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# Diclofenac ## Overview Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain, reduce inflammation, and lower fever. It works by inhibiting cyclooxygenase (COX) enzymes, which are responsible for prostaglandin synthesis. ## Primary Indications * Pain associated with osteoarthritis, rheumatoid arthritis, ankylosing spondylitis * Acute pain * Primary dysmenorrhea ## Adult Dosing * **Osteoarthritis:** 150 mg orally per day, divided into 2-3 doses (e.g., 50 mg three times daily or 75 mg twice daily). Maximum daily dose is 150 mg. * **Rheumatoid Arthritis, Ankylosing Spondylitis:** 150 mg orally per day, divided into 3 doses (e.g., 50 mg three times daily). Maximum daily dose is 150 mg. * **Acute Pain:** Initial dose 50 mg orally, followed by 50 mg every 8 hours as needed. Maximum daily dose is 150 mg. * **Primary Dysmenorrhea:** Initial dose 50 mg orally, followed by 50 mg every 8 hours as needed. Maximum daily dose is 150 mg. * Extended-release formulations have different dosing frequencies. ## Pediatric Dosing * **Rheumatoid Arthritis:** Limited data. Generally **not recommended** for children under 12 years of age without specific expert guidance. * **Pain and Fever:** Oral diclofenac is **not approved** by the FDA for use in children for pain and fever. ## Dose Adjustments * **Renal Impairment:** Use with caution. No specific dose adjustment is routinely recommended, but close monitoring for renal adverse effects is advised, especially in patients with pre-existing renal disease or those taking concomitant nephrotoxic agents. * **Hepatic Impairment:** Use with caution. Mild to moderate hepatic impairment generally does not require dose adjustment, but monitor liver function closely. Discontinue if signs of liver disease develop. Severe hepatic impairment is a contraindication. ## Contraindications * Hypersensitivity to diclofenac, aspirin, or 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. * Advanced renal disease. * Severe hepatic impairment. * Inflammatory bowel disease (active). * Pregnancy (third trimester). ## Adverse Effects * **Common:** Dyspepsia, nausea, abdominal pain, diarrhea, constipation, headache, dizziness, rash. * **Serious:** * **Cardiovascular:** Increased risk of myocardial infarction, stroke, heart failure. * **Gastrointestinal:** Bleeding, ulceration, perforation. * **Renal:** Renal insufficiency, acute kidney injury. * **Hepatic:** Hepatotoxicity, elevated liver enzymes. * **Dermatologic:** Serious skin reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis). * **Hematologic:** Anemia, prolonged bleeding time. ## Key Drug Interactions * **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. * **Antiplatelet agents (e.g., aspirin, clopidogrel):** Increased risk of bleeding. * **Corticosteroids:** Increased risk of GI ulceration and bleeding. * **SSRIs/SNRIs:** Increased risk of GI bleeding. * **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment. * **Lithium:** Increased lithium levels. * **Methotrexate:** Increased methotrexate levels and toxicity. * **CYP2C9 inhibitors (e.g., fluconazole):** May increase diclofenac exposure. ## Monitoring * **GI:** Monitor for signs and symptoms of GI bleeding and ulceration. * **Cardiovascular:** Assess cardiovascular risk factors and monitor for signs of MI or stroke. * **Renal:** Monitor renal function (BUN, creatinine) especially in patients with pre-existing renal disease, dehydration, heart failure, or those taking diuretics or ACE inhibitors. * **Hepatic:** Monitor liver function tests (ALT, AST) periodically, especially in patients with pre-existing liver disease. * **Blood pressure:** Monitor blood pressure, as NSAIDs can cause or worsen hypertension. ## Clinical Pearls * Use the lowest effective dose for the shortest duration necessary to minimize risks. * Consider gastroprotective agents (e.g., PPIs) for patients at increased risk of GI complications. * Avoid concomitant use with other NSAIDs, including aspirin unless specifically indicated for cardioprotection at a low dose. * Patients with a history of cardiovascular disease or risk factors should use diclofenac with extreme caution. * Discontinue immediately if any signs of liver toxicity or serious skin reactions occur. *** **Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and your healthcare provider for definitive guidance on drug use.