By Tim Thwaites
A novel skin preparation which can deliver drugs and relieve aches and pains 20 times faster than existing methods and an improved anti-malarial compound are examples of the work being undertaken by Monash University researchers.
The researchers, in the Department of Pharmaceutics of the Victorian College of Pharmacy at the university's Parkville campus, are contracted by pharmaceutical companies both in Australia and overseas to study stabilisation, formulation and delivery of drugs. A more stable compound delivered directly to its intended site works more efficiently and can be taken in smaller amounts with fewer side effects. And that means people are more likely to stick with their medication with better results.
Pharmaceutics research is being done increasingly outside the multinational drug companies, says researcher Professor Bill Charman. "The big companies now concentrate on making and screening molecules, which leaves them holding the intellectual property, the patents. But innovative drug delivery is typically being undertaken by start-up companies and pharmacy school researchers."
And
innovative is a good word to describe the activity of Professor Charman, (pictured
right) and his colleague, senior lecturer Dr Barrie Finnin, (pictured left).
Take the work on the anti-malarial drug, for example.
Anyone who uses salad dressing knows that fats and oils do not mix with water. But cell membranes are made of fat-based materials. So, to improve the absorption of small pharmaceutically active molecules, the researchers have been coating them with lipids (fats), making them less water soluble and more fat soluble.
But that is only the beginning, because once these lipid-coated compounds are absorbed and pass into the circulation system, they can be picked up by lipoproteins - proteins whose role is to transport fat-based molecules around the body. Cell membranes in different tissues in different parts of the body contain receptors which can pull specific lipid compounds off the lipoproteins. In fact, lipid coatings can be designed to target the receptors on particular tissues. So the lipid coat becomes an envelope for delivering a drug package to the site on the body where its action will do most good.
And that is exactly the sort of work the Pharmacy College researchers have been doing for British pharmaceutical company SmithKline Beecham on an anti-malarial drug known as Halofantrine. "We have come up with a new range of formulations using lipids to improve the drug's efficiency," Professor Charman said. "They provide enhanced absorption of the drug in the small intestine and it goes straight into the red blood cells where it is needed. This means a decrease of the dosage given."
Dr Finnin is an expert in the delivery of drugs through the skin. "The skin is a pretty good barrier. That's its job," he says. In order to deliver drugs through the skin more rapidly, you have to find ways of perturbing this barrier.
Between the cells on the outer surface of the skin is a meshwork of lipids and water. Dr Finnin has been working with chemicals to alter the constituency of this intercellular environment by interacting with the lipids to alter their structural arrangement. This can allow particular compounds to go through more easily.
One example is the anti-inflammatory drug Ibuprofen which is marketed as a skin gel. Using his techniques, Dr Finnin has been able to move the drug through the skin about 20 times faster than is possible in the present product.
But the work of the Pharmaceutics department has a more general application than improving individual drugs. "Melbourne as a city is good at manufacturing," Professor Charman says. "In the long run, much of manufacturing is to do with formulation - whether of cosmetics, food, plastics or paint. But the College of Pharmacy is the only place which teaches innovation in formulation."
The Pharmaceutics department is currently constructing a new undergraduate course on how to develop products. The Bachelor of Applied Science (Product Development) will be a university-industry collaboration and will be presented for the first time in 2000.