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# Diclofenac (Tablet)
## Overview
Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) that exhibits analgesic, anti-inflammatory, and antipyretic properties via non-selective inhibition of cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis.
## Primary Indications
* Osteoarthritis
* Rheumatoid arthritis
* Ankylosing spondylitis
* Short-term management of acute pain (e.g., dysmenorrhea, post-surgical)
## Adult Dosing
* **Osteoarthritis:** 50 mg twice or three times daily, or 75 mg twice daily (Max: 150 mg/day).
* **Rheumatoid Arthritis:** 50 mg three or four times daily, or 75 mg twice daily (Max: 225 mg/day).
* **Ankylosing Spondylitis:** 25 mg four times daily, plus an additional 25 mg at bedtime if needed (Max: 125 mg/day).
* **Acute Pain:** 50 mg three times daily (Max: 150 mg/day).
*Note: Use the lowest effective dose for the shortest duration necessary.*
## Pediatric Dosing
Safety and efficacy have not been established for children (<18 years). Use is generally avoided unless directed by a pediatric specialist for off-label management (e.g., Juvenile Idiopathic Arthritis), where dosing typically ranges from 2–3 mg/kg/day divided into 2–4 doses.
## Dose Adjustments
* **Renal Impairment:** Avoid in patients with advanced renal disease (CrCl <30 mL/min). Use with caution in mild-to-moderate impairment.
* **Hepatic Impairment:** Use with caution; monitor liver enzymes. Consider dose reduction in Child-Pugh Class B. Avoid in severe hepatic impairment.
* **Geriatric:** Start at the lowest end of the dosing range due to increased risk of GI bleeding and renal 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
* **Gastrointestinal:** Dyspepsia, nausea, abdominal pain, increased risk of ulcers/GI bleeds.
* **Cardiovascular:** Hypertension, edema, increased risk of myocardial infarction or stroke.
* **Renal:** Elevated creatinine, interstitial nephritis, hyperkalemia.
* **Hepatic:** Elevated transaminases (ALT/AST); rare severe hepatotoxicity.
## Key Drug Interactions
* **Anticoagulants/Antiplatelets (e.g., Warfarin, Clopidogrel):** Increased risk of bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive effect and increased risk of acute kidney injury.
* **Lithium/Methotrexate:** Diclofenac can increase serum levels and toxicity of these agents.
* **Corticosteroids/SSRIs:** Increased risk of gastrointestinal ulceration.
## Monitoring
* **Baseline:** Complete blood count (CBC), serum creatinine/BUN, liver function tests (LFTs), and blood pressure.
* **Ongoing:** Periodic monitoring of renal function, LFTs (if long-term therapy), and blood pressure. Assess for signs of GI bleeding (e.g., melena, hematemesis).
## Clinical Pearls
* **GI Protection:** Consider a concomitant proton pump inhibitor (PPI) or misoprostol in patients with high GI risk factors.
* **CV Risk:** All NSAIDs (except aspirin) carry a boxed warning for increased risk of serious cardiovascular thrombotic events.
* **Formulation Warning:** Ensure patients do not confuse immediate-release tablets with extended-release formulations, which are not interchangeable.
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**Disclaimer:** This information is for educational purposes and does not replace professional clinical judgment. Always verify exact dosing, contraindications, and local institutional protocols against the most current drug information resources (e.g., UpToDate, Lexicomp, or the official prescribing information/package insert) before prescribing or administering medication.
