The Food and Drug Administration has been able to streamline its process for approving new drugs to the point where, at least in one case, the manufacturer couldn't keep up with it.

Hoffman-La Roche Inc. yesterday began marketing a new prescription drug called Accutane, which could help up to 90 percent of the 360,000 Americans who suffer from severe cystic acne. But it took the company nearly four months to get the drug on the market after the FDA approved it for use last May.

"It was fast-tracked through the FDA," explained a company spokesman, "and approval came through so fast that it came as quite a surprise to everyone, including people at the FDA. Obviously they felt it was an important new drug that was needed urgently."

The company said it still needed to make decisions on what form the drug would take and its marketing strategy when the FDA approved the product, 9 1/2 months after the company submitted its application.

Although drug companies complain about the time the agency takes to get new drugs approved, the FDA has taken only 10 months, on average, over the past few years to approve drugs like Accutane that are considered to be significant advances. The firm's spokesman said, however, that it has been several years since the company had a new drug that fell into that category.

Accutane, known chemically as isotretinoin, is said to help those who have been unable to treat their lesions with the creams and pills that are now on the market. Hoffman-La Roche describes the product as a "medical breakthrough" because it can "reverse the physical and social trauma that accompanies" cystic acne. FDA Commissioner Arthur Hull Hayes Jr. used similar words when he announced the drug's approval, saying "it holds promise for the many sufferers of this physicially and psychologically debilitating disease."

The United States is the first country to approve the drug's use, a fact Reagan administration officials noted prominently when approval was announced.

After Hoffman-La Roche submitted its application last year, Accutane was classified 1A, the FDA's top priority. Eighteen other drugs were given that designation last year, and half have been approved.

The agency also approved 27 new drug compounds last year, the most in the 20 years since the new drug approval process was put in place, and 15 more than the year before.

When the FDA approved Accutane, it had been tested on 170 patients at the National Cancer Institute and at four universities. Hoffman-La Roche estimates that 500 people have been treated with the drug and that the success rate is about 75 percent.

But there is some concern about potential side-effects. The drug has been shown to cause birth defects in laboratory animals, and dries out the mucous membranes. Ninety percent of those who took the drug in field tests developed chapped lips, nearly half developed conjunctivitis, some reported fatigue and a few developed rashes, alopecia, skin infections and an increased sensitivity to the sun. Chemical abnormalities were also found in the livers of some patients.

Because of the potential problems, the drug is not supposed to be used by pregnant women or those with liver problems.

"I hope this drug will not be abused and used for mild acne," said Dr. Brent Schillinger, who participated in clinical trials involving 55 patients at the Downstate Medical Center of the State University of New York. "For our patients, some of whom have suffered chronic cystic acne for 25 years, we were able to help 80 to 90 percent of them.

But, he added, "It has only been tried on a few people and more work needs to be done before we could decide whether it would help them."

An FDA spokesman said yesterday that an agency advisory panel considered that a 170-patient sample, in combination with the animal and laboratory studies performed, was sufficient to demonstrate the drug's safety and efficacy.