Dic

Diclofenac

A nonsteroidal anti-inflammatory drug (NSAID) used to treat pain and inflammatory disorders

Dic
INN
Drug class
Routes of administration	Oral, topical, rectal, intravenous, intramuscular
Pregnancy category
Bioavailability	50–60%
Metabolism	Liver (CYP2C9)
Elimination half-life	1.2–2 hours
Excretion	Urine (65%), feces (35%)
Legal status
CAS Number	15307-86-5
PubChem	3033
DrugBank	DB00586
ChemSpider	2928
KEGG	D07893

Introduction

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) commonly used to treat pain and inflammatory disorders such as arthritis. It is available in various forms, including oral tablets, topical gels, and injections. Diclofenac works by inhibiting the production of prostaglandins, which are chemicals in the body that promote inflammation, pain, and fever.

Pharmacology

Mechanism of Action

Diclofenac exerts its effects by inhibiting the enzyme cyclooxygenase (COX), which is responsible for the conversion of arachidonic acid to prostaglandins. There are two main isoforms of COX: COX-1 and COX-2. Diclofenac is a non-selective inhibitor, meaning it affects both COX-1 and COX-2, although it has a slightly higher affinity for COX-2.

Pharmacokinetics

Diclofenac is well absorbed from the gastrointestinal tract, with a bioavailability of 50-60% due to first-pass metabolism in the liver. It is highly protein-bound (>99%) and is metabolized primarily by the liver enzyme CYP2C9. The elimination half-life of diclofenac is approximately 1.2 to 2 hours, and it is excreted in the urine (65%) and feces (35%).

Clinical Uses

Indications

Diclofenac is indicated for the treatment of various conditions, including:

• Osteoarthritis
• Rheumatoid arthritis
• Ankylosing spondylitis
• Acute pain, such as postoperative pain
• Migraine
• Dysmenorrhea (painful menstruation)

Dosage Forms

Diclofenac is available in several formulations, including:

• Oral tablets and capsules
• Topical gels and creams
• Transdermal patches
• Rectal suppositories
• Intramuscular and intravenous injections

Adverse Effects

Common Side Effects

Common side effects of diclofenac include:

• Gastrointestinal discomfort, such as nausea and dyspepsia
• Headache
• Dizziness
• Elevated liver enzymes

Serious Side Effects

Serious side effects may include:

• Gastrointestinal bleeding
• Cardiovascular events, such as myocardial infarction and stroke
• Renal impairment
• Hepatotoxicity

Contraindications

Diclofenac is contraindicated in patients with:

• Known hypersensitivity to diclofenac or other NSAIDs
• History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs
• Active peptic ulcer disease
• Severe hepatic impairment
• Severe renal impairment

Interactions

Diclofenac may interact with other medications, including:

• Anticoagulants (e.g., warfarin)
• Antihypertensives (e.g., ACE inhibitors, diuretics)
• Lithium
• Methotrexate

Conclusion

Diclofenac is a widely used NSAID with proven efficacy in treating pain and inflammation. However, its use must be carefully monitored due to potential adverse effects, particularly gastrointestinal and cardiovascular risks. It is important for healthcare providers to consider individual patient risk factors when prescribing diclofenac.

See Also

• Nonsteroidal anti-inflammatory drug
• Cyclooxygenase
• Prostaglandin

External Links

• Drugs.com: Diclofenac
• MedlinePlus: Diclofenac