Has the medication used in PAS been tested and approved by the FDA?

The answer is "No."  While the individual medications are FDA approved, the medication consumed by a patient is a "cocktail" of various drugs, which has been developed by physicians that participate with physician-assisted suicides. The information about the drug mixture in the "cocktail" is shared by physician to physician.  If a physician decides to modify the "cocktail," probably to make it work more efficiently, they are free to do so. This has occurred in the past, sometimes with bad results. In the physician-assisted suicide world the patient is also the test subject. The "cocktail" is not FDA approved.