Drug Delivery Systems based on hydrogels

Gel systems have found extensive applications in the medicinal/pharmaceutical field because of their ease of preparation, ability for modifications, and responsiveness to external chemical or physical stimuli. Gels usually act as hosts for active pharmaceutical agents for a variety of pathological conditions. They function as controllers of the release of pharmaceuticals that have proven to be “problematic” because they are either unsuitably insoluble to biological fluids, or they are metabolized unacceptably rapidly. In this presentation the use of silica-based hydrogels as controlled release drug delivery systems will be discussed, with emphasis on drugs against osteoporosisUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Nasal Drug Delivery Systems: An Overview

Since ancient times, drugs have been administered via the nasal route for therapeutic and recreational purposes. The interest in, and importance, of the systemic effects of drugs administered through the nasal route, have expanded over recent decades. Intra-nasal administration of drugs offers an interesting alternative for achieving systemic therapeutic effects of drugs that are comparable to the parenteral route, which can be inconvenient at times or oral administration, which can result in unacceptably low drug bioavailability. So, it is important to understand the potential and limitations of various nasal drug delivery systems. Therefore, the aim of this review article is to discuss the various pharmaceutical dosage forms that have the potential to be utilised for local or systemic drug administration. It is intuitively expected that this review will help to understand and further to develop suitable intra-nasal formulations to achieve specific therapeutic objectives

Microfluidics for Advanced Drug Delivery Systems.

Considerable efforts have been devoted towards developing effective drug delivery methods. Microfluidic systems, with their capability for precise handling and transport of small liquid quantities, have emerged as a promising platform for designing advanced drug delivery systems. Thus, microfluidic systems have been increasingly used for fabrication of drug carriers or direct drug delivery to a targeted tissue. In this review, the recent advances in these areas are critically reviewed and the shortcomings and opportunities are discussed. In addition, we highlight the efforts towards developing smart drug delivery platforms with integrated sensing and drug delivery components

Intrathecal drug delivery systems for the management of chronic non-cancer pain : a systematic review of economic evaluations

Background: Intrathecal drug delivery (ITDD) systems are one of a limited number of management options for chronic non-cancer pain, cancer pain and spasticity. Concerns over their effectiveness and high initial costs led NHS England to decommission ITDD for patients with chronic non-cancer pain. However, the extent to which this decision is in line with existing economic evidence is unclear. The aim of this systematic review is to identify and review the existing evidence on the cost-effectiveness of ITDD for chronic non-cancer pain. Methods: Full and partial economic evaluations on ITDD were identified through systematic searches in MEDLINE, EMBASE, Web of Science and the National Health Service Centre for Reviews and Dissemination databases. Database searches were complemented by hand searching of reference lists of relevant studies and searches of grey literature. Study selection was carried out by two assessors, independently. Study quality assessment was performed to inform critical appraisal of health economics studies. Data were extracted using a data extraction form developed for this study. Results: 4464 unique studies were identified, of which seven met the inclusion criteria. With the exception of one study, the studies found ITDD to be either cost-saving or cost-effective compared to conventional medical management. ITDD becomes cost-ineffective in one further study following price year adjustment to 2016. Conclusions: Study findings show ITDD as not cost-effective only in extremely conservative scenarios. There is limited evidence on the effectiveness of ITDD in non-cancer pain; however, the available economic evidence controverts arguments to refute the treatment on economic grounds

Kinetic limitations of cooperativity based drug delivery systems

We study theoretically a novel drug delivery system that utilizes the overexpression of certain proteins in cancerous cells for cell specific chemotherapy. The system consists of dendrimers conjugated with "keys" (ex: folic acid) which "key-lock" bind to particular cell membrane proteins (ex: folate receptor). The increased concentration of "locks" on the surface leads to a longer residence time for the dendrimer and greater incorporation into the cell. Cooperative binding of the nanocomplexes leads to an enhancement of cell specificity. However, both our theory and detailed analysis of in-vitro experiments indicate that the degree of cooperativity is kinetically limited. We demonstrate that cooperativity and hence the specificity to particular cell type can be increased by making the strength of individual bonds weaker, and suggest a particular implementation of this idea. The implications of the work for optimizing the design of drug delivery vehicles are discussed.Comment: 4 pages, 4 figures, v3: minor revision

Formation of porous membranes for drug delivery systems

Highly crystalline porous hollow poly (-lactide) (PLLA) fibres suitable for the delivery of various drugs were obtained using a dry-wet spinning process. The pore structure of the fibres could be regulated by changing the spinning systems and spinning conditions. Using the spinning system PLLA-dioxane-water, fibres with a dense toplayer and a spongy sublayer were obtained. The spinning system PLLA-chloroform/toluene-methanol yielded fibres with a very open porous structure. The membrane formation of the former system probably occurs by liquid-liquid demixing followed by crystallization of the polymer rich phase. In the membrane formation process of the spinning system, PLLA-chloroform/toluene-methanol crystallization probably plays a dominant role. The membrane formation process will be related to basic principles of phase separation. The fibres are suitable for the long term zero order delivery of the contraceptive 3-ketodesogestrel and the short term zero order delivery of the cytostatic agent, cisplatin. The drugs are released by dissolution of the drug crystals in the fibre core followed by diffusion through the membrane structure. Short term release of adriamycin could be obtained through an adsorption-desorption mechanism. The pore structures of the fibres have a large influence on the release rates of the drugs investigated. When fibres with dense toplayers were used, low release rates of drugs were observed whereas fibres with well interconnected pore structures over the fibre wall showed very high release rates

Mucoadhesive drug delivery systems

O efeito de fármacos pode ser potencializado através do desenvolvimento de novos sistemas de liberação como os sistemas mucoadesivos. Estes sistemas permanecem em contato íntimo com o tecido de absorção, as mucosas, liberando o fármaco no local de ação, com o consequente aumento da biodisponibilidade, podendo promover efeitos locais e sistêmicos. A mucoadesão, atualmente, é explicada por seis teorias, a eletrônica, da adsorção, da molhabilidade, da difusão, da fratura e a mecânica. Para estudar seus mecanismos e quantificá-la, são propostas várias metodologias in vitro e in vivo. Porém, a mucoadesão ainda não é totalmente compreendida. Esse trabalho tem por objetivo revisar os mecanismos e as teorias envolvidas na mucoadesão, além de descrever as metodologias e os polímeros mais utilizados em sistemas mucoadesivos para liberação de fármacos.Drug actions can be improved by developing new drug delivery systems, such as the mucoadhesive system. These systems remain in close contact with the absorption tissue, the mucous membrane, releasing the drug at the action site leading to a bioavailability increase and both local and systemic effects. Mucoadhesion is currently explained by six theories: electronic, adsorption, wettability, diffusion, fracture and mechanical. Several in vitro and in vivo methodologies are proposed for studying its mechanisms. However, mucoadhesion is not yet well understood. The aim of this study was to review the mechanisms and theories involved in mucoadhesion, as well as to describe the most-used methodologies and polymers in mucoadhesive drug delivery systems

Implantable Drug Delivery Systems

Traditional drug delivery methods provide very little, if any, control over the timing and pattern of drug release Medication concentration absorption at the point of action. Undefined medication concentration in plasma is a typical and obvious issue with the traditional dose method. Thus to overcome such problems efforts have been made by researchers and pharmaceutical scientists to the betterment of the drug delivery system and that lead to the development of the Novel Drug Delivery System (NDDS). NDDS is the approach and technology to deliver the drug in low concentration and follow the zero-order release of the drug in a controlled manner. Additionally, the NDDS's development results in the creation of an implantable drug delivery system (IDDS). a system for implantable medication delivery is a new approach of medicine delivery In this technique, the medicine is delivered under controlled conditions to the precise location where the implant is placed. The formulation, preparation, evaluation criteria, and future aspects of the implantable drug delivery system are the subjects of this study

pH-Dependent Drug Delivery Systems

Gastric carcinoma, or stomach cancer, is a major disease in the world today. Although it only accounts for about 2% of all cancer cases in the United States, it is much more prevalent in nations such as Korea, Japan, Great Britain, South America, and Iceland. While the most common treatment for gastric carcinoma is surgery, there are chemotherapeutic alternatives including the application of doxorubicin, also known as Adriamycin?. However, as with nearly all chemotherapy drugs, doxorubicin causes dose-dependent toxicity that results in severe biological side effects and, potentially, death. Many of the adverse effects of doxorubicin may be attributed to the fact that it is normally administered intravenously; thus, although the drug?s target is the stomach, the doxorubicin is systemically rampant. Hence, we have developed a delivery system for doxorubicin that we hope will limit the drug?s action to the stomach alone. We begin with a means for encasing the doxorubicin inside two types of hydrogels whose diffusive properties vary depending on temperature and pH levels, such that diffusion may be maximized in the stomach and minimized at all other locations inside the gastrointestinal tract. This original design was modeled as a 1-D radial line to represent the spherical shape of the pill. After investigation, another design involving a hollowed out hemisphere was modeled and tested. Results comparison shows that the second design scheme is superior to the first both in outward drug flux and in the amount of drug able to be delivered. Ultimately, results of the study showed that pH-dependent drug release can be attained at a steady and reliable rate, with significantly greater rates of release inside the stomach. However, we were unable to attain a clinically adequate amount of total doxorubicin release with our model designs. Still, it may be possible to achieve medically useful results with pH-dependent drug delivery systems given certain technological improvements in the future