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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.
## Primary Indications
* Osteoarthritis
* Rheumatoid arthritis
* Ankylosing spondylitis
* Mild to moderate pain
* Primary dysmenorrhea
## Adult Dosing
* **Osteoarthritis:** 50 mg orally 2–3 times daily or 75 mg twice daily.
* **Rheumatoid Arthritis:** 50 mg 3–4 times daily or 75 mg twice daily.
* **Ankylosing Spondylitis:** 25 mg 4 times daily (additional 25 mg at bedtime may be added if needed).
* **Maximum Dose:** Generally 150 mg/day.
## Pediatric Dosing
* **Juvenile Rheumatoid Arthritis (≥2 years):** 2–3 mg/kg/day divided into 2–3 doses.
* **Note:** Always verify specific product labeling, as some formulations are not indicated for pediatric use.
## Dose Adjustments
* **Renal Impairment:** Avoid in severe renal impairment (CrCl <30 mL/min). Use caution and monitor closely in mild-to-moderate impairment.
* **Hepatic Impairment:** Use with caution. Monitor liver function tests (LFTs) if therapy is prolonged.
* **Geriatric:** Initiate at the lowest effective dose; increased risk of gastrointestinal (GI) toxicity.
## Contraindications
* Known hypersensitivity to diclofenac or other NSAIDs (including aspirin-induced asthma/urticaria).
* History of GI bleeding or perforation related to previous NSAID therapy.
* Active peptic ulcer disease or inflammatory bowel disease.
* **Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.**
* Severe heart failure (NYHA Class III/IV).
## Adverse Effects
* **GI:** Abdominal pain, dyspepsia, nausea, risk of ulceration/bleeding.
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, and hypertension.
* **Renal:** Fluid retention, edema, acute kidney injury.
* **Hepatic:** Potential for elevated transaminases; rare idiosyncratic hepatotoxicity.
## Key Drug Interactions
* **Anticoagulants (e.g., Warfarin):** Increased risk of bleeding.
* **Antiplatelets (e.g., Clopidogrel, Aspirin):** Synergistic increased GI bleeding risk.
* **SSRIs:** Increased risk of GI bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive effect and increased risk of nephrotoxicity.
* **Lithium/Methotrexate:** NSAIDs may decrease clearance, increasing toxicity risk.
## Monitoring
* **Baseline/Intermittent:** CBC, serum creatinine, BUN, and LFTs (especially ALT/AST).
* **Blood Pressure:** Monitor regularly during initiation and dose increases.
* **Symptoms:** Monitor for occult GI bleeding (melena, hematemesis) and signs of cardiovascular events.
## Clinical Pearls
* Take with food or milk to minimize GI irritation, although peak absorption may be delayed.
* Use the smallest effective dose for the shortest duration necessary to control symptoms.
* Diclofenac carriers a "black box" warning for cardiovascular thrombotic events and serious gastrointestinal bleeding.
* Avoid concomitant use with other NSAIDs (including topical) to prevent additive toxicity.
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*Disclaimer: This information is for educational purposes only. Always consult current clinical practice guidelines, institutional protocols, and official prescribing information (package inserts) before prescribing or administering medication.*
