Making medicine – Biology
Discovering new medicines –
- New drugs are being developed all the time.
- Historically drugs have come from nature, as parts of plants and microorganisms
have been extracted. One of the most famous discoveries was made by Sir Alexander
Fleming, who discovered the antibiotic penicillin from the penicillium mould. By
chance, he discovered that where an agar plate of bacteria had been contaminated
by a mould, the bacteria had been killed.
Antibiotics are still very important in the fight against disease.
Plant extracts
Certain drugs can be extracted from natural sources, and have been known about for a long
time. For example, willow bark was used by the ancient Greeks to help cure fevers and
pains.
It was later discovered that the active ingredient was salicylic acid. This was modified by
chemists into the substance we call aspirin, which is less irritating to the stomach than
salicylic acid. Another example is the heart drug, digitalis which is extracted from foxgloves.
Plants are still important today, but most drugs are now created in a laboratory by scientist
at pharmaceutical companies. These companies now have synthetic versions of the plant
extracts, and use these as the starting point to develop new drugs.
The development and testing of new drugs
New drugs need to be tested and trialled before doctors prescribe them and patients take
them.
Three stages of testing drugs
There are three main stages of testing:
- Preclinical drug trials –
The drugs are tested using computer models and human cells grown in the laboratory. This
allows the efficacy and possible side effects to be tested. Many substances fail this test
because they damage cells or do not seem to work.
, - Animal trials
Drugs that pass the first stage are tested on animals. In the UK, new medicines have to
undergo these tests. But it is illegal to test cosmetics and tobacco products on animals. A
typical test involves giving a known amount of the substance to the animals, then
monitoring them carefully for any side-effects.
- Human clinical trials
-Drugs that have passed animal tests are used in clinical trials. They are tested on healthy
volunteers to check that they are safe. The substances are then tested on people with the
illness to ensure that they are safe and that they work. Low doses of the drug are used
initially, and if this is safe the dosage increases until the optimum dosage is identified.
Some people consider drug trials to be dangerous. Everything comes with a level of risk.
A historical case study - Thalidomide
Thalidomide is a medical drug that caused unexpected and serious damage to unborn
babies in the 1950s and 1960s.
- Thalidomide was developed as a sleeping pill, but it was also thought to be useful for
easing morning sickness in pregnant women. Unfortunately, it had not been tested
for use in this way.
Birth defects
By 1960, thalidomide was found to damage the development of unborn babies, especially if
it had been taken in the first four to eight weeks of pregnancy. The drug led to the arms or
legs of the babies being very short or incompletely formed.
- More than 10,000 babies were affected around the world. As a result of this
disaster, thalidomide was banned. Drug testing was also made more rigorous than
before.
Thalidomide today
Thalidomide is now used as a treatment for leprosy and bone cancer. Its use is heavily
regulated, however, to prevent a repeat of the problems it caused in the last century.
Discovering new medicines –
- New drugs are being developed all the time.
- Historically drugs have come from nature, as parts of plants and microorganisms
have been extracted. One of the most famous discoveries was made by Sir Alexander
Fleming, who discovered the antibiotic penicillin from the penicillium mould. By
chance, he discovered that where an agar plate of bacteria had been contaminated
by a mould, the bacteria had been killed.
Antibiotics are still very important in the fight against disease.
Plant extracts
Certain drugs can be extracted from natural sources, and have been known about for a long
time. For example, willow bark was used by the ancient Greeks to help cure fevers and
pains.
It was later discovered that the active ingredient was salicylic acid. This was modified by
chemists into the substance we call aspirin, which is less irritating to the stomach than
salicylic acid. Another example is the heart drug, digitalis which is extracted from foxgloves.
Plants are still important today, but most drugs are now created in a laboratory by scientist
at pharmaceutical companies. These companies now have synthetic versions of the plant
extracts, and use these as the starting point to develop new drugs.
The development and testing of new drugs
New drugs need to be tested and trialled before doctors prescribe them and patients take
them.
Three stages of testing drugs
There are three main stages of testing:
- Preclinical drug trials –
The drugs are tested using computer models and human cells grown in the laboratory. This
allows the efficacy and possible side effects to be tested. Many substances fail this test
because they damage cells or do not seem to work.
, - Animal trials
Drugs that pass the first stage are tested on animals. In the UK, new medicines have to
undergo these tests. But it is illegal to test cosmetics and tobacco products on animals. A
typical test involves giving a known amount of the substance to the animals, then
monitoring them carefully for any side-effects.
- Human clinical trials
-Drugs that have passed animal tests are used in clinical trials. They are tested on healthy
volunteers to check that they are safe. The substances are then tested on people with the
illness to ensure that they are safe and that they work. Low doses of the drug are used
initially, and if this is safe the dosage increases until the optimum dosage is identified.
Some people consider drug trials to be dangerous. Everything comes with a level of risk.
A historical case study - Thalidomide
Thalidomide is a medical drug that caused unexpected and serious damage to unborn
babies in the 1950s and 1960s.
- Thalidomide was developed as a sleeping pill, but it was also thought to be useful for
easing morning sickness in pregnant women. Unfortunately, it had not been tested
for use in this way.
Birth defects
By 1960, thalidomide was found to damage the development of unborn babies, especially if
it had been taken in the first four to eight weeks of pregnancy. The drug led to the arms or
legs of the babies being very short or incompletely formed.
- More than 10,000 babies were affected around the world. As a result of this
disaster, thalidomide was banned. Drug testing was also made more rigorous than
before.
Thalidomide today
Thalidomide is now used as a treatment for leprosy and bone cancer. Its use is heavily
regulated, however, to prevent a repeat of the problems it caused in the last century.
