What happens when you swallow a painkiller?

1. Ingestion

You swallow a tablet of paracetamol.

• It travels down your oesophagus into your stomach.

• The pill starts to dissolve in stomach acid.

Fun Fact: Some tablets are coated to survive the stomach!

2. Absorption

Small Intestine: Absorption Zone

• The drug moves into the small intestine.

• Tiny blood vessels in the intestinal wall absorb the drug into your bloodstream.

Key Word: Absorption = Drug enters the blood.

3. First-Pass Metabolism

First Stop: The Liver

• Before reaching the rest of the body, the blood carrying the drug flows to the liver.

• The liver breaks down some of the drug → this is called first-pass metabolism.

⚠️ Only part of the drug survives this step to do its job.

4. Distribution

Now it travels!

• The remaining active drug is now sent around the body via the bloodstream.

• It reaches the brain, where it blocks pain signals.

Key Word: Distribution = Drug travels to target organs/tissues.

5. Metabolism

More Breakdown Happens

• As time passes, more of the drug is broken down by the liver.

• This makes the drug easier to remove from the body.

6. Elimination and Excretion

Out of the Body

• The kidneys filter out the leftover drug.

• You pass it out in your urine.

• Elimination includes metabolism and excretion; excretion is just the drug's removal.

Key Word: Excretion = Getting rid of the waste.