Active ingredient doesn't last long

The medical case surrounding the death of Madam Chew Kim Kee involves conflicting academic views, affects the interests of various parties, and may result in people having misconceptions of Chinese medicine ("Cordyceps 'likely led to post-op bleeding'"; last Friday, and "Taking cordyceps? Keep doc informed"; last Saturday).

Any drug that enters the body has to go through the process of absorption, distribution, metabolism and elimination.

The drug is distributed to the rest of the body through the circulatory system. The amount of time that it stays in the blood circulation system determines the time period that the drug can act on the body.

The time taken for the drug concentration to reduce by half in the bloodstream is termed its plasma half-life. The amount of time for any drug to be retained in the body is two to five times its plasma half-life.

As a traditional Chinese medicine practitioner, I did a literature search on the plasma half-life of commonly used blood thinners and anticoagulants.

Adenosine, the active ingredient in cordyceps, has a plasma half-life of less than 10 seconds. This means it stays in the bloodstream for merely 20 to 30 seconds. This is why it is seldom used orally but is administered through intravenous injection.

If a patient consumed cordyceps one week before an operation, its adenosine would have been eliminated long before the surgery.

Hence, unless Madam Chew had taken cordyceps on the day of the operation, the diffuse bleeding she suffered is unlikely to have been related to the blood-thinning effect of adenosine.

Koh Chin Aik (Dr)

A version of this article appeared in the print edition of The Straits Times on June 02, 2016, with the headline 'Active ingredient doesn't last long'. Print Edition | Subscribe