Eco-Friendly UPLC-MS/MS Method for Determination of a Fostamatinib Metabolite, Tamatinib, in Plasma: Pharmacokinetic Application in Rats.

Fostamatinib is a prodrug of the active metabolite tamatinib, which is a spleen tyrosine kinase (Syk) inhibitor used in the treatment of primary chronic adult immune thrombocytopenia and rheumatoid arthritis. A highly sensitive, rapid, reliable, and green method was developed and validated using ultra-performance liquid chromatography and tandem mass spectrometry (UPLC-MS/MS) for quantification of tamatinib in rat plasma. Ibrutinib was used as internal standard and liquid-liquid extraction was applied using tert-butyl methyl ether. The analyte was separated on an AcquityTM CSH C18 (2.1 mm × 100 mm, 1.7 µm) column using mobile phase consisting of 10 mM ammonium acetate and acetonitrile (10:90) and the flow rate was 0.25 mL/min. Electrospray ionization (ESI) was carried out in positive mode. Quantitation of tamatinib and the IS was performed using multiple reaction monitoring mode with precursor-to-product transitions of m/z 471.1 > 122.0 and m/z 441.1 > 84.0, respectively. The calibration range was 0.1-1000.0 ng/mL and the linearity of the method was ≥0.997. The developed method greenness was investigated. All principal parameters for the method, including linearity, accuracy, precision, recovery, and stability, were within acceptable ranges. Tamatinib pharmacokinetic study in rats was successfully carried out using the developed method.

Saliva as a potential matrix for evaluating pharmacologically active dolutegravir concentration in plasma.

Therapeutic drug monitoring (TDM) is used in certain clinically selected cases and in research settings to optimize the response to antiretroviral therapy. Plasma of blood is commonly used for TDM, but blood sampling is invasive and at risk for transmission of infectious agents. On the other hand, saliva sampling is noninvasive, safe, cheap, and easily performed compared to blood. Dolutegravir (DTG) is now widely prescribed as a key component of antiretroviral therapy for HIV infection. In this study, we examined the relationship between DTG concentrations in plasma and saliva of treated patients to explore the possibility of using saliva as an alternative body fluid of TDM. A total of 17 pairs of blood and saliva samples were obtained from 15 consented HIV-1-infected subjects treated with DTG containing regimens for more than one month. Both blood and saliva samples were collected within 1 h of each other. Drug concentrations were determined by liquid chromatography-tandem mass spectrometry using DTG-d5 as an internal standard. The LLOQ was 0.5 ng/mL. The calibration curves were prepared with pooled plasma or saliva containing DTG in a range of 0.5-100 ng/mL with precision of <14.4% and accuracy within ±14.7%. The DTG concentrations in the plasma and saliva were significantly correlated (Pearson's correlation coefficient r = 0.76, p < 0.001). The median ratio of the drug concentration in saliva to those in plasma was 0.0056, which is close to the rate of non-protein-bound DTG in plasma (0.70%), suggesting that only free DTG in plasma is transported to the salivary glands and secreted into saliva. The present study demonstrates that DTG concentration in saliva reflects the pharmacologically active drug concentration in plasma and may provide an easily accessible alternative for monitoring effective antiretroviral treatment.

Multivalent cation and polycation polymer preparations influence pharmacokinetics of dolutegravir via chelation-type drug interactions.

Dolutegravir (DTG) is an integrase inhibitor, whose gastrointestinal absorption is impaired by the formation of chelates with multivalent metal cation preparations. However, little is known regarding the interactions of DTG with preparations containing other multivalent metal cations or with polycation polymer preparations. This study examined how the pharmacokinetics of DTG are affected by co-administration with Al(OH)3, LaCO3, and the polycation polymers bixalomer (Bxl) and sevelamer (Svl). Prior to oral administration of DTG (5 mg/kg), rats were orally administered Al(OH)3 (150 or 300 mg/kg), LaCO3 (50 or 75 mg/kg), Bxl (250 or 500 mg/kg), or Svl (300 or 600 mg/kg). Serum concentrations of DTG were then measured over the next 24 h. Compared to the administration of DTG alone, its co-administration with Al(OH)3, LaCO3, Bxl, and Svl led to reduced serum concentration of DTG, and consequently, a significantly reduced area under the curve. These comparisons also revealed a considerable reduction in the maximum concentration, suggesting that the interactions of these agents with DTG in the intestinal tract inhibit absorption of DTG. The above results demonstrate that Al(OH)3, LaCO3, Bxl, and Svl affect the pharmacokinetics of DTG and indicate the need for caution when combining any of the above preparations with DTG.

Simultaneous quantification of plasma levels of 12 antimicrobial agents including carbapenem, anti-methicillin-resistant Staphylococcus aureus agent, quinolone and azole used in intensive care unit using UHPLC-MS/MS method.

OBJECTIVES: Critically ill patients in intensive care unit (ICU) are susceptible to infectious diseases, thus empirical therapy is recommended. However, the therapeutic effect in ICU patients is difficult to predict due to fluctuation in pharmacokinetics because of various factors. This problem can be solved by developing personalized medicine through therapeutic drug monitoring. However, when different measurement systems are used for various drugs, measurements are complicated and time consuming in clinical practice. In this study, we aimed to develop an assay using ultra-high performance liquid chromatography coupled with tandem mass spectrometry for simultaneous quantification of 12 antimicrobial agents commonly used in ICU: doripenem, meropenem, linezolid, tedizolid, daptomycin, ciprofloxacin, levofloxacin, pazufloxacin, fluconazole, voriconazole, voriconazole N-oxide which is a major metabolite of voriconazole, and posaconazole. DESIGN & METHODS: Plasma protein was precipitated by adding acetonitrile and 50% MeOH containing standard and labeled IS. The analytes were separated with an ACQUITY UHPLC CSH C18 column, under a gradient mobile phase consisting of water and acetonitrile containing 0.1% formic acid and 2 mM ammonium formate. RESULTS: The method fulfilled the criteria of US Food and Drug Administration for assay validation. The recovery rate was more than 84.8%. Matrix effect ranged from 79.1% to 119.3%. All the calibration curves showed good linearity (back calculation of calibrators: relative error ≤ 15%) over wide concentration ranges, which allowed determination of Cmax and Ctrough. Clinical applicability of the novel method was confirmed. CONCLUSIONS: We have developed an assay for simultaneous quantification of 12 antimicrobial agents using a small sample volume of 50 µL with a short assay time of 7 min. Our novel method may contribute to simultaneous calculation of pharmacokinetic and pharmacodynamic parameters.

Older Age is Associated with Higher Dolutegravir Exposure in Plasma and Cerebrospinal Fluid of People Living with HIV.

BACKGROUND: People living with human immunodeficiency virus are ageing under combination antiretroviral treatments but data on drug exposure in serum and cerebrospinal fluid are limited. Dolutegravir is a widely used second-generation integrase strand transfer inhibitor: conflicting data suggest that neuropsychiatric side effects may present at a higher frequency in patients with higher dolutegravir serum concentrations. METHODS: We performed a retrospective analysis of our therapeutic drug monitoring registry identifying patients receiving once-daily dolutegravir without concomitant interacting drugs and significant clinical conditions. Data were analysed stratifying time after drug dose intake (maximum concentration 0.5-4 and trough concentration 21-27 h). Cerebrospinal fluid samples from patients enrolled in neurological studies and receiving dolutegravir were analysed for dolutegravir cerebrospinal fluid concentrations and cerebrospinal fluid-to-plasma ratios. Serum and cerebrospinal fluid concentrations were measured through validated chromatographic methods. RESULTS: We included 207 (providing 457 serum samples) and 41 patients (providing 41 cerebrospinal fluid samples). Participants were mostly male (68.2-72.8%) of median age of 50 years (50-53 years). Non-significant changes in dolutegravir maximum concentration and trough concentration were observed with age at Spearman's test (p values > 0.05); linear logistic regression showed a significant effect of age on dolutegravir trough concentration (p = 0.0013) (Fig. 1). Dolutegravir maximum concentration [3830 ng/mL (2311-5057) vs 4230 ng/mL (2919-5272), p = 0.311] and trough concentration [838 ng/mL (362-1587) vs 966 ng/mL (460-2085), p = 0.056] were non-significantly or borderline higher in patients aged > 50 years. Cerebrospinal dolutegravir concentrations were associated with plasma concentrations (ρ = 0.374, p = 0.016) and age (ρ = 0.537, p = 0.003); cerebrospinal fluid dolutegravir concentrations (13.8 vs 7.3 ng/mL, p = 0.015) and cerebrospinal fluid-to-plasma ratios (0.57 vs 0.32%, p = 0.017] were higher in participants aged > 50 years. CONCLUSIONS: We observed an increase in dolutegravir exposure in serum and in cerebrospinal fluid in older patients living with human immunodeficiency virus.

The effect of veno-arterial extracorporeal oxygenation and nasogastric tube administration on the pharmacokinetic profile of abacavir, lamivudine and dolutegravir: a case report.

BACKGROUND: Pharmacokinetic (PK) changes can affect antiretroviral (ARV) systemic exposure for critically ill patients living with HIV (CI-PLWH). Studies to guide ARV adjustments in this population are limited. METHODS: A PK analysis was conducted in a 44-year-old CI-PLWH who presented for a heart and lung transplant on veno-arterial extracorporeal membrane oxygenation (VA ECMO). Home ARV therapy (ART) of co-formulated abacavir/lamivudine/dolutegravir (ABC/3TC/DTG) was continued. ARV serum concentrations were obtained during and after VA ECMO. Two blood levels were drawn at 1 h, for maximum serum concentration (Cmax) and a serum trough (Ct). ARVs were given as a single tablet crushed via nasogastric tube. RESULTS: Area under the concentration-time curve (AUC0-t) was calculated using non-compartmental analysis. Cmax and AUC0-t were higher during VA ECMO compared with post-decannulation. The Cmax of ABC was >2.5-fold higher than the mean in the reference. Cmax and Ct post VA ECMO were within range of referenced literature for all ARVs. Cmax and AUC0-t of DTG post VA ECMO was approximately four- to fivefold lower than referenced literature. HIV virological suppression was maintained throughout the hospitalization. CONCLUSIONS: ART adjustments would not be required for this patient. Additional studies are needed to assess effects of VA ECMO and crushed tube administration of ARVs in CI-PLWH.

Case Report of Increased Exposure to Antiretrovirals following Sleeve Gastrectomy.

Bariatric surgery is increasingly performed in morbidly obese HIV patients. Limited data exist regarding antiretroviral drug exposure after bariatric surgery. We report a case of a morbidly obese HIV patient who underwent sleeve gastrectomy. Abacavir, lamivudine, and dolutegravir therapeutic drug monitoring was performed at several time points pre- and postsurgery. Significantly increased levels were measured, particularly for abacavir, whose levels increased ∼12-fold. Several mechanistic explanations for these findings are discussed.

An LC/ESI-MS/MS method to quantify the PI3K inhibitor GDC-0084 in human plasma and cerebrospinal fluid: Validation and clinical application.

A liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method was developed and validated to measure GDC-0084 in human plasma and cerebrospinal fluid (CSF). Reverse-phase chromatography with gradient elution was performed using a C18 column (50 × 2.0 mm, 3 µm). Solid-phase extraction of plasma and CSF was employed to give excellent recovery. MS detection was performed with positive ion screening in multiple reaction monitoring mode. The precursor to the product ions (Q1 → Q3) selected for GDC-0084 and GDC-0084-d6 were 383.2 → 353.2 and 389.2 → 353.2, respectively. A separate calibration curve was established for human plasma and CSF. Both calibration curves, ranging from 0.2 to 200 ng/mL, were linear and had acceptable intra- and inter-day precision and accuracy. The lower limit of quantitation and limit of detection for GDC-0084 in human plasma were 0.2 ng/mL (signal/noise ≥47) and 0.005 ng/mL (signal/noise ≥3.5), respectively, and for GDC-0084 in human CSF were 0.2 ng/mL (signal/noise ≥19.7) and 0.04 ng/mL (signal/noise ≥7.2). This method was successfully applied to analyze serial plasma samples obtained from children with diffuse intrinsic pontine gliomas and other midline gliomas who participated in pharmacokinetic studies as part of a phase I clinical trial of GDC-0084.

The BACE-1 inhibitor CNP520 for prevention trials in Alzheimer's disease.

The beta-site amyloid precursor protein cleaving enzyme-1 (BACE-1) initiates the generation of amyloid-ß (Aß), and the amyloid cascade leading to amyloid plaque deposition, neurodegeneration, and dementia in Alzheimer's disease (AD). Clinical failures of anti-Aß therapies in dementia stages suggest that treatment has to start in the early, asymptomatic disease states. The BACE-1 inhibitor CNP520 has a selectivity, pharmacodynamics, and distribution profile suitable for AD prevention studies. CNP520 reduced brain and cerebrospinal fluid (CSF) Aß in rats and dogs, and Aß plaque deposition in APP-transgenic mice. Animal toxicology studies of CNP520 demonstrated sufficient safety margins, with no signs of hair depigmentation, retina degeneration, liver toxicity, or cardiovascular effects. In healthy adults ≥ 60 years old, treatment with CNP520 was safe and well tolerated and resulted in robust and dose-dependent Aß reduction in the cerebrospinal fluid. Thus, long-term, pivotal studies with CNP520 have been initiated in the Generation Program.

Clinical pharmacokinetics and pharmacodynamic target attainment of pazufloxacin in prostate tissue: Dosing considerations for prostatitis.

The present study examined the clinical pharmacokinetics of pazufloxacin in prostate tissue and estimated the probability of target attainment for tissue-specific pharmacodynamic goals related to treating prostatitis using various intravenous dosing regimens. Patients with prostatic hypertrophy received prophylactic infusions of pazufloxacin (500 mg, n = 23; 1000 mg, n = 25) for 0.5 h prior to transurethral prostate resection. Drug concentrations in plasma (0.5-5 h) and prostate tissue (0.5-1.5 h) were measured by high-performance liquid chromatography and used for subsequent noncompartmental and three-compartmental analysis. Monte Carlo simulation was performed to evaluate the probability of target attainment of a specific minimum inhibitory concentration (MIC) in prostate tissue: the proportion that achieved both area under the drug concentration over time curve (AUC)/MIC = 100 and maximum concentration (Cmax)/MIC = 8. Prostatic penetration of pazufloxacin was good with mean Cmax ratios (prostate tissue/plasma) of 0.82-0.99 and for AUC, 0.80-0.98. The probability of reaching target MIC concentrations in prostate tissue was more than 90% for dosing schedules of 0.25 mg/L for 500 mg every 24 h (500 mg daily), 0.5 mg/L for 500 mg every 12 h (1000 mg daily), 1 mg/L for 1000 mg every 24 h (1000 mg daily), and 2 mg/L for 1000 mg every 12 h (2000 mg daily). Importantly, the 2000 mg daily regimen of pazufloxacin produced a profile sufficient to have an antibacterial effect in prostate tissue against clinical isolates of Escherichia coli and Klebsiella pneumonia with MIC values less than 2 mg/L.

Effects of ranitidine (antacid), food, and formulation on the pharmacokinetics of fostamatinib: results from five phase I clinical studies.

PURPOSE: Fostamatinib is an orally dosed phosphate prodrug that is cleaved by intestinal alkaline phosphatase to the active metabolite R406. Clinical studies were performed to assess the effect of food and ranitidine on exposure, to support in vitro-in vivo relationships (IVIVR) understanding and formulation transitions and to investigate absolute oral bioavailability. METHODS: A series of in vitro dissolution and clinical pharmacokinetic studies were performed to support the design and introduction of a new formulation, understand the impact of changes in in vitro dissolution on in vivo performance for two fostamatinib formulations, to characterize the effects of food and ranitidine on exposure, and determine the absolute oral bioavailability. RESULTS: The in vivo performance of fostamatinib was generally insensitive to changes in in vitro dissolution performance, although marked slowing of the dissolution rate did impact exposures. Food and ranitidine had minor effects on R406 exposure that were not considered clinically relevant. The absolute oral bioavailability of fostamatinib was 54.6 %. CONCLUSIONS: The absolute oral bioavailability of fostamatinib was ~55 %. Food and ranitidine had minor effects on R406 exposure. An in vitro dissolution versus clinical performance relationship was determined that supported formulation transitions.

Characterization of the disposition of fostamatinib in Japanese subjects including pharmacokinetic assessment in dry blood spots: results from two phase I clinical studies.

PURPOSE: The aims of the present study were to characterize the pharmacokinetics of fostamatinib in two phase I studies in healthy Japanese subjects after single- and multiple-dose administration, and to evaluate the utility of dried blood spot (DBS) sampling. METHODS: In study A, 40 Japanese and 16 white subjects were randomized in a double-blind parallel group study consisting of seven cohorts, which received either placebo or a fostamatinib dose between 50 and 200 mg after single and multiple dosing. Pharmacokinetics of R406 (active metabolite of fostamatinib) in plasma and urine was assessed, and safety was intensively monitored. Study B was an open-label study that assessed fostamatinib 100 and 200 mg in 24 Japanese subjects. In addition to plasma and urine sampling (as for study A), pharmacokinetics was also assessed in blood. RESULTS: Mean maximum plasma concentration (C max) and area under total plasma concentration­time curve (AUC) increased with increasing dose in Japanese subjects. Steady state was achieved in 5­7 days for all doses. C max and AUC were both higher in Japanese subjects administered a 150-mg single dose than in white subjects. This difference was maintained for steady state exposure by day 10. Overall, R406 blood concentrations were consistent and ∼2.5-fold higher than in plasma. Minimal (<0.1 %) R406 was excreted in urine. Fostamatinib was well tolerated at all doses. CONCLUSIONS: Fostamatinib pharmacokinetics following single- and multiple-dose administration was approximately dose proportional at all doses ≤150 mg and greater than dose proportional at 200 mg in Japanese subjects. Japanese subjects administered fostamatinib 150 mg had higher exposure than white subjects. R406 could be measured in DBS samples and distributed into red blood cells, and DBS sampling was a useful method for assessing R406 pharmacokinetics.

Effects of Fostamatinib on the Pharmacokinetics of Digoxin (a P-Glycoprotein Substrate): Results From in Vitro and Phase I Clinical Studies.

PURPOSE: Fostamatinib, a spleen tyrosine kinase inhibitor and prodrug of the active metabolite R406, is being developed as an anti-inflammatory drug for several indications for which polypharmacy is likely. Digoxin, indicated for congestive cardiac failure, may be used for certain supraventricular dysrhythmias. The studies reported herein examined whether fostamatinib and R406 are inhibitors of P-glycoprotein (P-gp) in vitro and evaluated the effect of fostamatinib on the pharmacokinetic parameters of digoxin to understand drug-drug interaction (DDI) potential in the clinic. METHODS: Inhibition of P-gp-mediated digoxin transport by fostamatinib and R406 was determined across Caco-2 cell monolayers. Apparent permeability of digoxin was determined and used to calculate efflux ratios and percentage inhibition. Half maximal inhibitory concentrations (IC50) and theoretical gastrointestinal concentration [I2] (dose in moles per 250 mL) were calculated to gauge clinical DDI potential. In a subsequent Phase I study, the plasma concentration-time profiles and resulting pharmacokinetic parameters were examined across 2 treatment periods: (1) oral digoxin loading dose of 0.25 mg BID on day 1 and 0.25 mg once daily on days 2 to 8, and (2) oral digoxin 0.25 mg once daily and oral fostamatinib 100 mg BID on days 9 to 15. FINDINGS: Fostamatinib (but not R406) was determined to be a P-gp inhibitor in vitro (IC50 = 3.2 µM). On the basis of a theoretical gastrointestinal concentration (I2)/IC50 ratio of 216 ([I2] = 691 µM), predictions indicated the potential for absorption-based DDI in vivo through inhibition of intestinal P-gp. In the clinical study, when digoxin was co-administered with fostamatinib, digoxin levels were higher before dosing and throughout the dosing interval, and an increase in exposure to digoxin was observed. Co-administration led to a 1.70-fold increase in digoxin maximum plasma concentration at steady state (Cmax,ss) versus digoxin administration alone (2.18 vs 1.32 ng/mL). Median digoxin time of Cmax was earlier when digoxin was co-administered with fostamatinib (1.00 vs 1.48 hours). The digoxin AUC during the dosing interval at steady state was increased 1.37-fold with co-administration. No severe or serious adverse events or deaths were reported. IMPLICATIONS: Fostamatinib was confirmed to be a P-gp inhibitor in vitro and in vivo, and a DDI with digoxin was apparent. Co-administration of digoxin and fostamatinib was generally well tolerated. However, continued review of digoxin response and dose is advisable should these agents be prescribed concomitantly. ClinicalTrials.gov identifier: NCT01355354.

Pharmacokinetic-pharmacodynamic modeling of fostamatinib efficacy on ACR20 to support dose selection in patients with rheumatoid arthritis (RA).

R788 (fostamatinib) is an oral prodrug that is rapidly converted into a relatively selective spleen tyrosine kinase (SYK) inhibitor R406, evaluated for the treatment of rheumatoid arthritis (RA). This analysis aimed at developing a pharmacodynamic model for efficacy using pooled ACR20 data from two phase II studies in patients with rheumatoid arthritis (TASKi1 and TASKi2), describing the effect of fostamatinib as a function of fostamatinib exposure (dose, R406 plasma concentration) and other explanatory variables. The exposure-response relationship of fostamatinib was implemented into a continuous time Markov model describing the time course of transition probabilities between the three possible states of ACR20 non-responder, responder, and dropout at each visit. The probability of transition to the ACR20 response state was linearly (at the rate constant level) related to average R406 plasma concentrations and the onset of this drug effect was fast. Further, increases of fostamatinib dose resulted in increased dropout and subsequent loss of efficacy. This analysis provided an increased understanding of the exposure-response relationship, and provided support for fostamatinib 100 mg BID an appropriate dose regimen for further clinical evaluation.

Theoretical evaluation of antiemetic effects of 5-HT3 receptor antagonists for prevention of vomiting induced by cisplatin.

5-HT(3) receptor antagonists are widely used as antiemetic agents in clinical setting, of which palonosetron, with a long elimination half life (t(1/2)), has recently become available. It is important to evaluate the concentration of serotonin when investigating the antiemetic effects of 5-HT(3) receptor antagonists, as those effects are not based solely on the t(1/2) value. We theoretically evaluated the antiemetic effects of three 5-HT(3) receptor antagonists (granisetron, azasetron, palonosetron) on cisplatin-induced nausea and vomiting by estimating the time course of the 5-HT(3) receptor occupancy of serotonin. We estimated the 5-HT(3) receptor occupancy of serotonin in the small intestine, based on the time course of plasma concentration of each 5-HT(3) receptor antagonist and the time course of concentration of serotonin near the 5-HT(3) receptor in the small intestine after administration of cisplatin. The antiemetic effect of each 5-HT(3) receptor antagonist was evaluated based on the normal level of 5-HT(3) receptor occupancy of serotonin. Our results suggest that an adequate antiemetic effect will be provided when a dose of 75 mg/m(2) of cisplatin is given to patients along with any single administration of granisetron, azasetron, or palonosetron at a usual dose. On the other hand, the 5-HT(3) receptor occupancy of serotonin was found to be significantly lower than normal for several days after administration of palonosetron, as compared to granisetron and azasetron, indicating that constipation may be induced. Our results show that granisetron, azasetron, and palonosetron each have an adequate antiemetic effect after administration of 75 mg/m(2) of cisplatin.

Exposure vs. response of blood pressure in patients with rheumatoid arthritis following treatment with fostamatinib.

Fostamatinib is an oral spleen tyrosine kinase (SYK) inhibitor which has been evaluated as a potential treatment for rheumatoid arthritis (RA). Treatment with fostamatinib has been associated with an increase in blood pressure (BP). In this work, we present a pooled analysis of the pharmacokinetic-pharmacodynamic (PKPD) relationship for BP, based on 3 Phase III studies, aiming to increase the knowledge about fostamatinib's effect on BP in the RA population. Fostamatinib is rapidly and extensively converted to R406 after oral administration of fostamatinib, and the PK of R406 could be described by a two-compartment population PK model with first order absorption, with an estimated CL/F of 18.7 L/h. Average steady-state concentrations, predicted based on the individual CL/F estimates, were subsequently used in the PKPD analysis. The population PKPD analysis revealed a concentration dependent increase of BP with increasing R406 concentrations, where a power model and an Emax model best described the increase in SBP and DBP, respectively. The predicted increases were +5.2 mmHg for SBP and +4.2 mmHg for DBP, for a 100 mg bid dose. The impact of covariates on the PKPD relationship was investigated but covariates did only explain a minor part of the overall high variability in BP.

Effects of switching from efavirenz to raltegravir on endothelial function, bone mineral metabolism, inflammation, and renal function: a randomized, controlled trial.

We performed a randomized controlled trial in 30 HIV-infected participants to either continue tenofovir/emtricitabine/efavirenz (Continuation Group) or switch to tenofovir/emtricitabine/raltegravir (Switch Group) for 24 weeks. There were no significant differences in the changes in flow-mediated dilation, 25(OH) vitamin D, or parathyroid hormone levels. Total cholesterol, high sensitivity C-reactive protein, serum alkaline phosphatase, sCD14 levels, and renal function significantly declined in the Switch Group compared with the Continuation Group; however, sCD163 levels significantly increased in the Switch Group. These findings suggest that raltegravir is not inherently more beneficial to endothelial function compared with efavirenz but may impact renal function and monocyte activation.

A rapid and sensitive LC-ESI-MS/MS method for the detection of YF-49-92.MLS in rat plasma.

BACKGROUND: YF-49-92.MLS is a novel candidate for TB treatment. An accurate, precise and specific LC-MS/MS method for the quantification of YF-49-92.MLS in rat plasma using verapamil as an IS is reported in this paper. METHODOLOGY: Proper retention time and excellent peak shape were acquired using an Agilent Zorbax(®) SB-C18 column with the mobile phase of 5 mmol/l ammonium acetate, 0.1% formic acid-methanol (30:70, v/v). The LLOQ was 1 ng/ml. The calibration curves encompassed concentrations from 20 to 5000 ng/ml. Intra- and inter-assay precision and accuracy were within 15% by determining low, medium and high concentration samples. Extraction recovery, stability, and matrix effects were also fully validated. CONCLUSION: This method has been validated to be rapid and sensitive, and successfully applied to the PK study of YF-49-92.MLS in rat plasma.

[Determination of pazufloxacin concentration in saliva, gingival crevicular fluid and serum of healthy adults using high-performance liquid chromatography].

OBJECTIVE: To establish a rapid and sensitive high-performance liquid chromatography (HPLC) method for detecting pazufloxacin concentrations in the saliva, gingival crevicular fluid and serum of healthy adults. METHODS: Samples of saliva, gingival crevicular fluid and serum were obtained from healthy adults receiving intravenous infusion of pazufloxacin. The concentrations of pazufloxacin in the samples were quantified by HPLC equipped with a reversed-phase column (Agilent Zorbax SB-C18 5 µm, 250 mm×4.6 mm). The mobile phase for pazufloxacin was a mixture of acetonitrile and 0.5% phosphoric acid containing 1% triethylamine (155:850), and 20 µl of the resulting solution was injected into the HPLC system at a flow rate of 1.0 ml/min. The detection wavelength was set at 245 nm. The samples were first deproteinized by precipitation with methanol followed by supernatant drying; the residue was reconstituted with the mobile phase and centrifuged, and the supernatants were directly injected into the HPLC system. RESULTS: Pazufloxacin in the samples were totally separated without interference by any endogenous substances. The calibration curves showed a good linear regression (r>0.999). The detection limit was 10 ng/ml with within-day and between-day coefficients of variation performance all below 5% and recovery rates all above 91%. CONCLUSION: HPLC is both sensitive and selective for quantification of pazufloxacin in saliva, gingival crevicular fluid and serum.

Formulation and in vitro/in vivo correlation of a drug-in-adhesive transdermal patch containing azasetron.

The aim of the present study was to develop a transdermal drug delivery system for azasetron and evaluate the correlation between in vitro and in vivo release. The effects of different adhesives, permeation enhancers, and loadings of azasetron used in patches on the penetration of azasetron through rabbit skin were investigated using two-chamber diffusion cells in vitro. For in vivo studies, azasetron pharmacokinetic parameters in Bama miniature pigs were determined according to a noncompartment model method after topical application of transdermal patches and intravenous administration of azasetron injections. The best permeation profile was obtained with the formulation containing DURO-TAK 87-9301 as adhesive, 5% of isopropyl myristate as penetration enhancer, and 5% of azasetron. The optimal patch formulation exhibited sustained release profiles in vivo for 216 h. The in vivo absorption curve in Bama miniature pigs obtained by deconvolution approach using WinNonlin® program was correlated well with the in vitro permeation curve of the azasetron patch. These findings indicated that the developed patch for azasetron is promising for the treatment of delayed chemotherapy-induced nausea and vomiting, and the in vitro skin permeation experiments could be useful to predict the in vivo performance of transdermal azasetron patches.