In the conduct of non-clinical research on herbal medicines, standard methods are usually employed. However, the use of novel technologies and methods resulting from scientific progress should be encouraged.
1. Pharmacodynamic and general pharmacological methods should utilize animal models or bioassays that closely relate to human disease as described by either traditional or modern medicine (see Guidelines).
2. Toxicological methods
Animal and other toxicity studies are conducted according to generally accepted principles, referred to collectively as Good Laboratory Practice (GLP), which should be consulted in order to design appropriate studies (see Guidelines C).
a. Systemic toxicity tests
Systemic toxicity tests refer to alteration of either physiology, anatomy (gross or microscopic) or clinical chemistry (including haematology) that result from pathological changes in any organ distant from the site at which a herbal medicine is administered.
i. Acute toxicity tests aim to determine toxic manifestations of the test substance that occur when animals are exposed to one or more doses of the test substance within a single 24-hour period.
ii. Long-term toxicity tests aim to determine toxic reactions when animals are exposed to the test drug for periods as long as their lifetime. In such tests, the animals are observed for behavioural changes as well as anatomical, physiological and biochemical manifestations of tissue damage. If pathological changes are detected during the period of drug administration, and the changes are not serious, it may be advisable to determine whether such changes are reversible after the drug is withdrawn. Thus, observations are made at intervals during continuous administration of the drug and then, at intervals after the drug has been withdrawn to determine whether such pathology is reversible.
b. Local toxicity tests are done to determine the local irritation and/or systemic absorption of a herbal medicine used for local applications (such as respiratory inhalants, drugs applied to skin or mucosa).
c. Special toxicity test - regulatory requirements for special toxicity tests vary among Member States. For herbal medicines containing commonly used herbs which have been used clinically for a long period of time, some countries may not require special tests. Mutagenicity tests, however, are commonly required. If any deviation from traditional use is contemplated (such as new use, new preparation, new route of administration or more prolonged administration), additional toxicity tests such as carcinogenicity, teratogenicity and reproduction studies may be recommended.