Diclofenac (Voltarol, Voltaren, Akis)

Mechanism of action

NSAID - Inhibits cyclooxygenase 1 and 2 which results in block of production of prostaglandins, normally involved in the mechanism of inflammation and pain signalling. 

Indications and dose


Onset of action

  • Immediate release pills: 15 minutes
  • Prolonged release pills: 1.5–2 hours to peak concentration

Duration of action

  • Immediate release pills: 8 hours
  • Prolonged release pills: up to 24 hours 

Half-life of elimination: 3 hours

Metabolism: Hepatic (significant first-pass effect)

Elimination: Kidneys (60 %), liver

Directions for administration

Can be administered perorally, intramuscularly, subcutaneously or by intravenous bolus injection. 

Medicinal forms


  • Immediate release pills– 25 mg, 50 mg, 
  • Prolonged release pills – 75 mg, 100 mg

Solution for injection/infusion (50 mg/ml, 75 mg/ml)


Rash, eczema, erythema, pruritus

Dermatitis bullous



  1. Diclofenac: Uses, Interactions, Mechanism of Action | DrugBank Online
  2. https://www.medicines.org.uk/emc/search?q=diclofenac
  3. Diclofenac Extended Release Tablets 100mg: Package Insert / Prescribing Information - Drugs.com