Diclofenac

# Diclofenac ## Overview - **Classification**: Non-steroidal Anti-Inflammatory Drug (NSAID) - **Mechanism**: Inhibits cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis. This leads to anti-inflammatory, analgesic, and antipyretic effects. ## Primary Indications 1. **Osteoarthritis/Rheumatoid Arthritis**: Management of pain and inflammation. 2. **Ankylosing Spondylitis**: Symptomatic treatment. 3. **Acute Pain**: Mild to moderate pain relief (e.g., dysmenorrhea, post-operative pain). 4. **Migraine**: Acute treatment of migraine attacks (specific formulations). 5. **Actinic Keratosis**: Topical treatment of skin lesions. ## Adult Dosing ### Standard Dosing **Osteoarthritis** - **Dose**: **50 mg** (delayed-release) - **Frequency**: BID or TID - **Route**: Oral - **Maximum**: **150 mg/day** **Rheumatoid Arthritis** - **Dose**: **50 mg** (delayed-release) - **Frequency**: TID or QID - **Route**: Oral - **Maximum**: **200 mg/day** **Acute Pain/Dysmenorrhea** - **Dose**: **50 mg** (immediate-release) - **Frequency**: TID - **Route**: Oral - **Maximum**: **150 mg/day** **Topical Gel (e.g., for Osteoarthritis)** - **Dose**: **2-4 grams** (depending on joint size) - **Frequency**: QID - **Route**: Topical - **Maximum**: **32 grams/day** total body ### Dose Adjustments - **Renal Impairment**: Use lowest effective dose. Avoid in severe impairment (CrCl < 30 mL/min). Monitor renal function closely. - **Hepatic Impairment**: Avoid in severe impairment. Use caution and lower doses in mild-moderate impairment. - **Elderly Patients**: Start at the lower end of the dosing range due to increased risk of GI/renal adverse effects. ## Pediatric Dosing **Systemic oral diclofenac is generally not recommended or routinely used in children <18 years for general pain/fever.** ### Neonates (0-28 days) - **Dose**: **Not recommended**. - **Special Notes**: Lack of safety and efficacy data. ### Infants (1-12 months) - **Dose**: **Not recommended**. - **Special Notes**: Lack of safety and efficacy data. ### Children (1-12 years) - **Dose**: **Not recommended for systemic oral use** for general indications. - **Specific Use (Topical Gel 1% for Juvenile Idiopathic Arthritis - JIA, >6 years)**: **2 grams** applied **4 times daily** per joint. - **Maximum (Topical)**: **8 grams/day** per joint (max 4 joints treated). - **Special Notes**: Limited data; use only under specialist guidance. ### Adolescents (13-18 years) - **Dose**: Consider adult dosing with caution for specific indications (e.g., JIA). - **Frequency**: Use lowest effective dose. - **Maximum**: Max **150-200 mg/day** (oral) depending on indication, similar to adults. - **Special Notes**: Weigh risks vs. benefits carefully. ## Safety Information ### Contraindications - **Absolute**: History of aspirin/NSAID-induced asthma, urticaria, or allergic reactions. - **Absolute**: Peri-operative pain in the setting of coronary artery bypass graft (CABG) surgery. - **Absolute**: Active gastrointestinal bleeding or peptic ulcer disease. - **Absolute**: Severe uncontrolled heart failure (NYHA Class III/IV). - **Absolute**: Pregnancy (third trimester). ### Common Adverse Effects - **Very Common (>10%)**: Gastrointestinal upset (nausea, dyspepsia, abdominal pain). - **Common (1-10%)**: Diarrhea, constipation, headache, dizziness, edema, elevated liver enzymes. - **Serious but Rare**: GI bleeding/perforation, cardiovascular thrombotic events (MI, stroke), acute kidney injury, severe skin reactions (SJS/TEN), hepatic failure, anaphylaxis. ### Key Drug Interactions - **Anticoagulants (e.g., warfarin, DOACs)**: Increased risk of serious bleeding. **Monitor INR/bleeding signs**. - **SSRIs/SNRIs**: Increased risk of GI bleeding. - **Lithium, Digoxin, Methotrexate**: Diclofenac can increase plasma concentrations. **Monitor levels** of these drugs. - **ACE Inhibitors/ARBs/Diuretics**: May reduce antihypertensive effect and increase risk of renal dysfunction. **Monitor BP and renal function**. - **Corticosteroids**: Increased risk of GI ulceration/bleeding. ## Monitoring & Follow-up - **Before Treatment**: Baseline complete blood count (CBC), liver function tests (LFTs), renal function (SCr, eGFR), blood pressure (BP). - **During Treatment**: Periodically monitor renal function, LFTs (especially with prolonged use), CBC (long-term use), and BP. - **Clinical Signs**: Watch for signs of GI bleeding (black/tarry stools, severe abdominal pain), edema, rash, yellowing skin/eyes, shortness of breath. ## Clinical Pearls - 💡 Take oral diclofenac with food or milk to minimize GI upset. - 💡 Advise patients of potential cardiovascular and gastrointestinal risks, especially with long-term or high-dose use. - 💡 Patients should avoid alcohol while on diclofenac to further reduce GI irritation and bleeding risk. - 💡 Topical diclofenac formulations have significantly lower systemic absorption, reducing systemic side effects. - 💡 Ensure adequate hydration to help protect kidney function, especially with concomitant diuretics. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.