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diflunisal (Rx)Brand and Other Names:

 
 
 

Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet

  • 500mg
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Pain

500-1000 mg PO first dose, THEN

250-500 mg PO q8-12hr; not to exceed 1.5 g/day

Osteoarthritis

500-1000 mg PO daily divided q12hr

Maximum dose: 1500 mg/day

Rheumatoid Arthritis

500-1000 mg PO daily divided q12hr

Maximum dose: 1500 mg/day

Renal Impairment

Initiate at lower dose, monitor for ADRs

CrCl<50 mL/min: 50% of regular dose

Hepatic Impairment

Initiate at lower dose, monitor for ADRs

Administration

Take with food or 8-12 oz water to avoid GI effects

Other Indications & Uses

Off-label: Vascular headache

<12 years old: Safety & efficacy not established

Pain

500-1000 mg PO first dose, THEN

250-500 mg PO q8-12hr; not to exceed 1.5 g/day

Osteoarthritis

500-1000 mg PO daily divided q12hr

Maximum dose: 1500 mg/day

Rheumatoid Arthritis

500-1000 mg PO daily divided q12hr

Maximum dose: 1500 mg/day

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Interactions

Interaction Checker

diflunisal and

No Results

     
     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            >10%

            Increased liver function test (up to 15%)

            1-10%

            Body fluid retention

            Rash

            Abdominal pain

            Constipation

            Diarrhea

            Flatulence

            Indigestion

            Nausea

            Dizziness

            Headache

            Insomnia

            Tinnitus

            <1%

            Edema (<1%)

            Hypertension

            Myocardial infarction

            Vasculitis (<1%)

            Erythema multiforme (<1%)

            Scaling eczema, Stevens-Johnson syndrome (<1%)

            Toxic epidermal necrolysis (<1%)

            Gastrointestinal hemorrhage (<1%)

            Gastrointestinal perforation (<1%)

            Inflammatory disorder of digestive tract

            Agranulocytosis (<1%)

            Anemia (<1%)

            Thrombocytopenia (<1%)

            Hepatitis (<1%)

            Jaundice (<1%)

            Anaphylactoid reaction (<1%)

            Immune hypersensitivity reaction (<1%)

            Cerebrovascular accident

            Impaired renal function disorder (<1%)

            Interstitial nephritis (<1%)

            Renal failure (<1%)

            Bronchospasm

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            Warnings

            Black Box Warnings

            Cardiovascular Risk

            • NSAIDs may increase risk of serious cardiovascular thrombotic events, myocardial infarction (MI), & stroke, which can be fatal
            • Risk may increase with duration of use
            • Patients with risk factors for or existing cardiovascular disease may be at greater risk
            • NSAIDs are contraindicated for perioperative pain in the setting of coronary artery bypass graft (CABG) surgery (increased risk of MI & stroke)

            Gastrointestinal Risk

            • NSAIDs increase risk of serious GI adverse events including bleeding, ulceration, & perforation of the stomach or intestines, which can be fatal
            • GI adverse events may occur at any time during use & without warning symptoms
            • Elderly patients are at greater risk for serious GI events

            Contraindications

            Absolute: hypersensitivity to diflunisal, ASA allergy, history of aspirin triad, CABG

            Relative: bleeding disorders, duodenal/gastric/peptic ulcer, renal impairment, stomatitis, ulcerative colitis, upper GI dz, late pregnancy (risk of premature closure of ductus arteriosus)

            Cautions

            Bronchospasm, cardiac disease, CHF, hepatic/renal impairment, HTN, SLE, fluid retention, >65 years

            Potential risk of cardiovascular damage

            Long-term administration of NSAIDs may result in renal papillary necrosis and other renal injury; patients at greatest risk include the elderly, or those with impaired renal function, hypovolemia, heart failure, liver dysfunction, salt depletion, and individuals taking diuretics, ACE inhibitors, or ARBs

            Risk of serious skin reactions

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            Pregnancy & Lactation

            Pregnancy Category: C (avoid in late pregnancy; may cause premature closure of ductus arteriosus)

            The Quebec Pregnancy Registry identified 4705 women who had spontaneous abortions by 20 weeks' gestation; each case was matched to 10 control subjects (n=47,050) who had not had spontaneous abortions; exposure to nonaspirin NSAIDs during pregnancy was documented in approximately 7.5% of cases of spontaneous abortions and in approximately 2.6% of controls. (CMAJ, September 6, 2011; DOI:10.1503/cmaj.110454)

            Lactation: enters breast milk/not recommended

            Pregnancy Categories

            A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA:Information not available.

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            Pharmacology

            Mechanism of Action

            Inhibits cyclooxygenase-1 (COX-1) & -2 (COX-2), thereby inhibiting prostaglandin synthesis

            Pharmcokinetics

            Bioavailability: 80-100%

            Peak Plasma Time: within 2-3 hr

            Protein Bound: at least 98-99%

            Vd: 0.11 L/kg

            Metabolism: Liver (to glucuronide conjugates, not to salicylic acid)

            Metabolites: salicylurate, salicyl phenolic glucuronide, salicyl acyl glucuronide, 2,5-dihydroxybenzoic acid (gentisic acid), 2,3-dihydroxybenzoic acid, 2,3,5-trihydroxybenzoic acid, gentisuric acid (active)

            Enzymes inhibited: Prostaglandin synthesis (insignificant)

            Half-life: 8-12 hr

            Excretion: Urine ~90%; feces <5%

            Renal Clearance: 80-100% in 24-72 hr

            Dialyzable: Yes

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            Images

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            Formulary

            FormularyPatient Discounts

            To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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