It seems to me that no one knows just what the optimum dose is or how broad the effective range is, although there is a clear idea of how much is toxic. I heard somewhere that the reason why 2 5 mg pills per day is perscribed is that is the dose used in the clinical trials. In the trials a large enough dose is given to ensure that the drug is clearly doing what it is supposed to do for the most people being given it. Phil Tompkins Hoboken NJ age 60/dx 1990