WASHINGTON (Reuters) - U.S. President Donald Trump said he will push to cut prescription drug prices by 59%, but gave no further details about his plan to lower medicine costs ahead of a health-related event at the White House later on Monday.

On Sunday, Trump said he would sign an executive order to pursue what is known as "most favored nation" pricing or international reference pricing. The Republican president previously tried to implement such a program during his first term in office but was blocked by the courts.

"Drug prices to be cut by 59%" Trump wrote on Monday in capital letters on his social media platform as global pharma shares traded lower. Shares of U.S. drugmakers fell between 2% and 3% following his weekend comments before Trump's latest post Monday morning.

Trump is scheduled to hold an event at the White House with U.S. Health Secretary Robert F. Kennedy Jr. at 9:30 a.m. (1330 GMT)

Drugmakers have been expecting an order focusing on the federal Medicare health insurance program for people aged 65 and older and the disabled, according to four drug industry lobbyists who said they had been briefed by the White House.

Reuters previously reported such a policy was under consideration.

The United States pays the highest prices for prescription drugs, often nearly three times more than other developed nations. Trump has pledged to close the gap but not detailed how he will implement it.