstrated apparent dose-proportionality. A higher dose of PMO may be needed to achieve maximal gut response. www.clinicaltrials.gov NCT03295747.

Triiodothyroacetic Acid Cross-Reacts With Measurement of Triiodothyronine (T3) on Various Immunoassay Platforms

OBJECTIVES

Thyroid hormone analog 3,5,3'-triiodothyroacetic acid (TRIAC) is effective in reducing the hypermetabolism in monocarboxylate transporter 8 (MCT8)-deficient individuals. Because of the structural similarity between TRIAC and 3,3',5'-triiodothyronine (T3), we sought to investigate the degree of cross-reactivity of TRIAC with various commercially available total and free T3 assays.

METHODS

Varying concentrations (50-1,000 ng/dL) of TRIAC (Sigma Aldrich) were added to pooled serum and assayed for total T3 (TT3) and free T3 (FT3) on the following platforms: e602 (Roche Diagnostics), Architect (Abbott Diagnostics), Centaur (Siemens Healthcare Diagnostics), IMMULITE (Siemens Healthcare Diagnostics), DxI (Beckman Coulter), and Vitros (Ortho Clinical Diagnostics). TT3 competition assay with TRIAC was performed by adding increasing amounts of T3 to pooled serum samples that contained a constant concentration of TRIAC (250 ng/dL).

RESULTS

Significant overestimation of TT3 and FT3 assays were observed across all platforms corresponding to increasing concentrations of TRIAC. The TRIAC effect at 250 ng/dL showed a constant interference of approximately 190 ng/dL TT3.

CONCLUSIONS

All commercial TT3 and FT3 assays tested in this work cross-react significantly with TRIAC. Therefore, patients undergoing TRIAC therapy should have T3 hormone response monitored using alternative nonimmunoassay-based methods to avoid misinterpretation of thyroid function profiles.

Tandem Mass Spectrometry for the Analysis of Plasma/Serum Acylcarnitines for the Diagnosis of Certain Organic Acidurias and Fatty Acid Oxidation Disorders

Acylcarnitines are formed in the mitochondria by esterification between carnitine and acyl-CoAs. This occurs enzymatically via carnitine acyltransferases. Specific acylcarnitines accumulate as a result of various organic acidurias and fatty acid oxidation disorders, and, thus, acylcarnitines profiles are used for the diagnosis of these disorders. Acylcarnitines monitoring can also be used for the follow-up of patients with these disorders. Tandem mass spectrometry (MS/MS) is the most commonly used method for the analysis of acylcarnitines. An MS/MS method for the quantification of a number of acylcarnitines is described. The method involves butylation of acylcarnitines using acidified butanol. Butylated acylcarnitines are analyzed using flow injection and precursor ion scan. Multiple-reaction monitoring (MRM) is used for the analysis of low-molecular-weight acylcarnitines.

Quantitation of Neuroblastoma Markers Homovanillic Acid (HVA) and Vanillylmandelic Acid (VMA) in Urine by Gas Chromatography-Mass Spectrometry (GC/MS)

Neuroblastoma and other neural crest tumors can be characterized by the increased production and excretion of catecholamines and their metabolites. Homovanillic acid (HVA) and vanillylmandelic acid (VMA) are important catecholamine metabolites that can be measured to provide relatively rapid laboratory diagnosis and clinical follow-up of neuroblastoma. We present a procedure to quantify HVA and VMA in urine samples which have been diluted to a creatinine concentration of 2 mg/dL. Diluted samples are spiked with deuterated internal standards, acidified, and extracted with an organic solvent. A bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) and pyridine mixture is added to the dried extract to create trimethylsilyl derivatives of HVA and VMA. The derivatized compounds are measured using gas chromatography-mass spectrometry (GC/MS).

Erratum: Transverse Wobbling in ^{135}Pr [Phys. Rev. Lett. 114, 082501 (2015)]

This corrects the article DOI: 10.1103/PhysRevLett.114.082501.

An Evaluation of Two Capillary Sample Collection Kits for Laboratory Measurement of HbA1c

Background: The COVID-19 pandemic has impacted the conduct of clinic visits. We conducted a study to evaluate two academic laboratories' fingerstick capillary blood collection kits suitable for home use for laboratory measurement of HbA1c. Methods: Four clinical sites recruited 240 participants (aged 4-80 years, HbA1c 5.1%-13.5%). Capillary blood samples were obtained by the participant or parent using collection kits from two laboratories (University of Minnesota Advanced Research and Diagnostic Laboratory (ARDL) and Children's Mercy Hospital Laboratory (CMH)) and mailed under varying shipping conditions by United States Postal Service to the laboratories. Comparisons were made between HbA1c measurements from capillary samples and contemporaneously obtained venous samples. The primary outcome was percentage of capillary HbA1c values within 5% of the corresponding venous values. Results: HbA1c values were within 5% of venous values for 96% of ARDL kit specimens shipped with a cold pack and 98% without a cold pack and 99% and 99%, respectively, for the CMH kits. R² values were 0.98, 0.99, 0.99, and 0.99, respectively. Results appeared similar across HbA1c levels and for pediatric and adult participants. Usability survey scores were high. Conclusions: Capillary blood collection kits, suitable for home use, from two academic laboratories, were demonstrated to be easy to use and provided results that are comparable with those obtained from venous specimens. Based on these results, there is strong evidence that HbA1c measurements from capillary specimens obtained with these specific kits can be used interchangeably with HbA1c measurements from venous specimens for clinical research and clinical care.

Relationships between disaccharidase deficiencies, duodenal inflammation and symptom profile in children with abdominal pain

Abdominal pain has been associated with disaccharidase deficiencies. While relationships with individual symptoms have been assessed, relationships between disaccharidase deficiencies and symptom complexes or inflammation have not been evaluated in this group. The primary aims of the current study were to assess relationships between disaccharidase deficiency and symptoms or symptom complexes and duodenal inflammation, respectively. Patients with abdominal pain who underwent endoscopy with evaluation of disaccharidase activity levels were identified. After excluding all patients with inflammatory bowel disease, celiac disease, H. pylori, or gross endoscopic lesions, patients were evaluated for disaccharidase deficiency frequency. Disaccharidase were compared between patients with and without histologic duodenitis. Lastly, relationships between individual gastrointestinal symptoms or symptom complexes were evaluated. Lactase deficiency was found in 34.3% of patients and disaccharidase pan-deficiency in 7.6%. No individual symptoms or symptom complexes predicted disaccharidase deficiency. While duodenitis was not associated with disaccharidase deficiency, it was only present in 5.9% of patients. Disaccharidase deficiency, particularly lactase deficiency, is common in youth with abdominal pain and multiple deficiencies are not uncommon. Disaccharidase deficiency cannot be predicted by symptoms in this population. Further studies are needed to assess the clinical significance of disaccharidase deficiency.

Measuring hydroxyurea adherence by pharmacy and laboratory data compared with video observation in children with sickle cell disease

BACKGROUND

Hydroxyurea nonadherence is common among children with sickle cell disease (SCD), but it is unclear if current adherence measures are valid compared with video directly observed therapy (VDOT), a reference method. The objectives were to evaluate if hydroxyurea adherence by pharmacy records, urine assay, mean corpuscular volume (MCV), and/or fetal hemoglobin (HbF) correlated with and was sensitive and specific compared with VDOT.

METHODS

This was a cross-sectional analysis of adherence data from 34 children with SCD on a single-arm, six-month hydroxyurea adherence study. Spearman correlation coefficient compared participants' adherence by pharmacy records, MCV, and HbF to adherence by VDOT. The sensitivity and specificity of ≥80% adherence by pharmacy records, two urine samples with hydroxyurea, MCV ≥100 fl/L, and HbF ≥20% compared with ≥80% VDOT adherence were also calculated.

RESULTS

Median pharmacy and VDOT adherence rates were similar (87.8% vs 88.1%, P = 0.75) and mildly correlated (r_s  = 0.45; P = 0.008) but the sensitivity of ≥80% adherence by pharmacy records was 72.7% and specificity was 45.5%. MCV (r_s  = -0.02, P = 0.92) and HbF (r_s  = -0.2, P = 0.33) did not significantly correlate with VDOT adherence. Sensitivity and specificity were 83.3% and 33.3% for having two urine samples with hydroxyurea, 35% and 71.4% for MCV ≥100 fl/L, and 75% and 0% for HbF ≥20%, respectively.

CONCLUSIONS

Commonly used tools to measure hydroxyurea adherence may not correlate with or be valid compared with video adherence. Future studies to refine these measures are needed to effectively target adherence interventions to children with SCD who have the potential to benefit. (ClinicalTrials.gov NCT02578017).

Comparing directly measured versus mathematically calculated free serum 25-hydroxy vitamin D level in children

INTRODUCTION

25-Hydroxy vitamin D (25(OH)D) is essential for calcium homeostasis and bone metabolism. The majority of serum 25(OH)D is bound to vitamin D-binding protein (VDBP) (~ 85%) and to albumin (~ 15%), with only a miniscule amount circulating as free 25(OH)D. Free 25(OH)D can be calculated mathematically by Bikle method from the concentrations of total 25(OH)D, VDBP, and albumin or measured directly by ELISA. A direct head-to-head comparison between the two methods has not been done in children.

MATERIALS AND METHODS

The objective of the study was to compare the mathematically calculated versus directly measured free 25(OH) vitamin D in children. Serum samples from 74 children (ages 1-19 years) were simultaneously analyzed for total 25(OH)D, serum albumin, VDBP, and free 25(OH)D. Pearson correlation analysis and Bland-Altman plot were used to evaluate agreement between the two methods.

RESULTS

The mean age was 9.1 ± 5.1 years, with 61% boys, 76% Caucasians, and 24% African-Americans. The mean ± SD for total 25(OH)D was 38.7 ± 12.8 ng/mL, bioavailable 25(OH)D 3.1 ± 1.1 ng/mL, mathematically calculated free 25(OH)D 8.4 ± 3.2 pg/mL, and directly measured free 25(OH)D 8.9 ± 3.6 pg/mL. Pearson correlation reflected a significant correlation between mathematically calculated and directly measured free 25(OH)D (r = 0.66, p < 0.0005). Bland-Altman plot reflected a tight agreement within a 95% limit of agreement (mean = - 0.026 ± 2SD).

CONCLUSIONS

The directly measured and mathematically calculated free 25(OH)D are in close agreement and are interchangeable. Depending on the local availability of instruments and methods, free 25(OH)D can be either directly measured or mathematically calculated.

Longitudinal Wobbling Motion in ^{187}Au

The rare phenomenon of nuclear wobbling motion has been investigated in the nucleus ^{187}Au. A longitudinal wobbling-bands pair has been identified and clearly distinguished from the associated signature-partner band on the basis of angular distribution measurements. Theoretical calculations in the framework of the particle rotor model are found to agree well with the experimental observations. This is the first experimental evidence for longitudinal wobbling bands where the expected signature partner band has also been identified, and establishes this exotic collective mode as a general phenomenon over the nuclear chart.

Fragmentation of Single-Particle Strength around the Doubly Magic Nucleus ^{132}Sn and the Position of the 0f_{5/2} Proton-Hole State in ^{131}In

Spectroscopic factors of neutron-hole and proton-hole states in ^{131}Sn and ^{131}In, respectively, were measured using one-nucleon removal reactions from doubly magic ^{132}Sn at relativistic energies. For ^{131}In, a 2910(50)-keV γ ray was observed for the first time and tentatively assigned to a decay from a 5/2^{-} state at 3275(50) keV to the known 1/2^{-} level at 365 keV. The spectroscopic factors determined for this new excited state and three other single-hole states provide first evidence for a strong fragmentation of single-hole strength in ^{131}Sn and ^{131}In. The experimental results are compared to theoretical calculations based on the relativistic particle-vibration coupling model and to experimental information for single-hole states in the stable doubly magic nucleus ^{208}Pb.

The Fentanyl Epidemic and Evolution of Fentanyl Analogs in the United States and the European Union

BACKGROUND

Since 2013, an unprecedented surge in fentanyl overdose deaths has been caused by heroin laced with illicitly produced fentanyl and/or fentanyl analogs (FAs) sold as heroin. The US Drug Enforcement Agency's National Forensic Laboratory Information System reported a &gt;300% increase in fentanyl encounters from 4697 in 2014 to 14440 in 2015. In 2015, the CDC reported 9580 deaths caused by synthetic opioids, primarily fentanyl, a 72% increase from 2014. The European Monitoring Centre for Drugs and Drug Addiction has also encountered several new FAs in the heroin supply. Counterfeit pharmaceuticals containing mixtures of fentanyl and FAs continue to be a poorly recognized worldwide problem despite the WHO classifying several FAs as a serious threat to public health.

CONTENT

This review covers the epidemiology of fentanyl abuse and discusses the clinical practice implications of widespread fentanyl abuse. It includes a historical perspective on the illicit FAs that have appeared in the US and European Union and reviews the methods available to identify FAs and emerging technologies useful for identifying previously undescribed analogs. A compilation of structural and mass spectral data on FAs reported thus far is provided.

SUMMARY

Fentanyl and FAs have evolved into a global public health threat. It is important to understand the analytical, clinical, and regulatory efforts underway to assist communities affected by the current fentanyl epidemic.

25-Hydroxyvitamin D Testing: Immunoassays Versus Tandem Mass Spectrometry

Vitamin D has been associated with many health conditions. Because of widespread deficiency in the general population, laboratory testing of vitamin D has increased exponentially in recent years. Currently, 25-hydroxyvitamin D (25[OH]D) is considered the best marker of vitamin D status. Automated immunoassays and tandem mass spectrometry are the most widely used assays for the measurement of 25(OH)D. Because a medical decision of vitamin D deficiency and treatment are made based on specific levels, it is important that different 25(OH)D assays are harmonized. Despite standardization efforts, significant differences remain among various methods and laboratories for the measurement of 25(OH)D.

Hydroxycarbamide in children with sickle cell anaemia after first-dose vs. chronic therapy: pharmacokinetics and predictive models for drug exposure

AIMS

The purposes of this work were to: (1) compare pharmacokinetic (PK) parameters for hydroxycarbamide in children receiving their first dose (HC_new ) vs. those receiving chronic therapy (HC_chronic ), (2) assess the external validity of a published PK dosing strategy, and (3) explore the accuracy of dosing strategies based on a limited number of HC measurements.

METHODS

Utilizing data from two prospective, multicenter trials of hydroxycarbamide (Pharmacokinetics of Liquid Hydroxyurea in Pediatric Patients with Sickle Cell Anemia; NCT01506544 and Single-Dose (SD) and Steady-State (SS) Pharmacokinetics of Hydroxyurea in Children and Adolescents with Sickle Cell Disease), plasma drug concentration vs. time profiles were evaluated with a model independent approach in the HC_new and HC_chronic groups. Various predictive scenarios were analysed to evaluate whether systemic exposure with hydroxycarbamide could be accurately predicted.

RESULTS

Absorption of hydroxycarbamide was rapid, variable and dose independent. Dose-normalized peak plasma concentrations and drug exposure (AUC) were higher, and weight-normalized apparent oral clearance was lower in the HC_new group. We assessed a PK-guided dosing strategy along with other predictive scenarios and found that inclusion of plasma samples only slightly improved the accuracy of AUC predictions when compared to a population-based method.

CONCLUSIONS

Children naïve to hydroxycarbamide exhibit a different PK profile compared to children receiving chronic therapy. Accuracy of population-based dosing is sufficient to target AUCs in individual patients. Further clearance/bioavailability studies are needed to address the factors responsible for variability in the disposition of hydroxycarbamide.

Association of Biotin Ingestion With Performance of Hormone and Nonhormone Assays in Healthy Adults

IMPORTANCE

Biotinylated antibodies and analogues, with their strong binding to streptavidin, are used in many clinical laboratory tests. Excess biotin in blood due to supplemental biotin ingestion may affect biotin-streptavidin binding, leading to potential clinical misinterpretation. However, the degree of interference remains undefined in healthy adults.

OBJECTIVE

To assess performance of specific biotinylated immunoassays after 7 days of ingesting 10 mg/d of biotin, a dose common in over-the-counter supplements for healthy adults.

DESIGN, SETTING, AND PARTICIPANTS

Nonrandomized crossover trial involving 6 healthy adults who were treated at an academic medical center research laboratory.

EXPOSURE

Administration of 10 mg/d of biotin supplementation for 7 days.

MAIN OUTCOMES AND MEASURES

Analyte concentrations were compared with baseline (day 0) measures on the seventh day of biotin treatment and 7 days after treatment had stopped (day 14). The 11 analytes included 9 hormones (ie, thyroid-stimulating hormone, total thyroxine, total triiodothyronine, free thyroxine, free triiodothyronine, parathyroid hormone, prolactin, N-terminal pro-brain natriuretic peptide, 25-hydroxyvitamin D) and 2 nonhormones (prostate-specific antigen and ferritin). A total of 37 immunoassays for the 11 analytes were evaluated on 4 diagnostic systems, including 23 assays that incorporated biotin and streptavidin components and 14 assays that did not include biotin and streptavidin components and served as negative controls.

RESULTS

Among the 2 women and 4 men (mean age, 38 years [range, 31-45 years]) who took 10 mg/d of biotin for 7 days, biotin ingestion-associated interference was found in 9 of the 23 (39%) biotinylated assays compared with none of the 14 nonbiotinylated assays (P = .007). Results from 5 of 8 biotinylated (63%) competitive immunoassays tested falsely high and results from 4 out of 15 (27%) biotinylated sandwich immunoassays tested falsely low.

CONCLUSIONS AND RELEVANCE

In this preliminary study of 6 healthy adult participants and 11 hormone and nonhormone analytes measured by 37 immunoassays, ingesting 10 mg/d of biotin for 1 week was associated with potentially clinically important assay interference in some but not all biotinylated assays studied. These findings should be considered for patients taking biotin supplements before ordering blood tests or when interpreting results.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT03034707.

Analysis of U-47700, a Novel Synthetic Opioid, in Human Urine by LC-MS-MS and LC-QToF

The illicit drug market has rapidly evolved from synthetic cannabinoids to cathinone derivatives and now a new emerging threat of synthetic opioids. These compounds were mostly developed by pharmaceutical companies during drug discovery. The new psychoactive substances are not routinely covered in drug screening and may go undetected. Recently fentanyl analogous, AH-7921, MT-45 and now U-47700 have been encountered in clinical and forensic casework. U-47700 is gaining popularity on drug user forms as a legal alternative to heroin. It is a µ-receptor agonist that is part of the trans-1-2-diamine opioid analgesic drug class developed by The Upjohn Company in an attempt to develop a non-addicting analgesic. A LC-MS-MS method was developed and validated to detect and quantify U-47700. Additional analysis was conducted with an LC-QToF to identify the presence of the parent drug and metabolites. A total of four cases have been evaluated by the LC-MS-MS methodology which has an analytical range of 1-1,250 ng/mL and limit of detection of 1 ng/mL. The concentration of U-47700 in urine specimens ranged from below the limit of quantification to 224 ng/mL. The ToF analysis detected the presence of suspected phase I demethylated metabolites that may assist future analysis of this compound. The prevalence of designer opioids in casework highlights the importance of analysis for new psychoactive substances. Traditional opiates/opioids were not detected in the presented cases, but the available case histories revealed an opioid toxidrome. These findings suggest that U-47700 drug may cause significant morbidity and mortality within the United States as an emerging drug threat.

Observation of the Isovector Giant Monopole Resonance via the ^{28}Si(^{10}Be,^{10}B^{*}[1.74 MeV]) Reaction at 100 AMeV

The (^{10}Be,^{10}B^{*}[1.74  MeV]) charge-exchange reaction at 100  AMeV is presented as a new probe for isolating the isovector (ΔT=1) nonspin-transfer (ΔS=0) response of nuclei, with ^{28}Si being the first nucleus studied. By using a secondary ^{10}Be beam produced by fast fragmentation of ^{18}O nuclei at the NSCL Coupled Cyclotron Facility, applying the dispersion-matching technique with the S800 magnetic spectrometer to determine the excitation energy in ^{28}Al, and performing high-resolution γ-ray tracking with the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) to identify the 1022-keV γ ray associated with the decay from the 1.74-MeV T=1 isobaric analog state in ^{10}B, a ΔS=0 excitation-energy spectrum in ^{28}Al was extracted. Monopole and dipole contributions were determined through a multipole-decomposition analysis, and the isovector giant dipole resonance and isovector giant monopole resonance (IVGMR) were identified. The results show that this probe is a powerful tool for studying the elusive IVGMR, which is of interest for performing stringent tests of modern density functional theories at high excitation energies and for constraining the bulk properties of nuclei and nuclear matter. The extracted distributions were compared with theoretical calculations based on the normal-modes formalism and the proton-neutron relativistic time-blocking approximation. Calculated cross sections based on these strengths underestimate the data by about a factor of 2, which likely indicates deficiencies in the reaction calculations based on the distorted wave Born approximation.

Cetirizine Quantification by High-Performance Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

A multiple reaction monitoring (MRM), positive ion electrospray ionization, LC/MS/MS method is described for the quantification of cetirizine. The compound was isolated from human plasma by protein precipitation using acetonitrile. Cetirizine d4 was used as an internal standard. Chromatographic conditions were achieved using a C18 column and a combination of ammonium acetate, water, and methanol as the mobile phase. MRMs were: cetirizine, 389.26 → 165.16, 201.09; cetirizine d4, 393.09 → 165.15, 201.10. Calibration curves were constructed by plotting the peak area ratios of the calibrators' target MRM transition area to labeled internal standard target MRM transition area versus concentration.

Intravenous busulfan dose individualization - impact of modeling approach on dose recommendation

TDM is intended to limit unintended consequences of drugs with narrow therapeutic indices. However, the application of different sampling strategies and pharmacokinetic approaches results in different dosing recommendations and ostensibly different outcomes. TDM approaches for intravenous busulfan dose individualization employ compartmental or non-compartmental modeling with anywhere from three to seven drug levels. This investigation was designed to examine the differences in dosing recommendations that arise in children (n = 30) when five different TDM approaches were employed. Significant differences in recommended doses between modeling strategies were observed. More importantly, the recommendations were discordant in 13 cases with at least one model recommending a dose adjustment in the opposite direction relative to the remaining models. The mathematical differences introduced by the application of different TDM approaches are not purely academic. Unification of busulfan TDM approaches should be considered to mitigate inconsistently applied dose adjustment, and facilitate comparisons of outcome, between clinical centers.

Design and Testing of an EHR-Integrated, Busulfan Pharmacokinetic Decision Support Tool for the Point-of-Care Clinician

Background: Busulfan demonstrates a narrow therapeutic index for which clinicians routinely employ therapeutic drug monitoring (TDM). However, operationalizing TDM can be fraught with inefficiency. We developed and tested software encoding a clinical decision support tool (DST) that is embedded into our electronic health record (EHR) and designed to streamline the TDM process for our oncology partners.

Methods: Our development strategy was modeled based on the features associated with successful DSTs. An initial Requirements Analysis was performed to characterize tasks, information flow, user needs, and system requirements to enable push/pull from the EHR. Back-end development was coded based on the algorithm used when manually performing busulfan TDM. The code was independently validated in MATLAB using 10,000 simulated patient profiles. A 296-item heuristic checklist was used to guide design of the front-end user interface. Content experts and end-users (n = 28) were recruited to participate in traditional usability testing under an IRB approved protocol.

Results: Decision support software was developed to systematically walk the point-of-care clinician through the TDM process. The system is accessed through the EHR which transparently imports all of the requisite patient data. Data are visually inspected and then curve fit using a model-dependent approach. Quantitative goodness-of-fit are converted to single tachometer where “green” alerts the user that the model is strong, “yellow” signals caution and “red” indicates that there may be a problem with the fitting. Override features are embedded to permit application of a model-independent approach where appropriate. Simulations are performed to target a desired exposure or dose as entered by the clinician and the DST pushes the user approved recommendation back into the EHR. Usability testers were highly satisfied with our DST and quickly became proficient with the software.

Conclusions: With early and broad stake-holder engagement we developed a clinical DST for the non-pharmacologist. This tools affords our clinicians the ability to seamlessly transition from patient assessment, to pharmacokinetic modeling and simulation, and subsequent prescription order entry.

Determination of Menthol in Plasma and Urine by Gas Chromatography/Mass Spectrometry (GC/MS)

Menthol, a monoterpene, is a principal component of peppermint oil and is used extensively in consumer products as a flavoring aid. It is also commonly used medicinally as a topical skin coolant; to treat inflammation of the mucous membranes, digestive problems, and irritable bowel syndrome (IBS); and in preventing spasms during endoscopy and for its spasmolytic effect on the smooth muscle of the gastrointestinal tract. Menthol has a half life of 3-6 h and is rapidly metabolized to menthol glucuronide which is detectable in urine and serum following menthol use. We describe a method for the determination of total menthol in human plasma and urine using liquid/liquid extraction, gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring mode and menthol-d4 as the internal standard. Controls are prepared with menthol glucuronide and all samples undergo enzymatic hydrolysis for the quantification of total menthol. The method has a linear range of 5-1000 ng/mL, and coefficient of variation <10%.