Effectiveness and Safety of Complementary Medicines

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The growing consumer awareness of health issues, and the trend towards seeking non-traditional methods of treatment in some cases, has seen a surge in the use of complementary medicines in Australia, writes Grant Kardachi.

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It has been estimated that as many as two in three Australians use at least one complementary medicine on a regular basis. Many pharmacies stock a range of complementary medicines and pharmacists are an important source of advice about complementary medicines.
All medicines, including complementary medicines, must be accepted onto the Australian Register of Therapeutic Goods (ARTG) before they can be marketed in Australia. In May 2011 there were more than 10,000 complementary medicines on the ARTG. When assessing medicines for inclusion on t`he ARTG, the TGA places them into one of two categories:

• Higher risk products are individually assessed for quality, safety and effectiveness. If they are approved, they are included on the ARTG as Registered medicines and carry an identifying ‘AUST R’ number. A product must also undergo this registration process if the manufacturer wants to claim that it will ‘cure, manage, treat or,prevent’ a disease or disorder.


• Lower risk products are assessed for the quality and safety of their ingredients, but not for effectiveness. Approved products are included on the ARTG as ‘Listed medicines’ and carry an identifying ‘AUST L’ number. Listed products may only carry claims for health maintenance and health enhancement, or for symptom relief in non-serious, self-limiting conditions. Manufacturers of Listed medicines are required to hold evidence to support claims made for their products. This evidence may be audited by the TGA. Most (but not all) complementary medicines on the ARTG are Listed medicines.

Compared to interactions between conventional medicines, little is known about herb-drug (or herb-herb) interactions, although this situation is changing as more complementary medicines undergo quality clinical trials. This is partly due to a lack of scientific studies and partly due to the variability of herbal products. Some herbs can alter the way other medicines are absorbed or metabolised in the body. St John’s wort is the herb best known for interacting with other medicines. It reduces the therapeutic effects of many medicines by increasing their metabolism (i.e. causing them to be broken down more rapidly in the body). Combining St John’s wort with other medicines can lead to serious consequences including organ rejection (e.g. cyclosporin), worsening of HIV-AIDS (e.g. indinavir), risk of blood clots (e.g. warfarin) and breakthrough bleeding or unwanted pregnancy (e.g. oral contraceptives).
Some herbs may have therapeutic effects which are similar or opposite to those of a conventional medicine. Taking the herbal and conventional medicines together may result in the effects of the conventional medicine being either increased or reduced.
For example, many herbs (including evening primrose oil, fish oil, garlic and ginkgo) can increase the risk of bleeding when taken with medicines that prevent blood clotting (e.g. aspirin, warfarin). St John’s wort can increase the effects of antidepressants, and also increase the risk of potentially dangerous side effects. The effects of sleeping tablets and tranquilisers may be reduced by guarana.
Quality research into the effectiveness and safety of complementary medicine is increasing as demand for these products grows but there remains a lack of information about their effectiveness, side effects and possible interactions. However, a lack of scientific evidence does not mean that a complementary medicine is ineffective; it may be that the medicine has not been assessed in good-quality clinical trials.
Evaluating the results of clinical trials is complicated by the fact that there are many different forms and preparations of herbs and ‘natural’ products.
A herbal product may be produced from the leaves, stems, flowers, roots or seeds of a plant. Herbal medicines may contain a single herb or a combination of several different herbs.
They may contain many hundreds, or even thousands, of different ‘phytochemicals’, and different parts of the plant may contain different proportions of these chemicals. Indeed, two batches of the same herbal product may differ significantly in their therapeutic activity.
Clearly consumers should speak to their pharmacist about any complementary medicines and any possible interactions they may have with medicines the person is already taking. The pharmacist is the medicines expert and can provide the best advice to help improve the consumer’s health through quality use of medicines.

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“Quality research into the effectiveness and safety of complementary medicine is increasing as demand for these products grows but there remains a lack of information about their effectiveness, side effects and possible interactions.”

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Grant Kardachi
Grant Kardachi was recently re-elected president of the Pharmaceutical Society of Australia for a fourth term. He is a community pharmacist who recently sold his business interests but is still accredited to undertake medication reviews and sits on the Australian Association of Consultant Pharmacy.