The Food and Drug Administration proposed making an unapproved drug for Alzheimer's disease available to more patients stricken by the devastating disease by conducting a large study of its effectiveness.

Dr. Paul Leber of the FDA's division of neuropharmacological drugs products recommended the new study of tacrine, or THA, in a letter to the Parke-Davis Pharmaceutical Research Division of the Warner Lambert Co., the drug's maker."We hope you will consider discussing a proposal for a program of further study that would allow both expanded access and the rapid collection of useful scientific data," Leber wrote.

The Morris Plains, N.J., company failed last week to convince an FDA advisory panel to recommend approving the drug, which would be sold as Cognex. The committee said there was not enough evidence of the drug's effectiveness.

E. Peter Wolf, a company spokesman, said the firm would discuss the proposal with the FDA. But Wolf noted the company planned to submit more data about the drug to the FDA by April 1 and meet with the agency after that to discuss the drug's status.

FDA spokeswoman Faye Peterson said the concept of making an unapproved drug available to more patients while further testing is done is similar to what has been done for some promising AIDS drugs.

"It's a way for people to get a drug that has been through initial phases of testing. If the drug shows some potential effectiveness and safety, it can be made available this way. At the same time, you can get some good data that can be helpful," she said.