Diclofenac: A Comprehensive Drug Profile

What is Diclofenac?

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) widely used to reduce pain, inflammation, and fever. This medication belongs to the phenylacetic acid class of NSAIDs and is commonly prescribed for various inflammatory conditions. Diclofenac is available in multiple formulations including oral tablets, topical gels, eye drops, and injectable solutions.

Uses

Diclofenac is prescribed for several inflammatory and pain-related conditions:

• Arthritis: Treatment of rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis to reduce joint pain and stiffness
• Acute pain: Management of moderate to severe pain from injuries, dental procedures, or post-operative recovery
• Musculoskeletal disorders: Relief of pain and inflammation in conditions like tendinitis, bursitis, and muscle strains
• Menstrual pain: Treatment of primary dysmenorrhea and menstrual cramps
• Migraine: Acute treatment of migraine headaches, particularly when administered as a powder for oral solution

How it works

Diclofenac works by inhibiting cyclooxygenase (COX) enzymes, specifically COX-1 and COX-2, which are responsible for producing prostaglandins. Prostaglandins are chemical messengers that promote inflammation, pain, and fever in the body. By blocking these enzymes, diclofenac reduces the production of prostaglandins, thereby decreasing inflammation, relieving pain, and lowering fever.

Side effects

Common side effects include:

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• Stomach upset, nausea, or indigestion
• Headache
• Dizziness
• Diarrhea or constipation
• Skin rash or itching
• Fluid retention and swelling
• Elevated blood pressure
• Drowsiness or fatigue

Serious side effects requiring immediate medical attention:

• Gastrointestinal bleeding or ulceration (black stools, vomiting blood)
• Cardiovascular events (heart attack, stroke, chest pain)
• Severe allergic reactions (difficulty breathing, facial swelling)
• Liver damage (yellowing of skin or eyes, dark urine)
• Kidney problems (decreased urination, swelling in legs)

Warnings and precautions

• Cardiovascular risk: Diclofenac may increase the risk of heart attack and stroke, especially with long-term use or in patients with existing heart disease
• Gastrointestinal risks: Patients with a history of stomach ulcers, bleeding disorders, or taking blood thinners should use diclofenac with extreme caution
• Pregnancy considerations: Diclofenac should be avoided during pregnancy, particularly in the third trimester, as it may cause harm to the developing fetus and complications during delivery
• Kidney and liver function: Patients with impaired kidney or liver function require dose adjustments and careful monitoring during treatment
• Elderly patients: Older adults are at higher risk for serious side effects and should use the lowest effective dose for the shortest duration possible

Interactions

Diclofenac can interact with numerous medications and supplements:

• Warfarin and anticoagulants: Increased bleeding risk due to enhanced anticoagulant effects
• ACE inhibitors and ARBs: Reduced blood pressure-lowering effects and potential kidney damage
• Lithium: Diclofenac may increase lithium levels, leading to toxicity
• Methotrexate: Enhanced methotrexate toxicity due to reduced clearance
• Aspirin: Increased gastrointestinal bleeding risk and reduced cardioprotective effects of aspirin
• Diuretics: Decreased effectiveness of diuretics and potential kidney problems
• Cyclosporine: Increased risk of kidney damage when used together
• Digoxin: Potential increase in digoxin levels leading to toxicity

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Dosage

Typical adult dosages vary depending on the condition being treated and the formulation used. For oral tablets, the usual dose ranges from 50mg to 150mg daily, divided into 2-3 doses. For topical applications, a small amount of gel is typically applied to the affected area 3-4 times daily. The maximum recommended daily dose for oral diclofenac is generally 150mg. Healthcare providers will determine the appropriate dose based on the patient’s specific condition, age, kidney function, and response to treatment. Treatment should use the lowest effective dose for the shortest duration necessary to minimize risks.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

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