Guinter Kahn liked to say that there had always been three things in history that could never get a patent: a divining rod, a perpetual motion machine and anything to grow hair. He was wrong about the last one.
In 1986, the United States Patent and Trademark Office added Dr. Kahn’s name to the first patent ever granted for a baldness remedy, minoxidil, which is sold under the brand name Rogaine. It was an achievement for which hundreds of inventors over many years had filed patent applications, none successfully.
Minoxidil, which is applied directly to bald spots, was the only hair-raising drug ever approved by the Food and Drug Administration until 1977, when the agency approved finasteride, which is taken as a pill and sold under the brand names Proscar and Propecia.
Dr. Kahn, a rich, philanthropic, partly bald dermatologist — he was allergic to his own discovery — died on Wednesday in Miami, his daughter, Michelle Kahn, said. He had a stroke in 2006 and had been in a nursing home. He was 80.
Minoxidil had its drawbacks: It works best on earlier stages of baldness, and has to be applied twice a day to keep hair growing.
“But for its time, the treatment was revolutionary,” the American Hair Loss Association said on its website.
Dr. Kahn won recognition for his achievement only after a long, fierce legal battle.
The effort began in the late 1950s, when the Upjohn Company developed a chemical compound in pursuit of a new ulcer treatment. In trials using dogs, the compound did not help ulcers, but it did lower blood pressure. Upjohn synthesized more than 200 variations of the compound, including the one it made in 1963 and named minoxidil.
The company then requested, and received, permission from the F.D.A. to test the new drug as medicine for hypertension. It asked one of its consultants, Charles A. Chidsey, to study minoxidil at the University of Colorado’s medical school in Denver, where he was a professor.
In early 1971, Dr. Chidsey observed hair growth on patients who had taken the drug for hypertension. He asked the advice of a colleague at the school, Dr. Kahn, and Dr. Kahn’s medical resident, Dr. Paul J. Grant.
Dr. Kahn and Dr. Grant began examining the patients, including a woman who was sprouting hair all over her body. When they administered minoxidil to others, hair sprouted on their bodies.
“Right off the bat,” Dr. Grant told The Miami Herald in 1988, referring to Dr. Kahn, “he said, ‘Boy, this would be great stuff if we could apply it to the top of heads.’ ”
So they set about blending minoxidil in a solution that could be applied topically, and they hit on just the right formula.
“We were lucky that we chose the appropriate solution to put the minoxidil in,” Dr. Grant told The Herald. “We were lucky that we chose the correct percentage of minoxidil to put in the solution. Too much and we may have had negative side effects. Too little and we may have had no result.”
On Dec. 10, 1971, Dr. Kahn and Dr. Grant went to Upjohn’s headquarters in Kalamazoo, Mich., where they briefed scientists and executives. Dr. Kahn told them that the drug was a potential “gold mine,” Dr. Grant recalled.
They also made a demand: a 2 to 4 percent stake in the sale of all Upjohn products that included a topical minoxidil, according to a history prepared by the company. The executives did not directly answer them.
On Dec. 29, Upjohn, today a unit of Pfizer, filed a formal patent application for minoxidil as a hair-growing drug, naming Dr. Chidsey as the sole inventor. (He had been the first to report the growth of hair in conjunction with the drug.)
Upjohn then notified the F.D.A. that Dr. Kahn and Dr. Grant had experimented with minoxidil without the proper approvals from the agency. Upjohn did not tell the researchers about the patent application, but it did give them $6,000 to do more research on animals, an amount Dr. Kahn ridiculed as measly.
On their own, Dr. Kahn and Dr. Grant experimented on a balding person for the first time in 1973. The drug worked wonderfully, they found, and they filed a patent application the next year, only to find that an application for the same drug and the same use had already been filed. They said that they had told Dr. Chidsey about their successes before the Upjohn application, with only his name on it, had been filed.
The upshot was that they agreed to a proceeding in which the patent office would decide the issue. In the meantime they settled the financial aspects of the dispute, with Dr. Chidsey, Dr. Kahn and Dr. Grant all receiving substantial royalties.
In 1986, the patent office added Dr. Kahn’s name to Dr. Chidsey’s. Dr. Grant’s name was left off. But he told The Herald, “I’d be much more upset if they took my name off the royalties.”
In a 1987 interview with the British newspaper The Daily Mail, Dr. Chidsey accused Dr. Kahn and Dr. Grant of pilfering the drugs they had used in their tests, of not getting proper permission from Upjohn and federal regulators, and of putting money ahead of medicine. “It was cheap,” he said. “It was tacky.”
Upjohn went on to spend $100 million developing Rogaine, which the F.D.A. approved in 1988. In 1996, its patent expired, allowing the product to be sold over the counter under other brand names.
Dr. Kahn was born in Trier, Germany, on May 11, 1934. His family, which was Jewish, fled Germany in 1938 to escape the Nazi terror and immigrated to the United States. The family settled in Omaha. Despite knowing little English at first, he graduated from high school in three years. He then graduated from what is now the University of Nebraska at Omaha in three years.
Dr. Kahn earned his medical degree from what is now the University of Nebraska Medical Center in 1958. He was an Army emergency room doctor in Germany in 1959-60. After training at the University of Miami’s medical school, he became acting head of the University of Colorado’s dermatology department.
In 1989, the Intellectual Property Owners Foundation named Dr. Kahn and Dr. Chidsey “distinguished inventors.”
Dr. Kahn later maintained a private dermatology practice in Miami. His philanthropy included financing a new addition to the library at the University of Nebraska. He also lectured in the United States and Europe about the part doctors had played in the Holocaust.
In addition to his daughter, Dr. Kahn, who was divorced, is survived by his companion, Judy Felsenstein; his son, Bruce; his brother, Marcel; and two grandchildren.