Dosing

Dosing: Adult

Analgesia: Oral:

Immediate release tablet: Starting dose: 50 mg 3 times/day (maximum dose: 150 mg/day); may administer 100 mg loading dose, followed by 50 mg every 8 hours (maximum dose day 1: 200 mg/day; maximum dose day 2 and thereafter: 150 mg/day)

Canadian labeling: Maximum loading dose day 1: 200 mg/day; maximum dose day 2 and up to 7 days: 150 mg/day (50 mg every 6-8 hours)

Immediate release capsule: 25 mg 4 times/day

Primary dysmenorrhea: Oral: Immediate release tablet: Starting dose: 50 mg 3 times/day (maximum dose: 150 mg/day); may administer 100 mg loading dose, followed by 50 mg every 8 hours

Canadian labeling: Maximum loading dose day 1: 200 mg/day; maximum dose day 2 and up to 7 days: 150 mg/day (50 mg every 6-8 hours)

Rheumatoid arthritis:

Oral: Immediate release tablet: 150-200 mg/day in 3-4 divided doses; Delayed release tablet: 150-200 mg/day in 2-4 divided doses; Extended release tablet: 100 mg/day (may increase dose to 200 mg/day in 2 divided doses)

Canadian labeling: 150 mg/day in 3 divided doses (75-150 mg/day of slow release tablet)

Rectal suppository (not available in U.S.): Canadian labeling: Insert 50 mg or 100 mg rectally as single dose to substitute for final (third) oral daily dose (maximum combined dose [rectal and oral]: 150 mg/day

Osteoarthritis:

Oral: Immediate release tablet: 150-200 mg/day in 3-4 divided doses; Delayed release tablet: 150-200 mg/day in 2-4 divided doses; Extended release tablet: 100 mg/day; may increase dose to 200 mg/day in 2 divided doses

Canadian labeling: 150 mg/day in 3 divided doses (75-150 mg/day of slow release tablet)

Rectal suppository (not available in U.S.): Canadian labeling: Insert 50 mg or 100 mg rectally as single dose to substitute for final (third) oral daily dose (maximum combined dose [rectal and oral]: 150 mg/day)

Ankylosing spondylitis: Oral: Delayed release tablet: 100-125 mg/day in 4-5 divided doses

Migraine: Oral: Oral solution: 50 mg (one packet) as a single dose at the time of migraine onset; safety and efficacy of a second dose have not been established.

Use

Delayed-release tablet: Acute and chronic treatment of rheumatoid arthritis, osteoarthritis, ankylosing spondylitis

Extended-release tablet: Chronic treatment of osteoarthritis, rheumatoid arthritis

Adverse Reactions

1% to 10%:

Cardiovascular: Edema

Central nervous system: Dizziness, headache

Dermatologic: Pruritus, rash

Endocrine & metabolic: Fluid retention

Gastrointestinal: Abdominal distension, abdominal pain, constipation, diarrhea, dyspepsia, flatulence, GI perforation, heartburn, nausea, peptic ulcer/GI bleed, vomiting

Hematologic: Anemia, bleeding time increased

Hepatic: Liver enzyme abnormalities (>3 x ULN; ≤4%)

Otic: Tinnitus

Renal: Renal function abnormal

Miscellaneous: Diaphoresis increased

Contraindications

Hypersensitivity to diclofenac or any component of the formulation; patients who exhibit asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs; perioperative pain in the setting of coronary artery bypass graft (CABG) surgery

Warnings / Precautions Drug

Concerns related to adverse effects:

• Anaphylactoid reactions: Even in patients without prior exposure anaphylactoid reactions may occur; patients with "aspirin triad" (bronchial asthma, aspirin intolerance, rhinitis) may be at increased risk. Do not use in patients who experience bronchospasm, asthma, rhinitis, or urticaria with NSAID or aspirin therapy.

• Cardiovascular events: [U.S. Boxed Warning]: NSAIDs are associated with an increased risk of adverse cardiovascular thrombotic events, including MI and stroke. Risk may be increased with duration of use or pre-existing cardiovascular risk factors or disease. Carefully evaluate individual cardiovascular risk profiles prior to prescribing. Use caution with fluid retention. Avoid use in heart failure. Concurrent administration of ibuprofen, and potentially other nonselective NSAIDs, may interfere with aspirin’s cardioprotective effect. Use the lowest effective dose for the shortest duration of time, consistent with individual patient goals, to reduce risk of cardiovascular events; alternate therapies should be considered for patients at high risk.

• CNS effects: May cause drowsiness, dizziness, blurred vision, and other neurologic effects which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving). Discontinue use with blurred or diminished vision and perform ophthalmologic exam. Periodically evaluate vision in all patients receiving long term therapy.

• Gastrointestinal events: [U.S. Boxed Warning]: NSAIDs may increase risk of gastrointestinal irritation, inflammation, ulceration, bleeding, and perforation. These events may occur at any time during therapy and without warning. Use caution with a history of GI disease (bleeding or ulcers), concurrent therapy with aspirin, anticoagulants and/or corticosteroids, smoking, use of alcohol, the elderly or debilitated patients. Use the lowest effective dose for the shortest duration of time, consistent with individual patient goals, to reduce risk of GI adverse events; alternate therapies should be considered for patients at high risk. When used concomitantly with ≤325 mg of aspirin, a substantial increase in the risk of gastrointestinal complications (eg, ulcer) occurs; concomitant gastroprotective therapy (eg, proton pump inhibitors) is recommended (Bhatt, 2008).

• Genitourinary effects: Long-term NSAID use may result in renal papillary necrosis while persistent urinary symptoms (eg, dysuria, bladder pain), cystitis, or hematuria may occur anytime after initiating NSAID therapy. Discontinue therapy with symptom onset and evaluate for origin.

• Hematologic effects: Platelet adhesion and aggregation may be decreased; may prolong bleeding time; patients with coagulation disorders or who are receiving anticoagulants should be monitored closely. Anemia may occur; patients on long-term NSAID therapy should be monitored for anemia. Rarely, NSAID use has been associated with potentially severe blood dyscrasias (eg, agranulocytosis, thrombocytopenia, aplastic anemia).

• Hepatic effects: Transaminase elevations have been observed with chronic use, generally within in the first 2 months of therapy, but may occur at any time (manufacturer labeling). A recent clinical trial concluded that transaminase elevations occur 4-6 months after initiation of therapy (Laine, 2009). Significant elevations in transaminases (eg, >3 x ULN) occur before patients become symptomatic. Periodic transaminase monitoring should occur in patients on chronic therapy beginning 4-8 weeks after initiation. Rarely, severe hepatic reactions (eg, fulminant hepatitis, liver failure) have occurred with NSAID use. Use with caution in patients with hepatic porphyria (may trigger attack). Patients should be educated about symptoms of hepatotoxicity. Avoid concurrent hepatotoxins if possible and use the lowest effective dose for the shortest duration. Discontinue therapy if hepatic injury is suspected (persistent or worsening LFT abnormality, clinical signs/symptoms of liver disease, or systemic manifestations of hypersensitivity (eosinophilia, rash).

• Hyperkalemia: NSAID use may increase the risk of hyperkalemia, particularly in the elderly, diabetics, renal disease, and with concomitant use of other agents capable of inducing hyperkalemia (eg, ACE-inhibitors). Monitor potassium closely.

• Skin reactions: NSAIDs may cause photosensitivity as well as serious skin adverse events including exfoliative dermatitis, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN); discontinue use at first sign of skin rash or hypersensitivity.

Disease-related concerns:

• Aseptic meningitis: May increase the risk of aseptic meningitis, especially in patients with systemic lupus erythematosus (SLE) and mixed connective tissue disorders.

• Asthma: Do not administer to patients with aspirin-sensitive asthma; severe bronchospasm may occur. Use caution in patients with other forms of asthma.

• Coronary artery bypass graft surgery: [U.S. Boxed Warning]: Use is contraindicated for treatment of perioperative pain in the setting of coronary artery bypass graft (CABG) surgery. Risk of MI and stroke may be increased with use following CABG surgery.

• Hepatic impairment: Use with caution in patients with decreased hepatic function.

• Hypertension: Use with caution; may cause new-onset hypertension or worsening of existing hypertension. Monitor blood pressure closely with therapy initiation and during therapy.

• Renal impairment: NSAID use may compromise existing renal function; dose-dependent decreases in prostaglandin synthesis may result from NSAID use, reducing renal blood flow which may cause renal decompensation. Patients with impaired renal function, dehydration, heart failure, liver dysfunction, those taking diuretics and ACEI, and the elderly are at greater risk of renal toxicity. Rehydrate patient before starting therapy; monitor renal function closely. Not recommended for use in patients with advanced renal disease.

Special populations:

• Elderly: Avoid chronic use (unless alternative agents ineffective and patient can receive concomitant gastroprotective agent); nonselective oral NSAID use is associated with an increased risk of GI bleeding and peptic ulcer disease in older adults in high risk category (eg, >75 years or age or receiving concomitant oral/parenteral corticosteroids, anticoagulants, or antiplatelet agents) (Beers Criteria).

Interactions

ACE Inhibitors: May enhance the adverse/toxic effect of Nonsteroidal Anti-Inflammatory Agents. Specifically, the combination may result in a significant decrease in renal function. Nonsteroidal Anti-Inflammatory Agents may diminish the antihypertensive effect of ACE Inhibitors. Risk C: Monitor therapy

Agents with Antiplatelet Properties (e.g., P2Y12 inhibitors, NSAIDs, SSRIs, etc.): May enhance the anticoagulant effect of other Agents with Antiplatelet Properties. Risk C: Monitor therapy

Agents with Antiplatelet Properties (e.g., P2Y12 inhibitors, NSAIDs, SSRIs, etc.): Nonsteroidal Anti-Inflammatory Agents may enhance the adverse/toxic effect of Agents with Antiplatelet Properties. An increased risk of bleeding may occur. Nonsteroidal Anti-Inflammatory Agents may diminish the cardioprotective effect of Agents with Antiplatelet Properties. This interaction is likely specific to aspirin, and not to other antiplatelet agents. Risk C: Monitor therapy

Aliskiren: Nonsteroidal Anti-Inflammatory Agents may diminish the antihypertensive effect of Aliskiren. Nonsteroidal Anti-Inflammatory Agents may enhance the nephrotoxic effect of Aliskiren. Management: Monitor renal function periodically in patients receiving aliskiren and any nonsteroidal anti-inflammatory agent. Patients at elevated risk of renal dysfunction include those who are elderly, are volume depleted, or have pre-existing renal dysfunction. Risk C: Monitor therapy

Aminoglycosides: Nonsteroidal Anti-Inflammatory Agents may decrease the excretion of Aminoglycosides. Data only in premature infants. Risk C: Monitor therapy

Angiotensin II Receptor Blockers: May enhance the adverse/toxic effect of Nonsteroidal Anti-Inflammatory Agents. Specifically, the combination may result in a significant decrease in renal function. Nonsteroidal Anti-Inflammatory Agents may diminish the therapeutic effect of Angiotensin II Receptor Blockers. The combination of these two agents may also significantly decrease glomerular filtration and renal function. Risk C: Monitor therapy

Anticoagulants: Agents with Antiplatelet Properties may enhance the anticoagulant effect of Anticoagulants. Risk C: Monitor therapy

Anticoagulants: Nonsteroidal Anti-Inflammatory Agents may enhance the anticoagulant effect of Anticoagulants. Risk C: Monitor therapy

Antidepressants (Tricyclic, Tertiary Amine): May enhance the antiplatelet effect of NSAID (Nonselective). Risk C: Monitor therapy

ARIPiprazole: CYP3A4 Inhibitors (Weak) may increase the serum concentration of ARIPiprazole. Management: Monitor for increased aripiprazole pharmacologic effects. Aripiprazole dose adjustments may or may not be required based on concomitant therapy and/or indication. Consult full interaction monograph for specific recommendations. Risk C: Monitor therapy

Beta-Blockers: Nonsteroidal Anti-Inflammatory Agents may diminish the antihypertensive effect of Beta-Blockers. Exceptions: Levobunolol; Metipranolol. Risk C: Monitor therapy

Bile Acid Sequestrants: May decrease the absorption of Nonsteroidal Anti-Inflammatory Agents. Risk D: Consider therapy modification

Bisphosphonate Derivatives: Nonsteroidal Anti-Inflammatory Agents may enhance the adverse/toxic effect of Bisphosphonate Derivatives. Both an increased risk of gastrointestinal ulceration and an increased risk of nephrotoxicity are of concern. Risk C: Monitor therapy

Collagenase (Systemic): Agents with Antiplatelet Properties may enhance the adverse/toxic effect of Collagenase (Systemic). Specifically, the risk of injection site bruising and/or bleeding may be increased. Risk C: Monitor therapy

Corticosteroids (Systemic): May enhance the adverse/toxic effect of NSAID (Nonselective). Risk C: Monitor therapy

CycloSPORINE (Systemic): Nonsteroidal Anti-Inflammatory Agents may enhance the nephrotoxic effect of CycloSPORINE (Systemic). Nonsteroidal Anti-Inflammatory Agents may increase the serum concentration of CycloSPORINE (Systemic). CycloSPORINE (Systemic) may increase the serum concentration of Nonsteroidal Anti-Inflammatory Agents. Specifically, elevated diclofenac concentrations have been reported. Management: Consider alternatives to nonsteroidal anti-inflammatory agents (NSAIDs). Monitor for evidence of nephrotoxicity, as well as increased serum cyclosporine concentrations and systemic effects (e.g., hypertension) during concomitant therapy with NSAIDs. Risk D: Consider therapy modification

CYP2C9 Inducers (Strong): May decrease the serum concentration of Diclofenac (Systemic). Risk C: Monitor therapy

CYP2C9 Inhibitors (Strong): May increase the serum concentration of Diclofenac (Systemic). Management: Consider using a lower dose of diclofenac when used together with a strong CYP2C9 inhibitor. Arthrotec (diclofenac and misoprostol) labeling specifically recommends limiting the total daily dose to a maximum of 50 mg twice/day. Risk D: Consider therapy modification

Dabigatran Etexilate: Agents with Antiplatelet Properties may enhance the anticoagulant effect of Dabigatran Etexilate. Agents with Antiplatelet Properties may increase the serum concentration of Dabigatran Etexilate. This mechanism applies specifically to clopidogrel. Management: Increase monitoring for signs/symptoms of bleeding. The Canadian product monograph for dabigatran specifically recommends avoiding concomitant use with GIIb/IIIa inhibitors or ticlopidine, or with aspirin used for stroke prevention in atrial fibrillation. Risk C: Monitor therapy

Dasatinib: May enhance the anticoagulant effect of Agents with Antiplatelet Properties. Risk C: Monitor therapy

Deferasirox: Nonsteroidal Anti-Inflammatory Agents may enhance the adverse/toxic effect of Deferasirox. Specifically, the risk for GI ulceration/irritation or GI bleeding may be increased. Risk C: Monitor therapy

Deferiprone: UGT1A6 Inhibitors may increase the serum concentration of Deferiprone. Risk C: Monitor therapy

Desmopressin: Nonsteroidal Anti-Inflammatory Agents may enhance the adverse/toxic effect of Desmopressin. Risk C: Monitor therapy

Digoxin: Nonsteroidal Anti-Inflammatory Agents may increase the serum concentration of Digoxin. Risk C: Monitor therapy

Drotrecogin Alfa (Activated): Agents with Antiplatelet Properties may enhance the adverse/toxic effect of Drotrecogin Alfa (Activated). Bleeding may occur. Management: When possible, avoid use of drotrecogin within 7 days of use of any IIb/IIIa antagonists, higher dose aspirin (more than 650 mg/day), or use of other antiplatelet agents. Risk D: Consider therapy modification

Eplerenone: Nonsteroidal Anti-Inflammatory Agents may diminish the antihypertensive effect of Eplerenone. Nonsteroidal Anti-Inflammatory Agents may enhance the hyperkalemic effect of Eplerenone. Risk C: Monitor therapy

Floctafenine: May enhance the adverse/toxic effect of Nonsteroidal Anti-Inflammatory Agents. Risk X: Avoid combination

Glucosamine: May enhance the antiplatelet effect of Agents with Antiplatelet Properties. Risk C: Monitor therapy

Haloperidol: Nonsteroidal Anti-Inflammatory Agents may enhance the adverse/toxic effect of Haloperidol. Specifically including drowsiness and confusion. Risk C: Monitor therapy

Herbs (Anticoagulant/Antiplatelet Properties) (eg, Alfalfa, Anise, Bilberry): May enhance the adverse/toxic effect of Agents with Antiplatelet Properties. Bleeding may occur. Risk D: Consider therapy modification

Herbs (Anticoagulant/Antiplatelet Properties) (eg, Alfalfa, Anise, Bilberry): May enhance the adverse/toxic effect of Nonsteroidal Anti-Inflammatory Agents. Bleeding may occur. Management: Concomitant treatment with these agents should generally be avoided. If used concomitantly, increased diligence in monitoring for adverse effects (eg, bleeding, bruising, altered mental status due to CNS bleeds) must be employed. Risk D: Consider therapy modification

HydrALAZINE: Nonsteroidal Anti-Inflammatory Agents may diminish the antihypertensive effect of HydrALAZINE. Risk C: Monitor therapy

Ibritumomab: Agents with Antiplatelet Properties may enhance the adverse/toxic effect of Ibritumomab. Both agents may contribute to impaired platelet function and an increased risk of bleeding. Risk C: Monitor therapy

Ketorolac (Nasal): May enhance the adverse/toxic effect of Nonsteroidal Anti-Inflammatory Agents. Risk X: Avoid combination

Ketorolac (Systemic): May enhance the adverse/toxic effect of Nonsteroidal Anti-Inflammatory Agents. Risk X: Avoid combination

Lithium: Nonsteroidal Anti-Inflammatory Agents may increase the serum concentration of Lithium. Risk D: Consider therapy modification

Lomitapide: CYP3A4 Inhibitors (Weak) may increase the serum concentration of Lomitapide. Management: Limit the maximum adult dose of lomitapide to 30 mg daily when used in combination with any weak CYP3A4 inhibitor. Risk D: Consider therapy modification

Loop Diuretics: Nonsteroidal Anti-Inflammatory Agents may diminish the diuretic effect of Loop Diuretics. Management: Monitor for decreased therapeutic effects of loop diuretics with concurrent use of an NSAID. Consider avoiding concomitant use of these agents in CHF or cirrhosis with ascites. Concomitant use of bumetanide with indomethacin is not recommended. Risk D: Consider therapy modification

Methotrexate: Nonsteroidal Anti-Inflammatory Agents may increase the serum concentration of Methotrexate. Risk D: Consider therapy modification

Multivitamins/Minerals (with ADEK, Folate, Iron): May enhance the antiplatelet effect of Agents with Antiplatelet Properties. Risk C: Monitor therapy

Nonsteroidal Anti-Inflammatory Agents: May enhance the adverse/toxic effect of Agents with Antiplatelet Properties. An increased risk of bleeding may occur. Nonsteroidal Anti-Inflammatory Agents may diminish the cardioprotective effect of Agents with Antiplatelet Properties. This interaction is likely specific to aspirin, and not to other antiplatelet agents. Risk C: Monitor therapy

Nonsteroidal Anti-Inflammatory Agents: May enhance the adverse/toxic effect of other Nonsteroidal Anti-Inflammatory Agents. Risk C: Monitor therapy

NSAID (COX-2 Inhibitor): Nonsteroidal Anti-Inflammatory Agents may enhance the adverse/toxic effect of NSAID (COX-2 Inhibitor). Risk X: Avoid combination

Omacetaxine: Nonsteroidal Anti-Inflammatory Agents may enhance the adverse/toxic effect of Omacetaxine. Specifically, the risk for bleeding-related events may be increased. Management: Avoid concurrent use of nonsteroidal antiinflammatory drugs (NSAIDs) with omacetaxine in patients with a platelet count of less than 50,000/uL. Risk X: Avoid combination

Omega-3 Fatty Acids: May enhance the antiplatelet effect of Agents with Antiplatelet Properties. Risk C: Monitor therapy

Peginterferon Alfa-2b: May decrease the serum concentration of CYP2D6 Substrates. Risk C: Monitor therapy

PEMEtrexed: NSAID (Nonselective) may increase the serum concentration of PEMEtrexed. Management: Patients with mild-to-moderate renal insufficiency (estimated creatinine clearance 45-79 mL/min) should avoid NSAIDs for 2-5 days prior to, the day of, and 2 days after pemetrexed. Risk D: Consider therapy modification

Pentosan Polysulfate Sodium: May enhance the adverse/toxic effect of Agents with Antiplatelet Properties. Specifically, the risk of bleeding may be increased by concurrent use of these agents. Risk C: Monitor therapy

Pentoxifylline: May enhance the antiplatelet effect of Agents with Antiplatelet Properties. Risk C: Monitor therapy

Pimozide: CYP3A4 Inhibitors (Weak) may increase the serum concentration of Pimozide. Risk X: Avoid combination

Porfimer: Photosensitizing Agents may enhance the photosensitizing effect of Porfimer. Risk C: Monitor therapy

Potassium-Sparing Diuretics: Nonsteroidal Anti-Inflammatory Agents may diminish the antihypertensive effect of Potassium-Sparing Diuretics. Nonsteroidal Anti-Inflammatory Agents may enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Risk C: Monitor therapy

PRALAtrexate: Nonsteroidal Anti-Inflammatory Agents may increase the serum concentration of PRALAtrexate. More specifically, NSAIDS may decrease the renal excretion of pralatrexate. Management: Closely monitor for increased pralatrexate serum levels and/or toxicity if used concomitantly with an NSAID. Monitor for decreased pralatrexate serum levels with NSAID discontinuation. Risk C: Monitor therapy

Probenecid: May increase the serum concentration of Nonsteroidal Anti-Inflammatory Agents. Risk C: Monitor therapy

Prostacyclin Analogues: May enhance the antiplatelet effect of Agents with Antiplatelet Properties. Risk C: Monitor therapy

Quinolone Antibiotics: Nonsteroidal Anti-Inflammatory Agents may enhance the neuroexcitatory and/or seizure-potentiating effect of Quinolone Antibiotics. Nonsteroidal Anti-Inflammatory Agents may increase the serum concentration of Quinolone Antibiotics. Risk C: Monitor therapy

Rivaroxaban: Agents with Antiplatelet Properties may enhance the anticoagulant effect of Rivaroxaban. Management: Avoid concurrent use of clopidogrel with rivaroxaban unless the anticipated benefits outweigh the risks of bleeding. Avoid concurrent use of rivaroxaban with other antiplatelet agents whenever possible. Risk D: Consider therapy modification

Salicylates: NSAID (Nonselective) may enhance the adverse/toxic effect of Salicylates. An increased risk of bleeding may be associated with use of this combination. NSAID (Nonselective) may diminish the cardioprotective effect of Salicylates. Salicylates may decrease the serum concentration of NSAID (Nonselective). Exceptions: Choline Magnesium Trisalicylate. Risk D: Consider therapy modification

Salicylates: Agents with Antiplatelet Properties may enhance the adverse/toxic effect of Salicylates. Increased risk of bleeding may result. Risk C: Monitor therapy

Selective Serotonin Reuptake Inhibitors: May enhance the antiplatelet effect of NSAID (Nonselective). NSAID (Nonselective) may diminish the therapeutic effect of Selective Serotonin Reuptake Inhibitors. Management: Consider using alternative analgesics, when appropriate, and/or addition of an gastroprotective agent. Monitor patients closely for signs/symptoms of bleeding, and for evidence of diminished SSRI effectiveness with concurrent use. Risk D: Consider therapy modification

Serotonin/Norepinephrine Reuptake Inhibitors: May enhance the antiplatelet effect of NSAID (Nonselective). Risk C: Monitor therapy

Sodium Phosphates: May enhance the nephrotoxic effect of Nonsteroidal Anti-Inflammatory Agents. Specifically, the risk of acute phosphate nephropathy may be enhanced. Management: Consider avoiding this combination by temporarily suspending treatment with NSAIDs, or seeking alternatives to oral sodium phosphate bowel preparation. If the combination cannot be avoided, maintain adequate hydration and monitor renal function closely. Risk D: Consider therapy modification

Thiazide Diuretics: Nonsteroidal Anti-Inflammatory Agents may diminish the therapeutic effect of Thiazide Diuretics. Risk C: Monitor therapy

Thrombolytic Agents: Agents with Antiplatelet Properties may enhance the anticoagulant effect of Thrombolytic Agents. Risk C: Monitor therapy

Thrombolytic Agents: Nonsteroidal Anti-Inflammatory Agents may enhance the adverse/toxic effect of Thrombolytic Agents. An increased risk of bleeding may occur. Risk C: Monitor therapy

Tipranavir: May enhance the antiplatelet effect of Agents with Antiplatelet Properties. Risk C: Monitor therapy

Tositumomab and Iodine I 131 Tositumomab: Agents with Antiplatelet Properties may enhance the adverse/toxic effect of Tositumomab and Iodine I 131 Tositumomab. Specifically, the risk of bleeding-related adverse events may be increased. Risk C: Monitor therapy

Treprostinil: May enhance the adverse/toxic effect of Nonsteroidal Anti-Inflammatory Agents. Bleeding may occur. Risk C: Monitor therapy

Vancomycin: Nonsteroidal Anti-Inflammatory Agents may increase the serum concentration of Vancomycin. Risk C: Monitor therapy

Vitamin E: May enhance the antiplatelet effect of Agents with Antiplatelet Properties. Risk C: Monitor therapy

Vitamin K Antagonists (eg, warfarin): NSAID (Nonselective) may enhance the anticoagulant effect of Vitamin K Antagonists. Risk D: Consider therapy modification

Voriconazole: May increase the serum concentration of Diclofenac (Systemic). Management: Consider using a lower dose of diclofenac when used together with voriconazole. Arthrotec (diclofenac and misoprostol) labeling specifically recommends limiting the total daily dose to a maximum of 50 mg twice/day. Risk D: Consider therapy modification

Pregnancy

Pregnancy Implications Adverse events were not observed in the initial animal reproduction studies; therefore, manufacturers classify most dosage forms of diclofenac as pregnancy category C (oral: Category D ≥30 weeks gestation). Diclofenac crosses the placenta and can be detected in fetal tissue and amniotic fluid. NSAID exposure during the first trimester is not strongly associated with congenital malformations; however, cardiovascular anomalies and cleft palate have been observed following NSAID exposure in some studies. The use of a NSAID close to conception may be associated with an increased risk of miscarriage. Nonteratogenic effects have been observed following NSAID administration during the third trimester including: Myocardial degenerative changes, prenatal constriction of the ductus arteriosus, fetal tricuspid regurgitation, failure of the ductus arteriosus to close postnatally; renal dysfunction or failure, oligohydramnios; gastrointestinal bleeding or perforation, increased risk of necrotizing enterocolitis; intracranial bleeding (including intraventricular hemorrhage), platelet dysfunction with resultant bleeding; pulmonary hypertension. Because they may cause premature closure of the ductus arteriosus, use of NSAIDs late in pregnancy should be avoided (use after 31 or 32 weeks gestation is not recommended by some clinicians).

Lactation

Monitoring Parameters

Monitor CBC, liver enzymes (periodically during chronic therapy starting 4-8 weeks after initiation), BUN/serum creatinine; monitor urine output; occult blood loss

Mechanism of Action

Reversibly inhibits cyclooxygenase-1 and 2 (COX-1 and 2) enzymes, which results in decreased formation of prostaglandin precursors; has antipyretic, analgesic, and anti-inflammatory properties

Other proposed mechanisms not fully elucidated (and possibly contributing to the anti-inflammatory effect to varying degrees), include inhibiting chemotaxis, altering lymphocyte activity, inhibiting neutrophil aggregation/activation, and decreasing proinflammatory cytokine levels.

Pharmacodynamics / Kinetics

Distribution: ~1.4 L/kg

Protein binding: >99%, primarily to albumin

Metabolism: Hepatic; undergoes first-pass metabolism; forms several metabolites (1 with weak activity)

Bioavailability: 55%

Half-life elimination: ~2 hours

Time to peak, serum:

Tablet, XR (diclofenac sodium) ~5 hours

Tablet, delayed release (diclofenac sodium): ~2 hours

Excretion: Urine (~65%); feces (~35%)