Diclofenac | NSAID | CAS 15307-86-5 | Analgesic

Product Name: Diclofenac
CAS No.: 15307-86-5 (acid form)
Chemical Name: 2-[(2,6-dichlorophenyl)amino]phenylacetic acid
Molecular Formula: C₁₄H₁₁Cl₂NO₂
Appearance: White to slightly yellowish crystalline powder
Solubility: Sodium and potassium salts are freely soluble in water and methanol; the acid form is practically insoluble in water
Stability: Relatively stable but sensitive to light
Common salts: Sodium, potassium, diethylamine (for topical use)

1. Introduction

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) from the phenylacetic acid derivative group. It has pronounced analgesic, anti-inflammatory, and antipyretic effects. It inhibits cyclooxygenase (COX), reducing prostaglandin synthesis.

Diclofenac is one of the most widely used NSAIDs worldwide. Its popularity is due to its high efficacy in relieving pain and inflammation of various origins, from rheumatic diseases to postoperative pain and sports injuries. The mechanism of action of diclofenac is associated with the suppression of cyclooxygenase enzyme activity, key participants in the synthesis of prostaglandins – mediators of inflammation, pain, and fever.

2. Chemical Structure & Synthesis

Diclofenac is synthesized in several stages. One common method involves the reaction of 2,6-dichloroaniline with 2-chlorophenylacetic acid or its derivatives under Ullmann reaction conditions (copper-catalyzed), followed by ester saponification (if an acid ester was used).

3. Mechanism of Action

Diclofenac non-selectively inhibits both isoforms of cyclooxygenase (COX-1 and COX-2).

• COX-1 is involved in the synthesis of prostaglandins that perform protective functions (e.g., in the gastric mucosa)

• COX-2 is induced during inflammation and is responsible for the synthesis of pro-inflammatory prostaglandins

COX inhibition leads to reduced formation of prostaglandins, prostacyclin, and thromboxane, resulting in anti-inflammatory, analgesic, and antipyretic effects. Other mechanisms have also been proposed, such as effects on the lipoxygenase pathway.

4. Pharmacokinetics

Rapidly and almost completely absorbed after oral administration (especially immediate-release formulations). Undergoes significant first-pass metabolism in the liver. High degree of plasma protein binding (>99%). Penetrates into synovial fluid. Metabolized in the liver by hydroxylation and conjugation. Excreted in urine and bile as metabolites.

5. Applications

Diclofenac is used for the symptomatic treatment of pain and inflammation in various conditions:

• Rheumatic diseases: Rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, gouty arthritis

• Musculoskeletal disorders: Tendinitis, bursitis, myositis, lumbago, sciatica, sprains, contusions

• Pain syndromes: Headache, toothache, neuralgia, dysmenorrhea

• Postoperative and post-traumatic pain and inflammation

• Topical use (gels, ointments, patches): Joint and muscle pain, injuries

• Ophthalmic drops: Reduction of inflammation after ophthalmic surgeries, non-infectious conjunctivitis

6. Conclusion

Diclofenac is an effective and widely used NSAID for relieving pain and inflammation. Its various dosage forms allow selection of the optimal route of administration depending on the clinical situation. However, like other NSAIDs, diclofenac can cause side effects, particularly from the gastrointestinal tract and cardiovascular system, requiring cautious use, especially in patients at risk and during long-term treatment.