4.3.1.9 Discovery and development of drugs

digitalis

the plant foxglove was used to extract the heart drug digitalis

asprin

this painkiller was extracted from willow trees

penicillin

drugs were also extracted from microorganisms. The scientist Alexander Flemming discovered penicilin in the mould pencillium

Plants

The chemicals that plants use to kill pests and pathogens can be used to treat symptoms or human diseases.

Examples:

● Aspirin is used as a painkiller (originates from willow)

● Digitalis is used to treat heart problems (originates from foxgloves)

Microorganisms

Penicillin

○ Alexander Fleming was growing bacteria on plates

○ He found mould (Penicillium mould) on his culture plates, with clear rings around the mould indicating there was no longer any bacteria there

○ He found that the mould was producing a substance called penicillin, which killed bacteria

where do new drugs come from

they are synthesiesed by chemists working at pharmaceutical companies

but the starting point is still often a chemical extracted from a plant

what do new drugs need to be tested for

toxicity of the drug, is it safe for humans

is the drug effective and treats disease being looked at

work out the best does of the drug

what is the first testing of drug testing

Preclinical testing: using cells, tissues and live animals

not carried out on humans as the drug may be extremely toxic

second stage of drug testing

Clinical testing: using volunteers and patients ● It is first tested on healthy volunteers with a low dose to ensure there are no harmful side effects

● The drugs are then tested on patients to find the most effective dose

● To test how well it works, patients are split into two groups with one group receiving the drug and one receiving a placebo so the effect of the new drug can be observed

what is a placebo

o (appears to look like the drug but has no active ingredient so no effect) so the effect of the new drug can be observed

patients think they are being treated so they believe they are going to be better

single-blind

(only the doctor knows whether the patient is receiving the drug)

double blind

(neither the patient or doctor knows whether they are receiving the drug, removing any biases the doctor may have when they are recording the results)

peer reviewed

The results then need to be peer reviewed by other scientists to check for repeatability