Nicholas Piramal researcher Dr Ashok Patel argues the case for greater recognition of the importance of material science in the drug research arena
At first instance, the mere mention of material science brings forth images of metals, ceramics, composites and other things commonly associated with engineering - things that would appear rather dry and uninteresting to a pharmaceutical scientist. However, it has been recognised recently that material science has equal importance in the pharmaceutical field, where the principles and theories of material science are being applied to exciting areas such as drug delivery, control of drug form, manufacture and processing of nanoscopic or microscopic particle systems.
Although historically material science research has been an integral part of pharmaceuticals, its importance is increasing, with pharmaceutical and materials scientists collaborating in the genesis of a multidisciplinary field called pharmaceutical material science.
This emerging discipline encompasses a broad range of applications under one umbrella some of which are well established, having appeared in literature as early as the 1950s.
The majority of work has focused either on:
- studying the impact of the physico-chemical properties of formulation components on the performance of the final pharmaceutical dosage form, or
- the use of advanced analytical techniques for characterisation and design of drugs and drug delivery systems.
The advent of drug delivery research and increasing demand for new drugs has, however, led to a sudden interest in applying principles of material science to new pharmaceuticals fields. This burgeoning interest in pharmaceutical material science has opened up a vista of opportunities for material scientists, including: the design of API and custom materials with specific physical and chemical properties; the use of theoretical/mathematical models to predict the performance of dosage forms in biological environments; and the development of novel characterisation techniques for nanoscopic and micron-sized particles.
Engineering of particles with customised properties optimised for effective dosage form manufacture (tablet, capsule or ointment) has long been a goal of the pharmaceutical industry. Particles can be designed through modification of the size, morphology, and packing arrangement of the solids. Crystallisation is one process that determines all these properties. The importance of polymorphism, crystal morphology, and particle size in pharmaceutical materials science is well known and a great deal of research into crystallisation has already been undertaken to manipulate the size, morphology, and structure of the drug crystals.
The performance of a drug mostly depends on the dosage form characteristics, which are invariably controlled by the type of excipients added to the formulation. Excipients are inert compounds without any activity. However, they do impart certain functionality that leads to the desired performance of dosage form.
Traditionally, excipients were segregated based on their functionality, with each excipient specified for one particular role. However, increasingly attempts are now made to produce excipients with multi-functionality. By serving multiple functions, these excipients can decrease the number of materials required in the formulation, which helps minimise batch-to-batch variability and reduces cost.
Rational development of a delivery system is an expensive business. Formulation optimisation involves varying excipient levels, processing methods, identifying discriminating dissolution methods, and subsequent scale-up of the final product. Because quantitative and qualitative changes in a formulation may alter drug release and in vivo performance, developing tools that facilitate product development by reducing the necessity of bio studies is always desirable.
The concept of predictive models involves establishing the mathematical relationship between the in vitro performances of dosage form with the in vivo absorption. The increased interest in these predictive models stems from the fact that they can result in cost savings in terms of reduced in vivo studies and biowaivers.
Recent advances in nanotechnology have not only encouraged formulation scientists to find solutions to existing formulation problems but have also led to the development of innovative delivery systems with advanced properties. On the formulation front, this has opened up new doors for material scientists. These opportunities include development of various characterisation techniques ranging from basic electron microscopy to advanced probe microscopy; from in vivo sensors to BioMEMS.
While the field of pharmaceutical material science is not entirely new, the field is growing faster than ever before. This burgeoning interest is well justified by establishment of specialised research centres all over the world. For material scientists, it is a ripe time to tread these unexplored paths.
