It's a banned substance in sports not just boxing
Hunter suspended after testing positive for phentermine (espn.com) this is from 14 years ago when a Piston Player used it
Oscar Valdez's A- and B-sample tests show positive result for prohibited, central nervous-system stimulant, sources say (espn.com)
"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."