Steven Dana Shoob, 30, supervisor of the White House Office that receives public comments on presidential speeches, pleaded guilty in U.S. District Court yesterday to a charge that he obtained a narcotic drug through use of an altered prescription.

The charge, a misdemeanor, carries a penalty of up to one year in jail, a $1,000 fine or both. After accepting Shoob's guilty plea, U.S. Magistrate Jean Dwyer scheduled sentencing for Oct. 15.

The altered prescription was discovered earlier this month by investigators during a routine check at SaveMor Drugs at 18th and G streets NW. The prescription, written by a local doctor, had been filled at the pharmacy on Aug. 7 for 50 tablets of the drug Percocet, a synthetic painkiller similar to codeine. Shoob, who lives at 3556 13the St., NW, was arrested last week.

Law enforcement aughorities have saidthat the original prescription was tampered with to change both the type and quantity of drug initially prescribed by the doctor.

Shoob has worked at the White Housesince President Carter's inauguration 3 1/2 years ago and is an acquaintance of Carter's son Chip. Shoob recently has been working as the $18,171-a-year supervisor of the White House office which accepts and catalogues telephone calls, telegrams and letters from around the country about Carter's speeches.

A pharmacist at the Save-Mor store said last week that Shoob regularly filled prescriptions there and Shoob himself told court officials that he suffers from a painful arthritic condition. A White House spokesman said last week that Shoob had visited the White House informary five times in the past 18 months complaining of an arghritic condition and had been given non-narcotic anagesics.