D.3.2 Describe the use of derivatives of salicylic acids as mild analgesics, and compare the advantages and disadvantages of using aspirin and paracetamol (acetaminophen).

Salicylic Acid:

salicylic acid

Derivatives of salicylic acids are used in rubefacient substances (substances that dilates capillaries and increase blood circulation).

Examples include:
- Methyl Salicylate which soothes muscle pains
- Choline Salicylate which relieves pain in the aphthous ulcers or mouth ulcers
- Sodium Salicylate which is a non-steroidal (doesn't contain steroids), anti-inflammatory drug.


Synthesis of Aspirin

external image Aspirin-B-3D-balls.png
Aspirin: C9H8O4
Aspirin: C9H8O4

Aspirin is a non-steroidal anti-inflammatory drug which relieves pain by reducing inflammation (swelling). Aspirin is transmitted to the bloodstream through the lining of the stomach.

Advantages of Aspirin include:
  • Acts as a blood thinner
  • May prevent the recurrence of heart attacks and strokes
  • Protection from prostaglandin (lipid) production
  • Protection from fevers
  • Protection from swelling (effective for arthritis/joint pain)
  • Reduction of pain

The disadvantages of Aspirin include:
  • Ulceration
  • Stomach bleeding
  • Allergic reactions
  • Reye's syndrome in children (a potentially fatal liver and brain disorder)
  • Blood thinning where when one is cut, it takes quite a long time for the blood to clot and stop flowing out
  • Overdose may cause pH imbalance and respiratory disturbance and can be especially fatal in children
  • Effectiveness is hindered by high cholesterol to about 60% effectiveness
  • Not suitable for all patients; can cause fatal side-effects to patients with special conditions, such as stomach or liver problems


Paracetamol: C8H9NO2
Paracetamol: C8H9NO2

Acetaminophen/Paracetamol is an analgesic (pain reliever) and antipyretic (fever reducer) metabolized by the liver.

Advantages of paracetamol:
  • Suitable for people of all ages
  • Very safe in correct doses
  • Can reduce pain and suppress fevers
  • Does not create issues when other medicines are also administered at the same time
  • Can be effective for up to 48 hours after dosage
  • Virtually no side effects if using correct doses
  • Non-irritating alternative to aspirin; safe for those with gastric conditions like ulcers and gastroesophageal reflux disease

Disadvantages of paracetamol:
  • It does not help with inflammation or swelling like Aspirin does
  • Overdose can lead to serious liver damage, brain damage and even death
    • Overdose occurs when the patient ingests over 24 tablets(15 grams)
  • In rare cases causes blood disorders and kidney damage
  • Skin rashes, blood disorders, and swollen pancreas occasionally occur when the paracetamol is taken regularly over a long period of time