The aim of this study was to establish a high‐throughput and sensitive LC–MS/MS method for the determination of doxepin and its major active metabolite nordoxepin in human plasma. It has been designed for bioequivalence study for formulations containing 25 mg of doxepin. Doxepin and nordoxepin were extracted from human plasma samples by protein precipitation with acetonitrile by using protein precipitation 96‐well plates. The analyte was separated using a Phenomenex Kinetex Biphenyl column (100 × 2.1 mm, 2.6 μm) using isocratic elution with a mobile phase of 20 mM ammonium formate (30%) and acetonitrile:methanol 3:7 v:v (70%) at a flow rate of 0.5 mL/min and an injection volume of 10 μL. The detection was performed using a triple quadrupole mass spectrometer by multiple reaction monitoring mode to monitor the precursor‐to‐product ion transitions of m/z 280.4 → 107.0 and 283.4 → 235.0 for doxepin and doxepin‐D3, respectively, and 266.3 → 106.9 and 269.3 → 235.0 for nordoxepin and nordoxepin‐D3, respectively, in positive electrospray ionization mode. The total run time was 3.5 min. The method was validated over a concentration range of 50–10,000 pg/mL using a Triple Quad 4500 MS System (Sciex) for both analytes. The developed and validated method can be successfully used to study the bioequivalence/pharmacokinetics of doxepin and nordoxepin.
Background and Purpose: The incidences of intracranial aneurysm and aneurysmal subarachnoid hemorrhage are high in postmenopausal women. Although population-based studies suggest that hormone replacement therapy is beneficial for postmenopausal women with intracranial aneurysms, estrogen replacement may no longer be recommended for the prevention of chronic diseases given its association with adverse outcomes, such as cancer and ischemic stroke. The isoflavone daidzein and its intestinal metabolite equol are bioactive phytoestrogens and potent agonists of estrogen receptors. Given their estrogenic properties, we investigated whether the isoflavones daidzein and equol are protective against the formation and rupture of intracranial aneurysms in a mouse model of the postmenopausal state. Methods: We induced intracranial aneurysms in ovariectomized adult female mice using a combination of induced systemic hypertension and a single injection of elastase into the cerebrospinal fluid. We fed the mice with an isoflavone-free diet with/without daidzein supplementation, or in a combination of intraperitoneal equol, or oral vancomycin treatment. We also used estrogen receptor beta knockout mice. Results: Both dietary daidzein and supplementation with its metabolite, equol, were protective against aneurysm formation in ovariectomized mice. The protective effects of daidzein and equol required estrogen receptor-β. The disruption of the intestinal microbial conversion of daidzein to equol abolished daidzein’s protective effect against aneurysm formation. Mice treated with equol had lower inflammatory cytokines in the cerebral arteries, suggesting that phytoestrogens modulate inflammatory processes important to intracranial aneurysm pathogenesis. Conclusions: Our study establishes that both dietary daidzein and its metabolite, equol, protect against aneurysm formation in ovariectomized female mice through the activation of estrogen receptor-β and subsequent suppression of inflammation. Dietary daidzein’s protective effect required the intestinal conversion to equol. Our results indicate the potential therapeutic value of dietary daidzein and its metabolite, equol, for the prevention of the formation of intracranial aneurysms and related subarachnoid hemorrhage.
BACKGROUND 5-ALA SDT is not a blood-brain barrier disruption technique, but rather a first-in-class drug-device therapy exploiting the heme synthesis pathway in recurrent glioblastoma (rGBM). Following IV 5-ALA administration, aberrant tumor metabolism results in protoporphyrin-IX (PpIX) accumulation. Activation of PpIX by non-invasive, non-ablative magnetic resonance-guided focused ultrasound (MRgFUS) induces reactive oxygen species and tumor cell death. This first-in-human Phase 0/1 study investigates the feasibility, safety, and biological effects of 5-ALA SDT in rGBM patients. METHODS Six hours prior to SDT, adult patients with rGBM were administered 10mg/kg of an IV formulation of 5-ALA (SONALA-001). Patients were assigned to one of three ascending acoustic energy levels of MRgFUS (200J/400J/800J, measured at transducer surface), followed by a four-day interval prior to planned tumor resection. In each patient, 50% of the enhancing and nonenhancing tumor volume was targeted with MRgFUS with the untreated tumor serving as an internal control. The Optimal Biological Dose (OBD) associated with 5-ALA SDT is the energy level associated with greatest tumor cell death. RESULTS 8 patients were accrued across all energy levels, and none demonstrated drug- or device-related adverse events. Compared to internal control tissue, the apoptosis biomarker, cleaved caspase-3, was elevated in all patients, but most prominently at the 200J energy level. The oxidative stress biomarkers 4-hydroxynonenal, glutathione, cysteine, and thiol were elevated in treated vs. control tissues at all energy levels. The mean Cmax for 5-ALA and PpIX in plasma were 305 µM and 65 nM, respectively. No off-target histological or radiographic alterations were detected in any patient. CONCLUSIONS This first-in-human Phase 0/1 study of a new therapeutic modality for rGBM patients demonstrates that 5-ALA SDT is safe at 200 to 800J and likely induces targeted cell death in rGBM patients via oxidative stress. At 10mg/kg of 5-ALA, the OBD is at or lower than 200J.
A protein precipitation method for the determination of clobazam (CLB) and its major active metabolite N‐desmethylclobazam (N‐CLB) in human plasma by liquid chromatography tandem mass spectrometry (LC–MS/MS) was established. CLB and N‐CLB were extracted from human plasma samples by protein precipitation with methanol. Analyte separation was done using a Phenomenex Kinetex™ Biphenyl (50 × 2.1 mm, 1.7 μm) column using isocratic elution with a mobile phase of 5 mm ammonium formate with 0.01% ammonium hydroxide (40%) and methanol (60%) at a flow rate of 0.4 mL/min and an injection volume of 10 μL. The detection was performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode to monitor the precursor‐to‐product ion transitions of m/z 301.1 → 259.0, 306.0 → 263.9 for CLB and CLB‐D5 and 287.0 → 245.0, 292.0 → 250.0 for N‐CLB and N‐CLB‐D5 in positive electrospray ionization mode, respectively. The method was validated over a concentration range of 2.0–750 ng/mL for CLB and 0.7–200 ng/mL for N‐CLB on SCIEX Triple Quad 4500 MS System. Total run time was 5 min. This method has been designed for bioequivalence study for formulations containing 20 mg of CLB.
Loss-of-function parkin mutations cause oxidative stress and degeneration of dopaminergic neurons in the substantia nigra. Several consequences of parkin mutations have been described; to what degree they contribute to selective neurodegeneration remains unclear. Specific factors initiating excessive reactive oxygen species production, inefficient antioxidant capacity, or a combination are elusive. Identifying key oxidative stress contributors could inform targeted therapy. The absence of Drosophila parkin causes selective degeneration of a dopaminergic neuron cluster that is functionally homologous to the substantia nigra. By comparing observations in these to similar non-degenerating neurons, we may begin to understand mechanisms by which parkin loss of function causes selective degeneration. Using mitochondrially targeted redox-sensitive GFP2 fused with redox enzymes, we observed a sustained increased mitochondrial hydrogen peroxide levels in vulnerable dopaminergic neurons of parkin-null flies. Only transient increases in hydrogen peroxide were observed in similar but non-degenerating neurons. Glutathione redox equilibrium is preferentially dysregulated in vulnerable neuron mitochondria. To shed light on whether dysregulated glutathione redox equilibrium primarily contributes to oxidative stress, we supplemented food with folic acid, which can increase cysteine and glutathione levels. Folic acid improved survival, climbing, and transiently decreased hydrogen peroxide and glutathione redox equilibrium but did not mitigate whole-brain oxidative stress.
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