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# Diclofenac (Tablet)
## Overview
Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis. It possesses analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Osteoarthritis
* Rheumatoid arthritis
* Ankylosing spondylitis
* Management of acute pain (short-term)
## Adult Dosing
* **Osteoarthritis:** 50 mg twice daily or 75 mg twice daily (maximum 150 mg/day).
* **Rheumatoid Arthritis:** 50 mg three or four times daily, or 75 mg twice daily (maximum 225 mg/day).
* **Ankylosing Spondylitis:** 25 mg four times daily, plus an extra 25 mg at bedtime if needed (maximum 125 mg/day).
* **Acute Pain:** 50 mg three times daily (dosing protocols may vary by formulation/brand).
## Pediatric Dosing
Safety and efficacy in pediatric patients under 18 years have not been established. Use is generally avoided in children unless under the direction of a pediatric rheumatologist.
## 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:** Reduce dose in mild-to-moderate hepatic impairment. Contraindicated in severe hepatic impairment.
* **Geriatric:** Initiate at the lowest effective dose; monitor for increased risk of cardiovascular and gastrointestinal toxicity.
## Contraindications
* Hypersensitivity to diclofenac or any component.
* 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 (GI) bleeding or peptic ulcer disease.
* Severe heart failure or severe renal/hepatic impairment.
## Adverse Effects
* **GI:** Dyspepsia, nausea, abdominal pain, increased risk of gastric ulceration/bleeding.
* **Cardiovascular:** Hypertension, fluid retention, edema, increased risk of myocardial infarction or stroke.
* **Renal:** Acute kidney injury, interstitial nephritis, hyperkalemia.
* **Hepatic:** Elevated transaminases (ALT/AST).
* **Dermatologic:** Rash, photosensitivity.
## Key Drug Interactions
* **Anticoagulants/Antiplatelets (e.g., Warfarin, Rivaroxaban, Clopidogrel):** Increased risk of bleeding.
* **ACE Inhibitors/ARBs/Diuretics:** Reduced antihypertensive effect; increased risk of acute renal failure.
* **Lithium/Methotrexate:** Diclofenac may increase serum concentrations and toxicity.
* **Other NSAIDs/Corticosteroids:** Increased risk of GI toxicity and ulceration.
## Monitoring
* **Baseline/Intermittent:** CBC, serum creatinine, BUN, and liver function tests (LFTs).
* **Ongoing:** Blood pressure monitoring, signs/symptoms of GI bleeding, and cardiovascular status.
* **High Risk:** Monitor frequent LFTs for patients on long-term therapy.
## Clinical Pearls
* **Take with food or milk** to reduce GI upset.
* **Maximum Duration:** Use the lowest effective dose for the shortest duration possible to minimize cardiovascular and GI risks.
* **Formulation Note:** Oral diclofenac potassium (Cataflam) is typically used for immediate-release (pain/dysmenorrhea), while diclofenac sodium is used for chronic conditions. Do not substitute interchangeably without verifying the specific salt form.
* **Black Box Warning:** NSAIDs increase the risk of serious cardiovascular thrombotic events and serious gastrointestinal adverse events.
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**Educational Disclaimer:** This information is for educational purposes only. Drug dosing, contraindications, and interaction profiles are subject to change based on evolving evidence. Always verify current prescribing information in a trusted clinical resource (e.g., Lexicomp, UpToDate, or the official FDA package insert) before prescribing or administering medication.
