YONSA

Clinical safety rating: caution

Comprehensive clinical and safety monograph for YONSA (YONSA).

How it works

Abiraterone acetate is converted to abiraterone, a selective inhibitor of CYP17A1 (17α-hydroxylase/C17,20-lyase), which catalyzes androgen biosynthesis in the testes, adrenal glands, and prostate tumor tissue. Inhibition of CYP17A1 decreases serum testosterone and other androgens.

What the body does with it

Metabolism	Abiraterone acetate is metabolized by CYP3A4 to active metabolite abiraterone. Abiraterone undergoes further metabolism via hydroxylation, oxidation, and glucuronidation.
Excretion	Primarily hepatic metabolism via CYP3A4, with <5% of the dose excreted unchanged in feces and <1% in urine. Fecal elimination accounts for ~88% of total clearance (metabolites), biliary excretion is minimal.
Half-life	Terminal elimination half-life is approximately 59 hours (range 32–83 hours) in castration-resistant prostate cancer patients, allowing for once-daily dosing after an initial dose schedule.
Protein binding	>99% bound to plasma proteins, primarily to albumin and alpha-1-acid glycoprotein (AAG).
Volume of Distribution	Approximately 36 L (0.5 L/kg, assuming 70 kg) at steady state, indicating extensive tissue distribution.
Bioavailability	Oral bioavailability is approximately 30% (range 20–40%) under fed conditions; food increases AUC by 2-fold and Cmax by 2.5-fold compared to fasting.
Onset of Action	Oral: Steady-state concentrations are reached by day 8–12 with a loading dose regimen (day 1: 240 mg, days 2–28: 160 mg). Clinical effects (PSA decline) are typically observed within 4–6 weeks.
Duration of Action	Therapeutic effects persist throughout the dosing interval (24 hours) due to long half-life. Duration of response is variable and disease-dependent; continuous daily dosing is required.

Classification & Brands

Dosing & administration

1000 mg orally twice daily with food.

Dosage form	TABLET
Renal impairment	No dose adjustment required for mild to moderate renal impairment; not studied in severe renal impairment (CrCl <30 mL/min).
Liver impairment	Child-Pugh A: no dose adjustment; Child-Pugh B: reduce dose to 750 mg twice daily; Child-Pugh C: not recommended.
Pediatric use	Safety and efficacy not established in pediatric patients.
Geriatric use	No specific dose adjustment; consider renal function in elderly.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for YONSA (YONSA).

Breastfeeding

It is unknown whether abiraterone or its metabolites are excreted in human milk. Due to the potential for serious adverse reactions in nursing infants (e.g., androgen suppression), breastfeeding is contraindicated during treatment and for 1 week after the last dose. M/P ratio is not available.

Teratogenic Risk

YONSA (abiraterone acetate) is contraindicated in pregnancy. Based on its mechanism of action (CYP17 inhibitor) and animal studies, it can cause fetal harm. First trimester: Exposure to abiraterone, which suppresses androgen production, can disrupt fetal sexual differentiation, leading to urogenital abnormalities. Second and third trimesters: Continued androgen suppression may impair fetal growth and development. No adequate human studies exist; avoid use in pregnant women.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to abiraterone acetate or any excipient","Pregnancy and females of childbearing potential","Severe hepatic impairment (Child-Pugh Class C)"]

Clinical Precautions

Precautions

["Mineralocorticoid excess (hypertension, hypokalemia, fluid retention) due to CYP17 inhibition; manage with prednisone","Adrenocortical insufficiency","Hepatotoxicity (monitor liver function tests)","Cardiovascular adverse reactions (e.g., myocardial infarction, QT prolongation)"]

Clinical Tips & Counseling

Drug interactions

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YONSA

Clinical safety rating: caution

Comprehensive clinical and safety monograph for YONSA (YONSA).

How it works

What the body does with it

Metabolism	Abiraterone acetate is metabolized by CYP3A4 to active metabolite abiraterone. Abiraterone undergoes further metabolism via hydroxylation, oxidation, and glucuronidation.
Excretion	Primarily hepatic metabolism via CYP3A4, with <5% of the dose excreted unchanged in feces and <1% in urine. Fecal elimination accounts for ~88% of total clearance (metabolites), biliary excretion is minimal.
Half-life	Terminal elimination half-life is approximately 59 hours (range 32–83 hours) in castration-resistant prostate cancer patients, allowing for once-daily dosing after an initial dose schedule.
Protein binding	>99% bound to plasma proteins, primarily to albumin and alpha-1-acid glycoprotein (AAG).
Volume of Distribution	Approximately 36 L (0.5 L/kg, assuming 70 kg) at steady state, indicating extensive tissue distribution.
Bioavailability	Oral bioavailability is approximately 30% (range 20–40%) under fed conditions; food increases AUC by 2-fold and Cmax by 2.5-fold compared to fasting.
Onset of Action	Oral: Steady-state concentrations are reached by day 8–12 with a loading dose regimen (day 1: 240 mg, days 2–28: 160 mg). Clinical effects (PSA decline) are typically observed within 4–6 weeks.
Duration of Action	Therapeutic effects persist throughout the dosing interval (24 hours) due to long half-life. Duration of response is variable and disease-dependent; continuous daily dosing is required.

Classification & Brands

Dosing & administration

1000 mg orally twice daily with food.

Dosage form	TABLET
Renal impairment	No dose adjustment required for mild to moderate renal impairment; not studied in severe renal impairment (CrCl <30 mL/min).
Liver impairment	Child-Pugh A: no dose adjustment; Child-Pugh B: reduce dose to 750 mg twice daily; Child-Pugh C: not recommended.
Pediatric use	Safety and efficacy not established in pediatric patients.
Geriatric use	No specific dose adjustment; consider renal function in elderly.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for YONSA (YONSA).

Breastfeeding

Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to abiraterone acetate or any excipient","Pregnancy and females of childbearing potential","Severe hepatic impairment (Child-Pugh Class C)"]