Drug interactions involving complementary medicines: effects of phytoestrogenic isoflavones. [ 2001 - 2003 ]

Research Grant

Researchers: Prof Allan Evans (Principal investigator) ,  A/Pr Robert Milne ,  Prof Roger Nation

Brief description Isoflavones are naturally occurring chemicals that have become widely recognised as 'phytoestrogens'. These are plant-derived compounds with a biological activity that resembles that of the human hormone, estrogen. Pharmaceutical preparations containing isoflavones, as herbal extracts, are currently available over-the-counter from pharmacies and health-food outlets and are being heavily promoted in the lay press. For example, Promensil, which contains 40mg of isoflavones per tablet, is being promoted for use in women over the age of 45 years and Trinovin is being promoted for men over 50. It is well recognised that patients taking more than one drug may experience an adverse event as a consequence of one drug altering the way in which the body handles another. Therefore, a new 'conventional' drug cannot be marketed unless information on its ability to alter the handling of other drugs is provided to the relevant regulatory body. In stark contrast, there is comparatively little information required for the marketing of herbal products such as isoflavones, despite the fact that these products will be made available over-the-counter for self-medication. We hypothesise that isoflavones will be capable of interacting with conventional drugs and we will be conducting a range of experiments to address this hypothesis. At present little or no consideration is given to the safety issues that arise from the use of herbal remedies in general, not only the isoflavones. Therefore a patient taking a range of conventional drugs is able to purchase a herbal remedy, over-the-counter, with no consultation with a health professional. If we discover that isoflavones can alter the handling of conventional drugs by the body, then certain precautions will need to be taken in defining their safety in humans. The result may also have implications for the use of other complementary medicines.

Funding Amount $AUD 196,018.36

Funding Scheme NHMRC Project Grants

Notes Standard Project Grant