Antibiotics, painkillers and developing drugs · GCSE Biology

Antibiotics and painkillers

Antibiotics, such as penicillin, kill infective bacteria inside the body. Specific bacteria should be treated with specific antibiotics.
Antibiotics have greatly reduced deaths from infectious bacterial diseases.
Antibiotics cannot kill viruses. It is difficult to develop drugs that kill viruses without also damaging the body's cells.
Painkillers and other medicines treat the symptoms of disease but do not kill pathogens.

Bacteria can mutate; some mutations make them resistant to an antibiotic.
When the antibiotic is used, non-resistant bacteria die but resistant ones survive and reproduce, so the resistant strain spreads (for example MRSA).
To slow resistance: doctors should not prescribe antibiotics for non-serious or viral infections, patients should complete the full course, and farmers should limit their use in animals.

Traditionally, drugs were extracted from plants and microorganisms.
Digitalis, a heart drug, comes from foxgloves. Aspirin, a painkiller, comes from willow.
Penicillin was discovered by Alexander Fleming from the Penicillium mould.
Most new drugs are now made by chemists in the pharmaceutical industry, although the starting point may still be a chemical from a plant.

New drugs are tested for toxicity (is it safe?), efficacy (does it work?) and dose (how much?).
Preclinical testing is done in a laboratory using cells, tissues and live animals.
Clinical trials use healthy volunteers first, with very low doses to check safety, then patients, to find the optimum dose.
In double-blind trials, some patients get a placebo; neither the patients nor the doctors know who gets the drug until the end, which removes bias.
Results are checked by other scientists (peer review) before they are published.

Antibiotic: A medicine that kills bacteria inside the body, such as penicillin.
Painkiller: A medicine that relieves symptoms but does not kill pathogens.
Antibiotic resistance: When bacteria are no longer killed by an antibiotic.
Efficacy: How well a drug works.
Toxicity: How harmful a drug is.
Dose: The amount of a drug that should be taken.
Preclinical testing: Testing a new drug on cells, tissues and animals in a laboratory.
Clinical trial: Testing a new drug on healthy volunteers and patients.
Placebo: A dummy treatment that contains no drug.
Double-blind trial: A trial in which neither the patients nor the doctors know who receives the drug or the placebo.
Peer review: Checking of scientific work by other experts before publication.