Peoples Drug Stores Inc. reported record first-quarter earnings yesterday, while Fairchild Industries Inc. said its profit rose sharply in its fourth quarter but were down for the year as a whole because sales fell.

Another area firm, E.C. Ernst Inc., which is operating under Chapter 11 of the federal bankruptcy code, reported a quarterly loss of more than $1.3 million. And Federal Home Loan Mortgage Corp., the government-sponsored loan institution known as Freddie Mac, posted record earnings for the just-completed year.

Peoples Drug, based in Alexandria, said it earned $5.2 million ($1.03 a share) in the quarter ended Jan. 15, up 16 percent from $4.5 million (90 cents) a year ago. Sales in the period rose 15 percent to $248.8 million from $215.4 million. Peoples' first fiscal quarter covers 16 weeks including Christmas; its other quarters are 12 weeks each.

Germantown-based Fairchild, a major producer of aircraft, said its fourth-quarter earnings rose 126 percent, but its earnings for all of 1982 were off 45 percent. The company noted, however, that its 1981 fourth-quarter earnings were affected adversely by write-offs on its Boeing 757 subcontract program because of cost overruns.

For the year, Fairchild said earnings fell to $35.3 million ($1.90) from $64.3 million ($3.48) a year ago. Sales fell 19 percent to $1.1 billion from $1.4 billion. Fairchild earned $7.7 million (41 cents) in the fourth quarter compared with $3.4 million (19 cents) a year earlier. Sales fell 22 percent to $296.3 million from $362.1 million.

Fairchild said its 1982 results were hurt by a scheduled reduction in deliveries of the A10 aircraft to the Air Force and by lower volume in its commercial aircraft, aerospace fasteners and other lines as a result of the recession. The company cut employment by 4,900 persons and cut costs elsewhere because of the economic conditions, Fairchild said.

Hadron Inc., a Vienna maker of lasers and computer software, posted a profit for the third quarter and first nine months of its fiscal year after reporting losses in the same periods a year earlier. The company said it earned $51,000 (1 cent a share) in the third quarter ended Dec. 31 compared with a loss of $118,000 a year ago, as revenues rose to $6.2 million from $5 million. For the nine months, income was $56,000 (1 cent) compared with a $307,000 loss a year ago on revenues that rose to $19.8 million from $13.3 million a year ago.

E.C. Ernst, a Washington-based electrical contractor, said it lost $1.3 million in the quarter ended Dec. 31 and $1.2 million for the first nine months of its fiscal year. In the third quarter a year ago it lost $440,000, while it had a profit of $5.5 million in the first nine months of fiscal 1981, about half of which resulted from a net tax loss carry-forward.

Revenues for the third quarter were $13.8 million, up slightly from $13.6 million a year ago. For the nine months, revenues rose 4 percent to $39.1 million from $37.4 million.

Federal Home Loan Mortgage Corp., which purchases home mortgages from savings banks and savings and loan associations and resells the mortgages to investors, said it earned $59.9 million in 1982, nearly double the $30.9 million earnings of a year before.

Freddie Mac attributed much of the earnings gain to the organization's guarantor commitment program, which provides certificates that can be traded similarly to stock and bonds and were used in an attempt to breathe life into the moribund housing industry by spurring mortgage activity.

F&M National Corp., holding company for F&M National Bank in Winchester, posted net income last year of $1.95 million ($1.12 a share) compared with $2.2 million ($1.33) the year before. Fourth-quarter net income slipped slightly to $526,869 (30 cents) from $534,320 (31 cents) in the same period of 1981. Bank assets grew to $251.2 million, deposits increased to $217.4 million and net loans to $133.7 million.