Lloyd H. Conover, a chemist whose breakthrough invention of one of the most effective and widely prescribed antibiotics, tetracycline, led to a whole new approach to developing such drugs, died on Saturday in St. Petersburg, Fla. He was 93. His death was confirmed by his son Craig.
Dr. Conover started his research at Pfizer in Brooklyn in 1950. Became intrigued with two naturally occurring antibiotics that, except for two atoms, were chemically identical.
Using a routine chemical procedure, he stripped chlorine from one antibiotic and inserted hydrogen, creating a more stable molecule. He worked with a single assistant.
The result was tetracycline, a powerful antibiotic with fewer side effects than the drug from which it was derived. Virtually all antibiotics today are semisynthetic, meaning they are chemically altered to increase the number of infections that can be treated or to reduce side effects.
By the time the litigation ended, widespread use of tetracycline had caused many kinds of bacteria to become resistant to the antibiotic, reducing its potency against many infections.
At Pfizer, Dr. Conover was assigned to a team working to determine the chemical structures of two antibiotics that turned out to be very similar. When the task was completed, the senior scientists went off to write papers about their findings, leaving Dr. Conover with time on his hands.
Dr. Conover spent his entire career at Pfizer. He went on to help invent Pyrantel and Morantel, which are used to treat parasitic worm infections, and rose through the company’s executive ranks to become senior vice president of agricultural products research and development. He retired in 1984.
Although Pfizer vigorously defended Dr. Conover’s patent, the company was less aggressive than competitors in marketing his invention.