Microemulsões e fases líquidas cristalinas como sistemas de liberação de fármacos

A mistura de tensoativos com água, em determinadas proporções, na ausência ou na presença de substâncias lipofílicas pode formar diferentes tipos de agregados, entre os quais agregados polimorfos representados pelas microemulsões (ME) e mesofases liotrópicas - os cristais líquidos (LC), que estão intimamente ligados com a proporção e a natureza dos componentes da mistura. Nesse trabalho, foi discutido o papel desses sistemas na incorporação de fármacos com diferentes propriedades físico-químicas, influenciando fortemente a liberação, assim como a biodisponibilidade dos fármacos. Aspectos sobre a formação e a caracterização de microemulsões e cristais líquidos também foram discutidos. A análise da literatura indicou que, dependendo da polaridade do fármaco, o efeito da ME ou LC pode ser usado para otimizar o efeito terapêutico por meio do controle da velocidade ou do mecanismo de liberação do fármaco.

Latenciação e formas avançadas de transporte de fármacos

O processo de modificação molecular denominado latenciação é revisto, apresentando formas avançadas no transporte de fármacos, utilizando macromoléculas como transportadores e sistemas de liberação sítio-específica como: CDS (Chemical Delivery System), ADEPT (Antibody-Directed Enzyme Prodrug Therapy), GDEPT/VDEPT (Gene-Directed Enzyme Prodrug Therapy/Vírus-Directed Enzyme Prodrug Therapy), ODDS (Osteotropic Drug Delivery System), PDEPT (Polymer-Directed Enzyme Prodrug Therapy), PELT (Polymer-Enzyme Liposome Therapy) e LEAPT (Lectin-Directed Enzyme-Activated Prodrug Therapy).

O processo de latenciação no planejamento de fármacos

Short review about the main aspects of prodrug design, as its objectives, applicability and importance, showing the new trends in the research for selective latent forms, namely targeted drugs.

Anemia falciforme: desafios e avanços na busca de novos fármacos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Degradação de fármacos residuais por processos oxidativos avançados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biodiversidade: fonte potencial para a descoberta de fármacos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Planejamento racional de fármacos baseado em produtos naturais

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bifosfonatos (BFs) como transportadores osteotrópicos no planejamento de fármacos dirigidos

Drug therapy involving bone tissue diseases is difficult, calling for the design of specific drugs. The present paper is a brief review of a new site-directed system termed ODDS (osteotropic drug delivery system), based on a latenciation process, using bisphosphonates as bone carriers. This is an important tool for the rational prodrug design for obtaining selective drugs.

Interações medicamentosas de fitoterápicos e fármacos: Hypericum perforatum e Piper methysticum

A utilização de produtos naturais na medicina popular é milenar e persiste até os dias atuais. Entretanto, a idéia de que estes produtos são isentos de toxicidade torna o uso de medicamentos fitoterápicos cada vez maior e indiscriminado. Este trabalho trata de uma revisão sobre as interações que podem ocorrer com a utilização concomitante de Hypericum perforatum L. (erva de são joão) e Piper methysticum F. (kava-kava) com fármacos, podendo levar a sérios efeitos tóxicos, incluindo a fatalidade.

Sistemas para liberação colônica: Uma alternativa para a veiculação de fármacos para efeito local ou sistêmico

Problems related to the systemic administration of drugs, such as biodistribution, difficulty of targeting, necessity of high doses to achieve adequate levels of the drug in specific sites, toxicity, and undesirable side effects have lead to the development of systems able to direct the drug to specific sites in the body. Among the possible organs to the targeting of drugs, the colon can be used for local and systemic therapies. By developing such systems some models have been tested, using pH dependent release, release controlled by enzymatic degradation, time controlled release systems and pressure controlled release systems. This review presents an overview of the colonic release of drugs and the strategies used to achieve such targeting.

Polissacarídeos biodegradáveis úteis para a preparação de sistemas de liberação controlada de fármacos. Parte 1: Quitosana

Due to an increasing interest, a vast number of biodegradable polymers have been obtained recently. Polymers naturally produced, such as cellulose, starch, chitosan and alginate, represent biodegradable materials, with low toxicity and low cost. Among polysaccharides, chitosan has been of great interest of the industrial and academic research, due to its special qualities of biodegradability and biocompatibility and, on the other hand, to the versatility of its use in several physical forms and products. A significant growth in the development of new dosage forms capable to deliver the drug in a controlled and targeted way has been observed in these last years. Such pharmaceutical forms search, mainly, the reduction of the dose administered and of the administration frequency, the reduction of adverse side effects and, consequently, a better patient compliance. The present paper describes the use of chitosan in pharmaceutical products, especially in drug controlled delivery systems.

Microemulsões: Estrutura e aplicações como sistema de liberação de fármacos

Depending on formula composition, microemulsions may be used as a vehicle for drug administration. In this work the main applicable parameters used in the development of pharmaceutical microemulsions (ME) are analyzed. The conceptual description of the system, theoretical parameters related to formation of internal phases and some aspects of ME stability are described. The pseudo ternary phase diagram is used to characterize ME boundaries and to describe different structures in several regions of the diagram. Some applications of ME as drug delivery systems for different administration routes are also analyzed. ME offer advantages as drug delivery systems, because they favor drug absorption, being in most cases faster and more efficient than other methods in delivering the same amount of drug.

Produtos naturais como candidatos a fármacos úteis no tratamento do mal de Alzheimer

Alzheimer's disease (AD) is a progressive neurodegenerative pathology with severe economic and social impact. There is currently no cure, although cholinesterase inhibitors provide effective temporary relief of symptoms in some patients. Nowadays drug research and development are based on the cholinergic hypothesis that supports the cognition improvement by regulation of the synthesis and release of acetylcholine in the brain. There are only four commercial medicines approved for treatment of AD and natural products have played an important role in the research for new acetylcholinesterase inhibitors.

Determinação de fármacos diuréticos em associação por cromatografia em camada delgada e espectrofotometria

A rapid, sensitive and reliable thin-layer chromatography/spectrophotometry screening procedure was developed for quantitative determination of diuretics associated in pharmaceutical dosage forms. The chromatographic method employed microcrystalline cellulose and butanol : acetic acid : water (4:1:1) or amilic alcohol : ammonium hydroxide 25% (9:1) as mobile phases and detection by U.V. light. The drugs were extracted using a simple procedure and were quantified by U.V. spectrophotometry. Results varied from 97.5 to 102.5% and are similar to those obtained by conventional methods. This method of quantification of diuretics is promising for quality control of drugs.