Changes In Drug Concentration Research Articles

Correlation between Drug Loading Content and Biological Activity: The Complexity Demonstrated in Paclitaxel-Loaded Glycopolymer Micelle System.

Drug delivery carriers are now widely established because they can increase the therapeutic efficiency of drugs. In general, the aim in this field is to create effective carriers that have large amounts of drugs loaded to minimize drug carrier material that needs to be disposed of. However, there has been little attention so far in the literature on the effect of the amount of loaded drugs on the biological activity. In this paper, we are trying to answer the question of how the drug-loading content will affect the in vitro activity. We use two methods to load paclitaxel (PTX) into micelles based on the glycopolymer, poly(1- O-methacryloyl-β-d-fructopyranose)- block-poly(methyl methacylate) (Poly(1- O-MAFru)35- b-PMMA145). In the one-step method, the drug is loaded into the particles during the self-assembly process. However, the size of nanoparticle increased with the PTX content from 26 to 50 nm, triggering enhanced cellular uptake by MCF-7 and MDA-MB-231, which was caused by changes in diameter size and not by changes in drug concentration. To keep the nanoparticle size constant, preformed micelles were loaded with PTX (two-step process). The increasing amount of loaded drug led to decreased cellular uptake and reduced cytotoxicity by the cancer cell lines. Small-angle neutron scattering and small-angle X-ray scattering, supported by transmission electron microscopy and dynamic light scattering, exposed the PTX location in the shell. This caused shrinkage of the shell and lower levels of shell hydration, resulting in lower cellular uptake and lower cytotoxicity. Upon the release of PTX, the shell regained its original level of hydration. We could show that because drug loading causes morphology changes, in either the shell or the size, it is impossible to separate the parameters that will influence the biological activity. Although the same phenomenon may not apply to every drug delivery system, it needs to be considered that except for the well-known parameters that affect cell uptake-size, shape, surface chemistry, type of nanoparticle, and presence of bioactive groups-the amount of loaded drugs might change the physicochemical parameters of the nanoparticle and thus the in vitro and potentially the in vivo outcomes.

Canine mammary tumour cells exposure to sevoflurane: effects on cell proliferation and neuroepithelial transforming gene 1 expression

ObjectiveThe influence of perioperative factors, such as anaesthetic and analgesic techniques, on metastatic spread following surgery for primary cancer removal is of growing interest. The present study investigated the effects of sevoflurane on canine mammary tumour cell proliferation (MTT colorimetric assay) and on the expression of neuroepithelial transforming gene 1 (NET1). Study designProspective controlled in vitro trial. Study materialPrimary (CIPp) and metastatic canine tubular adenocarcinoma (CIPm) cells. MethodsTo perform MTT tests, cell lines were seeded at a density of 3000 cells per well and incubated with sevoflurane (1, 2.5 or 4 mM) or only with the culture medium (control). Sevoflurane was added to the cell cultures every hour to avoid changes in drug concentration. MTT assays were performed after 6 hours of exposure obtaining absolute values of absorbance. The RNA isolated from the lysates of the same cell lines underwent quantitative polymerase chain reaction to evaluate NET1 gene expression changes compared with controls. One- or two-way analysis of variance was used as appropriate (p < 0.05). ResultsA significant increase in cell proliferation compared with controls was observed in CIPp treated with lower sevoflurane concentrations, whereas a significant decrease in cell proliferation was found in CIPm treated with all the sevoflurane concentrations. All CIPp treatments did not induce changes in gene expression compared with controls, whereas a significant increase in gene expression was observed in CIPm between controls and the higher sevoflurane concentration. Conclusions and clinical relevanceSevoflurane treatments modified the cell proliferation rate in both cell lines showing an increase or decrease when applied to CIPp or CIPm, respectively. Expression of the NET1 gene increased after treatment with sevoflurane 4 mM in metastatic cells. The role of sevoflurane on cancer recurrence should be further investigated.

HIV Integrase Inhibitor Pharmacogenetics: An Exploratory Study

Integrase strand transfer inhibitors (INSTIs), dolutegravir, elvitegravir, and raltegravir, have become integral in the treatment of HIV, with close monitoring of continued efficacy and tolerability. As side effect occurrence varies among subjects receiving these drugs, we sought to perform an exploratory analysis examining the role of several single-nucleotide polymorphisms (SNPs) on drug concentration changes, selected clinical outcomes, and the occurrence of subject-reported adverse events. Adults (aged ≥ 18years) receiving INSTI-based regimens for treatment of HIV were recruited and genotyped with an iPLEX ADME PGx Pro v1.0 Panel. Multiple linear or logistic regression with covariates [age, sex, BMI, regimen (in the across-regimen group), regimen duration, and baseline variables (for continuous parameters)] was used to detect significant (p < 0.05) association of selected clinical data with genetic variants within the studypopulation. In a sample (n = 88) with a median age of 52.5years (IQR 45.7-57.2) being predominately Caucasian (88.6%) and male (86.4%), this exploratory study discovered several associations between variables and SNPs, when using INSTIs. Abnormal dream occurrence was statistically different (p = 0.028) between regimens. Additionally, several SNPs were found to be associated with adverse event profiles primarily when all regimens were grouped together. The associations found in this study point to a need for further assessment, within the population living with HIV, of factors contributing to unfavorable subject outcomes. These exploratory findings require confirmation in larger studies, which then may investigate pharmacogeneticmechanisms.

Long-Term Safety, Tolerability, and Efficacy of Cannabidiol in Children with Refractory Epilepsy: Results from an Expanded Access Program in the US.

Purified cannabidiol is a new antiepileptic drug that has recently been approved for use in patients with Lennox-Gastaut and Dravet syndromes, but most published studies have not extended beyond 12-16weeks. The objective of this study was to evaluate the long-term safety, tolerability, and efficacy of cannabidiol in children with epilepsy. Patients aged 1-17years with refractory epilepsy were enrolled in an open-label prospective study through individual patient and expanded access programs between April 2013 and December 2014. Seizure types were video-electroencephalogram confirmed prior to enrollment. After a 28-day evaluation period, during which baseline seizure frequency was assessed, cannabidiol was given as add-on therapy at 5mg/kg/day and titrated weekly by 5-mg/kg increments to a dose of 25mg/kg/day. Blood tests were performed at baseline, after 1, 2, and 3months, and every 3months thereafter. Trough concentrations of concomitant antiepileptic drugs were measured at baseline, after 1, 2, and 3months of therapy, and as clinically indicated afterwards. Concomitant antiepileptic drugs, ketogenic diet ratio, and vagal nerve stimulator settings remained unchanged during the baseline period and the first 3months of treatment, unless there was a significant increase in plasma concentrations. Seizure frequency was reported daily in seizure diaries by parents or caregivers. Clinical assessments occurred after 15days of treatment, at 1month, at 3months, and every 3months thereafter. Diaries of seizure frequency and adverse events were reviewed at each visit. The primary efficacy outcome was a reduction in seizure frequency and responders were defined as those patients achieving a > 50% reduction in motor seizures. Twenty-six children were enrolled. Most had genetic epilepsies with daily or weekly seizures and multiple seizure types. All were refractory to prior antiepileptic drugs (range 4-11, mean 7), and were taking two antiepileptic drugs on average. Duration of therapy ranged from 4 to 53months (mean 21months). Adverse events were reported in 21 patients (80.8%), including reduced appetite in ten (38.4%), diarrhea in nine (34.6%), and weight loss in eight (30.7%). Four (15.4%) had changes in antiepileptic drug concentrations and three had elevated aspartate aminotransferase and alanine aminotransferase levels when cannabidiol was administered together with valproate. Serious adverse events, reported in six patients (23.1%), included status epilepticus in three, catatonia in two, and hypoalbuminemia in one. Fifteen patients (57.7%) discontinued cannabidiol for lack of efficacy, one because of status epilepticus, and one for severe weight loss. The retention rate declined rapidly in the first 6months and more gradually thereafter. At 24months, the number of patients continuing cannabidiol as adjunctive therapy was nine of the original 26 (34.6%). Of these patients, seven (26.9%) had a sustained> 50% reduction in motor seizures, including three (11.5%) who remain seizure free. Over a 4-year period, cannabidiol was effective in 26.9% of children with otherwise refractory epilepsy. It was well tolerated in about 20% of patients, but 80.8% had adverse events, including 23.1% with serious adverse events. Decreased appetite and diarrhea were frequent along with weight loss that became evident only later in the treatment.

Stability and Compatibility of Diphenhydramine Hydrochloride in Intravenous Admixtures: A New Look at an Old Drug.

Purpose: Intravenous (IV) admixtures of diphenhydramine are widely used in hospitalized patients to prevent or treat hypersensitivity reactions. However, there is limited data to support the admixture preparation in this manner. This study was designed to investigate the stability and compatibility of diphenhydramine in IV admixtures with a goal to establish a 14-day beyond-use dating with storage under refrigeration. Methods: The commercially available 50 mg/mL diphenhydramine hydrochloride injection vials were used to prepare the 0.2 and 1.0 mg/mL IV admixtures in 0.9% sodium chloride injection and 5% dextrose injection in 50 mL polyvinyl chloride (PVC) bags. The IV bags were sealed and stored under refrigeration (2°C-8°C) for the stability study. At each predetermined time point, samples were taken for visual inspection, pH measurement, and analysis by a stability-indicating high-performance liquid chromatography (HPLC) method. Results: The freshly prepared IV admixtures appeared clear, colorless, and particulate-free with pH readings of 4.44 to 4.60. The initial drug concentrations of all samples were confirmed by HPLC to be within 101.8% to 103.6% of the label claims. Over the 14 days of the study period, there was no significant change in the appearance or pH values for all stability samples. The HPLC results also confirmed that there was no more than ±2% change of the initial drug concentration in any stability samples. Conclusion: Diphenhydramine hydrochloride IV admixtures of 0.2 and 1.0 mg/mL are compatible with 0.9% sodium chloride injection and 5% dextrose injection in PVC bags. These IV admixtures are stable chemically and physically for up to 14 days when stored under refrigeration (2°C-8°C).

Improving the Prediction of Local Drug Distribution Profiles in the Brain with a New 2D Mathematical Model

The development of drugs that target the brain is very challenging. A quantitative understanding is needed of the complex processes that govern the concentration–time profile of a drug (pharmacokinetics) within the brain. So far, there are no studies on predicting the drug concentration within the brain that focus not only on the transport of drugs to the brain through the blood–brain barrier (BBB), but also on drug transport and binding within the brain. Here, we develop a new model for a 2D square brain tissue unit, consisting of brain extracellular fluid (ECF) that is surrounded by the brain capillaries. We describe the change in free drug concentration within the brain ECF, by a partial differential equation (PDE). To include drug binding, we couple this PDE to two ordinary differential equations that describe the concentration–time profile of drug bound to specific as well as non-specific binding sites that we assume to be evenly distributed over the brain ECF. The model boundary conditions reflect how free drug enters and leaves the brain ECF by passing the BBB, located at the level of the brain capillaries. We study the influence of parameter values for BBB permeability, brain ECF bulk flow, drug diffusion through the brain ECF and drug binding kinetics, on the concentration–time profiles of free and bound drug.

Therapeutic efficacy of antimcrobials in critically ill patients

At any time, 50% of patients in intensive care units are receiving antibiotics. Source control and early and appropriate antibiotics administration along with other measures are vital interventions for patients with sepsis. Dose optimization is one critical tool that should be use by clinicians to improve outcomes in critically ill patients. Adequate dosing of these patients not only can improve clinical outcomes but also can impact positively in the emergence of bacterial resistance in the unit. Patients with sepsis and systemic inflammatory response (SIR) suffer from hemodynamic changes such as increased cardiac output, reduced peripheral vascular resistance, changes in the volume of distribution, and fluid shifts. In this setting, other systemic changes frequently take place such as hypoalbuminemia, hepatic impairment, and acute modification of renal function (e.g., augmented renal clearance and acute kidney injury). All these physiological adjustments to SIR lead to changing drug concentrations in serum and at the infection site of the antibiotics prescribed for the underlying infection. In this regard, doses of antibiotics usually administered to non-critically ill patients are probably inadequate in most of those patients with sepsis or SIR. Knowing the pharmacokinetics and pharmacodynamics characteristics of each antibiotic is essential to optimize drug treatment in this setting. Individualizing dosing based on patient clinical status and antibiotic properties should be encouraged. Loading dose, continuous infusion of time-dependent antibiotics, therapeutic drug monitoring, and direct administration at the infection site are among the tools that could improve antimicrobial use in critically ill patients. Discussion of optimization options for most commonly used antibiotics in ICU will be presented.

Apatinib, a selective VEGFR2 inhibitor, improves the delivery of chemotherapeutic agents to tumors by normalizing tumor vessels in LoVo colon cancer xenograft mice.

Tumor vascular normalization has been proposed as a therapeutic strategy for malignant neoplasms, which can also interpret the synergistic effect of anti-angiogenesis agents combined with chemotherapy. Apatinib (Apa), a highly selective VEGFR2 inhibitor, attracts much attentions due to its encouraging anticancer activity, especially in the clinical trials of combined treatment. In this study, we investigated whether Apa could promote vascular normalization in tumor in a certain time window. Mice bearing LoVo colon cancer xenograft were orally administrated Apa (150 mg kg-1 per day) for 5, 7, 10, or 12 days. Apa significantly inhibited tumor growth and decreased the microvessel density. Using multi-photon microscopy and electron microscopy, we found that Apa improved tumor vessel morphology by pruning distorted vessel branches and decreased the gap between endothelial cells after a 7-day treatment. Furthermore, Apa decreased vessel leakage and increased pericyte coverage on vascular endothelial cells, suggesting that tumor vessels were more mature and integrated. The intratumoral distribution of adriamycin (ADR) in Apa group was improved from day 7 to 10 without change in plasma drug concentration. Tumor blood perfusion was also increased in this window, and the expression of hypoxia induced factor 1α was downregulated, suggesting the effect of Apa on alleviating tumor hypoxic micro-environment. In conclusion, Apa may improve the effective perfusion of tumor vessels and increase the intratumoral distribution of ADR in a certain time window via normalizing tumor vessels. This normalization window (7 to 10 days of treatment) may contribute to develop a regimen of combined medication in clinic use of Apa.

Development of a tin oxide carrier with mesoporous structure for improving the dissolution rate and oral relative bioavailability of fenofibrate.

BackgroundBiopharmaceutics classification system class II drugs have low solubility, which limits their extent and speed of absorption after oral administration. Over the years, mesoporous materials have been widely used to increase the dissolution rate and oral relative bioavailability of poorly water-soluble drugs.ObjectivesIn order to improve the dissolution rate and increase oral relative bioavailability of the poorly water-soluble drugs, a tin oxide carrier (MSn) with a mesoporous structure was successfully synthesized.MethodsIn this study, MSn was synthesized using mesoporous silica material (SBA-15) as the template. Fenofibrate (FNB) was adsorbed into the channels of MSn by an adsorption method. Characterizations of the pure FNB, MSn, physical mixture of the drug and MSn (PM; 1:1) and FNB-loaded MSn (FNB-MSn) samples were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption, powder X-ray diffractometer (PXRD), differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy. Cytotoxicity assay (MTT) was used to evaluate the cytotoxicity of MSn. In vitro dissolution studies were performed to investigate the dissolution rate of FNB-MSn. In vivo pharmacokinetic studies were used to investigate the changes of plasma drug concentrations of FNB-MSn tablets and commercial FNB tablets in rabbits.ResultsDetailed characterization showed that FNB in the channels of MSn was present in an amorphous state. The in vitro release tests demonstrated that MSn with a good biocompatibility could effectively enhance the dissolution rate of FNB. Pharmacokinetic results indicated that MSn significantly increased the oral relative bioavailability of FNB.ConclusionMSn can be regarded as a promising carrier for an oral drug delivery system.

Clinical Pharmacokinetics and Drug‐Drug Interaction Potential for Coadministered SCY‐078, an Oral Fungicidal Glucan Synthase Inhibitor, and Tacrolimus

SCY-078 is an orally bioavailable triterpenoid glucan synthase inhibitor in clinical development as an intravenous and oral treatment of fungal infections caused by Candida and Aspergillus species. This was a sequential, single-center, open-label phase 1 study to assess the drug-drug interaction potential between SCY-078 and tacrolimus during concomitant administration in healthy subjects. In cohort 1, period 1, subjects received a single oral dose of tacrolimus 2mg in the fasted state. In period 2 after a ≥15 day washout, subjects received a single loading dose of SCY-078 1250mg on day 1 followed by maintenance doses of SCY-780 750mg on days 2 through 8. On day 3 of period 2, subjects also received a single dose of tacrolimus 2mg concurrent with SCY-078. In cohort 2, subjects received a loading dose of SCY-078 1250mg on day 1 followed by maintenance doses of SCY-780 750mg on days 2 and 3. Pharmacokinetic (PK) parameters were compared to assess both the impact of steady-state SCY-078 on tacrolimus and the impact of tacrolimus on the PK of steady-state SCY-078. The concurrent coadministration of tacrolimus and SCY-078 had no effect on the maximum blood levels of tacrolimus, as evidenced by no change in maximum concentration of drug in blood plasma and a 1.4-fold increase in total area under the plasma drug concentration-time curve. The concurrent coadministration of tacrolimus and SCY-078 resulted in a weaker interaction than typically observed with the azole class of antifungals. The current data indicate that an initial dose adjustment for tacrolimus may not be warranted when combined with SCY-078, as the modest increase in exposure is less than the therapeutic window, although tacrolimus monitoring, as with addition of any new medication, is recommended. These results support the coadministration of SCY-078 and tacrolimus.

Adsorption and Leachable Contamination of Flucloxacillin, Cyclosporin and Amiodarone Following Delivery Through an Intravenous Administration Set.

Interactions between a pharmaceutical drug and its delivery device can result in changes in drug concentration and leachable contamination. Flucloxacillin, amiodarone and cyclosporin were investigated for drug concentration changes and leachable contamination after delivery through an intravenous administration set. Flucloxacillin, amiodarone and cyclosporin were delivered through an intravenous administration set and the eluate analysed by HPLC-UV and HPLC-MS. The average recovery of flucloxacillin was 99.7% and no leachable compounds were identified. The average recovery of cyclosporin was 96.1%, which contrasts previous findings that have reported up to 50% loss of cyclosporin. This is likely due to the use of DEHP-free administration sets in this study, as adsorption of cyclosporin is linearly related to DEHP content. The average recovery of amiodarone was 91.5%. 5-hydroxymethylfurfural was identified in the amiodarone solution following delivery through the administration set as well as the 5% glucose solution used for delivery. Drug/administration set interactions may modify pharmaceuticals during delivery. In this study, only 90% of the amiodarone was delivered through a generic administration set. Given the growing use of generic administration sets in hospital settings, validation of the suitability of their use is required to ensure patient safety and expected levels of efficacy.

Darunavir for use in pregnant women with HIV

ABSTRACTIntroduction: Combination antiretroviral therapy is recommended during pregnancy to decrease the rate of HIV transmission to the baby and reduce morbidity in the mother. More than 50% of women are prescribed a protease inhibitor-based regimen during pregnancy. Darunavir was recently reclassified as a first-line protease inhibitor for use in pregnancy in the US Department of Health and Human Services Perinatal Guidelines.Areas covered: This is a brief review of the use of protease inhibitor therapy during pregnancy, and a discussion of darunavir’s utility in this area. Clinical pharmacology and trial data are reviewed, and the safety, efficacy and dosing of darunavir during pregnancy is discussed.Expert commentary: Darunavir has become an important option in the management of HIV during pregnancy. Both once-daily dosing and twice-daily dosing regimens have shown efficacy in clinical studies. Although a significant reduction in total (protein bound and unbound) plasma concentrations of darunavir has been noted during pregnancy, antiviral activity appears to be maintained with standard dosing. This is likely due to diminished changes in unbound drug concentrations. Preterm delivery and low birth weight have been noted for pregnancies of women on darunavir-containg regimens, but a causal relationship has not yet been demonstrated.

Sodium deoxycholate/TRIS-based hydrogels for multipurpose solute delivery vehicles: Ambient release, drug release, and enantiopreferential release

Herein, we report the investigation of sodium deoxycholate (NaDC)/TRIS-based hydrogels as delivery vehicles for a broad range of applications. Three hydrogel formulations were chosen for unique rheological behaviors that suggest a change in internal hydrogel structure with the application of a shear force. In this work, we compare solute release from sheared and non-sheared hydrogels in order to explore the effect of shear force on structure and release kinetics. It was found that the application of a shear force, in addition to changes in temperature, drug solubility, drug concentration, and hydrogel formulation each affected the amount of solute ultimately released from a hydrogel system. Moreover, the use of the inherent chirality of the hydrogel network for enantio-preferential drug release was also explored. We show significant enantio-preference in the release of model drugs tryptophan and ibuprofen from the hydrogel network. Furthermore, hydrophobic domains within the hydrogel network were exploited to enable ibuprofen loading at ten times the maximum water solubility. Retention of enantio-preference was observed at this higher ibuprofen concentration. Cyclodextrin modification to the hydrogel matrix allowed for enantio-preferential inversion which is an unprecedented observation.

Abstract 56: Individual Susceptibility to Drug-induced QTc Prolongation Did Not Correlate With Subject-specific Induced Pluripotent Stem Cells in a Small Sample of Healthy Subjects

Background: Induced pluripotent stem cells (iPSCs) carry patient-specific genetic information and have the potential to become an important tool for predicting individual clinical response to therapies in an in vitro assay. Here, we investigate if subject-specific iPSC cardiomyocytes (iPSC-CMs) derived from healthy volunteers could be used to predict individual response to 2 QT-prolonging drugs which they received in a clinical trial. Methods and Results: Independent stem cell manufacturer (Stem Cell Theranostics) used commercially available Sendai virus encoding for Oct4 , Sox2 , Klf4 , and c-Myc to reprogram subject’s peripheral blood mononuclear cells (PBMCs) into iPSCs. They then applied chemically defined growth factors, and serum-free protocols to successfully differentiate iPSCs into iPSC-CMs for 17 out of 20 subjects (one batch per subject) enrolled in a randomized, double-blind, placebo-controlled, cross-over trial of dofetilide and moxifloxacin. Effects of the same 2 drugs on cellular action potential duration (APD) were recorded for 16 iPSC-CMs lines using a high-throughput optical imaging system (CellOPTIQ, Clyde Biosciences) using consistent in vitro protocols, including reproducible drug doses and exposure, cell culture and recording conditions. Both dofetilide (0.5-8 nM) and moxifloxacin (10-200 μM) induced dose-dependent prolongation of rate-corrected action potential duration (APD) in each iPSC-CM line. iPSC-CM drug responses were compared with individual clinical response represented by the slope of the linear regression fit through baseline and placebo-controlled drug-induced changes in QTc interval vs. plasma drug concentration. We found no statistical significant correlation between subject-specific iPSC-CMs drug-induced APD prolongation and individual QTc prolongation to either moxifloxacin [Spearman’s ρ = 0.191] or dofetilide [Spearman’s ρ = 0.068]. Conclusion: This study failed to find correlation between clinical and stem cell drug responses in a small sample of healthy subjects. More experiments with a larger sample size and iPSC-CMs batch-to-batch variability controls are required to further investigate the potential of patient-derived stem cells to predict individual clinical response.

Osmolality of Orally Administered Solutions Influences Luminal Water Volume and Drug Absorption in Intestine

Intestinal water absorption is reportedly influenced by luminal osmolality. In this study, we examined whether differences in the osmolality of the vehicle used for oral administration of drugs influence luminal water volume and drug absorption in the gastrointestinal (GI) tract, by means of in situ rat intestinal closed loop studies using solutions of fluorescein isothiocyanate dextran 4000 (a non-absorbable compound), atenolol (a low-permeability drug), and antipyrine (a high-permeability drug) in various solvents. Determination of the remaining fraction of water revealed the following rank order for water absorption in rat jejunum: purified water > saline > phosphate buffer = isosmotic mannitol solution. The luminal concentration of fluorescein isothiocyanate-dextran 4000 after administration in purified water was significantly increased to 2.5 times the initial dosing concentration. Thus, osmolality-dependent changes in GI water absorption can cause significant changes of drug concentration in the GI fluid, potentially resulting in altered drug absorption characteristics. Indeed, the fraction absorbed of atenolol in jejunum was significantly greater when the drug was administered in purified water than in isosmotic solution. In contrast, no significant change in fraction absorbed of antipyrine was observed. Our results indicate that osmolality-dependent changes in GI water volume may influence drug absorption, especially of low-permeability drugs.

β-Asarone promotes Temozolomide’s entry into glioma cells and decreases the expression of P-glycoprotein and MDR1

Glioma is the most common primary brain tumor and has an undesirable prognosis due to the blood-brain barrier (BBB) and drug resistance. A thorough investigation of the changes in intracellular drug concentrations is important to observe therapeutic effects and cell resistance. P-glycoprotein (P-gp) is an essential protein of Multi-drug resistance 1 (MDR1). The over-expression of P-gp and MDR1 is associated with poor prognosis and drug-resistance in glioma. However, β-asarone can pass through the BBB easily and increase the drug concentration in the rat brain. Our aim is to study the effect of β-asarone on promoting the entry of temozolomide (TMZ) into human glioma U251 cells. The cells were divided into three groups: model group, TMZ group (300μM) and co-administration group (360μM β-asarone; 300μM TMZ). We further detected P-gp and MDR1 expression in U251 and rat glioma C6 cells in four groups: model group (U251/C6), TMZ group (U251 300μM, C6 420μM), β-asarone group (U251 360μM, C6 450μM) and co-administration group (β-asarone 360μM, TMZ 300μM for U251; β-asarone 450μM, TMZ 420μM for C6). Then, high performance liquid chromatography was used to determine the intracellular and extracellular levels of TMZ. Morphological changes in both cells were observed by the microscope. The Counting Kit-8 assay was used to measure the cell proliferation and toxicity. Cell immunohistochemistry/immunofluorescence, flowcytometry and western blot were synchronously used to examine the expression of P-gp. We also determined the levels of MDR1 mRNA by RT-PCR. The results showed that β-asarone could promote the entry of TMZ into U251 cells through the membrane. The co-administration of β-asarone and TMZ also decreased cell proliferation and the expression of P-gp and MDR1 better than single medication in U251 and C6 cells. All of the data suggest that β-asarone might contribute to treatment by promoting TMZ’s entry into glioma cells, thereby contributing to anti-cancer growth and inhibiting P-gp and MDR1 expression.

Impact of Micellar Surfactant on Supersaturation and Insight into Solubilization Mechanisms in Supersaturated Solutions of Atazanavir.

The goals of this study were to determine: 1) the impact of surfactants on the "amorphous solubility"; 2) the thermodynamic supersaturation in the presence of surfactant micelles; 3) the mechanism of solute solubilization by surfactant micelles in supersaturated solutions. The crystalline and amorphous solubility of atazanavir was determined in the presence of varying concentrations of micellar sodium dodecyl sulfate (SDS). Flux measurements, using a side-by-side diffusion cell, were employed to determine the free and micellar-bound drug concentrations. The solubilization mechanism as a function of atazanavir concentration was probed using fluorescence spectroscopy. Pulsed gradient spin-echo proton nuclear magnetic resonance (PGSE-NMR) spectroscopy was used to determine the change in micelle size with a change in drug concentration. Changes in the micelle/water partition coefficient, K m/w , as a function of atazanavir concentration led to erroneous estimates of the supersaturation when using concentration ratios. In contrast, determining the free drug concentration using flux measurements enabled improved determination of the thermodynamic supersaturation in the presence of micelles. Fluorescence spectroscopic studies suggested that K m/w changed based on the location of atazanavir solubilization which in turn changed with concentration. Thus, at a concentration equivalent to the crystalline solubility, atazanavir is solubilized by adsorption at the micelle corona, whereas in highly supersaturated solutions it is also solubilized in the micellar core. This difference in solubilization mechanism can lead to a breakdown in the prediction of amorphous solubility in the presence of SDS as well as challenges with determining supersaturation. PGSE-NMR suggested that the size of the SDS micelle is not impacted at the crystalline solubility of the drug but increases when the drug concentration reaches the amorphous solubility, in agreement with the proposed changes in solubilization mechanism. Micellar solubilization of atazanavir is complex, with the solubilization mechanism changing with differences in the degree of (super)saturation. This can result in erroneous predictions of the amorphous solubility and thermodynamic supersaturation in the presence of solubilizing additives. This in turn hinders understanding of the driving force for phase transformations and membrane transport, which is essential to better understand supersaturating dosage forms.

Antazoline-insights into drug-induced electrocardiographic and hemodynamic effects: Results of the ELEPHANT II substudy.

Antazoline is an old antihistaminic and new antiarrhythmic agent with unknown mechanisms of action which recently has been shown to effectively terminate atrial fibrillation. The aim of study was to examine the effects of antazoline on hemodynamic and ECG parameters. Antazoline was given intravenously in three 100mg boluses to 10 healthy volunteers (four males, mean age 40+11years). Hemodynamic and ECG parameters were measured using impedance cardiography [systolic (sBP), diastolic (dBP), mean (mBP) blood pressure, stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR) and heart rate (HR), P wave, PR interval, QRS complex, QT and corrected QT (QTcF) interval]. Plasma concentration of antazoline was also measured. Antazoline caused significant prolongation of P wave, QRS as well as QT and QTcF (101±10 vs 110±16ms, p<.05, and 101±12 vs 107±12ms, p<.05, 399±27 vs 444±23ms, p<.05, and 403±21 vs 448±27ms, p<.05, respectively). Also, a significant decrease in SV was noted (94.9±21.8 vs 82.4±19.6 ml, p<.05). A significant correlation between changes in plasma drug concentration and changes in CO, HR, and dBP was found. Antazoline impairs slightly hemodynamics, significantly reducing SV. Significant prolongation of P wave and QRS duration corresponds to drug-induced prolongation of conduction, whereas QT prolongation represents drug-induced prolongation of repolarization.

A Bioengineered Three-Dimensional Cell Culture Platform Integrated with Microfluidics To Address Antimicrobial Resistance in Tuberculosis.

ABSTRACTAntimicrobial resistance presents one of the most significant threats to human health, with the emergence of totally drug-resistant organisms. We have combined bioengineering, genetically modified bacteria, longitudinal readouts, and fluidics to develop a transformative platform to address the drug development bottleneck, utilizing Mycobacterium tuberculosis as the model organism. We generated microspheres incorporating virulent reporter bacilli, primary human cells, and an extracellular matrix by using bioelectrospray methodology. Granulomas form within the three-dimensional matrix, and mycobacterial stress genes are upregulated. Pyrazinamide, a vital first-line antibiotic for treating human tuberculosis, kills M. tuberculosis in a three-dimensional culture but not in a standard two-dimensional culture or Middlebrook 7H9 broth, demonstrating that antibiotic sensitivity within microspheres reflects conditions in patients. We then performed pharmacokinetic modeling by combining the microsphere system with a microfluidic plate and demonstrated that we can model the effect of dynamic antibiotic concentrations on mycobacterial killing. The microsphere system is highly tractable, permitting variation of cell content, the extracellular matrix, sphere size, the infectious dose, and the surrounding medium with the potential to address a wide array of human infections and the threat of antimicrobial resistance.

Comparative pharmacokinetics of eight major bioactive components in normal and bacterial diarrhea mini-pigs after oral administration of Gegen Qinlian Decoction.

Healthy animals are most widely used in current pharmacokinetic(PK) studies. However, neglecting the effects of specific diseases on drug absorption results in the PK parameters of those experiments not accurately reflecting in vivo drug concentration changes during treatment. In this study, an E. coli infective diarrheal minipig model was applied to explore the pharmacokinetics of Gegen Qinlian decoction (GQD). A simple and rapid ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to determine the concentrations of the eight GQD components in minipig plasma after intragastric administration of GQD. The PK parameters of the main GQD components in normal and model minipigs after oral administration of GQD were compared. There were statistically significant differences (p<0.05) in the pharmacokinetic parameters of Puerarin, Wogonin and Daidzein involving the AUC0-t, Cmax, MRT(0-t), t1/2z between normal and model minipigs. Results showed that bacterial diarrhea had a great impact on the biological availability of the main ingredients in GQD. More importantly, the results obtained suggest that the bacterial diarrheal minipig model can be successfully applied in PK studies and may be used in other PK studies of drugs targeting intestinal disease.