Determination of primary fatty acid amides in different biological fluids by LC-MS/MS in MRM mode with synthetic deuterated standards: Influence of biofluid matrix on sample preparation.

The recent growing interest in primary fatty acid amides (PFAMs) is due to the broad range of physiological effects they exhibit as bioindicator of pathological states. These bioactive lipids are usually in biological samples at the nanomolar level, making their detection and identification a challenging task. A method for quantitative analysis of seven main PFAMs (lauramide, myristamide, linoleamide, palmitamide, oleamide, stearamide and behenamide) in four human biofluids -namely, urine, plasma, saliva and sweat- is here reported. Two sample preparation procedures were compared to test their efficiency in each biofluid: solid-phase extraction (SPE) and protein precipitation. The latter was the best for plasma and urine, while the analysis of saliva and sweat required an SPE step for subsequent suited determination of PFAMs. Detection of the seven metabolites was performed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in multiple reaction monitoring (MRM) mode. Quantitative analysis was supported on the use of stable isotopically labeled internal standards (SIL-ISs) in the calibration method, which required the synthesis of each IS from the precursor deuterated fatty acids. Detection limits for the target analytes were within 0.3-3 ng mL-1. The method was applied to a small cohort of male and female volunteers (n = 6) to estimate the relative concentration profiles in the different biofluids. The analytical features of the method supported its applicability in clinical studies aimed at elucidating the role of PFAMs metabolism.

Evaluation and optimization of solid adsorbents for the sampling of gaseous methylated mercury species.

This study evaluates the suitability of commercially available adsorbents for the measurement of gaseous organic mercury species namely monomethylmercury (MMHg) and dimethylmercury (DMHg). Bond Elut ENV (BE), a new generation of divinylbenzene (DVB), is evaluated the first time for simultaneous sampling and quantification of ultra-trace levels of MMHg and DMHg in air and its performance compared against Carbotrap(®) B (CB) and Tenax(®) TA (TA), two commonly used adsorbents for mercury solid phase adsorption. The suitability of TA as an absorbent for MMHg (recovery 100±8.1%) but less so for DMHg (recovery 64±17.3%) was confirmed while the reverse was observed for CB with an average recovery of 100±0.3% for DMHg but only 61±32.5% for MMHg. BE is the only adsorbent that showed excellent performance for trapping both Hg species with recoveries of 98±9.2% and 95±8.1% for MMHg and DMHg, respectively. Furthermore, BE exhibited much higher sampling capacities (>100L at 4°C) and preservation of sample integrity (>1 month at -20°C in the dark). Overall, BE proves to be the most suitable adsorbent for simultaneous trapping of organic Hg species with high sampling capacity and sample stability but also very good chromatographic properties which are desirable characteristics for both collection traps and analytical traps. Bond Elut ENV is proposed as an alternative to both Tenax(®) TA and Carbotrap(®) B with additional advantages of offering more versatility and sampling options.

Comparative study of the stability of bimatoprost 0.03% and latanoprost 0.005%: a patient-use study.

BACKGROUND: The stability of ophthalmic preparations in multidose containers is influenced by the preservative as well as the stability of the active ingredient. Unstable drugs may require refrigeration to preserve their active ingredient level and they are more likely to degrade over time, therefore becoming more susceptible to degradation based on patient mishandling. The purpose of this study was to determine the degree of molecular degradation that occurs in bimatoprost and latanoprost in a patient-use setting. METHODS: This was an open-label, laboratory evaluation of the relative stability of bimatoprost and latanoprost. Patients presently using bimatoprost (n = 31) or latanoprost (n = 34) were identified at 2 clinical sites in Brazil. Patients were instructed to use and store their drops as usual and return all used medication bottles between day 28 and day 34 after opening. RESULTS: Bimatoprost demonstrated no degradation, but latanoprost degraded at various levels. The mean age of bimatoprost was 43.0 +/- 3.4 days and the mean age of latanoprost was 43.9 +/- 2.8 days (P = .072). The mean percentage of labeled concentration was 103.7% in the bimatoprost bottles and 88.1% in the latanoprost bottles (P < 001). CONCLUSION: This study showed that bimatoprost maintained > or =100% concentration throughout the study period while latanoprost did not.

Quantification of ropivacaine and its major metabolites in human urine samples utilizing microextraction in a packed syringe automated with liquid chromatography-tandem mass spectrometry (MEPS-LC-MS/MS).

The determination of ropivacaine and its major metabolites in urine was performed using microextraction in a packed syringe as an on-line sample preparation method with LC and MS/MS. The sampling sorbent utilized was polystyrene polymer. [2H7]ropivacaine was used as the internal standard. The lower LOQ was 5.0 nmol/L. The calibration curves were obtained within the concentration range 5-2000 nmol/ L in urine. The regression correlation coefficients for urine samples were > or = 0.999 for all runs. The between-batch accuracy and precision values were determined from six replicates of quality control (QC) samples at three different concentrations in human urine. The mean accuracy values for the QC samples, reported as the percentage difference from the nominal value, were in the range of 99-115%. The precisions, given as the RSDs, were in the range 1.9-11%. The present method is miniaturized and fully automated and can be used for pharmacokinetic and pharmacodynamic studies.

Oral isobutyramide therapy in patients with thalassemia intermedia: results of a phase II open study.

A pilot phase II open study on 12 patients with thalassemia intermedia (7 men, 5 women; age 31 +/- 2.0 years SE) treated with oral isobutyramide, a derivative of butyric acid (150 mg/kg body wt/day), was performed in order to evaluate the effect of this compound in stimulating hemoglobin F (HbF) production. No patient underwent blood transfusion in the 1-year time frame prior to the study. Nine patients were splenectomized. Safety was monitored by clinical and laboratory tests. Efficacy was assessed in terms of the non-alpha/alpha globin chain biosynthetic ratio and the percentage increase of HbF. The study design consisted of a screening phase, a treatment phase of 28 days, and a posttreatment follow-up of 28 days. All patients completed the study. Compliance to treatment was 100%. No drug-related adverse event was recorded. We observed little or no increase in the non-alpha/alpha ratio in the majority of patients. Six patients showed a percentage increase of HbF at the end of treatment and in 5 of those 6 further increases at the end of the follow-up period were observed. The change in percentage of HbF over time was close to significance both in the treatment period (P = 0. 06) and in the follow-up period (P = 0.08). These results indicate that butyrate derivatives can stimulate fetal hemoglobin in patients with intermediate thalassemia. Testing of the effects of different schedules of administration of isobutyramide will be required in order to determine the optimal use of this compound in the treatment of the beta-thalassemia syndromes.