there is no easy conversion. If you are giving a human dose in mg/kg use the same dose in rats as a starting point.

I agree with Peter.

Of course, It's not easy to do such conversion, but try to start with the equivalent of the human dose (calculate your dose with regard to the body weight of the experimental animal). Furthermore, the doses in animal are also dependent on the species used.

Some starting points for you to consider:

Sharma V1, McNeill JH. To scale or not to scale: the principles of dose extrapolation. Br J Pharmacol. 2009 Jul;157(6):907-21.  PMID 19508398

Sinha VK1, Vaarties K, De Buck SS, Fenu LA, Nijsen M, Gilissen RA, Sanderson W, Van Uytsel K, Hoeben E, Van Peer A, Mackie CE, Smit JW. Towards a better prediction of peak concentration, volume of distribution and half-life after oral drug administration in man, using allometry. Clin Pharmacokinet. 2011 May;50(5):307-18. PMID: 21456631

I apologize in advance for asking a question here: Along the same lines, does anyone know of how to extrapolate STEM CELL dose from rats to humans? More specifically, my group needs to extrapolate intra-carotid stem cell dosing given into the brain arterial circulation after stroke. thank you!

I am not agree with above answers.

For conversion of human dose to rat dose there is formula related to surface area, which can you find in Experimental Pharmacology, By M.N. Ghosh. Even lots of publication you can find out online for this surface area chart.

To complete the last answer, you can follow the rules published in the FDA Guidance for starting doses in humans (the document is attached).

See table 1 page 7 : there are conversion rules to calcute doses in humans from doses in animals. In your case, you can do the inverse.

Be aware that as a general rule (exceptions can exist is very specific cases), the dose in mg/kg in rodent species is higher than the dose (mg/kg) in humans. If you use the human dose (mg/kg) in the rodent, it will be highly underdosed.

The rationale of interspecies extarpolation of doses is explained by allometry.

Regards

For more information here is a review article published recently.

It is not very simple, however, I have found very good information from some experimental scientific published articles and FDA guidelines. I think its better to follow FDA guidelines to convert the dose which later could be a supportive reference as well.

All the learned people here, I have an extension to this problem. What if the dosage is plated on a medical device and is slowly released? Efficacy extrapolation for an antimicrobial medical implant surface for instance, how do we approach that scenario?