Are Voltaren (diclofenac) and Celebrex (celecoxib) both Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)?

Yes, Both Voltaren (Diclofenac) and Celebrex (Celecoxib) Are NSAIDs

Both Voltaren (diclofenac) and Celebrex (celecoxib) are classified as nonsteroidal anti-inflammatory drugs (NSAIDs), but they differ significantly in their mechanism of action and safety profiles. 1, 2

Key Classification Differences

Diclofenac (Voltaren)

• Diclofenac is a nonselective NSAID that inhibits both COX-1 and COX-2 enzymes, though it has relatively more COX-2 selectivity compared to other traditional NSAIDs like ibuprofen or naproxen 1
• It carries FDA black box warnings for both cardiovascular thrombotic events (myocardial infarction, stroke) and serious gastrointestinal adverse events (bleeding, ulceration, perforation) 1
• Diclofenac is associated with particularly high cardiovascular risk—meta-analyses show a 1.63-fold increased risk of vascular events compared to placebo, and registry data demonstrate a 2.40-fold increased mortality risk 1

Celecoxib (Celebrex)

• Celecoxib is a selective COX-2 inhibitor, specifically designed to block COX-2 while sparing COX-1 activity 2, 3
• The FDA label describes celecoxib as "a nonsteroidal anti-inflammatory drug" with the same black box warnings as traditional NSAIDs for cardiovascular and gastrointestinal risks 2
• Despite being COX-2 selective, celecoxib still carries similar cardiovascular risks to nonselective NSAIDs, particularly with prolonged use 4, 2

Clinical Implications of the Distinction

Gastrointestinal Safety Profile

• Celecoxib demonstrates superior GI safety compared to diclofenac, with endoscopic ulcer rates of 4% versus 15% after 24 weeks of treatment in rheumatoid arthritis patients 5
• In the large SUCCESS-I trial, celecoxib showed significantly fewer ulcer complications (0.1/100 patient-years) compared to nonselective NSAIDs including diclofenac (0.8/100 patient-years), with an odds ratio of 7.02 6
• However, this GI advantage is substantially diminished when patients take concomitant low-dose aspirin—the CLASS trial showed 4-fold higher complicated ulcer rates in celecoxib users taking aspirin versus those not taking aspirin 2

Cardiovascular Risk Considerations

• Both drugs carry similar cardiovascular risks, with the American Heart Association recommending caution in patients with or at risk for cardiovascular disease 1
• Diclofenac lies on the more COX-2-selective end of the nonselective NSAID spectrum, which explains why its cardiovascular risk profile resembles that of selective COX-2 inhibitors 1
• The American College of Cardiology suggests avoiding celecoxib entirely in patients with established cardiovascular disease, and the same caution applies to diclofenac given its high cardiovascular event rates 4

Efficacy Comparison

• Both medications demonstrate comparable anti-inflammatory and analgesic efficacy for osteoarthritis and rheumatoid arthritis 5, 6
• One study in hip osteoarthritis patients found diclofenac 50 mg three times daily superior to celecoxib 200 mg once daily, though this may reflect dosing differences rather than inherent drug superiority 7

Important Clinical Pitfalls

• Do not assume COX-2 selectivity eliminates cardiovascular risk—celecoxib carries the same black box warning as traditional NSAIDs 2
• Avoid prescribing either drug for perioperative pain in CABG surgery—this is an absolute contraindication for both medications 1, 2
• Monitor blood pressure with both agents—celecoxib may increase blood pressure by an average of 5 mm Hg, and similar effects occur with diclofenac 4
• Consider renal function carefully—approximately 2% of patients develop renal complications requiring discontinuation with either drug, and the National Kidney Foundation advises avoiding both in patients with renal disease 4, 2
• Recognize that celecoxib is a sulfonamide—it can cause allergic reactions in sulfa-sensitive patients, which is not a concern with diclofenac 2