Penicillin, Antibiotics and Testing new drugs By Sophie McGuckin

Antibiotics Antibiotics are substances that kill bacteria or prevent their growth. They do not work against viruses. It is difficult to develop drugs that kill viruses without damaging the body’s tissues. Drugs like paracetamol are different to drugs like penicillin because penicillin is an antibiotic so it kills unresistant bacteria but paracetamol just relieves pain and helps symptoms. Over time, bacteria can become resistant to certain antibiotics. This is an example of natural selection. In a large population of bacteria, there may be some that are not affected by the antibiotic. These survive and reproduce, creating more bacteria that are not affected by the antibiotic.

The main steps in the development of resistance are: 1. Random changes or mutations occur in the genes of individual bacterial cells. 2. Some mutations protect the bacterial cell from the effects of the antibiotic. 3. Bacteria without the mutation die or cannot reproduce with the antibiotic present. 4. The resistant bacteria are able to reproduce with less competition from normal bacterial strains.

pENICILLIN The first antibiotic was penicillin. It was discovered by Alexander Fleming in 1928. He noticed that some bacteria he had left in a petri dish had been killed by naturally occurring penicillium mould. It was difficult for him to make a medicine from this because he couldn’t extract penicillin from mould easily. Enrst Chain and Howard Fleming later developed the process which made it possible to mass produce penicillin for medical uses. Since the discovery of penicillin, many other antibiotics have been discovered or developed. Most of those used in medicine have been altered chemically to make them more effective and more safe for humans.

Testing new drugs This is the process scientists and doctors carry out to test new drugs: A new is produced by medical scientists. The drug is tested on cells or on computer simulation tissue. The scientists gain permission to test the drug on animals. The drug is tested on animals. Then, permission is given to test the drug on a small group of healthy humans for side effects. The drug is tested on a group of healthy humans using placebos or double blind tests. Permission to test the drug on patients with the disease is then given. The drug is then tested on small groups of patients with the disease. The control group expands and in some cases doctors gather information about long term effects.