GCSE AQA: Biology 1.3

Core Science biology 1.3

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Biology B1.3 The use and abuse of drugs
Scientists are continually developing new drugs:
New drugs are constantly being developed and must be tested in a series of stages to find out if they are safe
and effective.
New drugs are extensively tested for toxicity (serious side-effects), efficacy (capacity for producing the
desired medical effect) and dose (effect of different amounts):
o Drugs are tested in the laboratory, using cells, tissues first and then live animals, but drugs that affect
the whole body eg a blood pressure reducing drug, a blood cancer drug etc., can only be satisfactorily
tested in the end by using 'real people'.
o A drug may be tested on two or more live animals, to many people's objection (animal rights ethical
issue) but many scientists would argue this reduces the risks when testing the drug with human
volunteers.
o The first drug trials would be on healthy people, before doing further drug trials testing the drug on ill
patients.
o Very low doses of the drug are given at the start of the clinical trial to look for side-effects.
o The drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug
- the dose that is most effective with little side-effects.
It is almost impossible to develop a drug that has no side-effects with anyone. I'm afraid we all have slightly different
body chemistry and a certain % of people will show some undesired reaction to the drug.
In some double blind trials, some patients are given a placebo, which does not contain the drug.
A placebo, which is delivered like the actual drug (eg look and taste), contains no medication and enables the
clinicians to distinguish the effects of the drug from the volunteers who have not received the drug.
You can even do an extra check to avoid 'human bias' by doing a 'double-blind' drug trial in which the doctors or
pharmaceutical scientist don't know who is or is not given the drug until all the results are collated. This
hopefully avoids any prejudice on the part those conducting the trial.
Neither the doctors nor the patients know who has received a placebo and who has received the drug until the
trial is complete.
Statins are prescribed drugs that help reduce cholesterol levels and research trials have shown they can have a
significant effect in diabetic patients.
Increased cholesterol levels in your blood can lead to cardiovascular disease.
The statins drug trials were done using a large sample of people and half were given the drug and half were not.
Nobody knew who had the drug, half were given statins, but the other half, the control group, had a placebo -
a substance containing NO medication.
Several independent studies like this 'blind trial' have shown that people treated with statins had reduced
cholesterol levels.
Thalidomide is a drug that was developed as a sleeping pill in the 1950s.
o It was also found to be effective in relieving morning sickness in pregnant women.
o Thalidomide had not been tested for use in pregnant women; in particular it was not tested for relieving
morning sickness.
o It was unknown that the drug could pass through the placenta and into the foetus, it caused abnormal limb
development.
o Thousands of babies were affected and about half survived with missing limbs or malformed limbs.
o After many babies born to mothers who took the drug were born with severe limb abnormalities the drug was
banned.
o As a result, drug testing has become much more rigorous in an attempt to reduce the incidence of serious
side-effects from newly developed drugs.
o More recently, thalidomide has been used successfully in the treatment of leprosy and other diseases.

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The effects of misuse of the legal recreational drugs, alcohol and nicotine:
The misuse of the illegal recreational drugs ecstasy, cannabis and heroin may have adverse effects on the
heart and circulatory system.
Drugs may be described as 'hard' or 'soft'. Hard drugs, like heroin, are generally more addictive and potentially
harmful
Soft drugs like cannabis are implicated with mental health effects, heart and circulatory problems and chemicals
in the smoke and tar are carcinogenic - probably more than filter cigarettes.…read more

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