diclofénac

Diclofénac, or diclofenac, is a non-steroidal anti-inflammatory drug (NSAID) in the phenylacetic acid class. It is used to treat pain and inflammation in conditions such as osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, dental pain, post-surgical pain, and acute migraine attacks when used in certain formulations. It is available in oral tablets (including delayed-release forms), topical products (gels, creams, and patches), ophthalmic solutions, and suppositories. In many countries it is sold under brand names such as Voltaren.

Diclofenac works by inhibiting cyclooxygenase enzymes COX-1 and COX-2, reducing synthesis of prostaglandins that mediate inflammation and pain. This provides analgesic, anti-inflammatory, and antipyretic effects. The drug is frequently prescribed for short-term management of acute pain and for chronic inflammatory diseases, often at the lowest effective dose to minimize adverse effects.

Its absorption varies by formulation; oral diclofenac is rapidly absorbed with peak plasma levels within a couple of hours, while topical formulations deliver the drug locally. It is extensively bound to plasma proteins and undergoes hepatic metabolism, with renal and biliary excretion of metabolites. The half-life is generally short, but effects may persist with repeated dosing.

Common adverse effects include gastrointestinal upset, nausea, and gastritis; serious risks include gastrointestinal bleeding, cardiovascular events, and kidney impairment, particularly in older adults or those with comorbidities. Diclofenac should not be used in patients with active peptic ulcers, known hypersensitivity to NSAIDs, significant renal or hepatic impairment, or during the third trimester of pregnancy. Caution is advised with concomitant anticoagulants, other NSAIDs, or corticosteroids. Regulatory status varies by country, with some formulations available over the counter in some regions and prescription-only in others.