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diclofenac

Brand: Voltaren, Cataflam, Zipsor, Flector patch, Pennsaid topical

⚠ BBW Beers Criteria Prototype: ibuprofen
Drug Class: nonsteroidal anti-inflammatory drug (NSAID)
Drug Family: NSAID
Subclass: non-selective COX inhibitor (phenylacetic acid derivative)
Organ Systems: cnsmusculoskeletal

Mechanism of Action

Non-selective COX inhibitor with moderate selectivity toward COX-2 over COX-1; produces analgesia, antipyresis, and anti-inflammatory effects via prostaglandin synthesis inhibition. Available in multiple formulations including topical gel, which achieves local tissue concentrations with minimal systemic exposure.

COX-1COX-2

Indications

  • osteoarthritis (oral and topical)
  • rheumatoid arthritis
  • ankylosing spondylitis
  • acute pain
  • dysmenorrhea
  • actinic keratosis (topical)

Contraindications

  • active GI disease
  • aspirin sensitivity
  • third trimester pregnancy

Adverse Effects

Common

  • GI upset
  • elevated liver enzymes
  • edema
  • hypertension

Serious

  • hepatotoxicity (higher liver enzyme elevation rate than other NSAIDs)
  • GI bleeding/ulceration
  • AKI
  • cardiovascular events

Pharmacokinetics (ADME)

Absorption oral bioavailability ~55% (substantial first-pass); topical: systemic bioavailability ~6-10% for gel
Distribution protein binding >99%
Metabolism extensively CYP2C9; also CYP2C8 and UGT
Excretion renal (65%) and fecal (35%)
Half-life 1-2 hours (oral)
Onset 30-60 minutes (oral)
Peak 2-3 hours (oral)
Duration 6-8 hours
Protein Binding >99%
Vd 0.12-0.17 L/kg

Drug Interactions

Drug / Agent Mechanism Severity
anticoagulants additive bleeding risk major
ACE inhibitors/ARBs AKI risk; antihypertensive antagonism major
lithium increase lithium levels moderate

Nursing Considerations

  1. Monitor liver function tests; diclofenac has the highest rate of hepatotoxicity among commonly used NSAIDs — discontinue if ALT exceeds 3x ULN.
  2. Topical diclofenac gel (Voltaren) is OTC; systemic adverse effects are substantially reduced but not eliminated; monitor patients with renal or cardiovascular disease even with topical use.
  3. Same GI and renal precautions as other NSAIDs; use the lowest effective dose.
  4. Flector transdermal patch is applied to the most painful area; wash hands after handling patch.

Clinical Pearls

  • Topical diclofenac (Voltaren Arthritis Pain gel) achieves therapeutic concentrations in superficial joint tissue with much lower systemic exposure than oral NSAIDs — an important advantage for patients with osteoarthritis who have GI, cardiovascular, or renal risk factors.
  • Diclofenac has one of the most consistent associations with hepatotoxicity among NSAIDs; liver enzyme monitoring is recommended during chronic use.

Safety Profile

Pregnancy avoid
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Required
TDM Not required

Concordance Terms

Cross-referenced clinical concepts — click any term to see all content where it appears.

Actinic Keratosis (topical) Acute Pain Ankylosing Spondylitis Dysmenorrhea Nonsteroidal Anti-inflammatory Drug (NSAID) Osteoarthritis (oral And Topical) Rheumatoid Arthritis
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