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Traditional Drug Extraction

You can easily buy a packet of painkillers at the supermarket today, but for centuries, humans had to rely entirely on nature's pharmacy.
Historically, most drugs were extracted directly from plants and microorganisms.
Digitalis is a drug used to treat heart conditions (such as heart failure and irregular heartbeats) by strengthening the heart muscle. It was traditionally extracted from foxgloves (the Digitalis purpurea plant).
Aspirin is a painkiller (analgesic) used to reduce fever and inflammation. It originates from salicylic acid, a chemical found in willow bark.
Penicillin is an antibiotic discovered by Alexander Fleming in 1928 from the Penicillium mould. Fleming noticed that bacteria on a petri dish would not grow near the fungus because the mould released a chemical that killed them, creating a visible clear ring/zone around the mould.

Modern Drug Discovery and Synthesis

The starting point for many highly advanced modern medicines is actually still a chemical extracted from a simple plant or microorganism.
However, most new drugs are now synthesised by chemists within the pharmaceutical industry.
The process often begins with identifying a biological target, such as a specific protein molecule involved in a disease.
Scientists then use computer modelling software to simulate how potential drug molecules will interact with these targets before any physical laboratory work takes place.

Preclinical Testing: Cells and Animals

How do scientists know a newly synthesised chemical won't just poison the person taking it?
All new drugs must undergo preclinical testing. This stage does not involve humans.
In vitro testing: First, the drug is tested in a laboratory using computer models and human cells or tissues to identify potential toxicity and preliminary efficacy.
Animal testing: Next, the drug is tested on live animals to check its effect on a whole organism (including the complex interactions between multiple organ systems).

Students often state that healthy volunteers are used in Phase 1 trials to see if the drug works, but they are actually used only to check for safety and side effects, as they do not have the disease to test efficacy.

In 6-mark questions describing Fleming's discovery, examiners specifically look for the phrase 'clear ring' or 'clear zone' to describe where the bacteria were killed by the mould on the petri dish.

When explaining why drugs must be tested on live animals, always state that it checks the effect on a 'whole organism' to observe interactions between complex organ systems.

To get full marks when defining a double-blind trial, ensure you explicitly state that it eliminates bias (both observer bias from doctors and participant bias from patients).

A drug traditionally extracted from foxgloves, used to treat heart conditions by strengthening the heart muscle.

A painkilling drug traditionally originating from willow bark, used to reduce fever and inflammation.

An antibiotic discovered by Alexander Fleming from the Penicillium mould.

A measure of whether a drug is poisonous or has harmful side effects.

The ability of a drug to produce the intended or desired effect (i.e., whether it actually works).

The specific amount or concentration of a drug that should be administered.

The specific dose that is most effective at treating a disease with the fewest possible side effects.

A dummy treatment that contains no active ingredient, used as a control in clinical trials.

A clinical trial in which neither the participants nor the researchers know who is receiving the active drug or the placebo.

An inclination that might unfairly influence results, such as a doctor's or patient's expectations affecting the trial outcome.

A process where results are scrutinised by independent scientists to check for methodology flaws and ensure the data is valid before publication.