Commodore International Ltd. announced yesterday it lost $36.7 million in the quarter ending March 31 and has cut its work force by about 25 percent, or 1,100 jobs, since the start of the year. The results represented the fifth-straight quarterly loss for the struggling computer manufacturer.

Also yesterday, K mart Corp., the nation's second-largest retailer, reported its first-quarter profits rose 56.4 percent, citing "generally favorable economic conditions."

Commodore said net sales for the quarter were $182.3 million, up 8 percent from the same period in 1985. The loss per share was $1.17, compared with a loss of 67 cents a year earlier, when the company lost $20.8 million.

Revenue rose 8 percent to $182.3 million from $168.3 million a year earlier.

Commodore attributed the loss to cost-cutting measures and other unusual items, high marketing expenses and lower-than-expected sales of its Amiga microcomputer, introduced last year.

Commodore lost $127 million last year as a result of an industry slump and write-offs from its cost-cutting measures.

Chairman Irving Gould said Commodore continues to have the support of its major lenders. The company in February reached an agreement to establish a $135 million line of credit for a year, averting the threat of foreclosure.

For the first nine months of the fiscal year, Commodore said it had a net loss of $129.1 million, compared with net income of $10.1 million, or 33 cents a share, a year earlier. Revenue for nine months was $680.7 million, a 9 percent decline from $751.2 million a year earlier.

*K mart, which is based in Troy, Mich., said it earned $91.6 million (70 cents a share) in the 13 weeks ended April 30, compared with $58.5 million (46 cents) in the first quarter last year.

Sales were up 4.6 percent to $5.21 billion from $4.98 billion.

Sales in K mart stores that were open a full year advanced 2.6 percent from prior year levels.

"K mart's record sales and earnings were achieved as a result of favorable consumer response to our new merchandising programs and generally favorable economic conditions," said K mart Chairman Bernard Fauber.

In 1986, the company plans to open some 256 units, including 32 K mart stores, 80 Waldenbooks, 45 Builders Squares, 41 Pay Less Drug Stores, 15 Designer Depots, 10 cafeterias and 33 Bargain Harold's.