What is diclofenac (Nonsteroidal Anti-Inflammatory Drug, NSAID)?

From the Guidelines

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) that is commonly used to treat pain and inflammation, particularly in the management of osteoarthritis (OA) of the knee and hip, as supported by the most recent evidence from 2021 1.

Key Points

• Diclofenac works by blocking enzymes called cyclooxygenases (COX), which produce prostaglandins that cause pain, swelling, and inflammation.
• It is available in various forms, including tablets, gel, patches, and eye drops, with typical oral doses ranging from 50-150 mg daily, divided into 2-3 doses.
• The medication should be taken with food to reduce stomach irritation, and common side effects include stomach upset, heartburn, and headache.
• More serious risks include an increased chance of heart attack, stroke, and stomach bleeding, especially with long-term use, as noted in studies such as those referenced in 1 and 1.

Recommendations

• People with heart conditions, kidney problems, or a history of stomach ulcers should use diclofenac cautiously, and it should not be combined with other NSAIDs.
• Alcohol should be avoided while taking this medication, and patients should always follow their healthcare provider's specific instructions regarding dosage and duration of treatment.
• Topical diclofenac is considered a valuable option for managing OA pain in the knee, with a safety profile that includes fewer gastrointestinal adverse events but more local adverse events compared to oral NSAIDs, as reported in 1.

Considerations

• The use of diclofenac, especially in patients with increased gastrointestinal risk, should be carefully considered, and alternative strategies such as the use of proton-pump inhibitors or selective COX-2 inhibitors may be recommended, as discussed in 1 and 1.
• The benefits and risks of diclofenac should be weighed, particularly in patients with a history of symptomatic or complicated upper GI ulcer, and the decision to use diclofenac should be made on an individual basis, taking into account the patient's specific condition and medical history.

From the FDA Drug Label

Diclofenac has analgesic, anti-inflammatory, and antipyretic properties. The mechanism of action of diclofenac potassium tablets, like that of other NSAIDs, is not completely understood but involves inhibition of cyclooxygenase (COX-1 and COX-2). Diclofenac is a potent inhibitor of prostaglandin synthesis in vitro

Diclofenic is not mentioned in the provided drug labels. However, Diclofenac is discussed as a medication with analgesic, anti-inflammatory, and antipyretic properties. It is likely that "diclofenic" is a misspelling or variation of "diclofenac".

• Key points about diclofenac include:
  • Inhibition of cyclooxygenase (COX-1 and COX-2)
  • Potent inhibitor of prostaglandin synthesis
  • Analgesic, anti-inflammatory, and antipyretic properties 2

From the Research

Definition and Mechanism of Action

• Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) of the phenylacetic acid class with anti-inflammatory, analgesic, and antipyretic properties 3, 4.
• It competes with arachidonic acid for binding to cyclo-oxygenase, resulting in decreased formation of prostaglandins 3.
• Diclofenac inhibits cyclooxygenase (COX)-2 enzyme with greater potency than it does COX-1 4.

Uses and Efficacy

• Diclofenac is widely used to manage chronic inflammatory and degenerative joint diseases such as osteoarthritis (OA), rheumatoid arthritis (RA), ankylosing spondylitis, and extra-articular rheumatism 5, 6.
• It is effective in treating nociceptive pain and chronic central pain 5.
• Diclofenac has been shown to be an effective analgesic agent in clinical conditions marked by acute or chronic pain and inflammation, such as oral surgery, dysmenorrhea, low back pain, renal colic, and biliary colic 7.

Pharmacokinetics and Administration

• Diclofenac is efficiently absorbed from the gastrointestinal tract, with peak plasma concentrations occurring 1.5 to 2.0 hours after ingestion in fasting subjects 3.
• The recommended total daily dosage is 100 to 150 mg (osteoarthritis and ankylosing spondylitis) or 150 to 200 mg (rheumatoid arthritis) 3.
• Diclofenac is administered in divided doses with meals 3.

Adverse Effects and Safety

• The most frequent adverse effects reported for diclofenac were gastrointestinal, but these effects were fewer and less serious than occurred with aspirin or indomethacin 3.
• Diclofenac caused fewer central nervous system reactions than indomethacin 3.
• The overall benefit-risk profile of diclofenac was comparable to that of ibuprofen in OA 6.