Sulfonamide drugs

The sulfonamides, also known as sulfa drugs, halt the growth of bacteria. Their discovery paved the way for cheap and effective treatment of often fatal infections, including certain types of pneumonia.

Chemical Dyes Yield Medical Results

Before 1932, no synthetic (manufactured) chemicals existed for the treatment of bacterial infections. A new era in medicine was ushered in by German chemist Gerhard Domagk (1895-1964). It was Domagk who began a search for chemical substances to kill bacteria within the human body.

Domagk worked for I. G. Farben, a German chemical company. At Farben he served as director of the Laboratory for Experimental Pathology and Bacteriology. Domagk examined the properties of dyes synthesized by his colleagues, testing them for use as drugs. He found that dyes containing a sulfonamide group seemed to bind tightly to wool fabrics. Because both wool and bacteria are proteins, Domagk was interested. He reasoned that such dyes might fasten themselves to bacteria, inhibiting or killing them. In 1932 he discovered that a dye called Prontosil controlled streptococcal infections (strep) in mice. Prontosil also controlled staphylococcal infections in rabbits with no harm to the animals.

Testing the Drug

Domagk's employer began to test Prontosil on infections in humans. Domagk himself had an unexpected opportunity to test the dye's effectiveness close to home. The prick of a needle in his lab accidentally infected his young daughter with strep bacteria. While still uncertain of what the outcome would be, Domagk gave her Prontosil. She made a rapid recovery. It was suddenly clear that Prontosil had the ability to control streptococcus infections in humans. In 1936 Prontosil was given to the son of Franklin Delano Roosevelt (president of the United States from 1933-1945). Franklin D. Roosevelt, Jr., initially thought to be dying, then rapidly recovered from a streptococcal infection.

Improving the Drug

In 1936 French chemists Jacques and Thérése Trefouel, working with Daniele Bovet (1907-1922), separated sulfanilamide from Prontosil. Sulfanilamide is the parent sulfa compound. The researchers found that sulfanilamide, and not the dye itself, killed bacteria. Since then, more than 5,000 sulfa drugs have been prepared and tested. Repeated use of sulfa drugs does, however, cause bacteria to become resistant. Because of this, fewer than 20 sulfa drugs have been found to continually to kill the same bacteria strains.

The introduction of antibiotics like penicillin has decreased the need for sulfa drugs. However, sulfa drugs are still useful in the treatment of infections. Streptococcal infections, urinary tract infections, and ulcerative colitis (a digestive track disorder) are all treatable with sulfa drugs. In addition, sulfanilamide is still commonly used in veterinary medicine.