Expected results: If such a system proves to be effective to optimize prescribing of the drugs among in-patients having impaired renal function and if it is well accepted by the physicians, diffusion could be considered in centres of geriatrics. In the same way, similar studies in hospital medical wards with no geriatricians in their staff or also in family medicine settings could be considered. The algorithms will be made available for the developers which would wish to integrate it into other applications of regulations.