A former drug addict, Kenneth L. Barun of Houston, will direct Nancy Reagan's East Wing projects office, including her crusade against drug abuse, the White House announced yesterday.

Barun, 36, will succeed Ann Wrobleski, 32, considered to be the principal architect of Mrs. Reagan's drug abuse program. She will move to the State Department in a $60,000 post as deputy assistant secretary of state for international narcotics matters.

Sources said the appointments will complement White House plans to internationalize Mrs. Reagan's antidrug-abuse crusade.

Barun shifts to the $60,000-a-year White House post from the Department of Health and Human Services, where he began work three weeks ago as deputy assistant secretary for public affairs.

"I had no idea that this job was going to be offered to me," said Barun, who worked as a volunteer last fall in the Reagan-Bush campaign.

He said he first met President and Mrs. Reagan when he was president and chief executive officer of Cenikor Foundation Inc., a drug and alcohol rehabilitation program with facilities in Houston, Fort Worth and Denver. The president visited the Houston center at the urging of Mrs. Reagan, who had also seen the Denver operation.

Barun said his own addiction to a wide variety of drugs, including heroin, in the late 1960s and early 1970s was "a storybook history of drug abuse -- I came from a good family, very supportive of me, and I fell into drugs because of peer pressure and it was a time in my life when I didn't have a whole lot to grab onto."

In 1972, Barun spent a year in Cenikor's Denver facility working at "menial tasks and eventually working myself into a management position."

He said he had been an athlete and had suffered no physical damage from his drug use. "Now I really take care of myself," he said, "and stay in shape. I want to live and help others to live."

A sociology major at Long Island University who later finished at the University of Houston, Barun has three sons by his wife Maria and a daughter by a previous marriage.

Wrobleski, 32, worked eight years on Capitol Hill after graduating from Stephens College in Columbia, Mo. She was an assistant to former senator Edward Gurney, an assistant press secretary to former senator Richard Stone and a press secretary to Rep. Lou Frey, all of Florida. She also was a research assistant to the House Republican research committee.

At the State Department, where she will be one of two deputy assistants to Assistant Secretary Jon Thomas, she will be primary liaison with other federal agencies involved with drug abuse, a spokesman said.

"She will also be involved in the international drug problem and we think it is a fortunate coincidence that we will have someone intimately familiar with the operations of the first lady's office and particularly with the drug abuse program which she helped design for Mrs. Reagan," the spokesman said.

Wrobleski was in Atlanta yesterday making arrangements for the April 23-24 international drug abuse conference, to which Mrs. Reagan will escort first ladies from several countries.