What is the proper dosing and administration of Voltaren (diclofenac) gel?

Prescribing Voltaren Gel (Diclofenac Sodium Topical Solution)

For osteoarthritis pain relief, apply 2 pump actuations (40 mg diclofenac sodium) to each affected knee, twice daily, spreading evenly around front, back, and sides of the knee on clean, dry skin. 1

Dosing Instructions

• Prime the pump before first use by fully depressing the pump mechanism 4 times while holding the bottle upright; discard this portion to ensure proper priming 1
• After priming, completely depress the pump 2 times to achieve the prescribed 40 mg dose for one knee 1
• Apply to clean, dry skin, spreading evenly around front, back and sides of the knee 1
• Use the lowest effective dosage for the shortest duration consistent with treatment goals 1

Application Precautions

• Wash hands thoroughly after application 1
• Avoid showering/bathing for at least 30 minutes after application 1
• Wait until the treated area is completely dry before:
  • Covering with clothing 1
  • Applying sunscreen, insect repellent, cosmetics, or other topical medications 1
  • Allowing skin-to-skin contact between other people and the treated knee 1

Safety Considerations

• Do not apply to open wounds 1
• Avoid contact with eyes and mucous membranes 1
• Do not apply external heat or occlusive dressings to treated areas 1
• Protect treated areas from natural and artificial sunlight 1
• Avoid combination therapy with oral NSAIDs unless benefit outweighs risk 1
• Monitor for gastrointestinal side effects, as systemic absorption can occur even with topical application 2
• Use caution in patients with history of peptic ulcer, as cases of upper gastrointestinal hemorrhage have been reported with topical diclofenac use 2

Pharmacology and Absorption

• Diclofenac is a phenylacetic acid derivative NSAID that competes with arachidonic acid for binding to cyclo-oxygenase, resulting in decreased prostaglandin formation 3
• Despite topical application, approximately 6% of the dose is systemically absorbed through the skin 4
• The drug persists in synovial fluid despite its relatively short plasma half-life (1.5 hours) 3
• Diclofenac is metabolized in the liver and eliminated through urinary and biliary excretion 3

Clinical Efficacy

• Topical diclofenac penetrates into joint tissues, including synovial fluid, making it effective for localized joint pain 4
• Studies show diclofenac is comparable in efficacy to other NSAIDs for osteoarthritis pain relief 3
• Topical application may provide the benefit of pain relief with potentially fewer systemic side effects than oral administration 5