39
AYENA
Delivering pill, patch or implant effectively
H E A LT H & M E D I C I N E
The Drug Delivery System Excellence Center of Prince of Songkla University takes a multidisciplinary approach to developing drug delivery systems for the population. Pulmonary system: Pharmaceutical aerosols, such as an inhaler device, deliver proteins and peptides for systemic and localised effects through the lungs. Since many proteins are susceptible to chemical or physical degradation and deteriorate on swallowing, a “breathing in” delivery system could provide a suitable alternative. However, only a fraction of the formulated dose – and rarely more than 15 per cent – is delivered to the system, making the aerosol method unsuitable for the delivery of expensive drugs. Present research is focusing on morphology of the active drug and carrier substances to allow absorption of the drug molecules in the lung. Protein chemicals prepared in freeze dried conditions are often unstable, thus stabilisation of proteins in a solid state is of great importance to the success of drug delivery by inhalation. The design of aerosol devices is another key research area. Sufficient turbulence needs to be generated to dislodge drug particles from the carrier substance to efficiently deliver the correct amount of medicine to the lung tissue. It is difficult to predict drug quantities deposited in the lung from laboratory studies. Conventional lung deposition models have been adapted to take into account patients’ dynamic breathing patterns, drug particle size and velocity to predict the drug dose delivered to the lung. Skeletal drug delivery and tissue engineering: Biodegradable polymers and ceramics used to produce composite tablets, implants or injectable hydrogels have been developed to deliver antibiotics and therapeutic agents to specific skeletal sites. Biologists and engineers are collaborating to create tissues from cultured cells so as to repair or replace damaged bone tissue instead of patients having to undergo organ and tissue transplants. Osteoblast cells, responsible for bone formation, are obtained directly from the patient and grown on biodegradable scaffold supports to develop into bone tissue. Regulatory controls that stimulate osteoblasts to differentiate and become mineralised bone tissue need to be understood, and growth factor delivery systems will be important in transforming cultured cells into new tissues. The manufacture and design of scaffolds and their structural and biomechanical properties are being investigated and their biocompatibility, cellular interaction and biodegradability will also be assessed. R&D of materials for drug delivery: To maximise the therapeutic effects of drugs, optimal delivery to where they are needed is critical. Investigations have focused on the physical and chemical properties of pharmaceuticals, the stability and bioavailability of particular drugs, and the fraction of dosages administered that are taken up by the body. Furthermore, medicines that have poor water solubility are being improved through solid dispersion techniques to increase their bioavailability.
Nanotechnology: One strand of research has focused on the use of nano-biomaterials to improve all types of drug delivery. This would decrease drug toxicity, reduce treatment costs and improve drug bioavailability. Nanoencapsulation technology is one method being used to send drugs to a targeted organ. Transdermal patches: Delivering drugs through the skin for local and systemic effects prevents irritation of the gastrointestinal tract and prevent the active ingredients being metabolised by the liver. However, the outer layer of the skin presents a barrier, limiting drug diffusion into deeper skin layers. The latest research is investigating chemical enhancement of transdermal drug delivery using skin penetration enhancers to develop safe and effective transdermal delivery patches. Molecular recognition: Molecularly Imprinted Polymers (MIPs) – formed from a template imprint molecule – could be used to develop new medications and diagnostic tools as well as to monitor transdermal treatments. The research focuses on using novel functional monomers and cross linkages to improve polymer membrane performance. A complementary application could lead to extraction of pharmaceutical residues as well as toxic impurities from water sources.
For further information contact: Prof. Vimon Tantishaiyakul Email: vimon.t@psu.ac.th Assoc. Prof. Teerapol Srichana Email: teerapol.s@psu.ac.th Faculty of Pharmaceutical Sciences Prince of Songkla University, Thailand