John B. Fegan, a Washington doctor for 33 years, pleaded guilty in U.S. District Court here yesterday to two charges of illegally distributing biphetamines to a D.C. undercover agent.

Assistant U.S. Attorney Douglas J. Behr told Judge Barrington D. Parker that Fegan, 60, of 3356 Pennsylvania Ave. SE, regularly wrote drug prescriptions from last January through mid-July for patients whom he had barely examined and then asked what pills they wanted prescribed.

Fegan, whose office is at 2210 Martin Luther King Ave., SE, faces up to 10 years in prison and a $30,000 fine. He declined to comment about the case, but admitted as part of his guilty pleas that he had prescribed drugs "without regard for legitimate medical purpose or treatment and not in the usual course of accepted medical practice."

According to Behr, D.C. police detective William Larman, working undercover, went to Fegan's office last May 17 using the name Tom Gilbert and asked for "a prescription for biphetamines." When Fegan asked why, Larman replied that he was "feeling down, under the weather" and that biphetamines seemed to help.

After a medical examination that consisted only of a blood pressure check, Fegan gave Larman the prescription, according to a police affidavit in the case. In addition, Fegan later gave Larman a post-dated prescription for 1k Dexedrine pills and a Dalmane prescription for Larman's "mother" who the policeman said had trouble sleeping at night.

Fegan wrote prescriptions for Larman on two other occasions, according to the affidavit, and a total of 2,086 drug prescriptions between last March and early July.