Pulsatile drug delivery systems using hydrogels
ABSTRACT In recent years, temporal control of drug delivery has been of interest to achieve improved drug therapies. Intelligent drug delivery systems (DDS) are one expected result, demonstrating an ability to sense external environmental changes, judge the degree of external signal, and release appropriate amounts of drug. Intelligent DDS may be achieved using stimuli-responsive polymeric hydrogels which alter their structure and physical properties in response to external stimuli. Pulsatile drug release has the advantages of avoiding drug tolerance or matching the body's release of specific peptides or hormones. In this review, recent studies for pulsatile drug delivery in response to stimuli such as chemical agents, pH, electric fields, and temperature are discussed. Achievement of pulsatile drug release from stimuli-responsive polymeric hydrogels as on-off switches and its mechanism are reviewed in terms of control for stimuli-responsive swelling.
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ABSTRACT: Hydrogels are water swollen polymeric materials able to maintain a distinct three dimensional structure. They were the first biomaterials designed for clinical use in the early 1950's when Otto Wichterle and Drahoslav Lím initiated a research program aimed to the development of hydrogels for soft contact lenses. The fortunate use of hydrogels in ophthalmology, which translated, besides contact lenses, also in glaucoma microcapillary drains and fillings for the restoration of detached retina, was the driving force towards the exploration of many other biomedical applications. Indeed, hydrogels extended their use to coverings for perforated ear drums, implants for plastic surgery, drug delivery depots, etc. Amazingly, after 60 years, hydrogels are still inspiring the scientific community and progress in this field has moved forward at an impressive pace. Nowadays, novel synthetic methods for the design of gelgel-forming polymers and molecular biology have encompassed traditional chemical methods, resulting in self-assembling and environmentally sensitive hydrogels with controlled degradability and mechanical properties. Hydrogels have been applied, in addition to traditional areas, also to the delivery of biotechnologically derived drugs (proteins and peptides), tissue engineering, micro fluidics and nanotechnology. The success of hydrogels originates from their well known biocompatibility mainly due to their high water content and soft nature, These properties render hydrogels similar to biological tissues and consequently minimize cell adherence and inflammation once injected or implanted in the body. Furthermore, their water absorbing capacity facilitates the accommodation of cell or hydrophilic molecules such as protein and peptides within the polymeric network.International Journal of Pharmaceutical and Medicinal Research. 12/2013; 1(2):60-69.
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ABSTRACT: Recently, there has been increasing interest in remote heating of polymer nanocomposites for applications such as actuators, microfluidic valves, drug delivery devices, and hyperthermia treatment of cancer. In this study, magnetic hydrogel nanocomposites of poly(ethylene glycol) (PEG) with varying amounts of iron oxide nanoparticle loadings were synthesized. The nanocomposites were remotely heated using an alternating magnetic field (AMF) at three different AMF amplitudes, and the resultant temperatures were recorded. The rate of the temperature rise and the steady state temperatures were analyzed with a heat transfer model, and a correlation of heat generation per unit mass with the nanoparticle loadings was established for different AMF amplitudes. The temperature rise data of a PEG system with different swelling properties were found to be accurately predicted by the model. Furthermore, the correlations were used to simulate the temperatures of the nanocomposite and the surrounding tissue for potential hyperthermia cancer treatment applications. © 2010 American Institute of Chemical Engineers AIChE J, 2011AIChE Journal 03/2011; 57(4):852 - 860. · 2.58 Impact Factor
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ABSTRACT: Locally dropping the temperature in vivo is the main obstacle to the clinical use of a thermoresponsive drug delivery system. In this paper, a Peltier electronic element is incorporated with a thermoresponsive thin film based drug delivery system to form a new drug delivery device which can regulate the release of rhodamine B in a water environment at 37°C. Various current signals are used to control the temperature of the cold side of the Peltier device and the volume of water on top of the Peltier device affects the change in temperature. The pulsatile on-demand release profile of the model drug is obtained by turning the current signal on and off. The work has shown that the 2600 mAh power source is enough to power this device for 1.3hours. Furthermore, the excessive heat will not cause thermal damage in the body as it will be dissipated by the thermoregulation of the human body. Therefore, this simple novel device can be implanted and should work well in vivo.International Journal of Pharmaceutics 03/2013; · 3.99 Impact Factor