Impact assessment of metabolite instability in the development and validation of LC-MS/MS bioanalytical assays for measurement of rosuvastatin in human plasma and urine samples.

During bioanalytical assay development and validation, maintaining the stability of the parent drug and metabolites of interest is critical. While stability of the parent drug has been thoroughly investigated, the stability of unanalyzed metabolites is often overlooked. When an unstable metabolite is known or suspected to interfere with measurement of the parent drug or other metabolites of interest through back-conversion or other routes, additional tests with these unstable metabolites should be conducted. Here, the development and validation of two assays for quantification of rosuvastatin, one in human plasma and one in human urine, was reported. To this end, additional sets of quality control samples were added during assay validation to ensure the reliability of the assays. Acid treatment of samples is shown to be necessary for rosuvastatin quantification. In this regard, stability issues caused by the metabolite, rosuvastatin lactone, may have been overlooked if assay development and validation had only considered the parent drug, rosuvastatin. These assays represent a case study for how to develop and validate assays with unstable metabolites. Taken together, unstable metabolites should be included in all applicable stability tests.

Hematoma following primary total hip arthroplasty: a grave complication.

Hematoma following primary total hip arthroplasty (THA) can require a return to the operating room. The purpose of this study was to uncover risk factors for hematoma and how it affects the outcome of THA. This case-control study identified 38 patients requiring reoperation due to hematoma following THA between 2000 and 2007. The 38 patients were matched with 117 patients without hematoma. The mean follow-up was 4.1years (range, 2.1-9.6). Multivariate regression showed that blood loss, administration of fresh frozen plasma and Vitamin K, perioperative anticoagulation and hormonal therapy were independent predictors for hematoma formation. Chronic anticoagulation and autologous blood transfusion were independent risk factors for mortality. Hematoma itself was found to be an independent risk factor for adverse outcomes, increasing morbidity and mortality, despite adequate treatment.

Market Basket Survey of the Micronutrients Vitamin A, Vitamin D, Calcium, and Potassium in Eight Types of Commercial Plant-Based Milk Alternatives from United States Markets.

We performed a market basket survey of plant-based milk alternatives (PBMAs) from the US market for vitamin A, vitamin D, calcium, and potassium to identify the amount and variability of these micronutrients across various PBMAs. The PBMA types included in this analysis were almond, cashew, coconut, hemp, oat, pea, rice, and soy (n=90 total product units). Analyses for vitamin A (as retinyl palmitate), vitamin D2/D3, and minerals were performed using high-performance liquid chromatography, liquid chromatography-tandem mass spectrometry, and inductively coupled plasma-mass spectrometry, respectively. A majority of PBMA types had significant differences (P<0.05) in the amounts of target micronutrients across brands. The coefficient of variation (%CV) for micronutrient concentrations within one lot of a single brand ranged from 4.1-42.2% for vitamin A, 1.5-44.1% for vitamin D, 1.7%-37.6% for calcium, and 0.7%-39.0% for potassium. The variability of these micronutrients should be taken into account when considering the nutritional value of PBMAs.

Does international normalized ratio level predict pulmonary embolism?

BACKGROUND: Preventing pulmonary embolism is a priority after major musculoskeletal surgery. The literature contains discrepant data regarding the influence of anticoagulation on the incidence of pulmonary embolism after joint arthroplasty. The American College of Chest Physicians guidelines recommend administration of oral anticoagulants (warfarin), aiming for an international normalized ratio (INR) level between 2 and 3. However, recent studies show aggressive anticoagulation (INR > 2) can lead to hematoma formation and increased risk of subsequent infection. QUESTIONS/PURPOSES: We asked whether an INR greater than 2 protects against pulmonary embolism. PATIENTS AND METHODS: We identified 9112 patients with 10,122 admissions for joint arthroplasty between 2004 and 2008. All patients received warfarin for prophylaxis, aiming for an INR level of 2 or lower. We assessed 609 of 10,122 admissions (6%) for pulmonary embolism using CT, ventilation/perfusion scan, or pulmonary angiography, and 163 of 10,122 admissions (1.6%) had a proven pulmonary embolism. RESULTS: Fifteen of 163 admissions (9%) had an INR greater than 2 before or on the day of workup compared to 35 of 446 admissions (8%) who were negative. We observed no difference between the INR values in patients with or without pulmonary embolism. CONCLUSIONS: We found no clinically relevant difference in the INR values of patients who did or did not develop pulmonary embolism. The risk of bleeding should be weighed against the risk of pulmonary embolism when determining an appropriate target INR for each patient, as an INR less than 2 may reduce the risk of bleeding while still protecting against pulmonary embolism. LEVEL OF EVIDENCE: Level III, therapeutic study. See Instructions to Authors for a complete description of levels of evidence.

Outcome of modified Kidner procedure with subtalar arthroereisis for painful accessory navicular associated with planovalgus deformity.

BACKGROUND: Type II accessory naviculars are frequently associated with planovalgus deformity. Operative treatment for patients recalcitrant to nonoperative treatment involves resection, with or without takedown, and reattachment of the tibialis posterior tendon as described by Kidner. This does not address the planovalgus deformity. The authors hypothesized that adding a subtalar arthroereisis to the Kidner procedure would lead to improvement of pain and function and correction of the deformity. METHODS: Institutional Review Board-approved, prospectively collected data were reviewed for 20 patients (23 feet), who underwent a combined modified Kidner and subtalar arthroereisis for painful type II accessory navicular with planovalgus deformity recalcitrant to nonoperative treatment. The average age at the time of surgery was 18 years. Patients were evaluated preoperatively and at final follow-up clinically, radiographically, and via the visual analog pain scale (VAPS), the American Orthopaedic Foot and Ankle Society (AOFAS) ankle hindfoot score, and a satisfaction rating. Mean follow-up was 53.9 months. RESULTS: The mean AOFAS scores improved from 53 preoperatively to 95 at final follow-up and the mean VAPS score decreased from 7.4 preoperatively to 1.7 at final follow-up. Radiographically, the average Meary's angle improved from 18.5° apex plantar preoperatively to 3° apex plantar on weight-bearing lateral radiographs, and the average talar head uncoverage percentage on weight-bearing anteroposterior radiographs improved from 24% preoperatively to 3%. Nineteen of 20 patients reported good or excellent results. Three patients required implant removal because of pain; no recurrence of planovalgus deformity occurred after implant removal. No patients developed subtalar arthritis. CONCLUSION: The modified Kidner procedure combined with a subtalar arthroereisis resulted in significant pain and functional improvement. The deformity correction obtained at surgery was maintained even if the arthroereisis plug was removed. The extra-articular plug did not lead to subtalar arthritis.

Novel LC-MS/MS method for the determination of selumetinib (AZD6244) in whole blood collected with volumetric absorptive microsampling.

Aim: A method has been developed and validated for quantitation of selumetinib in human whole blood collected using a Mitra™ volumetric absorptive microsampling device. This device is patient-friendly, affording less-invasive sampling with broad applicability to clinical and diagnostic applications - specifically in pediatric populations. Materials & methods: In this method, drug is extracted from the Mitra device via sonication in methanol: Ammonium hydroxide, then analyzed by LC-MS/MS. The linear range for selumetinib analysis is 2.00-2000 ng/ml. Results: All validation parameters met acceptance criteria established in agreement with current regulatory guidance for bioanalytical method validation. The stability of selumetinib in Mitra tips was established at both ambient and frozen conditions. Conclusion: A simple method has been developed and validated for determination of selumetinib from human whole blood, collected using volumetric absorptive microsampling and analyzed by LC-MS/MS.