Key Terms You Must Know

📖 Key Terms You Must Know

Magic bullet

A term coined by Paul Ehrlich for a chemical compound that would selectively kill disease-causing bacteria inside the body without harming the patient's healthy cells. The concept was revolutionary because before Ehrlich, medicine had no way of targeting the cause of an infection — treatments could only manage symptoms. Salvarsan (1909) was the first successful magic bullet, killing the syphilis bacterium. The term is now used more broadly to describe any highly targeted medical treatment.

Salvarsan (Compound 606)

The first synthetic chemical drug, developed by Paul Ehrlich and his assistant Sahachiro Hata after testing 606 compounds. It targeted the bacterium Treponema pallidum, which causes syphilis, and was first used clinically in 1910. Despite side effects (it contained arsenic), it was far more effective than any previous treatment and transformed the lives of syphilis patients. It is called Compound 606 because it was the 606th compound Ehrlich tested — emphasising the systematic nature of his research method.

Sulphonamides (sulpha drugs)

A class of synthetic antibacterial drugs derived from Prontosil, discovered by Gerhard Domagk in 1932. The active ingredient, sulphonamide, inhibited bacterial growth. Sulphonamides were effective against streptococcal infections (blood poisoning, scarlet fever, puerperal fever) and were widely used in the 1930s and early 1940s before penicillin became available. They saved many lives during WW2. Domagk received the Nobel Prize for Medicine in 1939, though the Nazi government initially prevented him from accepting it.

Paul Ehrlich (1854–1915)

German scientist who developed the concept of the magic bullet and discovered Salvarsan. He worked in Koch's laboratory, where his deep knowledge of bacterial staining and immune responses led him to the idea of chemically targeting specific bacteria. His systematic research method — testing hundreds of compounds in a deliberate programme — was as influential as the specific discovery of Salvarsan. He received the Nobel Prize for Physiology or Medicine in 1908. His approach established the pharmaceutical research model that underpins drug discovery today.

Gerhard Domagk (1895–1964)

German bacteriologist and pharmacologist working for Bayer who discovered that the red dye Prontosil had antibacterial properties (1932). He tested it on streptococcal infections in mice and eventually on his own daughter when she developed a life-threatening blood infection. Prontosil's active ingredient — sulphonamide — became the basis for an entire class of drugs used throughout the 1930s and WW2. Domagk's work was a crucial bridge between Ehrlich's magic bullet concept and the antibiotic era.

Prontosil

A red azo dye discovered by Domagk in 1932 to have antibacterial properties against streptococci. It was the first commercially available sulphonamide drug. French scientists at the Pasteur Institute later discovered that the active antibacterial component was sulphonamide — a simpler compound that could be produced cheaply without infringing Bayer's patent. This led to rapid development of multiple sulpha drugs across Europe and America in the mid-1930s.