Description

Paracetamol, also known as Acetaminophen, is a widely used and well-tolerated drug that acts as a non-opioid analgesic (pain reliever) and antipyretic (fever reducer). It is a central-acting drug, meaning its effects are primarily mediated in the central nervous system (CNS). Unlike nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or aspirin, paracetamol has very little anti-inflammatory effect in the periphery.

Indications

Paracetamol is indicated for the symptomatic relief of a wide range of conditions. Its key indications include:

• Pain Relief: It is used for the treatment of mild to moderate pain, such as headaches, muscle aches, toothaches, and pain from colds and flu.
• Fever Reduction: It is a highly effective antipyretic for reducing fever in adults and children.

It is often the first-line treatment for pain and fever, especially in children and for individuals who cannot tolerate NSAIDs due to gastrointestinal issues or other conditions.

Mechanism of Action

The exact mechanism of action of paracetamol is not fully understood, but its effects are believed to be primarily central and distinct from those of traditional NSAIDs.

1. Central COX Inhibition: Paracetamol is a weak inhibitor of cyclooxygenase (COX) enzymes, particularly in the brain and spinal cord (the CNS). By inhibiting COX in the CNS, it reduces the synthesis of prostaglandins.
2. Reducing Pain Signals: In the CNS, prostaglandins play a key role in sensitizing nerve endings and transmitting pain signals. By reducing their synthesis, paracetamol raises the pain threshold, thereby providing its analgesic effect.
3. Antipyretic Effect: Fever is caused by the action of pyrogens on the hypothalamus in the brain, which leads to an increase in prostaglandin E2​ synthesis. Paracetamol inhibits this synthesis in the hypothalamus, which causes vasodilation (widening of blood vessels) and sweating, allowing the body to dissipate heat and lower the fever.
4. Lack of Peripheral Action: Unlike NSAIDs, paracetamol is a poor inhibitor of COX enzymes in the periphery (at the site of inflammation). This is why it has very little anti-inflammatory effect and does not cause the common gastrointestinal side effects associated with NSAIDs, such as stomach upset or ulcers.

In summary, paracetamol provides its pain-relieving and fever-reducing effects by inhibiting prostaglandin synthesis primarily in the central nervous system, without a significant anti-inflammatory effect in the periphery.