Oscar Valdez's A- and B-sample tests show positive result for prohibited, central nervous-system stimulant, sources say

Oscar Valdez has tested positive for phentermine, a central-nervous stimulant prohibited by the Voluntary Anti-Doping Association, multiple sources told ESPN.

The banned substance was found in both Valdez's A- and B-samples, according to sources, potentially jeopardizing his WBC 130-pound title defense against Robson Conceição on Sept. 10.

A ruling is expected soon on Valdez's status for the Sept. 10 fight in Tucson, Arizona, a Top Rank Boxing on ESPN+ main event. Both the A- and B-samples were collected on Aug. 13.

The WBC held a videoconference meeting Wednesday with Valdez's attorney, Pat English, along with officials from Top Rank and the Pascua Yaqui Tribe Athletic Commission, sources said. A ruling is expected soon. That commission sanctions very few fights annually, but since this bout falls under its jurisdiction and within its reservation, its participation was needed Wednesday.

Top Rank declined to comment, as did Valdez's manager, Frank Espinoza, and WBC president Mauricio Sulaiman. VADA founder Margaret Goodman didn't return a phone call seeking comment.

VADA informed involved parties of the test result on Sunday, sources said. The test was conducted as part of the WBC's Clean Boxing Program.

"I personally have given athletes phentermine, I know what it does. It is very powerful. It is like methamphetamine," Victor Conte, the founder of BALCO, told ESPN. Conte served time in prison after pleading guilty to conspiracy to distribute performance-enhancing drugs before founding SNAC, a sports nutrition company.

"You know why it's a performance-enhancing drug? Because it's a central-nervous stimulant," he added. "It accelerates your heart rate. It gives you energy. It gives you endurance. It gives you stamina. It makes it easier to breathe. Your training time to exhaustion would be much longer."

When fighters enroll in VADA testing, as the 30-year-old Valdez did, they are notified that there is no distinction between in competition and out of competition. A list of the banned substances -- phentermine is on it -- are sent to the fighter.

The World Anti-Doping Agency considers phentermine a banned substance in competition but not out of competition. The in-competition period begins at 11:59 p.m. the day before the fight and extends to post-fight testing. However, VADA tests for all prohibited substances at all times.

"If you're not being tested for stimulants, there is a loophole so large you can drive a Mack truck through it," Conte said. "Which one of the 70 stimulants would you like to use?"

In a legal letter obtained by ESPN on Tuesday, English writes: "Mr. Valdez had no knowledge that he was taking Phentermine and that we believe at this point it comes from an herbal tea."

"It's not an herbal tea, the molecular structure of phentermine is not an herbal tea," Conte said. "It's dog-ate-my-homework stuff. No promoter wants to lose money. This is not in contained supplements. This is designed to help you cut weight. It's an appetite suppressant which is what you're doing when you're cutting weight.

"It's a prescription-only medication. Does he have a doctor's prescription? Let's see it."

VADA reports adverse analytical findings; it does not adjudicate. However, there is precedent for VADA's rules leading to punishment. Billy Joe Saunders tested positive for the banned stimulant oxilofrine ahead of his scheduled title defense vs. Demetrius Andrade in 2018. The substance was deemed out of competition by WADA, yet Massachusetts recognized the VADA violation and suspended Saunders. The fight was cancelled as a result.

Top Rank promotes both Valdez and Conceição, yet the challenger's manager was informed of the adverse finding by ESPN.

"I had no idea. I'm upset," said Conceição's Brazil-based manager, Sergio Batarelli. "I learn now from you by surprise."

Valdez, ESPN's No. 1 junior lightweight, won the title with a spectacular one-punch knockout of Miguel Berchelt in February, the leading contender for KO of the Year. The two-time Olympian was also a champion at 126 pounds.

Valdez (29-0, 23 KOs) was defeated by Conceição when they met in the gold-medal match of the 2009 Pan American Games. Conceição (16-0, 8 KOs) went on to win gold at the 2016 Olympic Games. The 32-year-old Brazilian is unranked by ESPN.

Lou DiBella, who promotes the WBC's No. 2 junior lightweight, O'Shaquie Foster, is calling for Valdez to be stripped of the title unless the B-sample comes back negative for the banned substance.

"Unless Valdez is vindicated, O'Shaquie should be fighting [Miguel] Berchelt (the No. 1 contender) for the title and this kid (Valdez) should be facing some ramifications," DiBella told ESPN. "Every PED expert on Earth will tell you this is a PED and an unfair advantage shedding weight if you're having issues. And it helps you with your training."