The license of any physician or physician assistant to practice medicine in this state shall be subject to restriction, suspension, or revocation, as hereinafter provided, in case of inability of the licensee to practice medicine with reasonable skill or safety to patients by reason of one (1) or more of the following:
(1) Mental illness;
(2) Physical illness, including but not limited to, deterioration through the aging process, or loss of motor skill; or
(3) Excessive use or abuse of drugs, including alcohol.