fostemsavir (Rx)

Brand and Other Names:Rukobia
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablet, extended-release

  • 600mg

HIV Infection

Indicated in combination with other antiretroviral (ATV) drugs for treatment of HIV-1 infection in heavily treatment-experienced adults with multidrug-resistant HIV-1 infection failing their current antiretroviral treatment (ART) regimen owing to resistance, intolerance, or safety considerations

600 mg PO BID

Dosage Modifications

Any severity of hepatic or renal impairment, including hemodialysis: No dosage adjustment required

Safety and efficacy not established

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Interactions

Interaction Checker

and fostemsavir

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    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            >10%

            Creatinine >1.8 x ULN or 1.5 x baseline (19%)

            1-10%

            Nausea (10%)

            Direct bilirubin >ULN (7%)

            Hemoglobin <9 g/dL (6%)

            Cholesterol ≥300 mg/dL) (5%)

            Lipase >3x ULN (5%)

            Triglycerides >500 mg/dL (5%)

            ALT >5x ULN (5%)

            AST >5x ULN (4%)

            Hyperglycemia >250 mg/dL (4%)

            LDL cholesterol ≥190 mg/dL

            Neutrophils ≤599 cells/mm3 (4%)

            Diarrhea (4%)

            Headache (4%)

            Bilirubin ≥2.6x ULN (3%)

            Urate >12 mg/dL (3%)

            Abdominal pain (3%)

            Dyspepsia (3%)

            Fatigue (3%)

            Rash (3%)

            Sleep disturbance (3%)

            Immune reconstitution inflammatory syndrome (2%)

            Somnolence (2%)

            Vomiting (2%)

            Creatinine kinase ≥10x ULN (2%)

            <2%

            • Cardiac disorders: ECG QT prolonged (asymptomatic)
            • Musculoskeletal disorders: Myalgia
            • Nervous system disorders: Dizziness, dysgeusia, peripheral neuropathy
            • Skin and subcutaneous tissue disorders: Pruritus
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            Warnings

            Contraindications

            Hypersensitivity to fostemsavir or any of its components

            Coadministered strong CYP3A inducers (eg, enzalutamide, carbamazepine, phenytoin, rifampin, mitotane, St John’s wort), as significant decreases in temsavir (the active moiety of fostemsavir) plasma concentrations may occur, which may result in loss of virologic response

            Cautions

            Immune reconstitution syndrome reported with combination antiretroviral therapy; an inflammatory response to indolent or residual opportunistic infections (eg, Mycobacterium avium infection, cytomegalovirus, Pneumocystis jirovecii pneumonia, or tuberculosis) may occur, which may necessitate further evaluation and treatment; autoimmune disorders (eg, Grave disease, polymyositis, Guillain-Barré) also reported

            Monitor liver enzymes in patients coinfected with hepatitis B or C virus; elevated hepatic transaminases observed in greater proportion of coinfected individuals; maintain/initiate effective hepatitis B therapy when initiating fostemsavir to avoid hepatitis B reactivation

            Drug interaction overview

            • CYP3A4 inducers
              • Contraindicated
              • Temsavir (active moiety) is a CYP3A4 substrate
              • Coadministration with strong CYP3A4 inducers significantly decreases temsavir plasma concentrations, which may lead to loss of virologic response and resistance
            • QT prolongation
              • Caution with history of prolonged QT, torsade de Pointes, or cardiac disease prone to arrhythmias
              • Caution if coadministered with other drugs known to prolong QT interval
              • QTc prolongation reported with higher than recommended doses
              • Geriatric patients may be more prone to QT prolongation
            • OATP and BCRP substrates
              • Temsavir inhibits OATP1B1, OATP1B3, and BCRP
              • Caution; OATP1B1/3 or BCRP substrates (eg, grazoprevir, voxilaprevir, ethinyl estradiol, statins) may need to be avoided or require dosage modification
              • Temsavir inhibits organic anion transporting polypeptide (OATP)1B1/3, which may increase plasma concentration of substrate
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            Pregnancy & Lactation

            Pregnancy

            Antiretroviral pregnancy registry (APR): Clinicians are encouraged to register patients by calling 1-800-258-4263

            Human data are insufficient regarding use during pregnancy to adequately assess a drug-associated risk of birth defects and miscarriage

            Animal studies

            • Oral administration to pregnant rats and rabbits during organogenesis resulted in no adverse developmental effects at clinically relevant temsavir exposures

            Lactation

            The CDC recommends that HIV-1–infected mothers in the United States not breastfeed their infants to avoid risking postnatal transmission of HIV-1 infection

            Unknown if excreted in breast milk, affects milk production, or effects breastfed infants

            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

            Prodrug of temsavir; first-in-class HIV-1 attachment inhibitor that works by binding directly to the glycoprotein 120 (gp120) subunit on the surface of the virus

            By binding to this location on the virus, fostemsavir blocks HIV from attaching to host immune system CD4+ T cells and other immune cells, thereby preventing HIV from infecting those cells and multiplying

            Absorption

            Bioavailability: 26.9%

            Peak plasma time: 2 hr

            Peak plasma concentration: 1700 ng/mL

            Trough concentration: 478 ng/mL

            AUC: 12,900 ng⋅h/mL

            Distribution

            Protein bound: 88.4% (primarily to albumin)

            Vd: 29.5 L

            Metabolism

            Hydrolysis (esterases): 36.1%

            Oxidation (CYP3A4): 21.2%

            UGT: <1%

            Elimination

            Half-life: 11 hr

            Clearance: 17.9 L/hr

            Excretion: Urine (51%; <2% unchanged); feces (33%; 1.1 unchanged)

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            Administration

            Oral Administration

            May take with or without food

            Swallow tablets whole; do not chew, crush, or split

            Missed dose

            • Advise patients to avoid missing doses as it can result in development of resistance
            • If dose is missed; take as soon as remembered
            • Do not double next dose or take more than prescribed dose owing to risk of QT prolongation

            Storage

            Store at 20-25ºC (68-77ºF); excursions permitted to 15-30ºC (59-86ºF)

            Tablets may have slight vinegarlike odor

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            Formulary

            FormularyPatient Discounts

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            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.
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            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
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            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
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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.