A major study of thousands of hospital patients has found that no more than one patient in 3,600 dies because a doctor prescribed wrongly - evidence, the study's director says, that "we don't have a massive epidemic of people dying from drugs."

The study by Jane Porter and Dr. Hershel Jick of Boston University Medical Center is published in this week's issue of the Journal of the American Medical Association, out today.

Jick's previous figures have been used by critics of medicine to charge that adverse reactions to prescription drugs kill 29,000 American hospital patients a year.

But his newest ones would indicate that the death toll may be no more than 9,000, a fourth of which are probably preventable.

"I think very serious adverse reactions are about as infrequent as one could possibly expect given the enormous amount of exposure to drugs," Jick said in an interview.

This does not mean that over-prescribing or wrong use of drugs does not cause harm, he added. One of medicine's strongest critics - Dr. Sidney Wolfe, director of Ralph Nader's Health Research Group - pointed out that the new Porter-Jick study does not include many classes of people who are sickened or killed by drugs.

Nonetheless, Jick is a leader in the 10-year-old Boston Collaborative Drug Program. Financed in large part by the National Institutes of Health and the Food and Drug Administration, it has been called the nation's largest, most thorough effort to measure drug induced injury.

Wolfe and others, including health leaders in Congress, have often extrapolated from Jick's earlier statistics to demand tighter regulations of drugs and the ways doctors use them.

Jick and colleagues said in 1971 that study of 6,199 patients on hospital medical wards showed 27 deaths caused by drug reactions, or a rate of 4.4 percent 1,000. In today's article, he says that report was biased by including too many chronically ill patients - patients especially susceptible to the toxic drugs they must often be given.

Today he and Porter report the result of monitoring 26,462 patients in the medical wards of hospitals in the United States and six other countries between 1971 and 1976.

Among those patients there were 24 deaths (or 0.9 per 1,000) from a reaction to the drugs they were given. Most of these, Jick said, were gravely ill patients who had to be given a possibly toxic drug even if it endangered them.