Does it work? Can danshen treat heart disease?
BACKGROUND:Danshen is one of the most widely used herbs in Traditional Chinese Medicine (TCM). In 2010, a patented Chinese product containing danshen became the first TCM herbal remedy to successfully pass Phase II clinical trials under the Food and Drug Administration (FDA) in the US. The company is also seeking approval for its product through the equivalent European Medicines Agency (EMEA).
The product will now advance to Phase III clinical trials, which could see it become the first TCM herbal product approved as a drug in the US and Europe.
Danshen is the dried root of Salvia miltiorrhiza, also called Chinese sage. In TCM, it is viewed as a key ingredient in herbal mixtures used to improve blood and urine flow. The term danshen can be used for remedies containing only Salvia miltiorrhiza, or for those containing several herbs. The TCM product being evaluated by the FDA is called Compound Danshen Dripping Pill (or Cardiotonic Pill). As the name suggests, it is primarily used for heart problems. The product also contains notoginseng (similar to regular ginseng), ginger, borneol and other spices.
EVIDENCE FROM STUDIES
Since the 1970s, danshen has been investigated in numerous studies, almost all of which were published in Chinese. The Cochrane Collaboration now has a Chinese Centre which is conducting systematic reviews to make the results of Chinese trials available internationally.
The first Cochrane review of danshen examined its effectiveness when given shortly after a heart attack. It identified six controlled studies, but only one of these was randomised. This study found no statistical differences between danshen and placebo. In the other five studies, danshen did perform better than the control group. However, the Chinese authors noted that many of these studies were poorly conducted and reported. Another systematic review published in 2011 found some evidence of benefit for angina, but similarly found trial quality to be a major problem.
Study quality has been an ongoing problem with danshen research. Other Chinese authors examined 150 danshen studies, 52 of them using the Cardiotonic Pill. The authors rated only 10 of the 150 studies as being of high quality, with the average score being 1.9 out of 5. Also, while the number of trials has increased, their quality has not improved over the past 10 years. In addition, only 6 per cent of the trials had ethics approval or obtained informed consent from patients.
Such issues are why the proposed Phase III trials of Cardiotonic Pill are crucial. However, conducting them does not guarantee final approval and will likely take about 10 years. Phase III trials involve large numbers of participants to confirm a drug’s effectiveness and monitor for side effects. If these studies are successful, the producer would then apply to the FDA for approval to market the product as a drug in the US. Currently, it is classified only as an investigational new drug (the first TCM remedy to achieve such a classification).
The Cochrane review of danshen identified almost 1,000 reports of adverse effects. Some were allergic reactions, ranging from mild to anaphylactic shock. Other effects reported include low blood pressure, dizziness and increased risk of bleeding. This has been particularly problematic in patients taking warfarin. This blood-thinning agent is commonly taken by those with heart conditions, with danshen apparently increasing its effect.
Danshen has been studied in numerous clinical trials, but quality is an ongoing problem. This makes it difficult to be confident in the results. This is especially problematic given the seriousness of the conditions for which danshen is used. Gaining Phase II FDA approval is a major milestone, but much more research is needed before danshen is approved as an effective and safe medication.
Cardiotonic Pill is a specific mixture of herbs, and other danshen products may contain different ingredients. Until a specific product is approved by the FDA and EMEA, patients with heart conditions should continue to use only approved medications as prescribed by their doctors.
Dónal OMathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University