ABIRATERONE
ACETATE
(a′-bir-a′-ter-one as′-e-tate)
Zytiga
Classifications: ANTIANDROGEN;
ANDROGEN BIOSYNTHESIS INHIBITOR
Therapeutic: ANTIANDROGEN
Pregnancy Category: X
AVAILABILITY Tablet
ACTION & THERAPEUTIC EFFECT
Inhibits the enzyme required for androgen
biosynthesis in testicular, adrenal, and prostatic tumor tissues. Enzyme
inhibition may also result in increased mineralocorticoid production in the
adrenal glands. Decreased levels of serum testosterone
and other androgens slow the growth of androgen-sensitive carcinomas.
USES Metastatic castration-resistant prostate cancer.
CONTRAINDICATIONS Severe hepatic impairment (Child-Pugh class C); pregnancy
(category X).
CAUTIOUS USE History of CV
disease (e.g., heart failure,
hypertension,
recent MI, ventricular
arrhythmias); hypokalemia; fluid
retention; concurrent steroid therapy,
especially during dosage adjustment
or with concurrent infection or
stress; moderate hepatic impairment
(Child-Pugh class B). Abiratrone is
not indicated for use in children.
ROUTE & DOSAGE
Metastatic Prostate Cancer
Adult: PO 1000 mg once daily in combination with PO prednisone 5 mg b.i.d. Hepatic
Impairment Dosage Adjustment
Moderate impairment
(Child-Pugh class B): PO 250
mg once daily
Severe impairment
(Child-Pugh class C): Do not use
ADMINISTRATION
Oral
■ Give on an empty stomach 2 h before or
1 h after food.
■ Tablets should be swallowed whole with
water.
■ Women who are or may be pregnant must
use gloves to handle abiraterone.
■ Store at 15°–30° C (59°–86° F).
ADVERSE EFFECTS (≥1%) CV:
Arrhythmia, cardiac failure, chest pain or discomfort, hot flush, hypertension.
GI: Diarrhea, dyspepsia. Metabolic: Edema, elevated ALT
and AST, elevated total bilirubin, elevated triglycerides, hypokalemia, hypophosphatemia.
Musculoskeletal: Joint discomfort and swelling, muscle discomfort. Respiratory: Cough, upper
respiratory tract infection. Urogenital: Nocturia, urinary
frequency,
urinary tract infection.
INTERACTIONS Drug: Abiraterone can increase the levels of drugs
requiring CYP2D6 (e.g., dextromethorphan, thioridazine). Strong inhibitors of CYP3A4 (e.g., ketoconazole, itraconazole, clarithromycin, atazanavir, nefazodone,
saquinavir, telithromycin,
ritonavir, indinavir, nelfinavir,
voriconazole) increase abiraterone while inducers of
CYP3A4 (e.g., phenytoin, carbamazepine,
rifampin, rifabutin, rifapentine,
phenobarbital) decrease levels of abiraterone.
PHARMACOKINETICS: 2 h. Distribution:
Greater than 99% Plasma protein bound. Metabolism: In the liver to
an active metabolite. Elimination: Fecal (88%) and
renal (5%). Half-Life: 7–17
h.
NURSING IMPLICATIONS
Assessment & Drug
Effects
■ Monitor BP and cardiac function especially
with a history of CV disease. ■ Monitor for and
report signs of fluid retention (e.g., sudden weight gain, peripheral edema).
■ Monitor for and report S&S of
hypokalemia or hepatotoxicity (see Appendix F). Withhold drug and notify prescriber if AST/ALT is
above 5 × ULN
or bilirubin above 3 ×
ULN.
■ Monitor lab tests: ALT, AST, and bilirubin
at baseline, then q2wk for first 3 mo, then monthly thereafter; monitor serum
electrolytes (especially potassium).
Patient & Family Education
■ Do not take this drug within 2 h before
or 1 h after consuming food.
■ A
condom should be used during sexual intercourse with a woman who is or could
become pregnant.
■ Report
any of the following to a health care provider: Sudden weight gain, swelling of
feet or legs, palpitations, unusual weakness,
muscle
pain, S&S of a urinary tract infection.
