Health officials yesterday announced that an experimental drug for acquired immune deficiency syndrome (AIDS) has proven surprisingly successful in early tests and that they would quickly attempt to distribute it to as many as 60 percent of the nation's AIDS patients.

In a packed news conference at the Department of Health and Human Services, Assistant Secretary Robert E. Windom called the results of tests on the drug AZT "exciting" and said AZT is "the first therapeutic agent which seems to hold promise for some AIDS patients."

Distribution in capsules is expected to begin Sept. 29, when the manufacturer, the Burroughs-Wellcome Co., will send the first batches to qualified physicians and patients at no charge, according to David Barry, vice president for research at Burroughs.

Windom said he has asked the Food and Drug Administration to expedite approval for commercial sale of the drug.

Windom cautioned that the drug is not a cure and that promising tests, which have triggered the release of the drug, were carried out only on a limited group of AIDS victims. He said it is possible that the positive results seen so far may not persist and that unexpected side effects could appear.

A telephone hot line went into operation at noon yesterday to provide information to patients and doctors about getting AZT. The toll-free number, available seven days a week from 8 a.m. to midnight EDT is 800-843-9388.

AZT, however, will not be distributed to all callers or all 11,000 living AIDS patients in the United States. At least for the next few months AZT will be limited to AIDS victims whose key symptom is the infection called Pneumocystic carinii pneumonia, because those are the type of patients who were shown to benefit in tests of the drug.

The drug, called AZT for azidothymidine, is manufactured by Burroughs-Wellcome Co., a subsidiary of the British company, Wellcome Foundation Ltd.

AIDS is a viral infection that attacks the body's immune defenses, allowing a host of deadly infections and tumors to invade. So far, the disease appears invariably fatal. As of Sept. 15, about 13,700 victims had died from AIDS in the United States.

AZT halts the spread of the AIDS virus in the body but does not clear the body of virus already infecting cells. Sometimes the drug can regenerate the patient's immune system or halt its deterioration.

Burroughs will distribute the drug to physicians who have some expertise in treating AIDS patients, to be given to patients who meet the set criteria. The doctors will be required to make progress reports to the company.

Yesterday's announcement will trigger the review of virtually every AIDS drug experiment under way in the United States, said Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases. He said most experiments probably now will be changed to include AZT, possibly as a replacement for placebos or as a drug given in combination with others.

Fauci estimated that 6,000 to 7,500 patients will be eligible to get AZT soon. He emphasized, however, that testing with the drug must continue among other patients to determine if AZT shows promise with them.

AZT has been tested by Burroughs-Wellcome in 12 clinical centers in the United States in trials with 282 AIDS patients. Beginning in February, the drug was given to about half the patients while a placebo pill, which contained no drug, was given to the other half.

The placebo-controlled trial was stopped before it was scheduled to end because researchers decided they could not ethically continue to give placebos once it was clear that survival rates in the placebo and drug groups were markedly different.

Results from the trials were quoted at yesterday's conference: Survival rates, over the short term, were improved among those getting AZT. Sixteen of 135 patients receiving the placebo died during the trial. But only one of 145 getting the drug died.

Patients getting the drug gained weight on the average, and showed at least a short-term increase in the number of immune system cells.

The total occurrence of untoward events among the patients -- such as death or the acquisition of a life-threatening infection -- was 59 events in patients on the placebo, and 36 among those on AZT.

Negative effects of the drug include recurring mild headaches and anemia caused by suppression of the body's ability to make red and white blood cells. Some patients have needed blood tranfusions as a result, while doses were adjusted downward for others.

Dr. Samuel Broder of the National Cancer Institute said that some patients, those in the earliest tests, have been given AZT for up to a year. Among 19 in those tests, three patients died; the remaining 16 survive.

Burroughs has asked the Food and Drug Administration to approve the drug for commercial sale. Officials expect approval as early as January 1987. Windom said the drug was given "orphan drug" status last July.

"Orphan" status is usually reserved for drugs that would afford a manufacturer little profit because they treat rare conditions. It grants a company an exclusive market for seven years, as well as offering special tax incentives.

Some groups not eligible for the drug may still be included in placebo-controlled trials. Among those being considered are those infected with the AIDS virus who have shown few or no symptoms, and patients with the skin cancer called Kaposi's sarcoma, who generally live far longer than pneumocystis patients.

"We must not lose sight of the fact that there is still much to be learned," Dr. Fauci said. He pointed out that the information that triggered yesterday's announcement would not have been found if half the patients had not been given placebos.