Drugs and devices — blurring the boundaries

The combination of a pharmacological substance and a medical product — which itself has no effect on biochemical processes inside the human body — is one of the hot topics in the biotech industry today.

The global market for the combination preparations known as 'stents' is currently growing by an average of around 11% a year, as a study by the American analysts at BCC Research has shown. According to their calculations, the tiny, drug-eluting tubular implants that are used to support the walls of blood vessels will be generating sales worth eight billion US dollars by the year 2010.

In the past, the main market focus has been on so-called 'drug-eluting stents' for coronary heart diseases. Since 2002, surgeons have been using these drug-coated stents to combat hardening of the coronary arteries which ultimately leads to heart attacks. Although they are notably more expensive that the uncoated implants, patients are asking for them. However, the applications of drug-eluting stents are not confined to the coronary blood vessels. They can also be used in large vessels in the digestive tract or in the peripheral leg arteries.

Although coated stents have been on the market for a comparatively long time, there is still a long way to go in terms of their development. Hitherto, the principal coatings available for use in the coronary arteries have been the chemotherapy drug Paclitaxel and the immunosuppressant drug Sirolimus, which help to prevent blockages of the blood vessels. The search is now on for new, more effective medications, optimised dosages and even brand new ways of combining therapeutic substances with the tiny lattice tubes. At present, not even the standard preparations that would allow the use of coated stents in other vessels are available.

Five target areas for the use of drug-device combinations

Although very large sums of money are being invested in the development of drug-eluting stents, researchers are looking at other promising ways of combining medical products with new pharmacological substances. Apart from stents, there are four other areas where great strides are being made.

Catheters coated with antibiotics have been used to prevent infections of the urinary tract, while bone cement containing antibiotics reduces the risk of infection, particularly in the case of hip implants. Also falling into this category are biological products for treating wounds and transdermal plasters — typically used to transport hormones into the body through the skin. And photodynamic tumour therapy or PDT is a cancer treatment designed to kill off tumour cells by the targeted use of light. BCC Research estimates that the market for these four areas of application will be worth US$3.5 billion by 2010. With the exception of the orthopaedic applications, all forms of combination therapy are now seeing double-digit growth.