Simultaneous determination of levodopa, carbidopa, entacapone, tolcapone, 3-O-methyldopa and dopamine in human plasma by an HPLC-MS/MS method.

BACKGROUND: In this study, we developed and validated a HPLC-MS/MS method capable of simultaneously determining levodopa, carbidopa, entacapone, tolcapone, 3-O-methyldopa and dopamine in human plasma. RESULTS & METHODOLOGY: Chromatographic separation was achieved using a C8 column with a mobile phase consisting of a gradient of water and acetonitrile:methanol (90:10 v/v), both containing 0.1% formic acid. The developed method was selective, sensitive (LD<7.0 ng ml(-1)), linear (r>0.99), precise (RSD<11.3%), accurate (RE<11.8%) and free of residual and matrix effects. The developed method was successfully applied in plasma patients with Parkinson's disease using Stalevo®. CONCLUSION: The new method can be used for the clinical monitoring of these substances and applied to adjustments in drug dosages.

Estimation of measurement uncertainty associated to the determination of pesticide residues: a case study.

In the analytical analysis the measurement uncertainty is a quantitative indicator of the confidence describing the range around a reported or experimental result within which the true value can be expected. Several approaches can be used to estimate the measurement uncertainty associated to the analysis of pesticide residues: a) the top-down, the estimation can be referred to default values; b) the bottom-up the estimation is related to the uncertainty sources. Concerning the bottom-up approach, the following contributions have been investigated: weight of sample, calibration solutions, final volume of sample and intermediate repeatability studies. The commodity/residue combination selected in this study was celery/tau-fluvalinate pesticide. Tau-fluvalinate is a broad-spectrum insecticide in the pyrethroid class of pesticides. The Maximum Residue Limit (MRL) of tau-fluvalinate in celery has been set at 0.01 mg/kg. The tau- Fluvalinate showed two chromatographic peaks. Since the individual standards are not available, the two peaks were integrated separately and the instrumental responses were added. The total residue was calculated on the basis of resulted peaks. The present work aims to compare the uncertainty estimated by experimental data using repeated analysis (n = 12) of a real sample and a spiked sample. The relative expanded uncertainty for two data set, incurred and spiked, was 22 % and 20 %, respectively. No differences were observed from repeated determinations of real samples and spiked samples.

Development and validation of stability-indicating HPLC and UPLC methods for the determination of bicalutamide.

Six new process related impurities (Imp-08, Imp-09, Imp-10, Imp-12, Imp-13 and Imp-14) of bicalutamide (BCT) have been reported in this paper. BCT was subjected to oxidative, acid, alkaline, hydrolytic, thermal and photolytic degradation conditions and found to degrade in alkaline condition, yielding Imp-11. Stability-indicating high-performance liquid chromatography and ultra-performance liquid chromatography methods were developed for the determination of BCT in the presence of its 14 process-related impurities and 1 degradant by using Zorbax SB phenyl column (150 × 4.6 mm × 3.5 µm) and HSS T3 column (100 × 2.1 mm × 1.8 µm), respectively. Both the methods were validated as per International Conference on Harmonization guidelines. Quantitation limits (QL) were found be in the ranges of 0.02-0.03% for both the methods. Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. Linearity for the impurities was established in the range of QL to 200% of the specification level and the correlation coefficients derived from of the respective calibration curves were approximately 0.999. The recoveries obtained for purity (90-100%) and assay (98-102%) ensured the accuracy of the developed methods.

Determination of exposure multiples of human metabolites for MIST assessment in preclinical safety species without using reference standards or radiolabeled compounds.

A simple, reliable, and accurate method was developed for quantitative assessment of metabolite coverage in preclinical safety species by mixing equal volumes of human plasma with blank plasma of animal species and vice versa followed by an analysis using high-resolution full-scan accurate mass spectrometry. This approach provided comparable results (within (±15%) to those obtained from regulated bioanalysis and did not require synthetic standards or radiolabeled compounds. In addition, both qualitative and quantitative data were obtained from a single LC-MS analysis on all metabolites and, therefore, the coverage of any metabolite of interest can be obtained.

Standardization and in vivo antioxidant activity of ethanol extracts of fruit and leaf of Piper sarmentosum.

The present study aimed to investigate standardized ethanol extracts of fruit and leaves of Piper sarmentosum for their in vivo antioxidant activity in rats using a CCl (4)-induced oxidative stress model. The standardization was based on the quantification of the markers pellitorine, sarmentine and sarmentosine by high performance liquid chromatography (HPLC), and determination of total primary and secondary metabolites. The rats, divided into 7 groups each (n = 6), were used as follows: group 1 (CCl (4), negative control), group 2 (untreated, control), groups 3 and 4 (fruit extract 250 and 500 mg/kg, respectively), groups 5 and 6 (leaf extract 250 and 500 mg/kg, respectively) and group 7 (vitamin-E 100 mg/kg, positive control). The doses were administered orally for 14 days; 4 h following the last dose, a single dose of CCl (4) (1.5 mg/kg) was given orally to all the groups except group 2, and after 24 h, blood and liver of each animal were obtained. Analysis of plasma and liver homogenate exhibited significant preservation of markers of antioxidant activity, total plasma antioxidant activity (TPAA), total protein (TP), superoxide dismutase (SOD), catalase (CAT), and thiobarbituric acid reactive species (TBARS), in the pretreated groups as compared to the CCl (4) group (p < 0.05). Histology of the liver also evidenced the protection of hepatocytes against CCl (4) metabolites in the pretreated groups. The results of this study indicate the IN VIVO antioxidant activity of both extracts of the plant, which may be valuable to combat diseases involving free radicals.

Application of the industrial hygiene hierarchy of controls to prioritize and promote safer methods of pest control: a case study.

In 2005, the California Department of Public Health, Occupational Health Branch (OHB) investigated an incident of pesticide exposure and identified 27 vineyard workers who became ill due to drift of cyfluthrin, a pesticide being applied to a neighboring orange field to control katydids. Another pest, citrus thrips, was also present in the field. We investigated safer alternatives for katydid and thrips control to prevent illness due to pesticide exposure and used the industrial hygiene hierarchy of controls to prioritize the control methods. OHB evaluated factors that contributed to pesticide exposure and identified safer alternatives by conducting literature reviews on katydid and thrips control, drift prevention technology, and other relevant topics, and by interviewing integrated pest management advisors, conventional and organic growers, equipment manufacturers, county agricultural commissioners, pest control advisors, regulatory agencies, and others. We prioritized methods using the industrial hygiene hierarchy of controls. We identified safer pest control practices that incorporated hazard elimination, chemical substitution, engineering controls, and administrative controls, including employer policies and government regulations.

In vitro degradation of a biodegradable polyurethane foam, based on 1,4-butanediisocyanate: a three-year study at physiological and elevated temperature.

Biodegradable polyesterurethanes (PUs) may be used as scaffold materials for tissue regeneration applications, because of their excellent mechanical properties. In this study, the degradation of highly porous PU foams was evaluated in vitro. The PU had amorphous soft segments of DL-lactide/epsilon-caprolactone and uniform hard segments, synthesized from 1,4-butanediisocyanate and butanediol. The foams were degraded for 3 years in a Sörensen buffer solution (pH 7.4) at 37 and 60 degrees C. Dimensions of the foams, intrinsic viscosity, mass loss, thermal properties, and composition of the remaining material were evaluated. Copolyester (CP) foams of DL-lactide/epsilon-caprolactone served as controls. The PU foams kept their dimensions for 20 weeks at 37 degrees C, whereas CP foams collapsed after 3 weeks. PU mass loss reached a maximum of 80% at both 37 and 60 degrees C. CP mass loss reached 99.9% at 60 degrees , and 92% at 37 degrees C after 3 years. The degradation processes at 37 and 60 degrees C are initially the same, but eventually degradation products with different thermal properties are being formed. (1)H NMR studies showed that the hard urethane segments of the PU do not degrade in vitro at pH 7.4. It was concluded that the PU material has favorable characteristics for a scaffold material. Compared to long-term in vivo results of the same PU these in vitro results are not representative for the in vivo situation and therefore total resorption has to be investigated in long-term in vivo studies.

Dyeing process may alter the efficacy of insecticide-treated nets.

The biological efficacy as judged by mortality against Anopheles gambiae s.s. of three net samples, one white and two colored, treated with deltamethrin by conventional dipping was compared. Efficacy as well as chemical analysis results showed that uptake of insecticide by white net material was much higher than by colored nets. After a single wash, efficacy of colored nets was reduced significantly below 80% mortality, which is the minimum acceptable level for a field application. This unexpected result could be because of either low uptake of insecticide by colored fibers or high alkalinity on the fibers, resulting from the dyeing process (reduction clearing). alpha-Cyanopyrethroids, such as deltamethrin, have a low stability in alkaline conditions and rapidly degrade. Practical implications of this finding are of primary importance because the majority of nets currently purchased by institutional buyers for malaria prevention are colored.

[Studies of the dependence of alkoxycyanodiphenyl toxicity on structure with the aim of health-related group standardization]. / Izuchenie zavisimosti toksichnosti alkoksitsiandifenilov ot ikh struktury s tsel'iu gruppovogo gigienicheskogo normirovaniia.

The article presents results of toxicity and hazard effects studies of alcoxicyandiphenyl CnH2n+ 1OC12H8CN with n = 1-8, octilcyandiphenyl and octildiphenyl. Toxicity parameters were established in animal tests and on isolated mitochondria, and inhibiting concentrations were calculated. Correlation was established between the alcoxicyandiphenyl detainment in high-performance liquid chromatography and the inhibition rate constant. The allowable and hazard levels are also specified.

Routine determination of radiochemical purity of 99mTc-MIBI.

The manufacturer recommends that the radiochemical purity of 99mTc-MIBI be determined with alumina TLC plates developed in ethanol, but for routine use this is slow and requires care. After comparing a variety of systems, we obtained equivalent results using ITLC-SG strips developed with saline to determine [99mTc]pertechnetate and with acetone to determine 99mTc colloid; % 99mTc-MIBI was determined by difference from 100%. These separations are the opposite of those obtained with the routine polar 99mTc radiopharmaceuticals. Equivalent results were obtained even more rapidly by extracting 99mTc-MIBI from water into chloroform.

Pharmaceutical assessment of amygdalin (Laetrile) products.

The National Cancer Institute (NCI) recently acquired a large supply of formulated products of amygdalin manufactured by Cyto Pharma of Mexico, for possible use in a clinical trial in the US. Tablets for oral administration and ampules of the injectable produce were obtained. Both forms were extensively analyzed and evaluated by several analytic and pharmaceutical laboratories under contract with the NCI. Analytic test procedures were developed to determine the chemical integrity and quantitative composition of the formulated products. Routine physical and biologic tests were also performed to evaluate the manufacturing quality of both dosage forms. The results indicate that both the oral and injectable forms of amygdalin were substandard by US criteria for manufactured pharmaceutical products. All samples were determined to be chemically subpotent, mislabeled, and of poor manufacturing quality. More than 20 samples of the ampules were found by visual inspection to contain microbial contamination. Other samples were found to be pyrogenic. Based on the results of the testing performed, both tablet and ampule forms of amygdalin manufactured by Cyto Pharma of Mexico are considered unfit for use in man.