Drug Discovery: A Historical Perspective

Abstract

Drug discovery has a long history and dates back to the early days of human civilization even when the diseases were considered mysterial, supernatural and terrifying. In those ancient times, drugs were not just used for physical remedies but also were associated with religious and spiritual healing. The people tried to cure diseases by eating, drinking or applying substances obtained from animal, mineral and plant sources that are now referred to as herbal medicines. At that time, there was no possibility of understanding the nature of disease. Discoveries were made and preserved based upon observations of natural phenomena and the consequences of consumption of materials that alleviated distress. Many ancient populations have reported the medicinal properties of various plant extracts and elixirs which are result of necessary trial and error search for remedies of specific ailments (Sneader, 1985; Conn, 2005). Nature has always been the single most important source of drugs or drug precursors (Verpoorte, 1998). Today"s medicines are based on traditional medicines. Traditional medicines exist in every continent of the globe and in every cultural area of the world. Among the most famous ones are Ayurvedic medicine in India, Chinese medicine in East Asia, and formerly galenic medicine in Europe, have resemblance to each other. Each of these traditional medicines has its own origin and an individual basic philosophy. These medicines included ingredients such as opium, curare, the belladonna alkaloids, and the digitalis alkaloids. The use of these medicines was passed down by each generation through traditional practices (Vogel, 1991). Most of the drugs used before 1800 were prepared with water or water/alcohol-based plant extracts as tinctures, decoctions, infusions etc., which were sometimes very efficacious (or toxic) (Jones et al., 2006). Unfortunately none of them could actually fit into modern scientific definition of a drug. However, this era provided modern drug discovery with knowledge that led to the understanding of the biological activity of some substances found in nature. The pharmaceutical years before 1800s are called the age of botanicals. It was not until the late 18 th or early 19 th centuries that an analytical investigation of active components of medicinal plants and herbal remedies was At the turn of the 20th century, medicinal chemist Paul Ehrlich (who synthesized salvarsan, (the first chemical treatment for syphilis) initiated the transition from the study of plants or their extracts with specified therapeutic activities towards the synthesis of a specific drug substance in the laboratory. The discovery of the sulpha drugs in the 1930s further added great momentum to this concept. The synthesis of the first synthetic pharmaceutical drug, aspirin, occurred in this period which was later on recognized as universal pain reliever and this discovery spawned the era of therapeutic agents (Jack, 1997). The first documented "by chance" discovery of penicillin from the filamentous fungus, Penicillium...

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