The Food and Drug Administration, as part of a general push to speed up the availability of new drugs, yesterday announced the first approval of a medicine to help protect against deadly second heart attacks.

FDA Commissioner Dr. Arthur Hull Hayes Jr., said that use of this drug, timolol, as well as similiar drugs, will usher in a "new era in the treatment of heart disease, the nation's number one killer."

He said according to conservative estimates, 350,000 Americans receive treatment for heart attacks each year and would be "prime candidates" for followup drug therapy. Without treatment, about 15 percent, or 50,000, can be expected to die of their heart disease within two years, said Hayes.

The scientific data from a recent Norwegian study submitted to support the effectiveness of timolol suggests that the long-term use of the drug could cut the death rate by more than one-third.

"That will mean that about 17,000 of these people will live longer. Even if we can do half as well in practice as was done in the controlled Norwegian study, we may save 7,000 to 10,000 Americans a year," said Hayes.

Hayes told reporters that timolol was a "fast track" drug which had benefited from stepped-up approval procedures because it offered an "exciting therapy for patients." He said that the agency's decision to use a foreign study as the basis for approval was unusual, but that it was "good data" and another American study might not be justified.

Hayes said there was "no question" that he has tried to speed up the approval of new drugs, as long as safety and effectiveness is well demonstrated. An FDA spokesman later indicated that this may well be a "record year" in terms of the numbers of approvals of new drugs.

The press conference was the second in two weeks to highlight drug approvals. Both timolol, whose trade name is Blocadren, and a vaccine against hepatitis B announced last week are manufactured by Merck, Sharp and Dohme. Hayes said that they simply happened to "come along at this time."

Timolol is one of a group of drugs known as "beta blockers," which act on the nervous system and slow heart rate. They previously have been used to treat high blood pressure and angina. Last month a federal study involving a similiar drug, propranolol, also found it effective in preventing second heart attacks.

Hayes noted that timolol, which has been used to treat glaucoma, is the first of the five beta blockers already on the market to receive specific approval for victims of heart attacks. The agency is awaiting studies on some of the other drugs before they also are approved for this purpose, but doctors are free to prescribe available drugs as they choose.

A company spokesman said that use of timolol twice a day in tablet form is expected to cost 60 to 75 cents. He said the drug will be available next month.

The Norwegian study on timolol, involving 1,884 heart attack victims, showed that when the drug was begun soon after an initial heart attack--from 7 to 28 days--and continued for up to 33 months, the risk of death was reduced by 39.4 percent. The risk of a second heart attack decreased by 28.4 percent.

About 17 percent of those who did not receive the drug died during the study, compared to only 11 percent of those receiving the drug. About 20 percent of those not treated had a subsequent heart attack, while 14 percent of those on treatment did.

Hayes emphasized that timolol was not a "miracle" drug for everyone, since those with conditions such as bronchial asthma should not receive it. He also noted that researchers do not know how long patients should remain on the drug. Such information will require additional, expensive long-term studies.

The side effects include fatigue and lethargy, said the FDA commissioner.