The Advantage of Single Daily Dosages of Herbal Medicines
by Dr. Michael Murray
Since the early 1980s there has been a tremendous increase in the use and appreciation of herbal medicine in North America. I have termed this process the Herbal Renaissance. The key fuel for this increased popularity of herbal medicine has been scientific research. During the last 20 to 30 years there has been a virtual explosion of scientific information concerning the medicinal use of plants. Through science we now have a better understanding of how a particular herb might work to promote health. We also now know how to grow a plant for highest medicinal effect, when to harvest it and how to concentrate the medicinal components in extracts.
One area of herbal medicine that is still in its relative infancy is the field of pharmacokinetics - the study of the absorption of compounds by the body and their biotransformation, distribution, metabolism, and elimination from the body. The same scientific methods used to determine the pharmacokinetics of drugs have been applied to some of the more popular herbal medicines as well as other natural products.
Pharmacokinetic studies can provide the answer as to what is the best delivery vehicle for a substance. For example, some compounds need to be protected from the harsh secretions of the stomach by incorporating them into specially coated capsules or tablets that can withstand gastric acids while other compounds may be required to be administered in a soft-gelatin capsule with other lipid (fatty) substances for maximum absorption.
The alpha-lipoic acid example
One of my favorite examples in pharmacokinetics is immediate-release alpha-lipoic acid vs. timed-release alpha-lipoic acid. Alpha-lipoic acid is a vitamin-like substance that is often described as “nature’s perfect antioxidant.” The primary clinical use of alpha-lipoic acid has been for the treatment of diabetic neuropathy. In fact, it has been successfully used in Germany for over thirty years as an approved drug for this condition. Detailed absorption studies have shown that immediate-release alpha-lipoic acid is quickly absorbed with dosage proportionality – meaning that roughly the same percentage is absorbed whether the dosage is 50 or 600 mg with about 30% of the actual dosage getting into the bloodstream before it is broken down by the liver.1
While we know a great deal about how immediate-release alpha-lipoic acid is handled by the body and its clinical effectiveness, there has been only one study with a timed released preparation – it was a pharmacokinetic study that concluded that the timed-released formula was associated with an approximately 40% reduction in overall bioavailability compared to the immediate-release product.2 While the timed-release product was absorbed more slowly over time, it did not produce as high of peak value as the immediate release nor was the area under the curve (AUC) as high as the immediate release. The AUC is often used to show the total absorption of compound over time. In this ca