Discovery and development of drugs
Cards (12)
- Traditionally, drugs were extracted from plants or microorganisms such as moulds
- Digitalis and digoxin are drugs extracted from foxglove. Aspirin originates from a compound found in the bark of willow trees, its properties first recorded in 400 BC
- In 1982, Alexander Fleming was growing bacteria. After returning from holiday, he noticed moulds growing on his plates
- He noticed a clear ring in the agar around the spots of mould and realised something had killed the bacteria
- Fleming called the substance penicillin after the penicillium mould that produced it
- There is a drive to find new medicines but it is difficult to find chemicals that kill bacteria without damaging human cells
- A good medicine is:
- effective - it must prevent or cure a disease
- safe - it must not be too toxic or have serious side effects
- stable - you must be able to use the medicine under normal conditions and store it for some time
- Testing a new drug can take up to 12 years and cost 1.7 billion pounds
- Pre-clinical trialsNew drugs are tested in the lab on cells and tissues for efficacy (effective - cures the disease) and toxicity. If they pass the test, they are tested on animals
- Clinical trials
- The drug is now tested on healthy volunteers and patients at low dose for side effects
- Then on small number of patients for efficacy
- Larger number of patients to find the optimum dosage
- Trials on humans involve double-blind trials where half the patients are given the drug and half are given a placebo (e.g. a pill that does not contain the new drug).
- Neither the patient nor the doctor know who has received the drug or the placebo to avoid bias.
- If both groups improve in a similar way, the patients improved because of the placebo effect (when the patients improve simply because they think they are being treated for the illness)
- The results are published in scientific journals after being scrutinised by peer-review, which means other scientists can check the results