Ibuprofen

What is Ibuprofen?

Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID) commonly used to relieve pain, reduce inflammation, and lower fever.

Unlike centrally acting analgesics such as paracetamol, ibuprofen works both peripherally at inflamed tissues and centrally within the nervous system, making it particularly effective for inflammatory pain conditions.

History & Development

Ibuprofen was developed in the 1960s by researchers seeking a safer alternative to high-dose aspirin. It later became one of the most widely used NSAIDs worldwide due to its balance between efficacy and tolerability.

Chemical Structure & Medicinal Chemistry

• IUPAC: (RS)-2-(4-(2-methylpropyl)phenyl)propanoic acid
• Molecular Formula: C₁₃H₁₈O₂
• Molar Mass: 206.28 g/mol
• Functional Groups: Carboxylic acid, aromatic ring

The carboxylic acid group is essential for cyclooxygenase (COX) enzyme inhibition — the primary mechanism responsible for its anti-inflammatory and analgesic effects.

Ibuprofen exists as a racemic mixture, although the S-enantiomer is pharmacologically more active, illustrating how stereochemistry can influence drug potency.

Mechanism of Action

Ibuprofen inhibits cyclooxygenase enzymes COX-1 and COX-2, reducing the conversion of arachidonic acid into prostaglandins.

• Lower prostaglandins → reduced inflammation
• Elevated pain threshold
• Improved fever regulation

However, inhibition of COX-1 also explains many gastrointestinal side effects, since protective prostaglandins in the stomach are reduced.

Pharmacokinetics

• Rapid oral absorption (~80% bioavailability)
• Peak plasma levels within 1–2 hours
• Extensive protein binding (~99%)
• Hepatic metabolism via CYP enzymes
• Renal elimination

Clinical Uses

• Inflammatory pain
• Osteoarthritis and rheumatoid arthritis
• Muscle injuries and sprains
• Menstrual cramps (dysmenorrhea)
• Dental pain
• Fever management

Safety and Responsible Use

When used at recommended doses, ibuprofen is generally safe for short-term treatment. However, prolonged or excessive use increases the likelihood of gastrointestinal, renal, and cardiovascular complications.

Common Side Effects

• Stomach irritation
• Heartburn
• Nausea
• Dizziness

Serious Risks

• Gastric ulcers and bleeding
• Kidney impairment with long-term use
• Elevated cardiovascular risk in susceptible patients

Who Should Use Caution?

• Individuals with peptic ulcer disease
• Patients with kidney disorders
• Those with cardiovascular conditions
• Late-stage pregnancy

Ibuprofen vs Paracetamol

Ibuprofen is typically preferred for inflammatory pain, while paracetamol is often chosen when gastrointestinal tolerability is a priority. Clinical selection depends on patient history and therapeutic goals.

Drug Interactions

• Other NSAIDs — increased bleeding risk
• Anticoagulants such as warfarin
• Antihypertensive medications
• Alcohol — elevated gastric irritation

References

• World Health Organization (WHO)
• U.S. Food and Drug Administration (FDA)
• PubChem Database
• National Center for Biotechnology Information (NCBI)