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# Diclofenac
## Overview
Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) with potent analgesic, anti-inflammatory, and antipyretic properties. It acts primarily by inhibiting cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis. Available in various oral (immediate-release/delayed-release) and topical formulations.
## Primary Indications
* Osteoarthritis
* Rheumatoid arthritis
* Ankylosing spondylitis
* Short-term management of acute pain and dysmenorrhea
## Adult Dosing
* **Diclofenac Sodium (Delayed-Release):** 50 mg orally 2–3 times daily or 75 mg twice daily; Max: 150 mg/day.
* **Diclofenac Potassium (Immediate-Release):** 50 mg orally 3 times daily; Max: 150 mg/day.
* **Diclofenac Sodium (Extended-Release):** 100 mg once daily; Max: 100 mg/day.
## Pediatric Dosing
Safety and effectiveness in pediatric patients (<18 years) have not been established for many oral formulations. Use is generally discouraged in pediatrics due to limited data and safety profile; consult local institutional pediatric protocols for juvenile idiopathic arthritis (JIA) if specialized liquid formulations are considered off-label.
## Dose Adjustments
* **Renal Impairment:** Avoid in advanced renal disease. Use with caution in mild-to-moderate impairment; monitor closely.
* **Hepatic Impairment:** Avoid in severe hepatic impairment. Reduce doses in moderate impairment. Monitor hepatic transaminases frequently.
* **Geriatrics:** Start at the lowest effective dose; higher risk of gastrointestinal (GI) toxicity and renal insufficiency.
## Contraindications
* Known hypersensitivity to diclofenac or other NSAIDs (including aspirin-induced asthma/urticaria).
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Setting of coronary artery bypass graft (CABG) surgery.
* Active GI bleeding or peptic ulcer disease.
* Severe heart failure (NYHA Class II-IV).
## Adverse Effects
* **GI:** Dyspepsia, nausea, abdominal pain, increased risk of GI ulceration and perforation.
* **Cardiovascular:** Hypertension, edema, increased risk of myocardial infarction and stroke (black box warning).
* **Renal/Hepatic:** Elevated liver enzymes, renal insufficiency, hyperkalemia.
* **Hematologic:** Potential for increased bleeding time.
## Key Drug Interactions
* **Anticoagulants/Antiplatelets (e.g., Warfarin, Clopidogrel):** Increased risk of major bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive effect and increased risk of acute kidney injury (e.g., "triple whammy" effect).
* **Lithium:** Increased lithium plasma concentrations (toxicity risk).
* **Methotrexate:** Increased risk of methotrexate toxicity due to reduced clearance.
* **SSRIs:** Increased risk of GI bleeding.
## Monitoring
* Baseline and periodic CBC, BMP (creatinine, BUN, potassium), and LFTs (specifically during long-term therapy).
* Monitor blood pressure periodically.
* Assess for occult blood loss or signs of GI toxicity.
## Clinical Pearls
* **GI Protection:** Consider adding a PPI or misoprostol if the patient is at high risk for GI complications.
* **Cardiovascular Risk:** Use the lowest effective dose for the shortest duration necessary; exercise extreme caution in patients with cardiovascular risk factors.
* **Administration:** Take with food or milk to minimize GI upset, though this may slightly delay absorption.
* **Dosing Limits:** Do not exceed 150 mg/day for sodium/potassium salts; 100 mg/day for extended-release formulations.
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*Disclaimer: This information is for educational purposes and does not replace professional clinical judgment. Always verify current prescribing information, institutional guidelines, and drug-specific package inserts before administration.*
