Sharply increased profits were reported yesterday by Washington's two biggest drug store chains, Peoples Drug Stores and Dart Drug Corp.

Dart's earnings jumped 18 percent in the latest quarter and were up 36 percent for te first nine months of the year from year-ago levels.

People' net income for the year rose 17 percent -- twice as much as sales increased -- to $6.46 million ($1.77 a share) from $5.52 million ($1.52) a year ago.

The Washington-based drug store chain's sales increased 9.1 percent to $441 million from $404 million for the year ended Sept. 29. People's latest fiscal period covered 52 weeks; the prior year included 53 weeks.

The year's performance was aided by a big swing in fourth quarter earnings, which jumped 20.4 percent to $1.6 million (44 cents) from $1.3 million (37 cents) even though sales increased only 6.4 percent to $102 million from $96.6 million.

Anaylzing the sharp improvement in profits, Peoples' Chairman Adrian C. Israel said the performance, "reflects the success of programs aimed at making us a more efficient, competitive and profitable company."

Peoples last week completed the acquistition of the Haag Drug Company in Indiana and will speed up opening of additional stores in its present markets next year, Israel said.

Dart reported profits for the nine months ended Oct. 31 of $2.30 million ($1.31) compared with $1.69 million (92 cents) in the same period a year ago. Sales climbed to $164 million from $148 million.

For the latest three months, Dart earnings were up 18 percent to $877,000 (51 cents) from $741,000 (40 cents). Sales were $55 million compared with $48.7 million.

Dart President Herbert A. Haft said higher markups, tightened expense control and stepped-up sales promotion contributed to the surge in earnings.

Dart also benefitted from expansion, adding two drug stores, three Crown Books stores and the first three units of its new Trak Auto division during the quarter. Four more Trak stores and an additional drug store have opened since the end of the quarter.