The RIHF announced in a statement that players at the national training camp took meldonium under an official programme but stopped in the autumn when it was announced the drug would be placed on the World Anti-Doping Agency's (WADA) banned list from Jan. 1 2016.
"The Russian Ice Hockey Federation has made the decision, in conjunction with the Sports Ministry to change the roster of the U-18 side in order to protect their rights," the Russian ice hockey governing body said.
The United States will host the world championships from April 14 to 24 in Grand Forks, North Dakota.
"As prescribed by the doctors, players of the Viktor Tikhonov center used the Mildronate drug (meldonium) so as to protect the heart muscle in periods of high exertion," the RIHF statement added. "Supplies of the drug were carried out officially in accordance with the Federal Medical-Biology agency.
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"After Mildronate was included in the banned drugs category by the (World) Anti-Doping agency in autumn of 2015, the players stopped using this drug."
ADDITIONAL TESTS
The RIHF said more work was needed to determine how long meldonium -- which helps boost blood flow and increases the amount of oxygen taken in by the body, allowing athletes to recover faster while training -- can remain in a person's system.
"It is impossible to know the degree of guilt from a sportsman without knowing accurately how quickly the substance can be removed from one's body, while additional tests need to be carried out to learn about the effects the drug has on one's body," the RIHF statement said.
Meldonium, marketed as Mildronate and a common medicine across eastern Europe, was developed to treat heart conditions such as angina. It was also used extensively for three decades to toughen up Soviet troops in action at high altitude.
Russian Sports Minister Vitaly Mutko was quoted by the Interfax news agency on Thursday saying several hundred Russian sportspeople used to take meldonium before it was banned, and Russian anti-doping services know who can be tested for it.
Up to 30 percent of all Russian sports teams had used meldonium in the past, Mutko said.
Russian athletics was banned from international competition in November following a WADA report which exposed systematic state-sponsored doping and related corruption.
The IAAF said last month Russia had "significant work" to do for the ban to be lifted before the Rio Olympics in August.
(Reporting by Dmitriy Rogovitskiy; Editing by Ken Ferris)
