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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
* Pain/Dysmenorrhea (immediate-release formulations)
## Adult Dosing
* **Osteoarthritis:** 100–150 mg/day in divided doses (e.g., 50 mg BID-TID).
* **Rheumatoid Arthritis:** 150–200 mg/day in divided doses (e.g., 50 mg QID).
* **Ankylosing Spondylitis:** 100–125 mg/day (divided doses, typically 25 mg QID with an extra 25 mg at bedtime if needed).
* **Maximum Dose:** 200 mg/day. Use the lowest effective dose for the shortest duration.
## Pediatric Dosing
* **Safety/Efficacy:** Not established for children <18 years. Use is generally off-label or avoided in favor of ibuprofen or naproxen. If prescribed per institutional protocol, dosing is generally 2–3 mg/kg/day divided BID-TID.
## Dose Adjustments
* **Renal Impairment:** Avoid in severe renal impairment (CrCl <30 mL/min). Use with caution in moderate impairment.
* **Hepatic Impairment:** Use with caution; monitor for transaminase elevations. Avoid in severe hepatic impairment.
* **Geriatric:** Start at the lowest end of the dosing range due to increased risk of GI bleeding and renal complications.
## Contraindications
* Known hypersensitivity to diclofenac or aspirin/other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal bleeding or peptic ulcer disease.
## Adverse Effects
* **Gastrointestinal:** Dyspepsia, nausea, occult GI bleeding, ulceration, perforation.
* **Cardiovascular:** Hypertension, fluid retention, edema; increased risk of serious thrombotic events, MI, and stroke.
* **Renal:** Acute kidney injury, interstitial nephritis, hyperkalemia.
* **Hepatic:** Elevated liver enzymes (monitor ALT/AST).
## Key Drug Interactions
* **Anticoagulants/Antiplatelets:** Increased risk of bleeding (e.g., warfarin, clopidogrel).
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive effect; increased risk of renal impairment (the "triple whammy").
* **Lithium/Methotrexate:** Increased plasma concentrations and risk of toxicity of these drugs due to reduced renal clearance.
## Monitoring
* **Baseline:** CBC, LFTs, SCr/BUN, blood pressure.
* **Ongoing:** Periodically monitor LFTs (specifically during the first few months of therapy), renal function, and assess for occult GI bleeding.
## Clinical Pearls
* **Formulations:** Diclofenac potassium (immediate-release) is absorbed faster; Diclofenac sodium (delayed-release) is designed for chronic pain management. These are not always interchangeable dose-for-dose.
* **GI Protection:** Consider co-therapy with a proton pump inhibitor (PPI) or misoprostol if the patient is at high risk for GI complications.
* **Cardiovascular Risk:** All NSAIDs (except aspirin) carry a boxed warning for increased risk of serious cardiovascular thrombotic events.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice protocols vary by institution. Always verify dosages, contraindications, and drug interactions using current, peer-reviewed clinical databases (e.g., Lexicomp, UpToDate) and local prescribing guidelines before administration.
