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# Diclofenac (Oral)
## Overview
Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis. This leads to analgesic, anti-inflammatory, and antipyretic effects.
## Primary Indications
* Pain (mild to moderate)
* Inflammation associated with osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, gout, dysmenorrhea.
## Adult Dosing
* **Pain/Osteoarthritis/Rheumatoid Arthritis:** 200 mg per day, divided into 2-4 doses. Immediate-release formulations: 50 mg two to three times daily. Extended-release formulations: 100 mg once daily or 200 mg once daily.
* **Ankylosing Spondylitis:** 25 mg four times daily; 100 mg once daily (extended-release).
* **Dysmenorrhea:** 50 mg every 8 hours as needed, or 100 mg initially, followed by 50 mg every 8 hours as needed.
* **Maximum Dose:** 150 mg/day for immediate-release, 200 mg/day for extended-release. Note: Some sources may recommend up to 200 mg/day for severe rheumatoid arthritis, but this is less common.
## Pediatric Dosing
* **Rheumatoid Arthritis:** Generally not recommended for use in children under 12 years of age due to lack of established dosing and safety data.
* Specific pediatric dosing for other indications is not well-established.
## Dose Adjustments
* **Hepatic Impairment:** Use with caution. Mild to moderate hepatic impairment may require dose reduction. Avoid in severe hepatic impairment.
* **Renal Impairment:** Use with caution. Monitor renal function. Dose adjustments may be necessary in moderate to severe renal impairment, but specific guidelines are not well-defined. Avoid in severe renal impairment.
* **Elderly:** Increased risk of adverse effects; consider lower doses.
## 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.
* Active gastrointestinal bleeding or perforation.
* Inflammatory bowel disease.
* Heart failure, established ischemic heart disease, peripheral arterial disease.
## Adverse Effects
* **Gastrointestinal:** Dyspepsia, abdominal pain, nausea, diarrhea, constipation, GI bleeding, perforation, ulceration.
* **Cardiovascular:** Increased risk of myocardial infarction and stroke. Hypertension. Fluid retention, edema.
* **Renal:** Acute kidney injury, interstitial nephritis, papillary necrosis.
* **Hepatic:** Elevated liver enzymes, hepatitis, jaundice.
* **Dermatologic:** Rash, pruritus.
* **Hematologic:** Anemia, increased bleeding time.
* **Other:** Headache, dizziness, tinnitus, hypersensitivity reactions.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin) and Antiplatelets (e.g., aspirin, clopidogrel):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **ACE inhibitors, ARBs, Beta-blockers:** Reduced antihypertensive effect. Increased risk of renal impairment.
* **Diuretics:** Reduced diuretic effect. Increased risk of renal impairment.
* **Lithium:** Increased lithium levels and risk of toxicity.
* **Methotrexate:** Increased methotrexate levels and toxicity.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **CYP2C9 inhibitors (e.g., fluconazole):** May increase diclofenac plasma concentrations.
## Monitoring
* **Baseline and Periodic:** Renal function (creatinine, BUN), liver function tests (ALT, AST), complete blood count (CBC), stool guaiac for occult blood.
* **Cardiovascular Risk Factors:** Blood pressure, signs/symptoms of heart failure.
* **Signs and Symptoms:** Of GI bleeding (melena, hematemesis), hypersensitivity reactions, and renal dysfunction.
## Clinical Pearls
* Diclofenac carries a black box warning for serious cardiovascular thrombotic events and gastrointestinal bleeding, ulceration, and perforation.
* Use the lowest effective dose for the shortest duration necessary.
* Administer with food or milk to minimize GI upset.
* Extended-release formulations should not be crushed or chewed.
* Consider gastroprotective agents (e.g., PPIs) in patients at high risk for GI complications.
* Monitor for signs of hepatotoxicity, especially with prolonged use.
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**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 relevant guidelines before making any treatment decisions.
