Ian Pyka, a U.S. shot putter who withdrew from the Pan American Games along with 11 teammates Tuesday, said yesterday he thinks the American athletes were discriminated against by officials testing for banned drugs, particularly anabolic steroids.

Pyka, a University of Maryland graduate, said at a Jersey City, N.J., news conference that the Americans were placed at a disadvantage because they had not been given adequate notice of the intense drug-testing procedures instituted in Caracas.

The athletes who left the games did so before their competitions began and after being advised of the stringent testing. Some claimed family emergencies and others said they withdrew to protest the testing.

Pyka said he withdrew because he feared detection of caffeine in over-the-counter pills and of an antihistamine he took for a sinus condition before leaving Miami for the games. He denied ever using steroids.

Pyka said Pan Am officials "mishandled the situation" by not telling the American athletes of the testing to be done before competition.

"This equipment could test for substances way back to childhood," he said. "We were informed two days before our competition."

Dave McKenzie, the national record holder in the hammer throw, denied that most of the Americans withdrew to avoid the tests.

"The list is unbelievably long for things you can't take," McKenzie told United Press International. "It wasn't worth losing my Olympic eligibility for taking Dristan two weeks ago."

Because the testing equipment in Caracas is more sophisticated than that used at the World Track and Field Championships in Helsinki earlier this month, where most of the competitors were European, Pyka said he believes the Americans were targeted for disqualification.

Hurdler Mark Patrick said yesterday he left Caracas because of an old shoulder injury. His left shoulder, which he dislocated in a car accident while in high school, had "popped out of place" three times since his arrival at the games last Friday, he said.

Patrick told the Centralia (Ill.) Evening Sentinel that the shoulder kept him out of his event, the 400-meter hurdles, so he decided to come home. He said he has never used steroids and that he did not know why the other athletes withdrew.

Gary Bastien, a decathlete from Auburn, Ala., was originally reported among those athletes who withdrew, but, according to his wife Kathy, he remained in Caracas and has not officially withdrawn.

"He had said he might not run because he injured a calf muscle, but he did not withdraw," she said. "He read in the papers down there that he was on a plane home with the others, but he told me he is not coming back until the games are over, even if he doesn't compete."