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abiraterone (Rx)Brand and Other Names:Zytiga

 
 
 

Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet

  • 250mg
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Prostate Cancer

Indicated for treatment of metastatic castration-resistant prostate cancer (CRPC) in patients who are chemotherapy-naive or in those who have received prior chemotherapy containing docetaxel; administer with prednisone

4 tabs (1000 mg) PO qDay with prednisone 5 mg PO q12hr

Dosage Modifications

Coadministration with strong CYP3A4 inducers: Avoid if possible; if must be coadministered, increase dosage frequency of abiraterone from qDay to BID (eg, from 1,000 mg qDay to 1,000 mg BID)

Reduce the dose back to the previous dose and frequency, if the concomitant strong CYP3A4 inducer is discontinued

Renal Impairment

Dose adjustment not required

Hepatic Impairment

Baseline LFTs

  • Mild (Child-Pugh A): Dose adjustment not required
  • Moderate (Child-Pugh B): Reduce starting dose to 250 mg PO qDay
  • Severe (Child-Pugh C): Avoid use; not studied in this population and no dose adjustment can be predicted

Increased LFT during treatment

  • Interrupt treatment; may reinitiate at reduced dose of 750 mg PO qDay following return of LFTs to baseline or to AST/ALT ≤2.5 xULN and total bilirubin ≤1.5 xULN
  • For patients who resume treatment, monitor serum transaminases and bilirubin at least q2Weeks for 3 months, and then monthly thereafter
  • If hepatotoxicity recurs at 750 mg/day, may restart at 500 mg/day (after LFTs decrease as above)
  • If hepatoxicity recurs at reduced dose of 500 mg/day, discontinue treatment

Administration

Take on empty stomach, at least 1 hr ac or 2 hr pc

Food increases AUC up to 10-fold

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

Not indicated

Of the total number of patients in a phase 3 trial, 71% of patients were 65 yr or older and 28% were 75 yr or older

No overall differences in safety or effectiveness were observed between these elderly patients and younger patients

Metastatic castration-resistant prostate cancer

4 tabs (1000 mg) PO qDay with prednisone 5 mg PO q12hr

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Interactions

Interaction Checker

abiraterone 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%

            Joint swelling/discomfort (30%)

            Hypokalemia (28%; all grades)

            Edema (27%)

            Muscle discomfort (26%)

            Hypophosphatemia (24%; all grades)

            Hot flush (19%)

            Diarrhea (18%)

            Urinary tract infection (12%)

            Cough (11%)

            1-10%

            Hypertension (9%)

            Arrhythmia (7%)

            Urinary frequency (7%)

            Hypophosphatemia (7%; grade 3-4)

            Nocturia (6%)

            Dyspepsia (6%)

            Fractures (5.9%)

            Hypokalemia (5%; grade 3-4)

            Upper respiratory tract infection (5%)

            Chest pain/discomfort (4%)

            Cardiac failure (2%)

            Hepatotoxicity (2%)

            Postmarketing Reports

            Respiratory, thoracic and mediastinal disorders: Noninfectious pneumonitis

            Rhabdomyolysis

            Myopathy

            Acute hepatic failure

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            Warnings

            Contraindications

            Hypersensitivity

            Women who are or may become pregnant

            Cautions

            Not for use in patients with preexisting severe hepatic impairment (Child-Pugh class C)

            Mineralocorticoid excess: caution in patients with a history of cardiovascular disease; safety in patients with LVEF <50% or NYHA Class III or IV heart failure is not established

            Hypertension, hypokalemia, and fluid retention may result from increased mineralocorticoid due to CYP17 inhibition; control hypertension and correct hypokalemia before treatment; monitor blood pressure, serum potassium, and symptoms of fluid retention at least monthly

            Monitor for symptoms and signs of adrenocortical insufficiency; increased corticosteroid dosage may be indicated before, during, and after stressful situations; concurrent infection or interruption of daily corticosteroids associated with adrenocortical insufficiency

            Hepatotoxicity: Increases in liver enzymes have led to drug interruption, dose modification, and/or discontinuation (typically within the first 3 months of threatment); monitor liver function and modify, interrupt, or discontinue dosing as recommended

            Strong inhibitor of CYP1A2 and CYP2D6; moderate inhibitor of CYP2C9, CYP2C19, and CYP3A4

            CYP3A4 substrate (in vitro); avoid or use caution with drugs that are strong inhibitors or inducers of CYP3A4

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            Pregnancy & Lactation

            Pregnancy Category: X

            Lactation: Unknown whether distributed in breast milk; do not use, not indicated for use in women

            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

            Androgen biosynthesis inhibitor that inhibits 17 alpha-hydroxylase/C17,20-lyase (CYP17); this enzyme is expressed in testicular, adrenal, and prostatic tumor tissues and is required for androgen biosynthesis

            Pharmacokinetics

            Peak Plasma Time: 2 hr

            Peak Plasma Concentration: 226 ng/mL ± 178 ng/mL (at steady state)

            AUC: 1173 ± 690 ng.hr/mL; increases up to 10-fold when administered with food

            Protein Bound: >99% (albumin, alpha-1 acid glycoprotein)

            Vd: 19,669 ± 13,358 L (at steady state)

            Not a substrate of P-glycoprotein

            Excretion: feces (88%), urine (5%)

            Half-life: 12 ± 5 hr (prolonged by hepatic impairment to 18-19 hr)

            Metabolism

            • Metabolism:  Abiraterone acetate is hydrolyzed to abiraterone (active metabolite); hydrolysis is likely via esterase activity and is not CYP mediated; CYP3A4 and SULT2A1 enzymes are involved in the formation of 2 inactive metabolites, N-oxide abiraterone sulphate and abiraterone sulphate
            • Enzyme inhibition: Strong inhibitor of CYP1A2 and CYP2D6; moderate inhibitor of CYP2C9, CYP2C19, and CYP3A4
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            Formulary

            FormularyPatient Discounts

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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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