There have been many drugs - for preventative purposes or cures - that have been developed throughout history. However, to determine those that are the most important, the drugs have to be developed for life-threatening conditions or paved the way for further development of other drugs. The scale of the drug's use and the amount of people it has treated must also been considered.

Taking those into account, here are the top 10 most important medicines developed.

1. Penicillin

Developed in 1928, it was one of the biggest medical innovations as it has led to the innovation and advancements of antibiotics. It has been estimated that the antibiotic has saved over 80 million lives and without its discovery, 75% of the current population would not exist. It has been used to treat many conditions such as pneumonia and scarlet fever, as well as ear, skin and throat infections. Recently, a 90-year old swatch of penicillin mould from the original laboratory of Alexander Fleming that contributed to the discovery, was sold for more than USD14,600.

2. Insulin

Insulin was discovered in 1921 by Charles Best and Frederick Grant Banting before it was commercialised in 1922. Before its use, patients were given a near-starvation diet to ward off the symptoms of diabetes, therefore it has saved many diabetic patients. It is also understood to have paved the way for future hormone therapies such as contraceptives for women that produced a profound social effect and improved women's health, and adrenaline that is used to treat anaphylaxis, cardiac arrest and superficial bleeding.

3. Aspirin

Hippocrates mentioned willow bark to treat pain, but it was not until 1899 when a pharmacist at Bayer isolated acetylsalycilc acid from willow to alleviate his father's rheumatism. Now, aspirin is widely used to relieve pain and fight inflammation caused by heart disease and numerous cancers. However, for those suffering from muscle pain, arthritis or headaches, aspirin is inappropriate due to its side-effects.

4. Smallpox vaccine

Many children died from infectious diseases especially during the smallpox pandemic - over 10% of the population died from it. Thanks to Edward Jenner and Sarah Nelmes, the milkmaid, the smallpox vaccine was developed in 1798 and wiped out the disease. This breakthrough paved the way for many vaccines to eradicate infectious diseases in the future such as polio, malaria and measles.

5. Morphine

Morphine was first discovered in 1804 by German pharmacist Friedrich Serturner. Two decades later, Merck began its commercialisation of morphine in 1827. The drug took off after the development of the hypodermic syringe in 1852. The benefits of the painkiller were also deemed to outweigh the possibility of addiction by patients. Without the drug, millions of individuals especially those on the battlefield, would have spent their lives in a great amount of pain. This discovery also opened up the discovery of a new generation of pain management drugs.

6. Ether

The discovery of ether happened 300 years before it was used as an anaesthetic by Crawford Williamson Long in 1842 to remove a tumour from the neck of his patient James M. Venable. With its development, patients did not need to be held down while having their limbs amputated or experience pain during surgeries. Over the past few decades, newer and improved anaesthetics have been developed on the basis of ether.

7. Chemotherapy drugs

Initially used as a weapon in World War I, mustard gas was one of the first chemotherapy agents to treat cancer after it proved to kill cancer cells. However, it also significantly damaged healthy cells, leading to little survival benefit. In 1956, a breakthrough by Roy Hertz and Min C. Li, uncovered methotrexate as the first drug to prove itself against cancer by curing a rare tumour called choriocarcinoma. This led to advances in chemotherapy over the past few decades which increased today's survival rates of cancer.

8. HIV protease inhibitors

Phase 1 trials of the first HIV protease inhibitor, saquinavir began in 1989, and was subsequently approved for prescription use in 1995. It was first developed by researchers working for Hoffmann-LaRoche Inc, Abbot and Merck. Four months later, two other protease inhibitors, ritonavir and indinavir, were approved. Since then, more protease inhibitors have emerged, saving the lives of many people suffering from AIDS.

9. Botox

Alan B. Scott first tested botulinum toxin A in humans in 1978 after he received permission from the FDA to study the drug's effect on strabismus. Ten years later, Allergan acquired the rights to distribute the drug and marketed it as Oculinum to treat eye muscle hyperactivity and blepharospasm. Even though it is widely used for cosmetic purposes now, botox is also used for treating hyperactive nerve disorders, relaxing the clenching of muscles including the oesophagus, jaw, lower urinary tract and bladder.

10. Warfarin

The discovery of warfarin began with hundreds of cows that succumbed to major haemorrhaging after dehorning or castration in Northern US and Canada in the early 1920s. Wisconsin-based chemist, Dr Karl Paul Link dived into the problem in 1933 and managed to isolate and identify the molecule dicoumarol in 1939. A more potent version of dicoumarol was named warfarin, and approved as a rat poison. But its medical usage was realised after it was found out that the effect could be reversed with vitamin K. 60 years on, warfarin has played a role for clotting conditions. MIMS

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