Paulo C. P. Costa

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Over recent years, drug release/dissolution from solid pharmaceutical dosage forms has been the subject of intense and profitable scientific developments. Whenever a new solid dosage form is developed or produced, it is necessary to ensure that drug dissolution occurs in an appropriate manner. The pharmaceutical industry and the registration authorities do(More)
Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) was used to identify drought-responsive proteins during progressive water deprivation of two-year old maritime pine seedlings. Stress was applied by withholding water during vegetative growth. Needles were sampled before, during and after the stress. Out of about 1000 spots that were quantified by(More)
Solid dispersions are one of the most promising strategies to improve the oral bioavailability of poorly water soluble drugs. By reducing drug particle size to the absolute minimum, and hence improving drug wettability, bioavailability may be significantly improved. They are usually presented as amorphous products, mainly obtained by two major different(More)
  • P Costa
  • International journal of pharmaceutics
  • 2001
This paper addresses an alternative method to the evaluation of similarity factor f(2) as a criterion for assessment of similarity between two in-vitro dissolution profiles as proposed in the SUPAC-IR Guidance (1995). Diltiazem hydrochloride Sustained-Release (SR) tablets were tested and the following independent-model dissolution parameters were used: t10%(More)
Bacterial cellulose (BC) is a highly pure form of cellulose, produced in the form of a swollen membrane by several bacteria that demonstrated to be able to modulate the skin release of model drugs. In the present study, the skin irritation potential of BC was evaluated in human subjects. BC membranes with and without glycerin (acting as plasticizer) were(More)
Compressed mini-tablets systems are presented as a biphasic delivery system designed for zero-order sustained drug release. The outer layer that fills the void spaces between the mini-tablets was formulated to release the drug in a very short time (fast release), while the mini-tablets provided a prolonged release. Different composition (HPMC or EC) and(More)
The effect of some viticultural parameters on the grape carotenoid profile was investigated. Grape cultivar, ripeness stage, sunlight and shade exposure, altitude, and vegetative height were studied. Differences between cultivars were observed in eight different black grape varieties: Touriga Brasileira (TBR), Tinta Barroca (TB), Tinta Amarela (TA), Souzão(More)
Toxic effects of ultraviolet (UV) radiation on skin include protein and lipid oxidation, and DNA damage. The latter is known to play a major role in photocarcinogenesis and photoaging. Many plant extracts and natural compounds are emerging as photoprotective agents. Castanea sativa leaf extract is able to scavenge several reactive species that have been(More)
A growing body of evidence suggests that free radicals are generated by UV irradiation being responsible for skin injury. In this regard, the topical use of formulations composed of plant extracts with antioxidant activity could represent a useful strategy for the prevention of photoaging and oxidative-stress-mediated diseases. The aim of this study was to(More)
The purpose of the present research was to produce a quick/slow biphasic delivery system for ibuprofen. A dual-component tablet made of a sustained release tableted core and an immediate release tableted coat was prepared by direct compression. Both the core and the coat contained a model drug (ibuprofen). The sustained release effect was achieved with a(More)