Meldonium is manufactured in Latvia and used medically to treat heart problems like angina and myocardial infarction. It is also an effective treatment for ischemia – or lack of blood flow.It is most commonly used in Russia and it is not approved by the Food and Drug Administration for use in the US.Murray added: “I read that 55 athletes have failed tests for that substance since 1 January.“You just don’t expect high level athletes at the top of many sports to have heart conditions.”Calling on players to take responsibility for what they put into their bodies, 28-year-old Murray expressed his surprise at the stance of racket company Head for their statement over their deal with Sharapova.“I think it’s a strange stance given everything that’s happened the last few days,” he said. “I don’t really know what else to say on that, but that’s not something I believe. “I think at this stage it’s important really to get hold of the facts and let things play out, like more information coming out before making a decision to extend the contract like that, in my view. I personally wouldn’t have responded like that.”As he prepares for the BNP Paribas Masters, Murray called for more testing in tennis as a whole, adding: “I think all sports can do more.“It’s better than it was a few years ago, last year I got tested a lot but this year I’ve been tested twice so far this year, three months into the year, which is clearly not enough.” The Dunblane ace said: “It’s not up to me to decide the punishment, but if you’re taking performance enhancing drugs and you fail a drugs test, you have to get suspended.”World number two Murray has been a long-term critic of tennis’ attitude to dealing with doping and believes it is wrong to take a drug purely for performance.He added: “I think taking a prescription drug that you don’t necessarily need, but just because it’s legal, that’s wrong, clearly. That’s wrong.“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. And I don’t think that that’s right.” Andy Murray says Maria Sharapova deserves to be banned after failing a drugs test during this year’s Australian Open.Scottish ace Murray was questioned over tennis’ big story in Indian Wells after this week’s announcement that the Russian superstar had been caught taking meldonium.Former world number one Sharapova claimed she had been taking the drug legally for ten years but had failed to check correspondence from the International Tennis Federation and the Women’s Tennis Association that the substance would be banned from January 2016.Murray also had strong words for his racket manufacturer Head, who are looking to extend their contract with Sharapova despite the controversy.