Malcolm Gladwell's June 16 article "Researchers Identify Haldol as HIV Partial Suppressant" is an excellent example of how new uses for existing drugs can and should be used to treat society's most devastating illnesses.

Although new discoveries in drug therapy, or "breakthroughs," are important and certainly attract public and press attention, clearly, the process of finding new uses for existing drugs opens the way for even more dramatic progress in treatments, at a faster pace and lower cost to health care providers, insurance companies and the public.

However, this kind of vital research may be in jeopardy. To help hold down health care costs, Congress is considering legislation to limit the types and varieties of drugs available for Medicaid patients. This will reduce industry incentive to expand the pool of existing drugs, and fewer new uses will come from a smaller pool. In addition, the poor would be denied access to the drugs best suited to treat individual health problems.

Yes, health care costs must be controlled. And the pharmaceutical industry is working hard to find ways to do just that. But are we willing to give up the hope of treating or curing an illness simply because government officials say that certain medications are not immediately cost effective? I hope the answer will be a resounding no. RICHARD A. LEVY Vice President, Scientific Affairs National Pharmaceutical Council Reston

I find it ironic that in The Post's article about the failures of AIDS education {"Failures Seen in Education on 'Safe Sex,' " front page, June 24} used the out-dated and incorrect term "high-risk group" when discussing the AIDS epidemic. There is no such thing as a high-risk group, only high-risk behavior. Simply being a gay man or a sexually active heterosexual youth does not make one at high risk of contracting the AIDS virus. A person must participate in high-risk behavior to be at high risk for AIDS.

DONNA L. PIERCE Greenbelt