A representative drug molecule of the century

The work of chemists in developing life-saving drugs is central to modern medicine. These five drugs are among those that have transformed medical practice, the science of drug discovery, and even the very nature of society over the past 100 years.

Penicillin, one of the earliest antibiotics, has saved millions of lives by making once-fatal infections treatable. Its discovery in 1928 by Alexander Fleming—famously observed in a moldy petri dish—was a landmark in medical history. Eleven years later, Howard Florey and Ernst Chain at Oxford University tested penicillin’s bactericidal properties in mice and then humans. In 1941, a policeman in Oxford became the first patient to receive penicillin; although he initially improved, he ultimately died due to limited antibiotic supplies.

During World War II, British scientists collaborated with their American counterparts to scale up production. Penicillin was first used to treat infections in wounded Allied soldiers, and civilian use was strictly rationed. By the mid-1940s, large-scale fermentation made commercial production possible. Even today, despite the development of numerous other antibiotics, penicillin remains one of the most widely used and important antibiotics worldwide.

Chlorpromazine was one of the first drugs directly used to treat mental illness. Synthesized in December 1950 by chemists at the French pharmaceutical company Rhône-Poulenc, it arrived at a time when treatments for mental illnesses like schizophrenia were often ineffective and risky. Interestingly, chlorpromazine was not initially intended as a psychiatric drug. French physician Henri Labourie was exploring whether antihistamines could sedate patients under surgical anesthesia. In January 1952, he persuaded a colleague to administer chlorpromazine and several other medications to a 24-year-old patient with mental illness. After three weeks, the patient recovered and was discharged.

The success of chlorpromazine quickly spread worldwide, and in 1954 it was approved by the U.S. Food and Drug Administration. Its use marked the beginning of modern psychopharmacology, demonstrating that mental illness could be treated with medication and revolutionizing psychiatric practice. Even today, chlorpromazine remains in clinical use.

The oral contraceptive pill—commonly known as the birth control pill—had a transformative impact on society. While activists like Margaret Sanger and Katherine McCormick, biologist Gregory Pincus, and gynecologist John Rock are often credited with its development, chemists made the pill a practical reality.

By the 1920s, scientists knew that reproductive hormones such as progesterone could prevent pregnancy in animals. However, oral administration required impractically large doses. In 1951, chemists Carl Gerasi, Louis Miramontes, and George Rosenkrantz at Syntex synthesized norethindrone, the first progesterone analogue suitable for low-dose oral use. A year later, Frank B. Colton at G.D. Searle created a similar compound. Early trials revealed that pure norethindrone caused menstrual bleeding, so estradiol was added to formulate the first oral contraceptive.

In 1957, the U.S. Food and Drug Administration (FDA) approved Enovid, a combination of norethindrone and estradiol, to treat menstrual irregularities. By 1960, it was approved as the first oral contraceptive in the United States. Oral contraceptives gave women unprecedented control over family planning, fundamentally reshaping society.

The molecules shown here—tenofovir alafenamide, emtricitabine, and dolutegravir—are just three of over 30 drugs used in antiretroviral therapy (ART) for human immunodeficiency virus (HIV), often administered in combination. ART has transformed HIV from a death sentence into a manageable chronic disease, thanks to decades of research across academia, government, and industry.

In 1987, the U.S. Food and Drug Administration (FDA) approved zidovudine (AZT), the first drug to inhibit viral reverse transcriptase. However, AZT caused toxic side effects, and the virus quickly developed resistance. Scientists realized that controlling HIV required multi-target interventions. In 1995, the FDA approved saquinavir, the first protease inhibitor, and the following year, combination therapy demonstrated effective viral suppression. Between 1996 and 1999, HIV-related mortality in the U.S. and Europe dropped by more than 50%.

Today, a wide variety of antiretroviral drugs with fewer side effects are available. ART is prescribed immediately upon diagnosis, reducing mortality, morbidity, and transmission. High-risk individuals can also take these drugs prophylactically to prevent infection.

Imatinib was one of the first drugs designed to target a specific cancer-causing mutation, laying the foundation for precision medicine. Approved by the U.S. Food and Drug Administration in 2001 and marketed as Gleevec, imatinib dramatically improved outcomes for patients with chronic myeloid leukemia (CML), raising the 5-year survival rate from 30% to approximately 90%.

Developed in the late 1990s by Brian Drucker at Oregon Health & Science University and biochemist Nicholas Linden at Ciba-Geigy (now Novartis), imatinib blocks the ATP-binding site of tyrosine kinase, which sends proliferation signals to cancer cells. In CML, this kinase is produced by a mutated gene from a chromosomal DNA exchange. Previously, pharmaceutical companies avoided kinase inhibitors due to the risk of affecting beneficial subtypes. Imatinib proved it was possible.