Alec Saitman

Total synthesis of norcembrenolide B and scabrolide D.

An efficient stereoselective synthesis of norcembrenolide B (8) and scabrolide D (9) is reported. The strategy is inspired by biogenetic relationships of related cembrenoids. Central to this approach is the construction of norbipinnatin J which upon selective C2 deoxygenation and C8 oxygenation produces norrubifolide and norcoralloidolide A. A sequence of site-selective oxidations and skeletal reorganizations then yields, in a divergent manner, compounds 8 and 9. The studies allow revision of the proposed structure of scabrolide D (9), which is identical to norcembrenolide C.

Synthesis of a Highly Functionalized Core of Verrillin

An efficient stereoselective synthesis of furanoverrillin (5), a highly functionalized core of verrillin (1), is reported. The synthetic strategy is based on constructing bicyclic lactone 17 prior to the 10-membered ring macrocyclization. The effect of the C4 methyl group on the furan reactivity is also discussed.

Evaluation of the Waters MassTrak LC-MS/MS Assay for Tacrolimus and a Comparison to the Abbott Architect Immunoassay.

Background: Tacrolimus (Prograf, Advagraf, and FK-506) is the most commonly prescribed calcineurin inhibitor after kidney and liver transplantation. The use of tacrolimus (in conjunction with other drugs) has successfully contributed to the maintenance of solid organ allografts; however, it also exhibits toxic side effects. Therapeutic drug monitoring of tacrolimus is used as an aid to achieve drug concentrations within a narrow therapeutic window. Methods: The Waters MassTrak Immunosuppressants assay (LC–MS/MS) for the quantification of tacrolimus in whole blood was evaluated for precision, linearity, lower limit of quantification, matrix effects, and accuracy. A method comparison with the Abbott Architect Tacrolimus immunoassay was also performed. Results: The mean concentration (nanograms per milliliter) and coefficient of variation for low, mid, and high patient pools were 0.6 ± 19.9%, 16.0 ± 5.4%, and 31.2 ± 5.8%, respectively. The MassTrak assay was linear from 0.5 to 30.0 ng/mL. Although the MassTrak and Architect assays correlated well (R2 = 0.97) for patient samples, the MassTrak assay displayed an average negative bias of 18.5% versus Architect (range of 0.0–36.7%). Analysis of a certified tacrolimus reference material in human whole blood [European Reference Materials (ERM)-DA110a, LGC Standards] on both platforms failed to completely explain the observed difference for patient samples. Conclusions: Two widely used assays for therapeutic drug monitoring of tacrolimus are not in agreement with one another. Care should be exercised when interpreting results generated on these 2 assay platforms.

A Young Woman With Recurrent Gestational Hypercalcemia and Acute Pancreatitis Caused by CYP24A1 Deficiency.

The CYP24A1 gene encodes a mitochondrial 24‐hydroxylase that inactivates 1,25(OH)2D. Loss‐of‐function mutations in CYP24A1 cause hypercalcemia, nephrolithiasis and nephrocalcinosis. We describe a woman with CYP24A1 deficiency and recurrent gestational hypercalcemia. Her first pregnancy, at age 20, resulted with the intrauterine demise of twin fetuses. Postpartum, she developed severe hypercalcemia (14 mg/dL), altered mental status, and acute pancreatitis. Her PTH was suppressed (6 pg/mL) and her 1,25(OH)2D was elevated (165 and 195 pg/mL on postpartum day 1 and 5, respectively). Between one and three months postpartum, her serum calcium decreased from 11.4 to 10.2 mg/dL while her 1,25(OH)2D level decreased from 83 to 24 pg/mL. Her 24‐hour urine calcium was 277 mg. Six months postpartum, she became pregnant again. At 14 weeks, her albumin‐corrected calcium level was 10.4 mg/dL and her 1,25(OH)2D level exceeded 200 pg/mL. To establish the diagnosis of CYP24A1 deficiency, we showed her 24,25(OH)2D level to be undetectable (<2 ng/mL). Exon sequencing of the CYP24A1 gene revealed a homozygous, 8‐nucleotide deletion in exon 8, causing an S334V substitution and premature termination due to a frame shift (c.999_1006del, p.Ser334Valfs*9). To prevent hypercalcemia, she was advised to discontinue prenatal vitamins, avoid sun exposure and calcium‐rich foods, and start omeprazole and a calcium binder (250 mg K‐Phos‐neutral with meals). Despite these measures, both hypercalcemia (11.5 mg/dL) and acute pancreatitis recurred. Labor was induced and a healthy, normocalcemic boy was delivered. In the absence of lactation, maternal hypercalcemia resolved within 2 months. This report shows that CYP24A1‐deficient subjects may be normocalcemic at baseline. Hypercalcemia may be unmasked by pregnancy through the routine use of calciferol‐containing prenatal vitamins, increased 1‐alpha hydroxylation of VitD by the placenta and maternal kidney, and production of PTHrP by the uteroplacental unit. CYP24A1 deficiency should be considered in patients with unexplained vitamin D‐mediated hypercalcemia.

Evaluation and comparison of postmortem hydrocodone concentrations in peripheral blood, central blood and liver specimens: A minimal potential for redistribution

Postmortem changes can alter the concentration of drugs in the vascular compartment as compared with concentrations originally present at the time of death. Numerous drugs have been reported to increase due to postmortem redistribution (PMR). The potential for PMR of hydrocodone, a therapeutic opioid analgesic used to manage pain, is of particular interest due to its wide use. Hydrocodone concentrations in 39 peripheral blood, central blood, and liver specimens were compared. Dihydrocodeine (DHC), a commonly encountered hydrocodone metabolite, was present in 61% of the cases with an average concentration that was 29% of the hydrocodone value. Central blood to peripheral blood hydrocodone ratios were well correlated (R(2)=0.965) with an average (±S.D.) of 1.3 (±0.35) and a median of 1.2. The liver to peripheral blood (L/P) hydrocodone ratio was also well correlated (R(2)=0.915) with an average (±S.D.) of 3.4 (±1.7) L/kg and a median of 3.0 L/kg. This low L/P ratio suggests that hydrocodone is unlikely to undergo substantial PMR changes.

Dilution of Urine Followed by Adulteration in an Attempt to Deceive the Laboratory

Adulteration of samples submitted for toxicological analyses can present unique challenges to non-forensic clinical laboratories. With the number of overdose-related deaths expected to surpass 60,000 in 2018, it is incumbent on all members of the healthcare team to be active participants in curbing opioid dependence and identifying prescription drug misuse and diversion. Recently published guidelines have sought to provide guidance to laboratories overseeing prescription drug-monitoring programs. We present a case of sample adulteration in an attempt to conceal prescription non-compliance. The patient possessed only an active prescription for hydrocodone but on initial antibody-based screening the sample tested positive for benzodiazepines and oxycodone in addition to opiates. Active communication between the pain management clinic and the clinical laboratory alerted staff to conduct a more thorough investigation including sample validity testing, analyses of paired serum specimens by liquid chromatography tandem mass spectrometry. Analyses revealed the patient submitted a dilute urine specimen with a crushed hydrocodone pill inside in an attempt to hide prescription non-compliance. Previous screenings had been consistent with the medication list raising the question of whether this was an isolated incident or the patient had simply been more successful in manipulating specimens in the past. This case highlights the need for good communication among all members of the healthcare team and the widespread implementation of specimen validity testing for any laboratory that receives samples from pain clinics.