Safety Assessment of Monosaccharides, Disaccharides, and Related Ingredients as Used in Cosmetics.

The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of 25 monosaccharides, disaccharides, and related ingredients and concluded these are safe in the present practices of use and concentration described in the safety assessment. Many of these ingredients are common dietary sugars, dietary sugar replacements, or very closely related analogs and salts; 7 of the ingredients are listed by the Food and Drug Administration as generally recognized as safe food substances. The most commonly reported cosmetic function is as a skin-conditioning agent; other commonly reported functions are use as a humectant or as a flavoring agent. The Panel reviewed the animal and clinical data included in this assessment, acknowledged that the oral safety of many of these ingredients has been well established, and found it appropriate to extrapolate the existing information to conclude on the safety of all the monosaccharides, disaccharides, and related ingredients.

[Nasal resorption of prim-O-glucosylcimifugin and 5-O-methylvisammioside in rats].

In this experiment, rat nasal mucosa absorption characteristics of prim-O-glucosylcimifugin and 5-O-methylvisammioside were studied to provide a basis for drug delivery of Toutongning nasal spray. The nasal mucosa absorption test in rats was conducted with in situ nasal perfusion method after pH 6 buffer solution was used to prepare high, medium and low concentrations of prim-O-glucosylcimifugin, 5-O-methylvisammioside mixed solution as liquid circulation in nasal cavity. Then the concentrations of the circulating liquid compositions to be measured were determined by HPLC, and the absorption rates of prim-O-glucosylcimifugin and 5-O-methylvisammioside under different pH conditions were also investigated. According to the results, the absorption rate constant was (0.588±0.041)×10⁻³, (0.547±0.023)×10⁻³, (0.592±0.063)×10⁻³ min⁻¹ for prim-O-glucosylcimifugin high, middle and low concentrations, and (0.438±0.041)×10⁻³, (0.407±0.023)×10⁻³, and (0.412±0.063)×10⁻³ min⁻¹ for 5-O-methylvisammioside high, middle and low concentrations. There was no significant difference among high, middle and low concentration groups, and the absorption under pH 6 was better than that under other pH conditions. Therefore, we can get the conclusion that the main active ingredient of Toutongning nasal sprays can be absorbed through the nasal mucosa, and it is feasible to make nasal spray; in addition, pH 6 of nasal spray is scientific and reasonable.

Modification on the O-glucoside of Sergliflozin-A: A new strategy for SGLT2 inhibitor design.

Poor pharmacokinetic stability is one of the issues of O-glucoside SGLT2 inhibitors in clinical trials, hence C-glucoside inhibitors have been developed and extensively applied. Herein, we provided an alternative approach to improve the pharmacokinetic stability of such inhibitors. Nine derivatives of Sergliflozin-A with modifications on the O-glucoside fragment were prepared, among which the 4-O-methyl derivative exhibited similar pharmacodynamics potency in excreted glucose urine test. Most attractively, significantly increased pharmacokinetic stability was observed for 4-O-methyl derivative of O-glucosides. This work proved that modification on the O-glucoside fragment could be a promising approach to the future SGLT2 inhibitor design.

Synthesis and preclinical characterization of 1-(6'-deoxy-6'-[18F]fluoro-ß-d-allofuranosyl)-2-nitroimidazole (ß-6'-[18F]FAZAL) as a positron emission tomography radiotracer to assess tumor hypoxia.

Positron emission tomography (PET) using fluorine-18 (18F)-labeled 2-nitroimidazole radiotracers has proven useful for assessment of tumor oxygenation. However, the passive diffusion-driven cellular uptake of currently available radiotracers results in slow kinetics and low tumor-to-background ratios. With the aim to develop a compound that is actively transported into cells, 1-(6'-deoxy-6'-[18F]fluoro-ß-d-allofuranosyl)-2-nitroimidazole (ß-[18F]1), a putative nucleoside transporter substrate, was synthetized by nucleophilic [18F]fluoride substitution of an acetyl protected labeling precursor with a tosylate leaving group (ß-6) in a final radiochemical yield of 12±8% (n=10, based on [18F]fluoride starting activity) in a total synthesis time of 60min with a specific activity at end of synthesis of 218±58GBq/µmol (n=10). Both radiolabeling precursor ß-6 and unlabeled reference compound ß-1 were prepared in multistep syntheses starting from 1,2:5,6-di-O-isopropylidene-α-d-allofuranose. In vitro experiments demonstrated an interaction of ß-1 with SLC29A1 and SLC28A1/2/3 nucleoside transporter as well as hypoxia specific retention of ß-[18F]1 in tumor cell lines. In biodistribution studies in healthy mice ß-[18F]1 showed homogenous tissue distribution and excellent metabolic stability, which was unaffected by tissue oxygenation. PET studies in tumor bearing mice showed tumor-to-muscle ratios of 2.13±0.22 (n=4) at 2h after administration of ß-[18F]1. In ex vivo autoradiography experiments ß-[18F]1 distribution closely matched staining with the hypoxia marker pimonidazole. In conclusion, ß-[18F]1 shows potential as PET hypoxia radiotracer which merits further investigation.

Urinary excretion of polyols and sugars in children with chronic kidney disease.

BACKGROUND: The urinary concentrations of monosaccharides and polyols are used for diagnosing inborn errors of metabolism and renal tubular disorders. Reference values are age-related and depend on the method of detection. However, the influence of the renal function is often still neglected. In this study we examined the urinary excretion of monosaccharides and polyols in children with various degrees of chronic kidney disease (CKD), but with no known metabolic or renal tubular disorders. CASE DIAGNOSIS/TREATMENT: In 25 patients with CKD stage 1-5, urinary concentrations of 18 monosaccharides and polyols were measured by gas chromatography-mass spectrometry (GC-MS) in random urinary samples and were compared with age-related reference values. Serum creatinine was measured at the time of the urine sample, and the height-independent estimated glomerular filtration rate (eGFR-Pottel) was calculated. Urinary excretions of monosaccharides and polyols were above the reference values in 8-88% of all patients. A significant difference between CKD stage 1-2 compared with CKD stage 3-5 was found for allose, arabitol and sorbitol (p < 0.05) and for arabinose, fucose, myoinositol, ribitol, xylitol, and xylose (p < 0.01). CONCLUSIONS: We show that the excretion of polyols and sugars depends on eGFR, which warrants a cautious interpretation of the results in patients with CKD.

Pharmacokinetic Interaction of astragaloside IV with atractylenolide I and prim-O-glucosylcimifugin in male Sprague Dawley rats.

Astragaloside IV, atractylenolide I, and prim-O-glucosylcimifugin are main medicinal components of the traditional Chinese medicine prescription Yu-ping-feng which is composed of three herbs: Astragalus membranaceus, Atractylodes macrocephala, and Saposhnikovia divaricata. This study is aimed to assess the influence of atractylenolide I and prim-O-glucosylcimifugin on the pharmacokinetic profile of astragaloside IV so as to investigate the pharmacokinetic mechanisms of the Yu-ping-feng prescription. Fifteen Sprague Dawley rats were randomized to three groups; astragaloside IV, astragaloside IV plus atractylenolide I, and a combination of astragaloside IV, atractylenolide I, and prim-O-glucosylcimifugin were respectively administered to rats of these three groups via intragastric gavage. Serum samples were collected at different times after drug administration, and serum concentrations of astragaloside IV and atractylenolide I were simultaneously detected using HPLC-electrospray ionization-MS. Compared with administration of astragaloside IV alone, concentrations of astragaloside IV in the serum were significantly increased when it was given in combination with atractylenolide I or atractylenolide I+prim-O-glucosylcimifugin, with higher values for Cmax (p = 0.019 and p = 0.033 compared with astragaloside IV + atractylenolide I and astragaloside IV + atractylenolide I + prim-O-glucosylcimifugin groups, respectively) and AUC (p = 0.0052 and p = 0.0047 compared with astragaloside IV + atractylenolide I and astragaloside IV + atractylenolide I + prim-O-glucosylcimifugin groups, respectively). Improvement in mean oral Cmax and mean systemic serum exposure because of the pharmacokinetic interaction between astragaloside IV and atractylenolide I might explain the rationale for the use of multiple herbs in Yu-ping-feng and of combinations of A.membranaceus and A. macrocephala.

[Studies on effects of calycosin-7-O-ß-D-glucoside on prim-O-glucosylcimifugin and cimifugin in vivo pharmacokinetics].

Study on the effects of Astragali Radix main active flavone calycosin-7-O-ß-D-glucoside on Saposhnikoviae Radix main active ingredients prim-O-glucosylcimifugin and cimifugin, a UPLC-MS/MS method for simultaneous determination of prim-O-glucosylcimifugin and cimifugin in rat plasma was established, and the comparative pharmacokinetics of prim-O-glucosylcimifugin and cimifugin after oral administration of prim-O-glucosylcimifugin and calycosin-7-O-ß-D-glucoside-prim-O-glucosylcimifugin to rats were carried out, which might be conductive in exploring the rationality of Astragali Radix - Saposhnikoviae Radix herb couple. Twelve male SD rats were divided into two groups. Prim-O-glucosylcimifugin and cimifugin in rat plasma of different time points after oral administration of prim-O-glucosylcimifugin and calycosin-7-O-ß-D-glucoside - prim-O-glucosylcimifugin to rats were determinated. And the main pharmacokinetic parameters were investigated using DAS 3. 2. 4. The established method was rapid, accurate and sensitive for simultaneous determination of prim-O-glucosylcimifugin and cimifugin in rat plasma. The analysis was performed on a Waters Acquity BEH C18 column (2.1 mm x 100 mm, 1.7 µm) with the mixture of acetonitrile and 0.1% formic acid/water as mobile phase, and the gradient elution at a flow rate of 0.3 mL x min(-1). The analytes were detected by tandem mass spectrometry with the electrospray ionization (ESI) source and in the multiple reaction monitoring (MRM) mode. Compared with prim-O-glucosylcimifugin group, the AUC(0-t)., and AUC(0-∞) of p-O-glucosylcimifugin as well as the C(max) of cimifugin significantly increased (P < 0.05) in calycosin-7-O-ß-D-glucoside-prim-O-glucosylcimifugin group. Calycosin-7-O-ß-D-glucoside could enhance the absorption of prim-O-glucosylcimifugin and cimifugin and improve the bioavailability, explaining preliminarily the rationality of Astragali Radix-Saposhnikoviae Radix herb couple.

Synthesis, enzyme kinetics and computational evaluation of N-(ß-D-glucopyranosyl) oxadiazolecarboxamides as glycogen phosphorylase inhibitors.

All possible isomers of N-ß-D-glucopyranosyl aryl-substituted oxadiazolecarboxamides were synthesised. O-Peracetylated N-cyanocarbonyl-ß-D-glucopyranosylamine was transformed into the corresponding N-glucosyl tetrazole-5-carboxamide, which upon acylation gave N-glucosyl 5-aryl-1,3,4-oxadiazole-2-carboxamides. The nitrile group of the N-cyanocarbonyl derivative was converted to amidoxime which was ring closed by acylation to N-glucosyl 5-aryl-1,2,4-oxadiazole-3-carboxamides. A one-pot reaction of protected ß-D-glucopyranosylamine with oxalyl chloride and then with arenecarboxamidoximes furnished N-glucosyl 3-aryl-1,2,4-oxadiazole-5-carboxamides. Removal of the O-acetyl protecting groups by the Zemplén method produced test compounds which were evaluated as inhibitors of glycogen phosphorylase. Best inhibitors of these series were N-(ß-D-glucopyranosyl) 5-(naphth-1-yl)-1,2,4-oxadiazol-3-carboxamide (Ki = 30 µM), N-(ß-D-glucopyranosyl) 5-(naphth-2-yl)-1,3,4-oxadiazol-2-carboxamide (Ki =33 µM), and N-(ß-D-glucopyranosyl) 3-phenyl-1,2,4-oxadiazol-5-carboxamide (Ki = 104 µM). ADMET property predictions revealed these compounds to have promising oral drug-like properties without any toxicity.

C-Glucosides with heteroaryl thiophene as novel sodium-dependent glucose cotransporter 2 inhibitors.

Canagliflozin (1), a novel inhibitor for sodium-dependent glucose cotransporter 2 (SGLT2), has been developed for the treatment of type 2 diabetes. To investigate the effect of replacement of the phenyl ring in 1 with heteroaromatics, C-glucosides 2 were designed, synthesized, and evaluated for their inhibitory activities against SGLT2. Of these, 3-pyridyl, 2-pyrimidyl or 5-membered heteroaryl substituted derivatives showed highly potent inhibitory activity against SGLT2, while 5-pyrimidyl substitution was associated with slightly reduced activity. In particular, 2g (TA-3404) had remarkable anti-hyperglycemic effects in high-fat diet fed KK (HF-KK) mice.

[18F]fluoro-deoxy-glucose folate: a novel PET radiotracer with improved in vivo properties for folate receptor targeting.

The folate receptor (FR) is upregulated in various cancer types (FR-α isoform) and in activated macrophages (FR-ß isoform) which are involved in inflammatory and autoimmune diseases, but its expression in healthy tissues and organs is highly restricted to only a few sites (e.g kidneys). Therefore, the FR is a promising target for imaging and therapy of cancer and inflammation using folate-based radiopharmaceuticals. Herein, we report the synthesis and evaluation of a novel folic acid conjugate with improved properties suitable for positron emission tomography (PET). [(18)F]-fluoro-deoxy-glucose folate ([(18)F]3) was synthesized based on the click chemistry approach using 2-deoxy-2-[(18)F]fluoroglucopyranosyl azide and a folate alkyne derivative. The novel radiotracer [(18)F]3 was produced in good radiochemical yields (25% d.c.) and high specific radioactivity (90 GBq/µmol). Compared to previously published (18)F-folic acid derivatives, an increase in hydrophilicity was achieved by using a glucose entity as a prosthetic group. Biodistribution and PET imaging studies in KB tumor-bearing mice showed a high and specific uptake of the radiotracer in FR-positive tumors (10.03 ± 1.12%ID/g, 60 min p.i.) and kidneys (42.94 ± 2.04%ID/g, 60 min p.i.). FR-unspecific accumulation of radioactivity was only found in the liver (9.49 ± 1.13%ID/g, 60 min p.i.) and gallbladder (17.59 ± 7.22%ID/g, 60 min p.i.). No radiometabolites were detected in blood, urine, and liver tissue up to 30 min after injection of [(18)F]3. [(18)F]-fluoro-deoxy-glucose-folate ([(18)F]3) is thus a promising PET radioligand for imaging FR-positive tumors.

Comparative pharmacokinetics of prim-O-glucosylcimifugin and cimifugin by liquid chromatography-mass spectrometry after oral administration of Radix Saposhnikoviae extract, cimifugin monomer solution and prim-O-glucosylcimifugin monomer solution to rats.

A sensitive and reliable liquid chromatography-mass spectrometry method has been developed and validated for simultaneous determination of cimifugin and prim-O-glucosylcimifugin in rat plasma after oral administration of Radix Saposhnikoviae (RS) extract, prim-O-glucosylcimifugin monomer solution and cimifugin monomer solution. Plasma samples were pretreated by protein precipitation with acetonitrile containing the internal standards puerarin and daidzein. LC separation was achieved on a Zorbax SB-C(18) column (150 × 4.6 mm i.d., 5 µm) with 0.1% formic acid in water and methanol by isocratic elution. The detection was carried out in select-ion-monitoring mode with a positive electrospray ionization interface. The fully validated method was successfully applied to the pharmacokinetic study of the analytes in rats. A bimodal phenomenon appeared in the concentration-time curve of prim-O-glucosylcimifugin and cimifugin after oral administration of RS extract. Prim-O-glucosylcimifugin mainly transformed to cimifugin when it was absorbed into blood. Both absorption and elimination of cimifugin after oral administration of RS were longer than after administration of single cimifugin. The pharmacokinetic parameters (AUC(0-t) , AUC(0-∞) and t(1/2) ) of prim-O-glucosylcimifugin and cimifugin by giving cimifugin monomer solution, prim-O-glucosylcimifugin monomer solution and RS extract had significant differences (P < 0.05).

Advances in tracking of polysaccharides in vivo: Labeling strategies, potential factors and applications based on pharmacokinetic characteristics.

Due to their good physicochemical properties, high biocompatibility and low toxicity, polysaccharides have been widely used as biomaterials in the fields of medicine and biology. However, in vivo investigations of their pharmacokinetics are significantly restricted by the difficulty in detection of polysaccharides. To date, polysaccharide labeling has become one of the most promising approaches for tracking polysaccharides in vivo. Here, we review fluorescent and radioisotopic labeling methods for polysaccharides and their applications in tracking polysaccharides in vivo, and compare the advantages and disadvantages of different labeling methods. The potential factors affecting the pharmacokinetics of polysaccharides in vivo were summarized, including the monosaccharide composition, charge, molecular weight and dosage of polysaccharides, as well as the physiological state of the organism. This review also prospects the applications of polysaccharides in medicine based on the reported pharmacokinetic characteristics in vivo.

Imaging hypoxia in orthotopic rat liver tumors with iodine 124-labeled iodoazomycin galactopyranoside PET.

PURPOSE: To evaluate iodine 124 (124I)-labeled iodoazomycin galactopyranoside (IAZGP) positron emission tomography (PET) in the detection of hypoxia in an orthotopic rat liver tumor model by comparing regions of high (124)I-IAZGP uptake with independent measures of hypoxia and to determine the optimal time after injection to depict hypoxia. MATERIALS AND METHODS: The institutional animal care and use committee approved this study. Morris hepatoma tumors were established in the livers of 15 rats. Tumor oxygenation was measured in two rats with a fluorescence fiberoptic oxygen probe. (124)I-IAZGP was coadministered with the established hypoxia markers pimonidazole and EF5 in nine rats; 12-hour PET data acquisition was performed 24 hours later. Tumor cryosections were analyzed with immunofluorescence and autoradiography. In the four remaining rats, serial 20- and 60-minute PET data acquisition was peformed up to 48 hours after tracer administration. RESULTS: Oxygen probe measurements showed severe hypoxia (<1 mm Hg) distributed evenly throughout tumor tissue. Analysis of cryosections showed diffuse homogeneous uptake of (124)I-IAZGP throughout all tumors. The (124)I-IAZGP distribution correlated positively with pimonidazole (r = 0.78) and EF5 (r = 0.76) distribution. Tracer uptake in tumors was detectable with PET after 24 hours in seven of nine rats. In rats that underwent serial PET, tumor-to-liver contrast was sufficient to enable detection of hypoxia between 6 and 48 hours after tracer administration. The optimal ratio between signal intensity and tumor-to-liver contrast occurred 6 hours after tracer administration. CONCLUSION: Regions of high (124)I-IAZGP uptake in orthotopic rat liver tumors are consistent with independent measures of hypoxia; visualization of hypoxia with (124)I-IAZGP PET is optimal 6 hours after injection.

Tumor hypoxia imaging in orthotopic liver tumors and peritoneal metastasis: a comparative study featuring dynamic 18F-MISO and 124I-IAZG PET in the same study cohort.

PURPOSE: The purpose of this paper is to compare the uptake of two clinically promising positron emission tomography (PET) hypoxia targeting agents, (124)I-iodoazomycin galactopyranoside ((124)I-IAZG) and (18)F-fluoromisonidazole ((18)F-FMISO), by dynamic microPET imaging, in the same rats bearing liver tumors and peritoneal metastasis. METHODS: Morris hepatoma (RH7777) fragments were surgically implanted into the livers of four nude rats. Tumors formed in the liver and disseminated into the peritoneal cavity. Each rat had a total of two to three liver tumors and peritoneal metastasis measuring 10-15 mm in size. Animals were injected with (18)F-FMISO, followed on the next day (upon complete (18)F decay) by (124)I-IAZG. The animals were imaged in list mode on the microPET system from the time of injection of each tracer for 3 h and then again at 6 h and 24 h for the long-lived (124)I-IAZG tracer (4.2-day half-life). Micro computed tomography (CT) scans of each rat were performed for co-registration with the microPET scans acquired with a liver contrast agent, allowing tumor identification. Regions of interest (ROIs) were drawn over the heart, liver, muscle, and the hottest areas of the tumors. Time-activity curves (TACs) were drawn for each tissue ROI. RESULTS: The (18)F-FMISO signal increased in tumors over the 3-h time course of observation. In contrast, after the initial injection, the (124)I-IAZG signal slowly and continuously declined in the tumors. Nevertheless, the tumor-to-normal-tissue ratios of (124)I-IAZG increased, but more slowly than those of (18)F-FMISO and as a result of the differentially faster clearance from the surrounding normal tissues. These pharmacokinetic patterns were seen in all 11 tumors of the four animals. CONCLUSIONS: (18)F-FMISO localizes in the same intra-tumor regions as (124)I-IAZG. The contrast ratios (tumor/background) reach similar values for the two hypoxia tracers, but at later times for (124)I-IAZG than for (18)F-FMISO and, therefore, with poorer count statistics. As a consequence, the (18)F-FMISO images are of superior diagnostic image quality to the (124)I-IAZG images in the Morris hepatoma McA-R-7777 tumor model.

Kinsenoside: A Promising Bioactive Compound from Anoectochilus Species.

Kinsenoside is a main active component isolated from plants of the genus Anoectochilus, and exhibits many biological activities and pharmacological effects, including hepatoprotective, anti-hyperglycemic, anti-hyperliposis, anti-inflammatory, vascular protective and anti-osteoporosis effects and so on, which is contributing to its promising potency in disease treatments. This review aims to recapitulate the pharmacological functions of kinsenoside, as well as its source, extraction, identification, quantitative analysis, pharmacokinetics, synthesis and patent information. The data reported in this work can confirm the therapeutic potential of kinsenoside and provide useful information for further new drug development.

Determination of helicidum and its metabolites in dog plasma by LC/UV/MS/MS and its application to pharmacokinetic studies.

A simple, rapid and reliable method was developed for the identification and quantification of helicidum and its metabolites in beagle dog plasma by liquid chromatography/ultra-violet/electrospray ionization-ion trap mass spectrometry (LC/UV/ESI-ITMS). Two metabolites were identified by MS: formylphenyl-O-beta-d-pyranosyl alloside (I) and hydroxylmethylphenyl-O-beta-d-pyranosyl alloside (II). UV was used for concentration determination with the wavelength of 270 nm. Liquid-liquid extraction was used and the extraction recovery exceeded 90%. Kromacil C(18) column (5 microm, 4.6mm i.d. x 250 mm) was used as the analytical column. Linear detection responses were obtained for helicidum concentration ranging from 1.76 x 10(-4) to 70.4 x 10(-4) micromol/mL (0.050-2.00 microg/mL). The precision and accuracy data, based on intra- and inter-day variations over 3 days, were less than 5%. The limit of determination and quantitation (LOD, LOQ) for helicidum was 0.010 and 0.030 microg/mL, respectively. Pharmacokinetic data of helicidum and the two metabolites were obtained with this method after administration of intravenous injection and a single oral dose of tablets to six beagle dogs, respectively.

Development of a hydrophilic interaction liquid chromatography-tandem mass spectrometric method for the determination of kinsenoside, an antihyperlipidemic candidate, in rat plasma and its application to pharmacokinetic studies.

Kinsenoside is a major bioactive constituent isolated from Anoectochilus formosanus and is investigated as an antihyperlipidemic candidate. In this study, a rapid, sensitive, and reliable bioanalytical method was developed for the determination of kinsenoside in rat plasma using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The plasma sample was pretreated with 1% acetic acid, followed by protein precipitation with acetonitrile:methanol (70:30). Chromatographic separation was performed on a HILIC silica column (2.1mm×100mm, 3µm). The mobile phases consisted of 0.1% acetic acid in distilled water (solvent A) and 0.1% acetic acid in acetonitrile (solvent B). A gradient program was used at a flow rate of 0.2mL/min. For mass spectrometric detection, the multiple reaction monitoring mode was used; the MRM transitions were m/z 265.2→m/z 102.9 for kinsenoside and m/z 163.3→m/z 132.1 for the internal standard (IS) nicotine in the positive ionization mode. A calibration curve was constructed in the range of 2-500ng/mL. The intra- and interday precision and accuracy were within 5%. The HILIC-MS/MS method was specific, accurate, and reproducible and was successfully applied in a pharmacokinetic study of kinsenoside in rats.

Toxicological characterisation of a thio-arsenosugar-glycerol in human cells.

Arsenosugars are water-soluble arsenic species predominant in marine algae and other seafood including mussels and oysters. They typically occur at levels ranging from 2 to 50mg arsenic/kg dry weight. Most of the arsenosugars contain arsenic as a dimethylarsinoyl group (Me2As(O)-), commonly referred to as the oxo forms, but thio analogues have also been identified in marine organisms and as metabolic products of oxo-arsenosugars. So far, no data regarding toxicity and toxicokinetics of thio-arsenosugars are available. This in vitro-based study indicates that thio-dimethylarsenosugar-glycerol exerts neither pronounced cytotoxicity nor genotoxicity even though this arsenical was bioavailable to human hepatic (HepG2) and urothelial (UROtsa) cells. Experiments with the Caco-2 intestinal barrier model mimicking human absorption indicate for the thio-arsenosugar-glycerol higher intestinal bioavailability as compared to the oxo-arsenosugars. Nevertheless, absorption estimates were much lower in comparison to other arsenicals including arsenite and arsenic-containing hydrocarbons. Arsenic speciation in cell lysates revealed that HepG2 cells are able to metabolise the thio-arsenosugar-glycerol to some extent to dimethylarsinic acid (DMA). These first in vitro data cannot fully exclude risks to human health related to the presence of thio-arsenosugars in food.

Prediction of Plasma Concentration-time Profiles of Drugs in Humans from Animals Following Oral Administration: An Allometric Approach.

BACKGROUND: Allometric scaling is regularly used for the prediction of human pharmacokinetic (PK) parameters from animal PK studies. The predicted human PK parameters can also be used for the prediction of plasma concentration-time profiles in humans. OBJECTIVES: The main objective of this work is to predict human concentration-time profiles of drugs (one-compartment model) following oral administration using animal oral pharmacokinetic parameters. METHODS: Six drugs from the literature were chosen that were described by one-compartment model in both humans and animals following oral administration. Pharmacokinetic parameters such as oral clearance, oral volume of distribution of the central compartment, time to reach maximum plasma concentration, absorption rate constant, and half-life in humans were predicted from animals using allometric scaling. These predicted human pharmacokinetic parameters were then used to predict human plasma concentrations-time profiles of drugs. RESULTS: The results of this study indicate that the proposed method can be used to predict human plasma concentrations- time profiles of drugs with reasonable accuracy (≤50% prediction error). CONCLUSIONS: Given the complexity in the pharmacokinetics of oral drugs there remains some uncertainty in this entire exercise. One can minimize the prediction error by experience in allometric scaling, scientific judgment, and unconventional or innovative thinking.

Single- and multiple-dose pharmacokinetics of levovirin valinate hydrochloride (R1518) in healthy volunteers.

R1518 is a valine ester prodrug of levovirin as an investigational new drug for the treatment of hepatitis C virus. Two phase 1, single- and multiple-dose studies were conducted to investigate the pharmacokinetics of R1518 in healthy volunteers. After oral dosing, R1518 was rapidly and exclusively converted to levovirin. Levovirin plasma concentrations peaked at 2 hours, with T(1/2) ranging from 6 to 8 hours. The T(1/2) of R1518 was less than 1 hour, with relative exposures (R1518/levovirin) less than 6%. A high-fat meal did not affect the pharmacokinetics. The female groups in both studies had higher plasma levels than males did due to age and renal function difference. An accumulation ratio of 1.3 to 1.5 was observed with the twice-daily regimen. About 75% to 90% of the levovirin equivalent dose was recovered in urine. Increase in exposure was slightly disproportionate to increase in dose. Significantly improved oral absorption of levovirin was achieved following administration of R1518.