The word drug is derived from the French word ‘Drogue’ which means a dry herb. Thus a drug is defined as an agent intended for use in the diagnosis, mitigation, treatment, cure or prevention of disease in man or in other animals.

The use of drugs undoubtedly dates beyond recorded history. The instinct of primitive man to relieve the pain of a wound by bathing it in cool water or soothing it with a fresh leaf or protecting it with the application of mud and animal excreta, is all within the  scope of superstition and belief. It was Charak, a renowned ancient Indian physician, and later Sushruta, who described various medicinal preparations in Ayurveda. The ‘Charaka Samhita’ dealing mostly with plants and ‘Sushrut Samhita’ dealing with surgery are the best known ancient treatises in Ayurveda. The efficacy of Amla fruit as a tonic, the use of  Raulwolfia serpentina as a tranquilizer, the antileprotic action of Chaulmoogra fruit and stems of Aswagandha as a sedative were known to ancient Indians.

The synthesis of phenacetin as an analgesic (pain killer) in 1889 and aspirin in 1899 as an antipyretic (fever reducing) are perhaps the earliest efforts to find a new source of drugs based on synthetic organic chemistry. Early research to find synthetic drugs was focused on anesthetics (eather, chloroform and laughing gas), hypnotics (chloral hydrate and paraldehyde) and analgesics (phenacetin, aspirin etc.).

The pioneering work of Paul Ehrlich, a German bacteriologist and organic chemist (1854-1915) led to the emergence of chemotherapeutic drugs. The greatest impact in medicine was made by Louis Pasteur’s (1822-1895) development of a vaccine for hydrophobia (rabies). The medical field has been revolutionized by the phenomenal success of sulpha drugs and antibiotics. Sulpha drugs such as prontosil, sulphanilamide and sulpha diazine were the first compounds in the early 1930s found effective against bacterial diseases such as tuberculosis, pneumonia and diphtheria.

Gerhard, a German scientist, was testing certain drugs for their effect on germs in rats in the early 1930s. His daughter accidentally cut her fingers with a blade while playing, and infection set in. Every attempt was made including surgery to stop the spread of deadly infection but all failed. The doctors declared that there was no hope. In desperation Gerhand gave his little girl oral doses of one of the drugs that he was testing. Her fever dropped quickly and she recovered soon. He previously discovered that prontosil, a sulpha compound would cure infected mice and rabbits with no harmful side effects to the animals. Gerhard’s work attracted many researchers and within a few years, a number of sulpha drugs were prepared and tested. As a tribute to his pioneering work in the synthesis of sulpha drugs, Gerhard was selected for the 1939 Nobel Prize in medicine but Hitler, the then German Nazi ruler prohibited him from accepting it.

Penicillin was the first antibiotic to be discovered by Alexander Fleming in  1929. The first successful clinical trial of crude penicillin in 1941 and its requirements during war time led the discovery of a number of antibiotics such as streptomycin in 1943, chloro- amphenicol in 1947, chloro- tetracycline in 1948, neomycine in 1949, erythromycine in 1952, ampicillin, amoxicillin and many more earning that period a lasting place in history as the antibiotic age.

The early 1980s witnessed the products of modern pharmaceutical biotechnology. Some of the drugs are found to contain two isomers out of which one is effective towards microorganisms. Separation of isomers leading to effective isomer was possible due to efforts of three scientists namely Noles, Sarples and Neyori. These three scientists were honoured with nobel Prize for the year 2001. The two optically active isomers are called destro and laevo isomer. Many of us know the use of laevo cetrizine for the use in cold and laevo floxanine for its use in throat infection.

For an effective use of L-Dopa in the treatment of parkinson disease brought Nobel Prize to Carlson in Physiology and Medicine in 2000. Vigorous research is going on synthesis and use of new medicines for the treatment of new kinds of diseases arising in recent years.