An experimental Swiss drug soon could double the number of successful kidney transplants, a study presented to the American Society of Transplant Surgeons indicates.

"What this means is that the kidney survival rate, which is now 50 percent, will probably go up to about 80 percent, and for the first time we have been getting good results from all the research centers testing a drug such as this," Dr. Barry Kahan, director of the Organ Transplant Clinic at the University of Texas in Houston, said.

"Right now, there are about 4,000 successful kidney transplants per year in the United States. With the use of cyclosporine, I see the potential of that figure doubling," he said.

Cyclosporine A, marketed by the Sandoz Co. of Basel, Switzerland, under the brand name "Sandimmune," apparently can disarm the body's natural inclination to reject an invading substance, yet allow the body's infection defenses to stay on the job.

"It seems to exhibit what we call 'marked selectivity,' the ability to hit cells that reject foreign objects from the body but leave the infection-fighting cells alone," Kahan said. "Kidney transplants have had a very narrow 'window,' the space between the amount of drug needed to keep the kidney and the amount of drug that could cause so much suppression that the kidney gets infected. What cyclosporine does is increase the size of that window."

Besides UT-Houston, research centers contributing to the test results were the University of Minnesota; the Peter Bent Brigham Hospital in Boston, affiliated with Harvard University, and the University of Pittsburgh.

Cyclosporine recently received a 1A rating from the Food and Drug Administration, placing it near the head of the line when its license application is submitted for approval Sept. 1.

Kahan said he is optimistic that cyclosporine will increase the survival rate of heart and lung transplant patients as well, but those experiments in Houston and at Stanford University are too preliminary to produce meaningful statistics.

One of the physicians working with Kahan is Dr. Denton Cooley who, in 1968, performed the first successful heart transplant in the United States.