Formulation development of tazarotene-loaded PLGA nanoparticles for follicular delivery in the treatment of inflammatory skin diseases.

Tazarotene is a widely prescribed topical retinoid for acne vulgaris and plaque psoriasis and is associated with skin irritation, dryness, flaking, and photosensitivity. In vitro permeation of tazarotene was studied across the dermatomed human and full-thickness porcine skin. The conversion of tazarotene to the active form tazarotenic acid was studied in various skin models. Tazarotene-loaded PLGA nanoparticles were prepared using the nanoprecipitation technique to target skin and hair follicles effectively. The effect of formulation and processing variables on nanoparticle properties, such as particle size and drug loading, was investigated. The optimized nanoparticle batches with particle size <500 µm were characterized further for FT-IR analysis, which indicated no interactions between tazarotene and PLGA. Scanning electron microscopy analysis showed uniform, spherical, and non-agglomerated nanoparticles. In vitro release study using a dialysis membrane indicated a sustained release of 40-70 % for different batches over 36 h, following a diffusion-based release mechanism based on the Higuchi model. In vitro permeation testing (IVPT) in full-thickness porcine skin showed significantly enhanced follicular and skin delivery from nanoparticles compared to solution. The presence of tazarotenic acid in the skin from tazarotene nanoparticles indicated the effectiveness of nanoparticle formulations in retaining bioconversion ability and targeting follicular delivery.

Safety, Tolerability, and Pharmacokinetics of Tazarotene Clindamycin Cream: A Single-Dose, 3-Period Crossover Study.

The current study compared the safety, tolerability, and pharmacokinetics of the new compound pharmaceutical preparation tazarotene clindamycin cream, and 2 single pharmaceutical preparations, tazarotene cream and clindamycin phosphate gel. Twelve healthy volunteers were enrolled in this single-center, single-blind, 3-treatment, 3-period crossover, single-dose randomized study. An 800-cm2 area on volunteers' backs was evenly smeared with 1.6 g of the test preparation to form a film. Blood samples were collected at predetermined time points for pharmacokinetic analysis. Safety and tolerability were assessed via skin reaction evaluation and clinical laboratory tests. The incidences of skin reactions were 18.2% for tazarotene clindamycin cream, 25.0% for tazarotene cream, and 18.2% for clindamycin phosphate gel. There were no significant differences in safety or tolerability among the 3 groups. Erythema, desquamation, and pruritus occurred in 7 volunteers, but no burning or tingling occurred. All adverse events were mild and resolved spontaneously, and there were no severe adverse events. The respective maximum plasma concentrations of tazarotenic acid after local administration of tazarotene clindamycin cream and tazarotene cream were 11 ± 5 pg/mL and 18 ± 12 pg/mL, and the areas under the curve within 72 hours were 444 ± 341 pg · h/mL and 692 ± 462 pg · h/mL.

Simultaneous determination of tazarotene, clindamycin phosphate and their active metabolites in Bama mini-pig skin by LC-MS/MS: Application to the development of a tazarotene/clindamycin phosphate cream.

Topical tazarotene combined with clindamycin phosphate can significantly improve the adherence and outcomes for the treatment of acne vulgaris than monotherapy, a novel tazarotene (0.05%)/clindamycin phosphate (1.2%) cream is thus developed. However, the pharmacokinetics and potential interaction of tazarotene and clindamycin phosphate in skin when formulated together remain unknown, which should be investigated to assess this novel cream. In the present work, a sensitive and rapid LC-MS/MS method for simultaneous determination of tazarotene, clindamycin phosphate and their active metabolites tazarotenic acid, clindamycin in Bama mini-pig skin was developed and reported for the first time. After pretreatment of the skin samples, the analytes were well separated on a Hypersil BDS C8 column (4.6 × 100 mm, 2.4 µm) using 0.2% (v/v) formic acid-0.1% (w/v) ammonium acetate water solution and acetonitrile as mobile phase in linear gradient elution. Quantification of tazarotene, clindamycin phosphate and their active metabolites tazarotenic acid, clindamycin was conducted under positive electrospray ionization mode using multiple reactions monitoring detection. The LC-MS/MS method was fully validated and then applied to the dermal pharmacokinetic study of the tazarotene/clindamycin phosphate cream. According to the obtained results, tazarotene and clindamycin phosphate did not have any drug-drug interaction when they were formulated together in the cream for topical application. Their absorption and metabolism features in the skin were also characterized, which can support the clinical medication regimen of tazarotene/clindamycin phosphate cream.

Insights into the degradation chemistry of tazarotene, a third generation acetylenic retinoid: LC-HRMS (Orbitrap), LC-MSn and NMR characterization of its degradation products, and prediction of their physicochemical and ADMET properties.

Tazarotene is a prodrug that belongs to the acetylenic class of retinoids. The drug was subjected to hydrolytic, oxidative and photolytic stress testing to establish its comprehensive degradation chemistry. The drug proved to be unstable under acidic and basic hydrolytic conditions, yielding tazarotenic acid, which is a known major degradation product (DP) and an active metabolite. Additionally, two DPs each were generated upon interaction of drug and tazarotenic acid with HCl, used as an acid stressor. These were experimentally proven as pseudo DPs, as they did not originate when H2SO4 was employed as the stressor. The drug was also unstable under oxidative and photolytic conditions, yielding six DPs. All the products were separated on reversed phase (C18) column, using mobile phase composed of 10 mM ammonium formate (pH 3.5) and acetonitrile, which was run in a gradient mode. The separated DPs were subjected to LC-HRMS and LC-MSn studies for their initial characterization. Seven hydrolytic and oxidative DPs that could be isolated using semi-preparative column were subjected to extensive 1D (1H, 13C and DEPT-135) and 2D (COSY, HSQC and HMBC) NMR studies to confirm their structures. In total, five novel DPs were characterized, apart from two previously reported DPs, viz., tazarotenic acid and tazarotene sulfoxide, and four additional pseudo DPs. The complete degradation pathway of the drug was established. In silico ADMET properties of the drug and its DPs were evaluated using ADMET Predictor™.

Determination of clobetasol propionate, tazarotene and tazarotenic acid in Bama mini-pig skin by UPLC-MS/MS: Application to pharmacokinetic and drug-drug interaction studies.

Tazarotene and clobetasol propionate are efficacious for the treatment of psoriasis. The plasma pharmacokinetic assessments of tazarotene or clobetasol propionate have been reported. However, the pharmacokinetic characteristics of tazarotene and clobetasol propionate in skin when used together have not been studied. In the present study, sensitive and rapid methods were developed for the determination of clobetasol propionate, tazarotene and its active metabolite tazarotenic acid in Bama mini-pig skin by UPLC-MS/MS. After homogenization and pretreatment of skin samples, the separation was performed on a WondaSiL C18 column (4.6 × 150 mm, 5 µm) for tazarotene and clobetasol propionate. The separation of tazarotenic acid was achieved on a BDS HYPERSIL C18 column (4.6 × 100 mm, 2.4 µm). All the analytes were quantified with positive electrospray ionization and multiple reactions monitoring mode. The assay was validated in the range of 22-1111 ng/g for tazarotene and clobetasol propionate, 2-111 ng/g for tazarotenic acid in skin samples. The methods were fully validated to meet the requirements for bioassay in accuracy, precision, recovery, reproducibility, stabilities and matrix effects, and successfully applied to evaluate the novel combination ointment of tazarotene and clobetasol propionate. The obtained intradermal content-time curves characterized the dermal absorption and metabolism features of the combination ointment. It was also found that there was no significant drug-drug interaction trend between tazarotene and clobetasol propionate. The obtained results would be essential for the development and clinical applications of this novel combination ointment.

Time-resolved fluorescence microscopy with phasor analysis for visualizing multicomponent topical drug distribution within human skin.

Understanding a drug candidate's pharmacokinetic (PK) parameters is a challenging but essential aspect of drug development. Investigating the penetration and distribution of a topical drug's active pharmaceutical ingredient (API) allows for evaluating drug delivery and efficacy, which is necessary to ensure drug viability. A topical gel (BPX-05) was recently developed to treat moderate to severe acne vulgaris by directly delivering the combination of the topical antibiotic minocycline and the retinoid tazarotene to the pilosebaceous unit of the dermis. In order to evaluate the uptake of APIs within human facial skin and confirm accurate drug delivery, a selective visualization method to monitor and quantify local drug distributions within the skin was developed. This approach uses fluorescence lifetime imaging microscopy (FLIM) paired with a multicomponent phasor analysis algorithm to visualize drug localization. As minocycline and tazarotene have distinct fluorescence lifetimes from the lifetime of the skin's autofluorescence, these two APIs are viable targets for distinct visualization via FLIM. Here, we demonstrate that the analysis of the resulting FLIM output can be used to determine local distributions of minocycline and tazarotene within the skin. This approach is generalizable and can be applied to many multicomponent fluorescence lifetime imaging targets that require cellular resolution and molecular specificity.

Review on Characteristics and Analytical Methods of Tazarotene: An Update.

Tazarotene (TZR) is the first topical receptor-selective retinoid prodrug derived from vitamin A used for management of plaque psoriasis and efficacious in dealing of acne vulgaris, and photo aging. As per US food and drug administration (FDA), 0.1% strength of TZR is permitted for the treatment of acne. This article draws attention to various advanced and conventional analytical methods. The hyphenated and conventional chromatographic techniques such as LC-MS/MS and HPTLC, HPLC respectively. Moreover, spectrophotometric methods like UV/visible spectroscopy also used to quantify TZR as active pharmaceutical ingredient and its formulations, especially in topical preparations. Moreover, the TZR is required alternative methods for routine quality control and to estimate TZR in pharmaceutical dosage form especially in pharmacokinetic studies of topical preparation. This write up focus on critical review of characteristics, uses and the information about the physicochemical, pharmacokinetics properties, mechanisms of action and more emphasis on different analytical methods for estimation of TZR in pharmaceutical formulations.

Development of a simple method for simultaneous determination of tazarotene and betamethasone dipropionate and their metabolites using LC-MS method and its application to dermatopharmacokinetic study.

In our study, a method for the determination for tazarotene and betamethasone dipropionate in human tissue-engineered skin was established. Tazarotene gel, betamethasone dipropionate cream or a combination cream was administered to the skin. Then the skin was taken off at 0.25, 0.75, 1.75, 3, 5, 8, 12, 24, 36, 48 h time points after the residual drug was removed. The concentrations of tazarotene, betamethasone dipropionate and their major metabolites in skin were determined by LC-MS. Tazarotene and tazarotenic acid were detected in the concentration range of 2-200 µg/mL with an LLOQ of 2 µg/mL. Betamethasone dipropionate was detected in the concentration range 0.5-300 µg/mL with an LLOQ of 0.5 µg/mL, and betamethasone was detected at 2-200 µg/mL with an LLOQ of 2 µg/mL. The intra- and inter-day precisions of the four analytes in the skin homogenate were all <15% (RSD, %). The results showed that tazarotene could be metabolized to tazarotenic acid and betamethasone dipropionate could be metabolized to betamethasone in tissue-engineered skin. The results also revealed that this method was suitable for the simultaneous determination of tazarotene, betamethasone dipropionate and their metabolites in tissue-engineered skin.

Effect of Hepatic Organic Anion-Transporting Polypeptide 1B Inhibition and Chronic Kidney Disease on the Pharmacokinetics of a Liver-Targeted Glucokinase Activator: A Model-Based Evaluation.

PF-04991532 ((S)-6-(3-Cyclopentyl-2-(4-(trifluoromethyl)-1H-imidazol-1-yl) propanamido) nicotinic acid) is a glucokinase activator designed to achieve hepato-selectivity via organic anion-transporting polypeptides (OATP)s, so as to minimize systemic hypoglycemic effects. This study investigated the effect of OATP1B1/1B3 inhibition and renal impairment on PF-04991532 oral pharmacokinetics. Cyclosporine (600 mg single dose) increased mean area under the plasma curve (AUC) of PF-04991532 by approximately threefold in healthy subjects. In a renal impairment study, PF-04991532 AUC values were ~ 2.3-fold greater in subjects with mild, moderate, and severe kidney dysfunction, compared with healthy subjects. Physiologically-based pharmacokinetic (PBPK) model parameterizing hepatic and renal transporter-mediated disposition based on in vitro inputs, and verified using first-in-human data, indicated the key role of OATP-mediated hepatic uptake in the systematic and target-tissue exposure of PF-04991532. Mechanistic evaluation of the clinical data suggest reduced hepatic OATPs (~ 35%) and renal organic anion transporter (OAT)3 (80-90%) function with renal impairment. This study illustrates the adequacy and utility of the PBPK approach in assessing the impact of drug interactions and kidney dysfunction on transporter-mediated disposition.

Metabolism and excretion of (S)-6-(3-cyclopentyl-2-(4-trifluoromethyl)-1H-imidazol-1-yl)propanamido)nicotinic acid (PF-04991532), a hepatoselective glucokinase activator, in humans: confirmation of the MIST potential noted in first-in-Human metabolite scouting studies.

1. The absorption, metabolism, and excretion of a single oral 450-mg dose of [14C]-(S)-6-(3-cyclopentyl-2-(4-trifluoromethyl)-1H-imidazol-1-yl)propanamido)nicotinic acid (PF-04991532), a hepatoselective glucokinase activator, was investigated in humans. Mass balance was achieved with ∼94.6% of the administered dose recovered in urine and feces. The total administered radioactivity excreted in feces and urine was 70.6% and 24.1%, respectively. Unchanged PF-04991532 collectively accounted for ∼47.2% of the dose excreted in feces and urine, suggestive of moderate metabolic elimination in humans. 2. The biotransformation pathways involved acyl glucuronidation (M1), amide bond hydrolysis (M3), and CYP3A4-mediated oxidative metabolism on the cyclopentyl ring in PF-04991532 yielding monohydroxylated isomers (M2a-d). Unchanged PF-04991532 was the major circulating component (64.4% of total radioactivity) whereas M2a-d collectively represented 28.9% of the total plasma radioactivity. 3. Metabolites M2a-d were not detected systemically in rats and dogs, the preclinical species for the toxicological evaluation of PF-04991532. In contrast, cynomologus monkeys dosed orally with unlabeled PF-04991532 revealed M2a-d in circulation, whose UV abundance was comparable to the profile in humans. This observation suggested that monkeys could potentially serve as a non-rodent alternative for studying the toxicity of PF-04991532 and its metabolites M2a-d. 4. The present results are in excellent agreement with our previously generated metabolite scouting data, which provided preliminary evidence for the disproportionate metabolism of PF-04991532 in humans.

Pharmacokinetics of tazarotene and acitretin in psoriasis.

INTRODUCTION: Psoriasis is a prevalent cutaneous condition with severe physical and psychological manifestations. Since the advent of biologics, clinical outcomes in psoriasis have improved. However, retinoids are useful in the correct clinical context. Tazarotene and acitretin are currently the only US Food and Drug Administration approved retinoids for treatment of psoriasis. Both topical tazarotene and oral acitretin act on retinoic acid receptors and retinoid-X-receptors, resulting in altered gene expression of inflammatory cytokines and inhibition of keratinocyte proliferation. Areas covered: This article provides an in-depth pharmacologic and clinical review on the use of tazarotene and acitretin in psoriasis. The PubMed database was searched using combinations of keywords: acitretin, bioavailability, dosing, efficacy, etretinate, interactions, mechanism, pharmacodynamics, pharmacokinetics, pharmacogenetics, psoriasis, safety, tazarotene, tolerability, and toxicity. Expert opinion: Tazarotene and acitretin are effective treatments for psoriasis. Benefits include lack of immunosuppression and success treating inflammatory psoriasis. When combined with other topical and systemic agents, both retinoids improve clinical efficacy while lowering the treatment threshold. However, topical adherence and bothersome side effects can limit retinoid use. Acitretin and tazarotene both improve outcomes through a unique mechanism that especially benefits subsets of patients, despite side effects and limitations.

Development of a SPECT Tracer to Image c-Met Expression in a Xenograft Model of Non-Small Cell Lung Cancer.

Elevated expression of the c-Met receptor plays a crucial role in cancers. In non-small cell lung cancer (NSCLC), aberrant activation of the c-Met signaling pathway contributes to tumorigenesis and cancer progression and may mediate acquired resistance to epidermal growth factor receptor-targeted therapy. c-Met is therefore emerging as a promising therapeutic target for NSCLC, and methods for noninvasive in vivo assessment of c-Met expression would improve NSCLC treatment and diagnosis. Methods: We developed a new c-Met-binding peptide (cMBP) radiotracer, 99mTc-hydrazine nicotinamide (HYNIC)-cMBP, for SPECT imaging. Cell uptake assays were performed on 2 NSCLC cell lines with different c-Met expressions: H1993 (high expression) and H1299 (no expression). In vivo tumor specificity was assessed by SPECT imaging in tumor-bearing mice at 0.5, 1, 2, and 4 h after injection of the probe. Blocking assays, biodistribution, and autoradiography were also conducted to determine probe specificity. Results:99mTc-HYNIC-cMBP was prepared with high efficiency and showed higher uptake in H1993 cells than in H1299 cells. Biodistribution and autoradiography also showed significantly higher percentages of the injected dose for 99mTc-HYNIC-cMBP in H1993 tumors than in H1299 tumors at 0.5 h (4.74 ± 1.43%/g and 1.00 ± 0.37%/g, respectively; P < 0.05). H1993 tumors were clearly visualized at 0.5 h in SPECT images, whereas H1299 tumors were not observed at any time. The specificity of 99mTc-HYNIC-cMBP for c-Met was demonstrated by a competitive block with an excess of nonradiolabeled peptide. Conclusion: For c-Met-targeted SPECT imaging of NSCLC, we developed 99mTc-HYNIC-cMBP, a tracer that specifically binds to c-Met with favorable pharmacokinetics in vitro and in vivo.

Preclinical In Vitro and In Vivo Evaluation of [18F]FE@SUPPY for Cancer PET Imaging: Limitations of a Xenograft Model for Colorectal Cancer.

Molecular imaging probes such as PET-tracers have the potential to improve the accuracy of tumor characterization by directly visualizing the biochemical situation. Thus, molecular changes can be detected early before morphological manifestation. The A3 adenosine receptor (A3AR) is described to be highly expressed in colon cancer cell lines and human colorectal cancer (CRC), suggesting this receptor as a tumor marker. The aim of this preclinical study was the evaluation of [18F]FE@SUPPY as a PET-tracer for CRC using in vitro imaging and in vivo PET imaging. First, affinity and selectivity of FE@SUPPY and its metabolites were determined, proving the favorable binding profile of FE@SUPPY. The human adenocarcinoma cell line HT-29 was characterized regarding its hA3AR expression and was subsequently chosen as tumor graft. Promising results regarding the potential of [18F]FE@SUPPY as a PET-tracer for CRC imaging were obtained by autoradiography as ≥2.3-fold higher accumulation of [18F]FE@SUPPY was found in CRC tissue compared to adjacent healthy colon tissue from the same patient. Nevertheless, first in vivo studies using HT-29 xenografts showed insufficient tumor uptake due to (1) poor conservation of target expression in xenografts and (2) unfavorable pharmacokinetics of [18F]FE@SUPPY in mice. We therefore conclude that HT-29 xenografts are not adequate to visualize hA3ARs using [18F]FE@SUPPY.

Release behavior and bioefficacy of imazethapyr formulations based on biopolymeric hydrogels.

Controlled release formulations of imazethapyr herbicide have been developed employing guar gum-g-cl-polyacrylate/bentonite clay hydrogel composite (GG-HG) and guar gum-g-cl-PNIPAm nano hydrogel (GG-NHG) as carriers, to assess the suitability of biopolymeric hydrogels as controlled herbicide release devices. The kinetics of imazethapyr release from the developed formulations was studied in water and it revealed that the developed formulations of imazethapyr behaved as slow release formulations as compared to commercial formulation. The calculated diffusion exponent (n) values showed that Fickian diffusion was the predominant mechanism of imazethapyr release from the developed formulations. Time for release of half of the loaded imazethapyr (t1/2) ranged between 0.06 and 4.8 days in case of GG-NHG and 4.4 and 12.6 days for the GG-HG formulations. Weed control index (WCI) of GG-HG and GG-NHG formulations was similar to that of the commercial formulation and the herbicidal effect was observed for relatively longer period. Guar gum-based biopolymeric hydrogels in both macro and nano particle size range can serve as potential carriers in developing slow release herbicide formulations.

The Influence of Co-Ligands on Improving Tumor Targeting of 99mTc-HYNIC Conjugated Peptides.

Technetium-99m (99Tc) is widely used as a radionuclide for labeling of biomolecules in nuclear medicine practice. 6-hydrazinopyridine-3-carboxylic acid namely HYNIC is one of the best bifunctional chelating agents for attachment of 99mTc to the biomolecules such as peptides and proteins. Since HYNIC can only occupy one or two coordination sites of 99mTc, co-ligands are needed to complete the coordination sphere of the technetium. Selection of co-ligands can be impressive on the stability, lipophilicity and biodistribution of 99mTc-HYNIC conjugated peptides. The aim of this review was to explain the chemical and biological effects of various co-ligands on characteristics of 99mTc-HYNIC conjugates for tumor or diseases imaging.

A 99mTc-Labelled Tetrazine for Bioorthogonal Chemistry. Synthesis and Biodistribution Studies with Small Molecule trans-Cyclooctene Derivatives.

A convenient strategy to radiolabel a hydrazinonicotonic acid (HYNIC)-derived tetrazine with 99mTc was developed, and its utility for creating probes to image bone metabolism and bacterial infection using both active and pretargeting strategies was demonstrated. The 99mTc-labelled HYNIC-tetrazine was synthesized in 75% yield and exhibited high stability in vitro and in vivo. A trans-cyclooctene (TCO)-labelled bisphosphonate (TCO-BP) that binds to regions of active calcium metabolism was used to evaluate the utility of the labelled tetrazine for bioorthogonal chemistry. The pretargeting approach, with 99mTc-HYNIC-tetrazine administered to mice one hour after TCO-BP, showed significant uptake of radioactivity in regions of active bone metabolism (knees and shoulders) at 6 hours post-injection. For comparison, TCO-BP was reacted with 99mTc-HYNIC-tetrazine before injection and this active targeting also showed high specific uptake in the knees and shoulders, whereas control 99mTc-HYNIC-tetrazine alone did not. A TCO-vancomycin derivative was similarly employed for targeting Staphylococcus aureus infection in vitro and in vivo. Pretargeting and active targeting strategies showed 2.5- and 3-fold uptake, respectively, at the sites of a calf-muscle infection in a murine model, compared to the contralateral control muscle. These results demonstrate the utility of the 99mTc-HYNIC-tetrazine for preparing new technetium radiopharmaceuticals, including those based on small molecule targeting constructs containing TCO, using either active or pretargeting strategies.

Fab(nimotuzumab)-HYNIC-99mTc: Antibody Fragmentation for Molecular Imaging Agents.

Finally, fast blood clearance nimotuzumab is a humanized monoclonal antibody that recognise, with high specific affinity, the epidermal growth factor receptor (EGF-R) which play an important role in the growth process associated with many solid tumors. In this work, the whole antibody was digested with papain in order to generate a Fab fragment, derivatized with NHS-HYNIC-Tfa and radiolabel with technetium-99m (99mTc) as a potential agent of molecular imaging of cancer. Both, whole and fragment radiolabels were in-vivo and in-vitro characterized. Radiolabeling conditions with Tricine as coligand and quality controls were assessed to confirm the integrity of the labeled fragment. Biodistribution and imaging studies in normal and spontaneous adenocarcinoma mice were performed at different times to determine the in-vivo characteristics of the radiolabel fragment. Tumor localization was visualized by conventional gamma camera imaging studies, and the results were compared with the whole antibody. Also, an immunoreactivity assay was carried out for both. The results showed clearly the integrity of the nimotuzumab fragment and the affinity by the receptor was verified. Fab(nimotuzumab)-HYNIC was obtained with high purity and a simple strategy of radiolabeling was performed. Finally, a fast blood clearance was observed in the biodistribution studies increasing the tumor uptake of Fab(nimotuzumab)- HYNIC-99mTc over time, with tumor/muscle ratios of 3.81 ± 0.50, 5.16 ± 1.97 and 6.32 ± 1.98 at 1 h, 4 h and 24 h post injection. Urinary excretion resulted in 32.89 ± 3.91 %ID eliminated at 24 h. Scintigraphy images showed uptake in the tumor and the activity in non-target organs was consistent with the biodistribution data at the same time points. Hence, these preliminary results showed important further characteristic of Fab(nimotuzumab)-HYNIC-99mTc as a molecular imaging agent of cancer.

Pilot study of the pharmacokinetics of betel nut and betel quid biomarkers in saliva, urine, and hair of betel consumers.

Approximately 600 million people worldwide practise the carcinogenic habit of betel nut/quid chewing. Carcinogenic N-nitroso compounds have been identified in saliva or urine of betel chewers and the betel alkaloid arecoline in hair from habitual betel quid chewers. However, the pharmacokinetic parameters of these compounds have been little explored. Assessment of betel use by biomarkers is urgently needed to evaluate the effectiveness of cessation programmes aimed at reducing betel consumption to decrease the burden of cancers in regions of high betel consumption. In the search for biomarkers of betel consumption, we measured by liquid chromatography-mass spectrometry (LC-MS) the appearance and disappearance of betel alkaloids (characteristic for betel nuts), N-nitroso compounds, and chavibetol (characteristic for Piper Betle leaves) in saliva (n=4), hair (n=2), and urine (n=1) of occasional betel nut/quid chewers. The betel alkaloids arecoline, guvacoline, guvacine, and arecaidine were detected in saliva of all four participants and peaked within the first 2 h post-chewing before returning to baseline levels after 8 h. Salivary chavibetol was detected in participants consuming Piper Betle leaves in their quid and peaked ~1 h post-chewing. Urinary arecoline, guvacoline, and arecaidine excretion paralleled saliva almost exactly while chavibetol glucuronide excretion paralleled salivary chavibetol. No betel nut related compounds were detected in the tested hair samples using various extraction methods. From these preliminary results, we conclude that betel exposure can only be followed on a short-term basis (≤8 h post-chewing) using the applied biomarkers from urine and saliva while the feasibility of using hair has yet to be validated. Copyright © 2015 John Wiley & Sons, Ltd.

Co-exposure of silver nanoparticles and chiral herbicide imazethapyr to Arabidopsis thaliana: Enantioselective effects.

In this study, we investigated the possible combined exposure effects of silver nanoparticles (Ag-NPs) and chiral herbicide imazethapyr (IM) on Arabidopsis thaliana. Herein, we show that co-exposure of Ag-NPs and chiral herbicide IM to A. thaliana can amplify the enantioselective ecotoxicity. It was found that after co-exposure of the herbicidally active 0.2 µM (R)-IM and 100 µM Ag-NPs, the silver concentration in roots was 1.40-fold higher than the co-exposure of Ag-NPs and (S)-enantiomer, as well as occurring in shoots that Ag-NPs combined with (R)-IM increased the Ag(+) concentration 77.78% than that with (S)-IM, suggesting an (R)-enantiomer preferential silver uptake. Increase of Ag(+) release under co-exposure of Ag-NPs and (R)-enantiomer was also observed. Our experiments indicated that under co-exposure of Ag-NPs and (R)-enantiomers, more accumulated amino acids can form more adducts with Ag(+), resulting in more Ag(+) release from Ag-NPs and higher ecotoxicity.

Influence of the Supramolecular Micro-Assembly of Multiple Emulsions on their Biopharmaceutical Features and In vivo Therapeutic Response.

The ability of some surfactants to self-assemble in a water/oil bi-phase environment thus forming supramolecular structure leading to the formation of w/o/w multiple emulsions was investigated. The w/o/w multiple emulsions obtained by self-assembling (one-step preparation method) were compared with those prepared following the traditional two-step procedure. Methyl-nicotinate was used as a hydrophilic model drug. The formation of the multiple emulsion structure was evidenced by optical microscopy, which showed a mean size of the inner oil droplets of 6 µm and 10 µm for one-step and two-step multiple emulsions, respectively. The in vitrobiopharmaceutical features of the various w/o/w multiple emulsion formulations were evaluated by means of viscosimetry studies, drug release and in vitro percutaneous permeation experiments through human stratum corneum and viable epidermis membranes. The self-assembled multiple emulsions allowed a more gradual percutaneous permeation (a zero-order permeation rate) than the two-step ones. The in vivotopical carrier properties of the two different multiple emulsions were evaluated on healthy human volunteers by using the spectrophotometry of reflectance, an in vivonon invasive method. These multiple emulsion systems were also compared with conventional emulsion formulations. Our findings demonstrated that the multiple emulsions obtained by self-assembling were able to provide a more sustained drug delivery into the skin and hence a longer therapeutic action than two-step multiple emulsions and conventional emulsion formulations. Finally, our findings showed that the supramolecular micro-assembly of multiple emulsions was able to influence not only the biopharmaceutical characteristics but also the potential in vivotherapeutic response.