Virginia Electric and Power Co. said yesterday that increased use of coal and nuclear power enabled it to more than double its profits last month, but warned that it will not be able to continue its heavy reliance on the two economical fuels.

Woodward & Lothrop reported its earnings dropped 24 percent in the latest quarter despite a 1.9 percent boost in sales, and said the economy still is discouraging consumer spending.

Vepco earned $21.7 million (17 cents a share) last month, up from $9.1 million (5 cents) in October 1979.Revenues increased to $155.9 million from $142.7 million.

For the latest 12-month period, Vepco's profits were up 15.8 percent to $224.3 million ($1.77) from $193.7 million ($1.63) and revenues increased to $2.1 billion from $1.6 billion.

Vepco President William W. Berry attributed the gains to "much greater availability of nuclear- and coal-fired generation." In October last year, Vepco produced 26 percent of its electricity with coal, 3.6 percent with nuclear power, and 32 percent with oil.

With three nuclear plants in full-time use this year, Vepco got 53 percent of its power from atomic energy, production of power from coal increased to 32 percent and oil was used to make only 4.6 percent of Vepco's electricity.

Berry said the nuclear contribution to Vepco's power production already has been cut because the North Anna 2 plant is shut down for modifications. Use of nuclear power will be reduced further when the sister reactor at North Anna will be closed for refueling starting Dec. 15.

Vepco's directors declared the regular quarterly dividend of 35 cents a share on common stock and regular dividends on preferred and preference stocks, to be paid Dec. 20 to shareholders as of Dec. 2.

At Woodard & Lothrop, profits for its third quarter ended Oct. 31 fell to $2.1 million (87 cents a share) from $2.8 million ($1.15) a year ago, and nine-month profits dropped to $3.7 million ($1.50) from $4.9 million ($2).

Sales for the quarter climbed 1.9 percent -- to $76.2 million from $74.8 million -- and year-to-date sales were up 3.5 percent -- to $297.2 million from $200.1 million.