foscarnet (Rx)

Brand and Other Names:Foscavir, Phosphonoformic acid
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

injectable solution

  • 2.4g/100mL
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CMV Retinitis

Patients with AIDS: Combination therapy with ganciclovir indated for patients who have relapsed following monotherapy with either foscarnet or ganciclovir

Induction: 60 mg/kg q8hr IV x14-21 days; infuse IV over at least 60 min 

Maintenance: 90-120 mg/kg IV qDay; infuse IV over at least 60-90 min

Herpes Simplex

Indicated for Herpes simplex in patients with acyclovir resistance who are immunocompromised

Option 1: 40 mg/kg IV q8hr x14-21 days; infuse IV over at least 60 min 

Option 2: 40-60 mg/kg IV q12hr x14-21 days; infuse IV over at least 60 min

Other Information

Administer by slow IV infusion

Prehydrate with 750-1000 mL NS or D5W before first infusion to decrease risk for nephrotoxicity

See prescribing information for dose adjustments for CrCl <1.4 mL/min/kg

<18 years old: Safety and efficacy not established

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Interactions

Interaction Checker

and foscarnet

No Results

     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            >10%

            Fever (65%)

            Nausea (47%)

            Anemia (33%)

            Vomiting (33%)

            Diarrhea (30%)

            Abnormal renal function/decreased CrCl (27%)

            Headache (26%)

            Seizures (10%)

            1-10%

            Fatigue

            Depression

            Confusion

            Anxiety

            Dizziness

            Hypoesthesia

            Malaise

            Rash

            Electrolyte imbalance (especially potassium, calcium, magnesium, and phosphorus)

            Leukopenia

            Neutropenia

            Postmarketing reports

            Esophageal ulceration, renal tubular acidosis, renal tubular necrosis, and crystal-induced nephropathy, status epilepticus, ventricular arrhythmia, prolongation of QT interval, torsade de pointes, gamma GT increased, diabetes insipidus (usually nephrogenic), renal calculus, Fanconi syndrome acquired, hypercalcemia, hypernatremia, and muscle disorders including myopathy, myositis, administration site extravasation, localized edema, hypersensitivity reactions (including anaphylactic shock, urticaria and angioedema) (see WARNINGS section), gastrointestinal hemorrhage, increased lipase, glomerulonephritis, nephrotic syndrome, proteinuria

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            Warnings

            Black Box Warnings

            Renal impairment is the major toxicity; reduce nephrotoxicity risk by IV prehydration with normal saline

            Monitor serum creatinine level, and, if indicated, adjust dose according to renal impairment

            Seizures, related to alterations in plasma minerals and electrolytes, reported; mineral and electrolyte supplementation may be required

            Indicated for use only in immunocompromised patients with cytomegalovirus (CMV) retinitis and mucocutaneous acyclovir-resistant herpes simplex virus (HSV) infections

            Contraindications

            Hypersensitivity

            Cautions

            Caution with renal impairment

            Do not administer by rapid or bolus IV injection; use infusion pump

            May be associated with changes in serum electrolytes changes including hypocalcemia, hypo- or hyperphosphatemia, hypomagnesemia, or hypokalemia

            Serious acute hypersensitivity reactions (e.g., anaphylactic shock, urticaria, angioedema) reported; if such acute reactions occur, discontinue therapy; and institute appropriate medical therapy immediately

            Cases of status epilepticus reported; several cases of seizures associated with death; electrolyte abnormalities may increase risk of seizures

            Associated with prolongation of QT interval, an ECG abnormality that has been associated with torsades de pointes, reported during postmarketing surveillance; has occurred with confounding risk factors such as underlying cardiac disease, electrolyte abnormalities and other concomitant medications; use caution in patients with history of QT prolongation, taking medications known to prolong the QT interval, patients with electrolyte disturbances, or patients who have other risk factors for QT prolongation; electrocardiograms (ECGs) and measurement of electrolytes should be obtained prior to treatment initiation and periodically during treatment

            Due to sodium content of foscarnet (240 micromoles (5.5 mg) of sodium per mL); avoid foscarnet use when IV infusion of large amount of sodium or water may not be tolerated (e.g. in patients with cardiomyopathy); avoid foscarnet use in patients on a controlled sodium diet

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            Pregnancy & Lactation

            Pregnancy Category: C

            Lactation: not known if excreted in breast milk, do not nurse

            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 activity of pyrophosphate binding site on virus-specific DNA polymerases and reverse transcriptases; active against CMV, HSV-1, and HSV-2

            Absorption

            Peak Plasma Concentration: 589 µM (60 mg/kg q8hr), 623 µM (90 mg/kg q12hr)

            Distribution

            Protein Bound: 14-17%

            Volume of distribution: 0.41 L/kg (60 mg/kg q8hr), 0.52 L/kg (90 mg/kg q12hr)

            Elimination

            Half-life: 4 hr (60 mg/kg q8hr); 3.3 hr (90 mg/kg q12hr)

            Dialyzable: Not evaluated

            Renal clearance: 5.6 L/hr (60 mg/kg q8hr), 6.4 L/hr (90 mg/kg q12hr)

            Total body clearance: 6.2 L/hr (60 mg/kg q8hr); 7.1 L/hr (90 mg/kg q12hr)

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            Administration

            IV Incompatibilities

            Y-site: acyclovir, amphotericin B, diazepam, digoxin, diphenhydramine, dobutamine, droperidol, ganciclovir, haloperidol, leucovorin, lorazepam, midazolam, pentamidine, phenytoin, prochlorperazine edisylate, promethazine, TMP-SMX

            IV Compatabilities

            Solution: D5W, NS

            Additive: KCl

            Y-site (partial list): aldesleukin, amikacin, aminophylline, ampicillin, aztreonam, most cephalosporins, clindamycin, fluconazole, furosemide, heparin, metronidazole, morphine, tobramycin, vancomycin (maybe vancomycin concentration dependant)

            IV Preparation

            Should be diluted in D5W or NS & transferred to PVC containers

            For peripheral line administration, dilute to 12 mg/mL with D5W or NS

            For central line administration, may administer undiluted

            IV Administration

            Use an infusion pump, not exceeding 1 mg/kg/min

            Adult induction doses of 60 mg/kg are administered over a minimum 1 hr

            Adult maintenance doses of 90-120 mg are infused over 2 hr

            Storage

            Store at room temp

            Protect from temperatures >40°C and from freezing

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            Formulary

            FormularyPatient Discounts

            Adding plans allows you to compare formulary status to other drugs in the same class.

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

            Adding plans allows you to:

            • View the formulary and any restrictions for each plan.
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            • Compare formulary status to other drugs in the same class.
            • Access your plan list on any device – mobile or desktop.

            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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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.