Micromethod for Quantification of Carbamazepine, Phenobartital and Phenytoin in Human Plasma by HPLC-UV Detection for Therapeutic Drug Monitoring Application

A simple, rapid, selective and sensitive analytical method by HPLC with UV detection was developed for the quantification of carbamazepine, phenobarbital and phenytoin in only 0.2 mL of plasma. A C18 column (150 x 3.9 mm, 4 micra) using a binary mobile phase consisting of water and acetonitrile (70:30, v/v) at a flow rate of 0.5 mL/min were proposed. Validation of the analytical method showed a good linearity (0.3 to 20.0 mg/L for CBZ, 0.9 to 60.0 mg/L for PB and 0.6 to 40.0 mg/L for PHT), high sensitivity (LOQ: 0.3, 0.9 and 0.6 mg/L respectively). The method was applied for drug monitoring of antiepileptic drugs (AED) in 27 patients with epilepsy under polytherapy.

Copper salt-catalyzed homo-coupling reaction of potassium alkynyltrifluoroborates: a simple and efficient synthesis of symmetrical 1,3-diynes

The copper-catalyzed dimerization of alkynyltrifluoroborates proceeds readily with good yields. The homo-coupling reaction can be effected in DMSO, in the open air, using Cu(OAc)(2) as catalyst in the absence of any other additives. A variety of functional groups are tolerated. (C) 2008 Elsevier Ltd. All rights reserved.

ABCB1 and ABCC1 expression in peripheral mononuclear cells is influenced by gene polymorphisms and atorvastatin treatment

This study investigated the effects of atorvastatin on ABCB1 and ABCC1 mRNA expression on peripheral blood mononuclear cells (PBMC) and their relationship with gene polymorphisms and lowering-cholesterol response. one hundred and thirty-six individuals with hypercholesterolemia were selected and treated with atorvastatin (10 mg/day/4 weeks). Blood samples were collected for serum lipids and apolipoproteins measurements and DNA and RNA extraction. ABCB1 (C3435T and G2677T/A) and ABCC1 (G2012T) gene polymorphisms were identified by polymerase chain reaction-restriction (PCR)-RFLP and mRNA expression was measured in peripheral blood mononuclear cells by singleplex real-time PCR. ABCB1 polymorphisms were associated with risk for coronary artery disease (CAD) (p < 0.05). After atorvastatin treatment, both ABCB1 and ABCC1 genes showed 50% reduction of the mRNA expression (p < 0.05). Reduction of ABCB1 expression was associated with ABCB1 G2677T/A polymorphism (p = 0.039). Basal ABCB1 mRNA in the lower quartile (<0.024) was associated with lower reduction rate of serum low-density lipoprotein (LDL) cholesterol (33.4 +/- 12.4%) and apolipoprotein B (apoB) (17.0 +/- 31.3%) when compared with the higher quartile (>0.085: LDL-c = 40.3 +/- 14.3%; apoB = 32.5 +/- 10.7%; p < 0.05). ABCB1 substrates or inhibitors did not affect the baseline expression, while ABCB1 inhibitors reversed the effects of atorvastatin on both ABCB1 and ABCC1 transporters. In conclusion, ABCB1 and ABCC1 mRNA levels in PBMC are modulated by atorvastatin and ABCB1 G2677T/A polymorphism. and ABCB1 baseline expression is related to differences in serum LDL cholesterol and apoB in response to atorvastatin. (C) 2008 Elsevier Inc. All rights reserved.

Ultrasound-assisted synthesis of functionalized 1,3-enynes by palladium-catalyzed cross-coupling reaction of alpha-styrylbutyltelluride with alkynyltrifluoroborate salts

An ultrasound-assisted synthesis of functionalized 1,3-enyne scaffolds is described and illustrated by palladium-catalyzed cross-coupling of potassium alkynyltrifluoroborate salts and alpha-styrylbutyltellurides. This procedure offers easy access to 1,3-enyne architecture that contains aliphatic and aromatic groups in good to excellent yields.

Involvement of oxidative stress in the hepatotoxicity induced by aromatic antiepileptic drugs

The use of the classic aromatic antiepileptic drugs (AAEDs) has recently been expanded to a broad spectrum of psychiatric and neurological disorders. However, the clinical use of these drugs is limited by several adverse effects, mainly idiosyncratic hepatotoxicity. AAED-induced hepatotoxicity has been attributed to a defective detoxification by the epoxide hydrolase and accumulation of arene oxides. The underlying mechanism has been proposed as immune-mediated, but direct toxicity has also been suggested. In general, idiosyncratic drug-induced hepatotoxicity may be mediated, at least in part, by oxidative stress. On the other hand, the oxidative stress induced by the AAED metabolites has not been demonstrated yet. Therefore, in the present study we have evaluated the induction of oxidative stress by three classical AAEDs: carbamazepine. phenytoin and phenobarbital as well as by their metabolites. The toxic effects of the metabolites were evaluated by incubating the drug with rat liver microsomes. The AAED-induced oxidative stress was demonstrated by the increased malondialdehyde levels, oxidation of cardiolipin; oxidation of sulfhydryl proteins and alteration of the cellular redox status. Results suggest that the hepatotoxicity associated with AAED might be mediated by the oxidative stress induced by the drugs metabolites. (C) 2008 Elsevier Ltd. All rights reserved

Application of high-resolution electrospray mass spectrometry for the elucidation of the disproportionation reaction of iodobenzene diacetate

Disproportionation reactions take place in solution of (diacetoxyiodo)benzene (DIB) in acetonitrile in the presence of water, giving iodine(V) and iodine(l) species. This redox reaction is accelerated by the presence of water and by increasing the temperature. Several species of the solution of DIB were identified by high-resolution ESI-MS/MS, which allowed the elucidation of the mechanisms of disproportionation for DIB in gas phase and in solution. Key species in the process are the dimers [PhI(CH)OlPh](+) at m/z 440.8864, [PhI(OAc)OlPh](+) at m/z 482.8947, and [PhI(O)(OAc)OlPh](+) at m/z 498.8887. (C) 2008 Elsevier B.V. All rights reserved.

Enantioselective determination of chloroquine and its n-dealkylated metabolites in plasma using liquid-phase microextraction and LC-MS

A selective method using three-phase liquid-phase microextraction (LPME) in conjunction with LC-MS-MS was devised for the enantioselective determination of chloroquine and its n-dealkylated metabolites in plasma samples. After alkalinization of the samples, the analytes were extracted into n-octanol immobilized in the pores of a polypropylene hollow fiber membrane and back extracted into the acidic acceptor phase (0.1 M TFA) filled into the lumen of the hollow fiber. Following LPME, the analytes were resolved on a Chirobiotic V column using methanol/ACN/glacial aceti acid/diethylamine (90:10:0.5:0.5 by volume) as the mobile phase. The MS detection was carried out using multiple reaction monitoring with ESI in the positive ion mode. The optimized LPME method yielded extraction recoveries ranging from 28 to 66%. The method was linear over 5 - 500 ng/mL and precision (RSD) and accuracy (relative error) values were below 15% for all analytes. The developed method was applied to the determination of the analytes in rat plasma samples after oral administration of the racemic drug.

Crystal structure of Trypanosoma cruzi dihydroorotate dehydrogenase from Y strain

Trypanosoma cruzi is the etiological agent of Chagas` disease, a pathogenesis that affects millions of people in Latin America. Here, we report the crystal structure of dihydroorotate dehydrogenase (DHODH) from T cruzi strain Y solved at 2.2 angstrom resolution. DHODH is a flavin mononucleotide containing enzyme, which catalyses the oxidation Of L-dihydroorotate to orotate, the fourth step and only redox reaction in the de novo biosynthesis of pyrimidine nucleotides. Genetic studies have shown that DHODH is essential for T cruzi survival, validating the idea that this enzyme can be considered an attractive target for the development of antichagasic drugs. In our work, a detailed analysis of T cruzi DHODH crystal structure has allowed us to suggest potential sites to be further exploited for the design of highly specific inhibitors through the technology of structure-based drug design. (c) 2008 Elsevier Inc. All rights reserved.

Enantioselective analysis of mirtazapine and its two major metabolites in human plasma by liquid chromatography-mass spectrometry after three-phase liquid-phase microextraction

A three-phase liquid-phase microextraction (LPME) method using porous polypropylene hollow fibre membrane with a sealed end was developed for the extraction of mirtazapine (MRT) and its two major metabolites, 8-hydroxymirtazapine (8-OHM) and demethylmirtazapine (DMR), from human plasma. The analytes were extracted from 1.0 mL of plasma, previously diluted and alkalinized with 3.0 mL 0.5 mol L-1 pH 8 phosphate buffer solution and supplemented with 15% sodium chloride (NaCl), using n-hexyl ether as organic solvent and 0.01 moL L-1 acetic acid solution as the acceptor phase. Haloperidol was used as internal standard. The chromatographic analyses were carried out on a chiral column, using acetonitrile-methanol-ethanol (98:1:1, v/v/v) plus 0.2% diethylamine as mobile phase, at a flow rate of 1.0 mL min(-1). Multi-reaction monitoring (MRM) detection was performed by mass spectrometry (MS-MS) using a triple-stage quadrupole and electrospray ionization interface operating in the positive ion mode. The mean recoveries were in 18.3-45.5% range with linear responses over the 1.25-125 ng mL(-1) concentration range for all enantiomers evaluated. The quantification limit (LOQ) was 1.25 ng mL(-1). Within-day and between-day assay precision and accuracy (2.5, 50 and 100 ng mL(-1)) showed relative standard deviation and the relative error lower than 11.9% for all enantiomers evaluated. Finally, the method was successfully used for the determination of mirtazapine and its metabolite enantiomers in plasma samples obtained after single drug administration of mirtazapine to a healthy volunteer. (c) 2007 Elsevier B.V. All rights reserved.

Ruthenium-nitrite complex as pro-drug releases NO in a tissue and enzyme-dependent way

Nitric oxide (NO) plays an important role in the control of the vascular tone and the most often employed NO donors have limitations due to their harmful side-effects. In this context, new NO donors have been prepared, in order to minimize such undesirable effects. cis-[Ru(bpy)(2)(py)NO(2)](PF(6)) (RuBPY) is a new nitrite complex synthesized in our laboratory that releases NO in the presence of the vascular tissue only. In this work the vasorelaxation induced by this NO donor has been studied and compared to that obtained with the well known NO donor SNP. The relaxation induced by RuBPY is concentration-dependent in denuded rat aortas pre-contracted with phenylephrine (EC(50)). This new compound induced relaxation with efficacy similar to that of SNP, although its potency is lower. The time elapsed until maximum relaxation is achieved (E(max) = 240 s) is similar to measured for SNP (210 s). Vascular reactivity experiments demonstrated that aortic relaxation by RuBPY is inhibited by the soluble guanylyl-cyclase inhibitor 1H-[1,2,4] oxadiozolo[4,3-a]quinoxaline-1-one (ODQ 1 mu M). In a similar way, 1 mu M ODQ also reduces NO release from the complex as measured with DAF-2 DA by confocal microscopy. These findings suggest that this new complex RuBPY that has nitrite in its structure releases NO inside the vascular smooth muscle cell. This ruthenium complex releases significant amounts of NO only in the presence of the aortic tissue. Reduction of nitrite to NO is most probably dependent on the soluble guanylyl-cyclase enzyme, since NO release is inhibited by ODQ. (C) 2011 Elsevier Inc. All rights reserved.

In situ gelling hexagonal phases for sustained release of an anti-addiction drug

In this study, fluid precursor formulations for subcutaneous injection and in situ formation of hexagonal phase gels upon water absorption were developed as a strategy to sustain the release of naltrexone, a drug used for treatment of drug addiction. Precursor formulations were obtained by combining BRIJ 97 with propylene glycol (PG, 5-70%, w/w). To study the phase behavior of these formulations, water was added at 10-90% (w/w), and the resulting systems were characterized by polarized light microscopy. Two precursor formulations containing BRIJ:PG at 95:5 (w/w, referred to as BRIJ-95) and at 80:20 (w/w, referred to as BRIJ-80) were chosen. Naltrexone was dissolved at 1% or suspended at 5% (w/w). Precursor formulations were transformed into hexagonal phases when water content exceeded 20%. Water uptake followed second-order kinetics, and after 2-4 h all precursor formulations were transformed into hexagonal phases. Drug release was prolonged by the precursor formulations (compared to a drug solution in PBS), and followed pseudo-first order kinetics regardless of naltrexone concentration. The release from BRIJ-80 was significantly higher than that from BRIJ-95 after 48 h. The relative safety of the precursor formulations was assessed in cultured fibroblasts. Even though BRIJ-95 was more cytotoxic than BRIJ-80, both precursor formulations were significantly less cytotoxic than sodium lauryl sulfate (considered moderate-to-severe irritant) at the same concentration (up to 50 mu g/mL). These results suggest the potential of BRIJ-based precursor formulations for sustained naltrexone release. (C) 2011 Elsevier By. All rights reserved.

Effect of the Maillard reaction on properties of casein and casein films

The use of biodegradable natural polymers has increased due to the over-solid packaging waste. In this study, a chemical modification of the casein molecule was performed by Maillard reaction, and the modified polymer was evaluated by polyacrylamide gel electrophoresis (PAGE), thermogravimetry/derivative thermogravimetry (TG/DTG), FT-IR, and (1)H-NMR spectroscopy. Subsequently, films based on the modified casein were obtained and characterized by mechanical analysis, water vapor transmission, and erosion behavior. The PAGE results suggested an increase of molecular mass of the modified polymer, and FT-IR spectroscopy data indicated inclusion of C-OH groups into this molecule. The TG/DTG curves of modified casein presented a different thermal decomposition profile compared to the individual compounds. Mechanical tests showed that the chemical modification of the casein molecules provided higher elongation rates (45.5%) to the films, suggesting higher plasticity, than the original molecules (13.4%). The modified casein films presented higher permeability (0.505 +/- A 0.006 mu g/h mm(3)) than the original polymer (0.387 +/- A 0.006 mu g/h mm(3)) films at 90% relative humidity (RH). In pH 1.2, modified casein films presented higher erosion rates (32.690 +/- A 0.692%) than casein films (19.910 +/- A 2.083%) after 8 h, suggesting an increased sensibility for erosion of the modified casein films in acid environment. In water (pH 7.0), the films erosion profiles were similar. Those findings indicate that the modification of molecule by Maillard reaction provided films more plastic, hydrophilic, and sensitive to erosion in acid environment, suggesting that a new polymer with changed properties was founded.

Using Computer-aided Drug Design and Medicinal Chemistry Strategies in the Fight Against Diabetes

The aim of this work is to present a simple, practical and efficient protocol for drug design, in particular Diabetes, which includes selection of the illness, good choice of a target as well as a bioactive ligand and then usage of various computer aided drug design and medicinal chemistry tools to design novel potential drug candidates in different diseases. We have selected the validated target dipeptidyl peptidase IV (DPP-IV), whose inhibition contributes to reduce glucose levels in type 2 diabetes patients. The most active inhibitor with complex X-ray structure reported was initially extracted from the BindingDB database. By using molecular modification strategies widely used in medicinal chemistry, besides current state-of-the-art tools in drug design (including flexible docking, virtual screening, molecular interaction fields, molecular dynamics. ADME and toxicity predictions), we have proposed 4 novel potential DPP-IV inhibitors with drug properties for Diabetes control, which have been supported and validated by all the computational tools used herewith.

Iontophoretic transport of zinc phthalocyanine tetrasulfonic acid as a tool to improve drug topical delivery

Phthalocyanines have been used as systemic photosensitizers because of their high affinity towards tumour tissue, and the high rates of reactive oxygen species produced when they are irradiated during photodynamic therapy. However, the topical administration of these compounds is limited by their large size, poor hydrosolubility and ionic character. This study aimed to investigate the iontophoretic delivery of charged zinc phthalocyanine tetrasulfonic acid (ZnPcS(4)) from a hydrophilic gel to different skin layers by means of in-vitro and in-vivo studies. Six hours of passive administration was insufficient for ZnPcS(4) to cross the stratum corneum (SC) and to reach the epidermis and dermis. No positive effect was reached when anodal iontophoresis was performed, showing that the drug-electrode attraction effect was higher than the electro-osmosis contribution at a pH of 5.5. Cathodal iontophoresis, however, was able to transport significant amounts of the drug to the viable epidermis. In addition, the absence of NaCl in the formulation significantly increased (by five-fold) the amount of ZnPcS(4) that crossed the SC and accumulated in the epidermis and dermis. It was possible to visualize the drug accumulation in the follicle openings and in the epidermis, even after SC removal. In-vivo experiments in rat skin showed that these results were maintained in an in-vivo model, even with only 15 min of iontophoresis. In addition, confocal analysis of the treated skin showed a homogeneous distribution of ZnPcS(4) in the viable epidermis after this short period of cathodal iontophoresis. Anti-Cancer Drugs 22:783-793 (C) 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.