After a routine urine test provided by Mudryk returned an "adverse finding" he was provisionally suspended by the Football Association (FA) with immediate effect.
The 23-year-old, who is unable to play for or train with the club during his suspension has been backed by his manager Maresca who faced the media for the first time since the news broke.
"We are all upset, sad," Maresca said. "We are giving him general support.
"We trust Mykhailo, when these types of things happen you need to support your player in all the aspects. He is one of the players in my squad so it is my duty to be in contact with him, we are all there. The teammates, the club, me, we are all there.
"Trust means we believe Myka, we support him. We want to help him in anything he needs. It is normal that in this moment he needs help from the club and we are there to support."
The Italian head coach says he believes the Ukranian international will return to football once the situation clears up.
"We support Mykhailo and trust means that we believe Mykhailo," said Maresca.
"The club, the coaching staff and all of the people that are inside the training ground - we support and we trust Mykhailo.
"I think he is going to come back but we don't know when. But for sure he is going to come back."
Players found to have intentionally taken a banned substance can be banned for up to four years under FIFA guidelines which would be a huge blow for the winger’s career.