Isosinensetin is a polymethoxyflavone existing in various kinds of citrus. It has exhibited significant anti-proliferative activity and herb-drug interaction. To date, a specific determination method to quantify isosinensetin concentration in biological matrix has not been developed. In the present study, a highly specific, simple and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) approach was developed and validated for quantification of isosinensetin in rat plasma with subsequent application to a pharmacokinetic study. Isosinensetin and lysionotin (internal standard, IS) were extracted from rat plasma by a single step protein precipitation using acetonitrile as precipitation agent. The chromatographic separation was conducted using an Agilent C18 column with a gradient elution system (0.1 % formic acid aqueous solution and acetonitrile) within 3.5 min.  https://www.selleckchem.com/products/gsk-j4-hcl.html  An electrospray ionization (ESI) source operating in positive mode and multiple reaction monitoring (MRM) wereThe advantage of isothermal titration calorimetry (ITC) to determine the acid dissociation constant (pKa value) is the simultaneous determination of the binding constant and binding enthalpy, as well as being precise and easy to use. The pKa can be calculated from the binding constant, and the temperature dependency of the pKa can be calculated from the binding enthalpy. The use of ITC to study protonation reactions is less common compared to its more conventional use of studying macromolecules and ligands. Water will influence the equilibrium due to autoionization, meaning that both the conjugate base and acid will exist in the sample cell at the beginning of the experiment. These differences are accounted for by optimizing the theoretical model used to estimate the binding constant and binding enthalpy. Through simulations and experimental measurements, we show that ITC can be used to determine the pKa for ibuprofen, ascorbic acid, 2-morpholin-4-ylethanesulfonic acid and paracetamol. The pKa values were consistent with potentiometric or spectrophotometric determinations as well as literature values. Optimizing the theoretical model does not lead to an improved determination, so the "one set of sites" model is adequate for the determination of pKa values. V.Passive gastrointestinal absorption and membrane retention of twelve esters of (S,S)-ethylenediamine-N,N'-di-2-(3-cyclohexyl)propanoic acid (EDCP) and (S,S)-1,3-propanediamine-N,N'-di-2-(3-cyclohexyl)propanoic acid (PDCP), as well as of these two non-esterified acids were estimated using PAMPA test. Artificial PAMPA membrane used in this study for the simulation of gastrointestinal barrier was solution of egg lecithin in dodecane (1 % w/v). All tested compounds belong to class III (high membrane retention and low permeation), whereas EDCP, dipentyl ester of PDCP (DPE-PDCP) and diisopentyl ester of PDCP (DIPE-PDCP) belong to class I (negligible membrane retention and low permeation). Finally, quantitative structure - permeability and structure - retention relationships models were created in order to find quantitative relationships between physico-chemical properties of tested compounds and PAMPA membrane permeability/membrane retention parameters. Statistically the most reliable models were analysed and used for the design of new compounds for which favourable membrane permeability and retention can be expected. BACKGROUND It is unknown if targeted risk reduction counseling in the health care setting, after documented exposure to fentanyl, can affect behavior change to reduce risks and increase utilization of evidence-based overdose prevention strategies. METHODS We conducted a retrospective analysis of results (7/2018-6/2019) from questionnaire-facilitated counseling by recovery coaches in the emergency department (ED) and primary care settings following disclosure of a urine toxicology positive for fentanyl. RESULTS Seventy-five percent of N = 101 respondents were neither aware of nor expecting fentanyl in their substances of use. Fifty-three (70 %) of those initially unaware answered that learning about exposure to and the risks from fentanyl changed their thoughts about reducing or abstaining from use. A greater proportion of patients seen in the ED expressed desire to stop or reduce opioid use as compared to ambulatory clinic patients (91 % vs. 46 %, p less then 0.001). Of those not already engaged in treatment, 18 % and 15 % were interested in medication and behavioural health treatment, respectively, and each of them indicated a change in thought based on the counseling. Forty-five percent of individuals not yet receiving naloxone endorsed interest in receiving it, and 22 % of all respondents were somewhat or very interested in access to safe consumption sites. CONCLUSION This study suggests a novel clinical utility in toxicology screens to inform behavior in the setting of illicit fentanyl exposure. In addition to linkages to evidence-based treatment, linkages to harm-mitigating strategies associated with ongoing substance use may be critical to a comprehensive overdose prevention strategy in the clinical setting. BACKGROUND A non-fatal opioid overdose (NFOO) increases the risk of another overdose and identifies high-risk patients. We estimated the risk of repeat opioid overdose for patients with and without substance use disorder (SUD) diagnoses and the change in substance use treatment utilization rates associated with the first NFOO. METHODS We selected patients (>18 years of age) from Kaiser Permanente Northern California with a NFOO between 2009-2016 (n = 3,992). Cox proportional hazards models estimated the 1-year risk of opioid overdose associated with SUD diagnoses (opioid, alcohol, cannabis, amphetamine, sedative, and cocaine), controlling for patient characteristics. Among patients with an index NFOO, we calculated monthly utilization rates for outpatient substance use services and buprenorphine before and after the index overdose. Interrupted time series models estimated the change in level and trend in utilization rates associated with the index overdose. RESULTS Approximately 7.2 % of patients had a repeat opioid overdose during the year after the index NFOO.