PHG 415 Evidence-based herbal medicine

Standardization It is essential to provide the patient with high- quality botanical product. Standardization applies only to extracts.

Why is standardization of herbal extracts necessary?

The answer is:  Higher quality product is obtained, by stating minimum limits for unwanted material in the extract and stating a minimum concentration for active ingredients in the extract.  Provided that the product is registered, it thus becomes a medicine that should comply with the basic standards required for all drugs.  Standardization allows comparison of the clinical effectiveness, pharmacological effects and side effects of a series of products (e.g. against placebo).

 Such products give patients greater security and increase the level of trust people have in herbal products.

Types of standardized extracts: The problem is that extracts contain a mixture of active and inactive ingredients, but often it is not known which compounds contribute to the activity or the pharmacological effects of the extract.

Types of standardized extracts: 1- Truly standardized extracts (type A). This type of extract is sometimes referred to as “normalized” extract. Here, extracts are standardized to active constituents. 2-Quantified extracts (type B) Extracts standardized to constituents that contribute to the activity. 3-Other extracts (type C) Extracts standardized to lead compounds of unknown pharmacological relevance but serve as quality markers. Fundamentals of Pharmacognosy and Phytptherapy.

1-Truly standardized extracts are extracts for which the active constituents are known. They can thus be standardized to a defined content of the active constituents. Examples include: Digitalis leaf

Senna dry extract: standardized to % hydroxyanthracene glycosides, calculated as sennoside B with reference to dried extract. (Eur. Ph.).

Belladonna leaf dry extract: standardized to % alkaloids calculated as hyoscyamine (Eur. Ph.).

2-Quantified extracts (also known as special extracts) These are extracts with constituents having known therapeutic or pharmacological activity. The monograph must define a range of content of the selected constituents, some of which are lead compounds. Examples: -Ginkgo biloba L. leaf (maidenhair tree). -Hypericum perforatum L. aerial parts (St John's wort).

Examples of quantified extracts include: -Ginkgo biloba L. leaf (maidenhair tree)

Examples of quantified extracts include: Hypericum perforatum L. aerial parts (St John's wort).

3-Other extracts These are extracts accepted to be pharmacologically active. However, the constituents responsible for this activity are not known and consequently quality markers have to be defined. These give information on the overall quality of the phytomedicine for control purposes and may be used to monitor good manufacturing practice.

Examples of other standardized extracts: Crataegus aerial parts (hawthorn)

Examples of other standardized extracts Passiflora incarnata L. aerial parts (passion flower).

Summary From this lecture, it could be concluded that:  Standardization is crucial to herbal extracts.  There are different types of standardized extracts.  Standardization ensures the safe and proper use of herbal medicines.