Taking the risk of the benefit: the unbalanced situation of herbal medicinal products

Risk-benefit analysis is related to quality, safety and efficacy of the herbal in a specific context. In this context 3 variables can be considered: the patient, the intervention and the interpretation of the outcome.

A careful characterisation of the patient brings us to constitutional (childhood, pregnancy and aged) and contextual (pathological) risks. EMA herbal monographs cover 92 indications (of which 21 for well established use). Only one (skin disorders and minor wounds, Avenae fructus) does not have any age restriction. It is also the only one allowing the topical use in case of pregnancy. On the other hand, it remains difficult to fix upper limits as age is concerned.

Therapeutic interventions with herbals are more complex as several preparations of the same plant species can be made. The Herbal Medicinal Product Committee of EMA is restrictive on accepting herbal preparations. This contrasts with the wide range of herbal ingredients in food supplements. The question can be asked how far such preparations can move from traditional approaches: e.g. Exolise® (an 80% ethanolic dry extract of Camellia sinensis standardized at 25% catechins) had to be taken from the market after cases of severe hepatitis were linked to its use.

With adverse events as an outcome, clear factual evidence is needed: drug, event, source and patient must be well-defined before an investigation can start. Mostly one or several of these elements are failing. Causal relationship should be dressed according to validated methodology (e.g. Austin Bradford-Hill criteria or the Naranjo scale).