Counselling system: This system will operate in patients with ClCr <60 ml/mn. It will comprise three functionalities: (a) detection of orders of a drug contraindicated in case of renal failure and production of an alert message; (b) detection of excessive dose taking into account patient's ClCr and production of an alert message; (c) counsel to monitor plasma concentration of drugs having a renal elimination in the event of impaired renal function. This system will be very largely based on the data obtained to work out the reference frame.