Scottish tennis star Andy Murray reacted to Maria Sharapova's failed drug test by noting that he's careful to read everything that is relevant to him.

Sharapova said this week that she had tested positive for meldonium because she didn't read the email from the World Anti-Doping Agency that said the drug was on the prohibited list this year. The Russian called it a huge mistake.

"Everyone's obviously different," Murray said Thursday at the BNP Paribas Open. "Some people put a lot of trust in the people and the team around them so it's hard to say what's the right thing for everyone, but I think it's almost part of our job to know everything that's going into our bodies and not just rely on what a doctor is saying or a physio is saying."

Murray said since Sharapova's announcement he has been reading about meldonium, too, and what he's learned makes him wonder about those using it.

"The stories like this happen regularly," he said. "It seems like it's almost a weekly occurrence, so I wouldn't say it was shocking, really. Obviously, since then you try and read about it and learn as much as you can and try to understand what's really going on. I read that 55 athletes have failed tests for that substance since Jan. 1. You don't expect such high-level athletes, at the top of many sports, to have heart conditions."

Meldonium, virtually unheard of in the U.S., has been widely-used in Eastern Europe and former Soviet countries for heart conditions. But it was placed on the banned list because it enhances oxygen uptake and endurance.

A study recently released by the British Journal of Sports Medicine said that during last year's European Games meldonium may have been used by almost 500 athletes and there were 66 positive tests.

"This study highlights the widespread and inappropriate use and prescribing of this prescription drug in a generally healthy athlete population," the researchers said.

Murray thinks that's a problem with more than just meldonium, too.

"I think taking a prescription drug that you don't need just because it's legal, that's wrong," he said. "If you're taking a prescription drug and you're not using it for what that drug was meant for, then you don't need it, so you're just using it for the performance enhancing benefits that drug is giving you."

That being the case, Murray said, the penalty should be obvious.

"If you're taking performance-enhancing drugs and you fail a drug test you have to get suspended," he said.