Tennis reporter Ben Rothenberg has suggested that the vast majority of top players use Adderal in light of Verdasco's suspension.
The drug itself is banned by the anti-doping agency however players or athletes diagnosed with ADHD can apply for an exemption which allows them to use it and play. It's a fairly well-known drug that helps with focus and reaction time which is quite crucial in tennis.
In light of Verdasco forgetting to renew his exemption and getting banned many wondered whether he is the only one using it. Former player Pam Shriver called into question the integrity of the sport if the drug is being used by more players and she hinted at it with the Tweet.
Rothenberg followed up on that by claiming that a player told him that half of the top 100 probably use it creating all sorts of chaos on social media. Reilly Opelka even called it legal doping in his response to the news of Verdasco's ban.