George Herbert Hitchings researched and developed medications that targeted specific parts of DNA replication processes to treat cancers and various illnesses in the US during the twentieth century. By studying DNA analogs, or manmade substances that resemble the structure of naturally occurring DNA components and are capable of inhibiting DNA replication, Hitchings promoted a novel approach to pharmaceutical research and drug development, known as rational drug design. Using that novel approach, Hitchings and his research team created acyclovir, one of the first medications to effectively treat herpes, a condition that can be sexually transmitted but can also be passed from mother to child, causing life-threatening illness in infants. Hitchings also contributed to the development of cancer treatments, immunosuppressant medications, anti-viral medications, and anti-malarial medications. Hitchings’s research on DNA analogs established rational drug design as a method to create new pharmaceutical drugs, some of which treat sexually transmitted illnesses.

Acyclovir is an antiviral medication that scientists developed in the twentieth century to treat herpes, a disease caused by the viruses herpes simplex virus-1 and herpes simplex virus-2, or HSV-1 and HSV-2. The viruses cause painful lesions to develop on the mouth and genitals. Herpes is a very common condition and acyclovir was one of the first medications to effectively heal and reduce the duration of lesions caused by HSV-1 and HSV-2. Scientists at Wellcome Research Laboratories in Research Triangle Park, North Carolina, developed acyclovir with the specific aim of inhibiting the replication process of HSV-1 and HSV-2 in a host’s cell, which was a novel approach to drug development at the time. Physicians have since used acyclovir to treat other diseases caused by herpesviruses. Scientists have developed new drugs for the treatment of genital herpes based on acyclovir’s mechanism of action and, as of 2024, physicians still prescribe acyclovir to treat oral and genital herpes, providing relief to the millions of people living with herpes globally.

Penicillin is a type of drug called an antibiotic that can treat bacterial infections by killing the bacteria or making it difficult for the bacteria to grow. Before the availability of antibiotics, physicians could do little to help patients with bacterial infections, and many of those patients died of those infections. In 1928, Alexander Fleming, a Scottish physician, found a fungus growing in his lab that prevented the growth of certain bacteria. He termed the bacteria-killing substance penicillin. Later researchers built on Fleming’s findings and developed the substance into a drug, which became widely available after 1945. Penicillin was one of the first medications that could safely and effectively treat acute bacterial infections, such as staph infections and strep throat, as well as chronic bacterial infections such as syphilis. Additionally, by studying the mechanism of how penicillin works, researchers have created many other antibiotics. Penicillin and other antibiotics have allowed physicians to treat countless bacterial infections, and to develop new strategies to fight bacterial resistance to those antibiotics, saving the lives of millions.