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# Diclofenac (Oral)
## 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
* Mild to moderate acute pain (including primary dysmenorrhea)
## Adult Dosing
* **Osteoarthritis:** 50 mg BID to TID or 75 mg BID (Max: 150 mg/day).
* **Rheumatoid Arthritis:** 50 mg TID or 75 mg BID (Max: 225 mg/day).
* **Ankylosing Spondylitis:** 25 mg QID, with an extra 25 mg at bedtime if needed (Max: 125 mg/day).
* **Acute Pain:** 50 mg TID.
## Pediatric Dosing
* **Safety/Efficacy:** Not established for children <18 years in oral tablet formulation. Use is generally avoided in pediatrics due to availability of safer alternatives.
## Dose Adjustments
* **Renal Impairment:** Avoid in advanced renal disease (CrCl <30 mL/min). Use with caution in mild-to-moderate impairment; monitor closely.
* **Hepatic Impairment:** Use with caution; monitor for elevated transaminases. Avoid in severe hepatic impairment.
* **Geriatric:** Use the lowest effective dose for the shortest duration due to increased risk of GI bleeding and cardiovascular events.
## Contraindications
* Known hypersensitivity to diclofenac or components.
* 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 peptic ulcer disease or GI bleeding.
## Adverse Effects
* **Gastrointestinal:** Dyspepsia, nausea, abdominal pain, increased risk of GI ulceration/bleeding.
* **Cardiovascular:** Hypertension, edema, increased risk of myocardial infarction or stroke.
* **Renal:** Fluid retention, decreased creatinine clearance, interstitial nephritis.
* **Hepatic:** Elevated liver enzymes (ALT/AST).
## 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.
* **Lithium/Methotrexate:** Diclofenac may decrease renal clearance, increasing systemic toxicity of these agents.
* **SSRIs:** Increased risk of GI bleeding.
## Monitoring
* **Baseline/Intermittent:** CBC, chemistry (BUN/SCr), and liver function tests (LFTs).
* **Clinical:** Blood pressure control, signs of GI bleeding (melena, hematemesis), or peripheral edema.
## Clinical Pearls
* **CV Risk:** All NSAIDs carry a black box warning for serious cardiovascular thrombotic events and serious gastrointestinal adverse events.
* **Administration:** Take with food or milk to minimize GI upset.
* **Duration:** Use the lowest dose for the shortest duration necessary to maintain symptom control to mitigate safety risks.
* **Switching:** Diclofenac potassium (Cataflam) is absorbed more rapidly than diclofenac sodium; confirm which salt is being prescribed, as they are not therapeutically equivalent on a milligram-to-milligram basis regarding onset.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice standards vary; always consult current institutional protocols, the package insert, and professional drug reference databases (e.g., Lexicomp, Micromedex) before prescribing or administering medication.
