A history of medicines

Medicines have been used for thousands of years. Early medicines were not only aimed at curing disease, but were also used for spiritual healing and were administered by religious or spiritual leaders. The first medicines were usually made from plants. For example, the early Egyptians used willow leaves as an antiseptic dressing for wounds. Most early medicines were probably discovered through trial and error, and there was no formal testing to find out whether or not a medicine was effective and safe to use. Indeed, in many cases the treatments did not work and had dangerous side effects. Nevertheless, we now know that plants contain a large variety of chemicals, many of which can have an effect on illness and disease. Some historical remedies did have curative properties; indeed, some early plant-based medicines have been refined by chemists to develop modern medicinal products. For example, the active substance reserpine, which is used to lower blood pressure, is derived from the ‘Indian snakeroot’ or ‘sarpagandha’ (Rauwolfia serpintina) plant, which has been used for centuries in Eastern medicine.

Rauwolfia serpintina

Figure 1.1 Rauwolfia serpintina ("Rauvolfia serpentina in Kudayathoor" © 2010 Jeevan Jose, Kerala, India is used here under a Creative Commons Attribution-ShareAlike 4.0 International License)

We did not begin to develop a detailed understanding of the mechanisms of disease until the 18th century, when scientists made the link between symptoms and the physical changes observed in the organs of people who had died from different diseases. Gradually, the study of disease became more common, and in the 19th century scientists started to make the link between germs (microorganisms, such as bacteria) and disease. Previously, it was believed that the microorganisms present in disease suddenly appeared in the body. A French scientist, Louis Pasteur, was the first to disprove this, and called his breakthrough the ‘germ theory’. Using a series of experiments that he carried out during the 1860s, Pasteur showed that microorganisms are, in fact, transferred from one source to another in the environment, and thus they could cause disease by attacking the body from the outside.

Towards the end of the 19th century, scientific laboratories became more sophisticated and chemists started to produce medicines synthetically. Painkillers were among the first active substances that were mass produced and widely used. Plant-based medicines, such as opium, were refined by chemists to make substances such as morphine and codeine, and in 1874 acetylsalicylic acid was designed based on a molecule extracted from the bark of willow trees. By the early 1900s the first pharmaceutical companies had been established to develop and produce medicines.

The late 20th century saw progress in our understanding of the human genetic code (the molecules contained in each cell that hold instructions on how to build and maintain cells) and the proteins that make up our cells, leading to the development of new classes of medicines, such as biologics and gene therapy. Now, at the start of the 21st century, some of these new classes of medicines are still in the early stages of development, whereas others (e.g. the biologic version of insulin that is used in diabetes mellitus) have been in use for over three decades.