The consequences of international tennis star Maria Sharapova's positive test at the Australian Open for the World Anti-Doping Agency-banned drug, meldonium, may be more far-reaching even than Sharapova's possible four-year suspension. U.S. sports leagues have taken notice and are considering joining the mounting opposition to the drug.

Meldonium, which is meant to improve blood flow and boost exercise capacity and was originally developed for use by Soviet troops fighting in poor terrain, often high in the mountains, was banned by the WADA on Jan. 1.

While nearly all of the U.S.'s major sports leagues will first need to seek player approval before pronouncing the drug illegal, some or all are expected to add meldonium to their banned drug list sometime in the near future.

The PGA Tour already has plans in place to add the drug, which is marketed as Mildronate and was originally developed in Latvia, to its banned list. They tend to adhere closely to the WADA's decision-making and will outlaw meldonium as part of their 2016 revision to their banned list.

The MLB has "raised the issue" with players, though meldonium is already banned in the minor leagues where the MLB does not have to negotiate with players on such issues. Meldonium was banned in the minors shortly after the WADA's decision.

The NFL, NBA and NCAA all have non-specific plans to discuss a ban of the drug with their players. The NBA said it will bring the issue into consideration before its prohibited substances committee, which includes players' union members who will have to sign off on any decision regarding the drug's legality..

Only the NHL, who said they wouldn't be able to add the drug to their banned list until prior to next season at the earliest, did not state unequivocally that they plan to address the drug's usage or a potential ban with its players.

Since Jan. 1, the WADA has recorded 99 positive tests for meldonium, including Sharapova. It's use was said to be "widespread" for athletes competing at the European Games in Baku last year, with 66 positive tests, 13 by medal-winners. All told, positive tests were produced by athletes in 15 of the 21 events at the Games.

So while Sharapova was the highest profile athlete to be caught using the drug, she certainly wasn't, and very likely still isn't, alone.