The former world number one, who was scheduled to tee off in the company of American Ryan Moore and Swede Carl Pettersson at the TPC Scottsdale, cited a back injury for his withdrawal.
Singh, 49, was replaced in the field by American Richard H. Lee.
A three-times Major winner, Fijian Singh revealed earlier this week he had been using deer antler spray for a couple of months in an interview with Sports Illustrated magazine.
On Wednesday, he issued a statement in which he expressed shock that the spray contained IGF-1 (insulin-like growth factor), a natural anabolic hormone that stimulates muscle growth.
"While I have used deer antler spray, at no time was I aware that it may contain a substance that is banned under the PGA Tour anti-doping policy," said Singh, who has battled assorted health problems in recent years, especially with his back.
"I am absolutely shocked that deer antler spray may contain a banned substance and am angry that I have put myself in this position. I have been in contact with the PGA Tour and am cooperating fully with their review of this matter."
The US Tour is now "looking into the matter" and has a variety of sanctions at its disposal, including disqualification, a one-year suspension for a first violation and up to five years for a second violation.
Since the Tour's anti-doping programme was launched in 2008, American journeyman Doug Barron is the only player who has been suspended for a violation. Barron, then 40, was banned for one year in November 2009 for taking a performance-enhancing drug.
- Sports & Recreation
- TPC Scottsdale
- Carl Pettersson