A New Approach to Ex Vivo Permeation Studies in In-Situ Film-Forming Systems.

The skin is the largest human organ and an important topical route. Even with some challenges, it is an important ally in medication administration, mainly because it is painless and easy-to-apply. Semisolid formulations are the most used dosage forms for drug administration via this delivery route and can be optimized when transformed into a film, favoring on-site maintenance, and promoting drug permeation. However, in situ film-forming systems are difficult to assess and characterize using Franz-type diffusion cells once this apparatus is ideal to formulations without transition phases. The present study proposed a different method to characterize these formulations and provide complementary data on drug and penetration enhancer behaviors, as close as possible to real application conditions. This characterization method allowed us to analyze drug concentration on three necessary occasions: remaining in the polymer film, stratum corneum using adhesive tape, and skin to check where drugs will have a desirable effect. As a proof-of-concept, the proposed ex vivo permeation method was used to evaluate a film-forming system containing lidocaine and prilocaine. We could also evaluate transition phases of drug compositions and quantify drugs at key times after application. Hence, the developed method may be used to provide complementary data to the Franz diffusion cell method, in terms of drug and penetration enhancer behaviors incorporated into film-forming delivery systems.

Mucoadhesive Properties of Thiolated Pectin-Based Pellets Prepared by Extrusion-Spheronization Technique.

The aim of this study was to develop mucoadhesive pellets on a thiolated pectin base using the extrusion-spheronization technique. Thiolation of pectin was performed by esterification with thioglycolic acid. The molecular weight and thiol group content of the pectins were determined. Pellets containing pectin, microcrystalline cellulose, and ketoprofen were prepared and their mucoadhesive properties were evaluated through a wash-off test using porcine intestinal mucosa. The in vitro ketoprofen release was also evaluated. Thiolated pectin presented a thiol group content of 0.69 mmol/g. Thiolation caused a 13% increase in polymer molecular weight. Pellets containing thiolated pectin were still adhering to the intestinal mucosa after 480 min and showed a more gradual release of ketoprofen. Conversely, pellets prepared with nonthiolated pectin showed rapid disintegration and detached after only 15 min. It can be concluded that thiolated pectin-based pellets can be considered a potential platform for the development of mucoadhesive drug delivery systems for the oral route.

Determination of 2,5-hexanedione in urine by headspace solid-phase microextraction and gas chromatography.

2,5-Hexanedione (2,5-HD) is the most important metabolite of n-hexane and methyl ethyl ketone in human urine. Urinary 2,5-HD is used as a biomarker for biological monitoring of workers exposed to n-hexane. A simple method using headspace solid-phase microextraction (HS-SPME) and gas chromatography (GC) equipped with a flame-ionization detector (FID) was developed. The parameters that affect the HS-SPME-GC-FID process were optimized (i.e., fiber coating, sample volume, adsorption and heating time, salt addition, and extraction temperature). The assay presented linearity in the range of 0.075 to 20.0 mg/L, precision (coefficient of variation < 7.0%), and detection limit of 0.025 mg/L for 2,5-HD in urine. The method was successfully applied to the analysis of 2,5-HD in urine samples from eight workers occupationally exposed to n-hexane in shoemaker's glue.

Adesivos dentinários: estrutura; modo de açäo e consideraçöes clínicas / Dentin adhesives: structure, action and clinical considerations

Os autores fazem um levantamento atual sobre os adesivos dentinários enfocando sua composiçäo básica e modo de açäo. Abordam também, aspectos clínicos que devem ser considerados durante o seu emprego. Procuram, desta forma, tantosituar os adesivos dentre os materiais dentários com relaçäo à sus eficiência, quanto mostrar detalhes técnicos que devem ser realizados, com o intuito de se obter melhores resultados no que diz respeito à retençäo e infiltraçäo marginal em restauraçäo de resina cocmposta, essencialmente quando colocadas em áreas com pouca ou nenhuma quantidade de esmalte

Efeito de alguns tratamentos de superfície em dentina na resistência adesiva de uma resina composta / Effects of some dentin surface treatments on adhesive resistance of a composite resin

Estudou-se o efeito de alguns tratamentos de superfície na adesäo de uma resina composta (SILAR 3M do Brasil Ltda) em dentina humana. Foram testados o ácido fosfórico em forma líquida, em gel e uma soluçäo experimental proposta por Nakabayashi & Masuhara, associados ao adesivo Scotchbond (3M do Brasil Ltda) e agente de uniäo Silar. Concluiu-se que nos testes in vitro o adesivo Scotchbond foi o agente responsável pelos valores mais elevados na resistência à remoçäo por traçäo