Normally we do the acute toxicity studies first and then based on the results, we can calculate the dose for the studies. Usually 1/5th, 1/10th and 1/20th of the safe dose (determined from acute toxicity studies using OECD guidelines) is used for the studies involving plant extracts. For example if 2000 mg/kg p.o. is found to be safe, then we use 100, 200 and 400 mg/kg for the studies.

Depends on type of disease. But it will be helpful if taken on empty stomach.

I think it depends mainly on the type of herbs, some herbs might be toxic if taken with large amounts. and also one should take in consideration if the person is taking any medications, sometimes its expected that there might be negative interaction between the herbs and the medicine.

I am agree with the opinion about toxicity. Is LD 50 known for this drug? Also are there any data about doses used in previous experiments as well as about the main phytochemical components?

I recommend this paper

COS, P.; VLIETINCK, A.J.; BERGHE, D.V.; MAESA, L. Anti-infective potential of

natural products: How to develop a stronger in vitro ‘proof-of-concept’. J.

Ethnopharmacol. v.106, p.290–302, 2006.

Normally we do the acute toxicity studies first and then based on the results, we can calculate the dose for the studies. Usually 1/5th, 1/10th and 1/20th of the safe dose (determined from acute toxicity studies using OECD guidelines) is used for the studies involving plant extracts. For example if 2000 mg/kg p.o. is found to be safe, then we use 100, 200 and 400 mg/kg for the studies.

The question is sadly enough too unspecific to answer, as it all depends on what plant, what extract, what compounds in the extract, what preclinical work, what toxicological work, what read-outs, etc ...better to be specific about it, the answer might then be of more help to you!

I too agree with Jan Keppel Hesselink.

I am agree with Jan Keppel Hesselink.

Dr. Hesselink is right. The dose depends for example, on the actual effect in question, existing toxicological data, study population in question and so on.

Thank you very much to all of you for giving some valuable points and your answers is really help me a lot in my research and guidance to my PG Students

For every unknown herbal (whose safety not established) must go with toxicity assessment as per OECD guideline.

Totally agree with Dr. Nahata.

The form in which the drug will be administered is very important.If it is administered orally in a crude form the dose will increase,if decoction is prepared the dose will differ.Extract will certainly have more benefits over other dose forms.