Pharmacology · Nonsteroidal anti-inflammatory drugs (NSAIDs)

Celecoxib !

A COX-2-selective NSAID (a coxib): it eases pain and inflammation with less stomach damage, but does not protect arteries and can favor clots.

Updated 2026-11-01

Class: Nonsteroidal anti-inflammatory drugs (NSAIDs)
Enzyme: Cyclooxygenase 2 (COX-2)
ATC code: M01AH01

Cyclooxygenase 2 (COX-2)Celecoxib

The figure shows celecoxib in the active site of mouse COX-2, with its sulfonamide inside the side pocket unique to COX-2.

Target in 3D: Cyclooxygenase 2 (COX-2). PDB structure 3LN1 (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Celecoxib reversibly and selectively inhibits COX-2, the isoform that rises in inflamed tissue. Its sulfonamide group enters a side pocket that exists in COX-2 because a valine replaces the isoleucine of COX-1. It spares gastric and platelet COX-1: fewer ulcers, but no antiplatelet effect.

Its sulfonamide fits the side pocket found only in COX-2
Inflammatory prostaglandins fall; gastric COX-1 keeps working
Less pain and inflammation with less damage to the gastric lining
Less prostacyclin without less thromboxane: higher clot risk

Pharmacokinetics

Absorption: Oral; a high-fat meal delays the peak level.
Distribution: Highly bound to albumin.
Metabolism: Liver, mainly CYP2C9, to inactive metabolites.
Elimination: Feces and urine, as inactive metabolites.
Half-life: About 11 hours.

Indications

Knee osteoarthritis Knee Osteoarthritis →
Hip osteoarthritis Hip Osteoarthritis →
Ankylosing spondylitis Ankylosing spondylitis →
Rheumatoid arthritis (symptom control) Rheumatoid arthritis →
Primary dysmenorrhea and acute pain Dysmenorrhoea →

Adverse effects

Common

Dyspepsia and abdominal pain
Edema and high blood pressure
Headache

Contraindications

Sulfonamide allergy
The period right before or after coronary artery bypass surgery
Asthma or urticaria triggered by NSAIDs
Active ulcer or gastrointestinal bleeding
Established cardiovascular disease or severe heart failure (high risk)

Key interactions

CYP2C9 inhibitors (fluconazole): Raise celecoxib levels (fluconazole can double them).
Warfarin: More bleeding risk; the INR may rise.
Aspirin: Part of the coxib's gastric advantage is lost.
ACE inhibitors, ARBs, diuretics and lithium: More kidney risk, weaker antihypertensive effect and higher lithium levels.

What is monitored

Blood pressure
Kidney function with prolonged use

Test yourself

Think of the answer, then tap the question to see it.

Why can celecoxib not replace aspirin for preventing heart attacks?

It barely inhibits platelet COX-1, so it does not lower thromboxane A2 or platelet aggregation.

Which allergy history is asked about before celecoxib, and why?

Sulfonamide allergy, because the celecoxib molecule contains a sulfonamide group.

What is one advantage and one drawback of celecoxib compared with ibuprofen?

Advantage: fewer ulcers and gastrointestinal bleeds because gastric COX-1 is spared. Drawback: higher thrombotic risk from lower prostacyclin without blocking platelet thromboxane.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Celecoxib: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2021); Structure of celecoxib bound at the COX-2 active site (RCSB Protein Data Bank, 2010); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.