Jaime Conceição

Nanotechnological carriers for cancer chemotherapy: the state of the art.

Cancer is a term used for a heterogeneous group of malignant diseases in which abnormal cells divide without control and are able to invade other tissues, resulting in metastasis. According to the last data of World Health Organization the incidence and mortality rates of cancer are high and tend to increase. Chemotherapy is usually used in cancer treatments, but due to the lack of specificity of drugs, is associated to various and damaging side effects that have a severe impact on patients quality of life. Nanotechnology is actually an important area of interest in science and technology, which has been extensively explored during the last decade, particularly in the development of carriers for cytotoxic drugs. These carriers include vesicular and particulate systems such as liposomes, niosomes, transfersomes, ethosomes, micelles, dendrimers, and polymeric, protein and lipid nanoparticles. Polymer-drug conjugates and antibody-drug conjugates have also been studied. The present review is an attempt to contemplate the studied nanocarriers in the field of anticancer drugs delivery, their advantages and disadvantages and future perspectives.

Characterization, sensorial evaluation and moisturizing efficacy of nanolipidgel formulations.

Nanostructured lipid carriers (NLC) have been widely studied for cosmetic and dermatological applications due to their favourable properties that include the formation of an occlusive film on the skin surface that reduces the transepidermal water loss (TEWL) and increase in water content in the skin which improves the appearance on healthy human skin and reduces symptoms of some skin disorders like eczema.

Cyclodextrins as excipients in tablet formulations

This paper aims to provide a critical review of cyclodextrins as excipients in tablet formulations, highlighting: (i) the principal pharmaceutical applications of cyclodextrins; (ii) the most relevant technological aspects in pharmaceutical formulation development; and (iii) the actual regulatory status of cyclodextrins. Moreover, several illustrative examples are presented. Cyclodextrins can be used as complexing excipients in tablet formulations for low-dose drugs. By contrast, for medium-dose drugs and/or when the complexation efficiency is low, the methods to enhance the complexation efficiency play a key part in reducing the cyclodextrin quantity. In addition, these compounds are used as fillers, disintegrants, binders and multifunctional direct compression excipients of the tablets.

Cyclodextrins as drug carriers in Pharmaceutical Technology: The state of the art

BACKGROUND Cyclodextrins (CDs) are versatile excipients with an essential role in drug delivery, as they can form non-covalently bonded inclusion complexes (host-guest complexes) with several drugs either in solution or in the solid state. METHODS The main purpose of this publication was to carry out a state of the art of CDs as complexing agents in drug carrier systems. In this way, the history, properties and pharmaceutical applications of the CDs were highlighted with typical examples. The methods to enhance the Complexation Efficiency (CE) and the CDs applications in solid dosage forms were emphasized in more detail. RESULTS The main advantages of using these cyclic oligosaccharides are as follows: (1) to enhance solubility/ dissolution/ bioavailability of poorly soluble drugs; (2) to enhance drug stability; (3) to modify the drug release site and/or time profile; and (4) to reduce drug side effects (for example, gastric or ocular irritation). These compounds present favorable toxicological profile for human use and therefore there are various medicines containing CDs approved by regulatory authorities worldwide. On the other hand, the major drawback of CDs is the increase in formulation bulk, once the CE is, in general, very low. This aspect is particularly relevant in solid dosage forms and limits the use of CDs to potent drugs. CONCLUSION CDs have great potential as drug carriers in Pharmaceutical Technology and can be used by the formulator in order to improve the drug properties such as solubility, bioavailability and stability. Additionally, recent studies have shown that these compounds can be applied as active pharmaceutical ingredients.

The role of liposomes and lipid nanoparticles in the skin hydration

Cosmetics are much more than beauty products and the maintenance of skin hydration could be considered the most important step to getting healthy skin. The hydration could be supplied to the skin internally by ingestion of water, or externally, by applying cosmetic formulations containing moisturizing ingredients and/or components that reduce transepidermal water loss (TEWL). In recent years, liposomes and lipid nanoparticles (solid lipid nanoparticles and nanostructured lipid carriers) have received a great deal of attention in the field of pharmaceutical and cosmetic research. These nanosystems have proved to be very advantageous for skin applications and numerous studies were carried out with the aim of encapsulating numerous cosmetic ingredients in liposomes and lipid nanoparticles. Additionally, when applied on the skin, these systems form a transparent film that reduces the TEWL and increases hydration. The main objectives of this chapter include: presenting the importance of skin hydration to maintain health and the mechanisms that could be involved, exemplifying with moisturizing ingredients commonly used in cosmetics; discussing the application of lipid-based nanocarriers, referring to the advantages of these systems and the ingredients commonly used with benefits to skin; showing and discussing examples of some interesting studies performed in this field; and presenting some examples of marketed cosmetic formulations containing liposomes and lipid nanoparticles.

Characterization and stability studies of emulsion systems containing pumice

Emulsions are the most common form of skin care products. However, these systems may exhibit some instability. Therefore, when developing emulsions for topical application it is interesting to verify whether they have suitable physical and mechanical characteristics and further assess their stability. The aim of this work was to study the stability of emulsion systems, which varied in the proportion of the emulsifying agent cetearyl alcohol (and) sodium lauryl sulfate (and) sodium cetearyl sulfate (LSX), the nature of the oily phase (decyl oleate, cyclomethicone or dimethicone) and the presence or absence of pumice (5% w/w). While maintaining the samples at room temperature, rheology studies, texture analysis and microscopic observation of formulations with and without pumice were performed. Samples were also submitted to an accelerated stability study by centrifugation and to a thermal stress test. Through the testing, it was found that the amount of emulsifying agent affects the consistency and textural properties such as firmness and adhesiveness. So, formulations containing LSX (5% w/w) and decyl oleate or dimethicone as oily phase had a better consistency and remained stable with time, so exhibited the best features to be used for skin care products.

Hydroxypropyl-β-Cyclodextrin and β-Cyclodextrin as Tablet Fillers for Direct Compression

Cyclodextrins are cyclic carbohydrates widely used as complexing and non-complexing excipients in drug delivery systems. The purpose of this work was to study the ability of hydroxypropyl-β-cyclodextrin and β-cyclodextrin to act as tablet fillers for direct compression. In this way, several parameters of the cyclodextrins were evaluated, namely: (i) the flow properties such as angle of repose, flow time, Carr index, and Hausner ratio; (ii) the compaction behavior, specifically the energies and forces exerted during tableting, the plasticity index, the lubrication efficiency, and compression profiles (force/time and work/displacement of the upper punch); and (iii) the influence on carbamazepine release characteristics from uncoated tablets, i.e., dissolution rate and disintegration time. In addition, these properties of the cyclodextrins were compared with those from other commonly used direct compression fillers (lactose monohydrate, mannitol, calcium hydrogen phosphate dihydrate, and microcrystalline cellulose) and co-processed excipients (microcrystalline cellulose/mannitol and lactose monohydrate/cellulose). Three main conclusions can be drawn: (i) the studied cyclodextrins can be used as tablet fillers for direct compression; (ii) hydroxypropyl-β-cyclodextrin showed better properties than β-cyclodextrin mainly at the level of the physics of compression (higher values of plasticity index and lubrication efficiency) and of the drug release characteristics (faster and greater dissolution rate and a shorter disintegration time); and (iii) lactose monohydrate and hydroxypropyl-β-cyclodextrin displayed the best results. As there are people intolerant to lactose, hydroxypropyl-β-cyclodextrin, although its cost is higher, can be considered a good substitute for lactose.

Use of solid dispersions to increase stability of dithranol in topical formulations

Este trabalho teve como objetivo aumentar a estabalidade do ditranol atraves da preparacao de dispersoes solidas (DS). Prepararam-se duas DS diferentes em proporcao de 1:9 de ditranol/excipiente: em uma das DS utilizou-se beenato de glicerila como excipiente e na outra se utilizou mistura de oleo de argan com acido estearico (razao 1:8). Posteriormente, efetuou-se a incorporacao de ditranol puro e das DS contendo este farmaco num creme hidrofilo ou oleo-agua (O/A) e em pomada hidrofoba, na proporcao 1:10 (farmaco ou respetivas DS/base dermatologica). As propriedades fisicas e mecânicas das formulacoes semissolidas incorporando farmaco ou as respetivas DS previamente desenvolvidas, foram avaliadas atraves da analise do comportamento reologico e das propriedades de textura. Para avaliar a estabilidade, os parâmetros do espaco de cor L*a*b* das DS e das formulacoes semissolidas e o pH das preparacoes hidrofilas foram determinados em periodos de tempo definidos, durante um mes para cada amostra armazenada sob diferentes condicoes, especificamente, exposicao a luz (a temperatura ambiente), protegidas da luz a temperatura elevada (37 °C) e protegidas da luz (temperatura ambiente). Embora tenham apresentado valores de firmeza e de adesividade mais elevados, as pomadas hidrofobas apresentaram melhores caracteristicas reologicas do que os cremes oleo-agua. Alem disso, as pomadas hidrofobas tambem apresentaram melhor estabilidade, com pequenas alteracoes nos parâmetros do espaco de cor L*a*b*. Os resultados deste trabalho permitiram concluir que as DS desenvolvidas contribuiram para o aumento da estabilidade do ditranol.