Development and application of an ex vivo fosphenytoin nasal bioconversion/permeability evaluation method.

There is an increasing interest in the intranasal delivery of central nervous system-active drugs due to the existence of a direct nose-to-brain connection. However, poor solubility limits the amount of drug that can be administered within an aqueous solution. In the present work, the objectives were to develop an ex vivo bioconversion/permeability evaluation method and to study the ex vivo bioconversion of the hydrophilic phosphate ester prodrug fosphenytoin (FOS) to the active drug phenytoin (PHT) and their comparative nasal permeation. Bioconversion/permeability studies were performed in excised porcine nasal mucosa mounted in Ussing chambers. The physical integrity of the tissues was evaluated by measurement of the transepithelial electrical resistance (TEER). The simultaneous quantitative assay of FOS, PHT and its major metabolite, 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH) was developed and validated according to international guidelines using a liquid chromatography analytical method. The FOS bioconversion rate and PHT and FOS apparent permeability coefficients (Papp) were determined at different time points. FOS bioconversion was also qualitatively investigated in human nasal mucus. The developed liquid chromatography method combines a fast and inexpensive sample preparation with inactivation of the enzymatic metabolism of the prodrug during sample manipulation and storage. It was linear, precise, accurate, and presented a high analyte recovery. FOS was converted ex vivo to PHT but the metabolite HPPH was not detected. The bioconversion rate increased with FOS concentration and with time, which suggests a diffusion-limited process. FOS was also converted to its active drug by human nasal mucus. A novel mathematical data analysis method was developed to reduce the bias introduced by variable mucosal TEER in the permeability results. At comparable FOS and PHT concentrations the ln(Papp(PHT)) of both compounds showed little difference, which indicates that the use of a hydrophilic and charged prodrug did not hinder overall drug permeation. At the highest tested FOS concentration it was possible to quantify FOS in the receiver chambers, meaning that at a sufficiently high concentration the FOS permeation rate overcame its bioconversion rate. The ln(Papp(PHT)) tended to similar equilibrium values as the assay progressed, but with higher FOS concentrations that equilibrium was attained faster. Acidic pH reduced the permeability of both PHT and FOS. The developed bioconversion/permeability evaluation method will constitute an important tool to select the most promising formulations before proceeding to in vivo studies. Importantly, it allowed the demonstration of phosphatase activity and FOS bioconversion in nasal mucosa, as well as the prodrug's nasal permeation potential. Furthermore, this study demonstrates the possibility of formulating phosphate prodrugs of poorly soluble central nervous system-active drugs as a strategy to increase the solubilized drug doses administered through the nasal route.

Liquid chromatographic assay based on microextraction by packed sorbent for therapeutic drug monitoring of carbamazepine, lamotrigine, oxcarbazepine, phenobarbital, phenytoin and the active metabolites carbamazepine-10,11-epoxide and licarbazepine.

A new, sensitive and fast high-performance liquid chromatography-diode-array detection assay based on microextraction by packed sorbent (MEPS/HPLC-DAD) is herein reported, for the first time, to simultaneously quantify carbamazepine (CBZ), lamotrigine (LTG), oxcarbazepine (OXC), phenobarbital (PB), phenytoin (PHT), and the active metabolites carbamazepine-10,11-epoxide (CBZ-E) and licarbazepine (LIC) in human plasma. Chromatographic separation of analytes and ketoprofen, used as internal standard (IS), was achieved in less than 15min on a C18-column, at 35°C, using acetonitrile (6%) and a mixture (94%) of water-methanol-triethylamine (73.2:26.5:0.3, v/v/v; pH 6.5) pumped at 1mL/min. The analytes and IS were detected at 215, 237 or 280nm. The method showed to be selective, accurate [bias ±14.8% (or ±17.8% in the lower limit of quantification)], precise [coefficient variation ≤9.7% (or ≤17.7% in the lower limit of quantification)] and linear (r(2)≥0.9946) over the concentration ranges of 0.1-15µg/mL for CBZ; 0.1-20µg/mL for LTG; 0.1-5µg/mL for OXC and CBZ-E; 0.2-40µg/mL for PB; 0.3-30µg/mL for PHT; and 0.4-40µg/mL for LIC. The absolute extraction recovery of the analytes ranged from 57.8 to 98.1% and their stability was demonstrated in the studied conditions. This MEPS/HPLC-DAD assay was successfully applied to real plasma samples from patients, revealing to be a cost-effective tool for routine therapeutic drug monitoring of CBZ, LTG, OXC, PB and/or PHT.

Herb-drug pharmacokinetic interaction between carica papaya extract and amiodarone in rats.

PURPOSE: Carica papaya has been traditionally used worldwide in folk medicine to treat a wide range of ailments in humans, including the management of obesity and digestive disorders. However, scientific information about its potential to interact with conventional drugs is lacking. Thus, this work aimed to investigate the interference of a standardized C. papaya extract (GMP certificate) on the systemic exposure to amiodarone (a narrow therapeutic index drug) in rats. METHODS: In the first pharmacokinetic study, rats were simultaneously co-administered with a single-dose of C. papaya (1230 mg/kg, p.o.) and amiodarone (50 mg/kg, p.o.); in the second study, rats were pre-treated for 14 days with C. papaya (1230 mg/kg/day, p.o.) and received amiodarone (50 mg/kg, p.o.) on the 15th day. Rats of the control groups received the herbal extract vehicle. Blood samples were collected before dosing and at 0.25, 0.5, 1, 2, 4, 6, 8 and 12 h following amiodarone administration; in addition, at 24 h post-dose, blood and tissues (heart, liver, kidneys and lungs) were also harvested. Thereafter, the concentrations of amiodarone and its major metabolite (mono-N-desethylamiodarone) were determined in plasma and tissue samples employing a high-performance liquid chromatography-diode array detection method previously developed and validated. RESULTS: In both studies was observed a delay in attaining the maximum plasma concentrations of amiodarone (tmax) in the rats treated with the extract. Nevertheless, it must be highlighted the marked increase (60-70%) of the extent of amiodarone systemic exposure (as assessed by AUC0-t and AUC0-∞) in the rats pre-treated with C. papaya comparatively with the control (vehicle) group. CONCLUSIONS: The results herein found suggest an herb-drug interaction between C. papaya extract and amiodarone, which clearly increase the drug bioavailability. To reliably assess the clinical impact of these findings appropriate human studies should be conducted.

Satisfação dos doentes renais submetidos a hemodiálise / Satisfaction of renal patients undergoing hemodialysis

Os doentes renais ao realizar hemodiálise como terapia de substituição das funções do rim, ficam sujeitos a um tratamento contínuo e exigente, afectando-os em termos físicos, psicológicos e socioeconómicos. A avaliação da satisfação dos cuidados a que são sujeitos, torna-se fundamental, pela busca contínua da qualidade nos serviços de saúde, e da satisfação do utente em relação aos mesmos. A presente investigação teve como objectivos descrever a satisfação dos doentes renais hemodialisados face à consulta hospitalar, unidade de diálise, impacto do tratamento na sua vida, estado de saúde, e acesso aos cuidados de saúde; analisar a sua satisfação com o tratamento; verificar se existe relação entre a satisfação com o tratamento de hemodiálise e as características sociodemográficas, clínicas, informação disponibilizada sobre o tratamento, condições físicas e ambientais da unidade de diálise, relacionamento/desempenho global dos enfermeiros, e modo de acesso à unidade. Este estudo surge integrado no projecto da Sociedade Portuguesa para a Qualidade de Saúde em conjunto com a Direcção Geral de Saúde sobre satisfação do doente em hemodiálise. É um estudo quantitativo, de natureza descritiva-correlacional, realizado a uma amostra de 189 doentes renais, submetidos a tratamento de hemodiálise em unidades privadas ou hospitalares da região centro, seleccionados de acordo com o método de amostragem não probabilística. O instrumento da colheita de dados utilizado consistiu num questionário. De acordo com os objectivos traçados, constatou-se que os doentes renais submetidos a hemodiálise: recebem pouca informação de esclarecimento sobre a doença e modalidades de tratamento antes de iniciar o mesmo; 90,8% encontram-se satisfeitos ou muito satisfeitos com o tratamento; verifica-se uma satisfação muito positiva com os profissionais das unidades, excepto com os psicólogos por sua inexistência nas mesmas; satisfação por o transporte ser disponibilizado gratuitamente; a hemodiálise tem um impacto positivo, associado a um melhor estado de saúde global; com aumento do nível de escolaridade aumenta a satisfação pelo tratamento; e a satisfação com o tratamento relaciona-se positivamente com a satisfação das condições físicas e ambientais da unidade de diálise. A idade, o género, situação laboral, informação sobre as diferentes modalidades de diálise, tempo de realização do tratamento de forma contínua, o relacionamento/desempenho dos enfermeiros, o tempo de deslocação para o tratamento, e o meio de transporte disponibilizado não apresentam diferenças significativas em relação à satisfação do doente com o tratamento de hemodiálise.

Development of novel pillared clays for the encapsulation of inorganic complexes.

Several pillared clays were prepared by using a polyalcohol (ethylene glycol or poly(vinyl alcohol)) or a poly(ethylene oxide) surfactant as an interlayer gallery template and an aluminum oligomer species as the pillaring agent. The use of polyalcohols or nonionic surfactants, such as Tergitol, gave materials which, in general, presented larger basal spacing than those found for the solids prepared by a similar procedure but without additives. The initial positive effect in the expansion of the clay interlayers was not totally retained after calcination of the materials; most probably, at the end, the basal spacing is still ruled by the intercalating aluminum species. The pillared clay with the largest basal spacing and specific surface area was used to encapsulate copper(II) complexes with pentadentate N3O2 Schiff base ligands derived from copper(II) acetylacetonate by in situ synthesis. The characterization made (X-ray diffraction, X-ray photoelectron spectroscopy, FTIR spectroscopy, chemical analysis, and low-temperature N2 adsorption) provided evidence that copper(II) complexes with pentadentate N3O2 Schiff base ligands were efficiently entrapped within the lower dimension pores of the pillared clay and that they interact strongly with the pillared clay matrix.