Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
AKEEGA vs AFINITOR
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Niraparib is a poly (ADP-ribose) polymerase (PARP) inhibitor that inhibits PARP-1, PARP-2, and PARP-3, leading to DNA damage repair inhibition and apoptosis in BRCA-mutated cells. Abiraterone acetate is a prodrug converted to abiraterone, a CYP17A1 inhibitor that suppresses androgen biosynthesis in testicular, adrenal, and prostate tumor tissues.
Inhibitor of mammalian target of rapamycin (m TOR), specifically the m TORC1 complex, by binding to the FKBP-12 protein, reducing cell proliferation, angiogenesis, and glucose uptake.
Treatment of adult patients with deleterious or suspected deleterious BRCA-mutated (germline and/or somatic) metastatic castration-resistant prostate cancer (m CRPC) in combination with prednisone.
Advanced hormone receptor-positive, HER2-negative breast cancer in postmenopausal women in combination with exemestane after failure of letrozole or anastrozole,Progressive neuroendocrine tumors of pancreatic origin (PNET) in unresectable, locally advanced or metastatic disease,Advanced renal cell carcinoma (RCC) after failure of sunitinib or sorafenib,Subependymal giant cell astrocytoma (SEGA) associated with tuberous sclerosis complex (TSC) in patients requiring therapeutic intervention but not amenable to curative resection
Recommended dose: 240 mg (niraparib) / 500 mg (abiraterone acetate) orally once daily with or without food.
10 mg orally once daily for advanced breast cancer, neuroendocrine tumors, and renal cell carcinoma; 10 mg orally once daily for subependymal giant cell astrocytoma (SEGA) in adults; 5 mg/m^2 orally once daily for SEGA in pediatric patients (titrated to trough levels 5-15 ng/m L).
Terminal half-life: 17–30 hours (mean ~24 h); allows once-daily dosing but may require dose adjustment in renal impairment.
Terminal elimination half-life: 30 hours (range 15–40 hours) in healthy subjects; increases to 40–70 hours in moderate hepatic impairment.
Niraparib is primarily metabolized by carboxylesterases (CEs) and to a lesser extent by CYP1A2 and CYP2D6. Abiraterone acetate is hydrolyzed to abiraterone, which is then metabolized by CYP3A4 and CYP2D6.
Substrate of CYP3A4; metabolized primarily by CYP3A4; also a substrate of P-glycoprotein (P-gp).
Renal: ~85% (primarily as unchanged drug); Biliary/Fecal: ~15%.
Primarily fecal (80%) and renal (5%) as unchanged drug and metabolites. Biliary excretion is significant.
~99% (bound primarily to α1-acid glycoprotein and albumin).
74% bound to plasma proteins (primarily albumin and α1-acid glycoprotein).
Vd: ~1.5–2.0 L/kg (indicates extensive tissue distribution).
Mean steady-state Vd: 342 L (approx. 4.9 L/kg in a 70 kg adult), indicating extensive tissue distribution.
Oral: ~90% (high oral bioavailability).
Oral bioavailability: approximately 16% (low due to P-glycoprotein efflux and first-pass metabolism); food reduces variability but does not alter AUC significantly.
No dose adjustment required for mild to moderate renal impairment (e GFR ≥30 m L/min). Not recommended for severe renal impairment (e GFR <30 m L/min) or end-stage renal disease.
No dose adjustment for mild to moderate renal impairment (Cr Cl >=30 m L/min). For severe renal impairment (Cr Cl <30 m L/min): reduce dose to 5 mg once daily. End-stage renal disease (Cr Cl <15 m L/min): use with caution, no specific recommendation.
Contraindicated in severe hepatic impairment (Child-Pugh class C). No dose adjustment for mild (Child-Pugh class A) or moderate (Child-Pugh class B) impairment; but monitor closely for toxicity.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose to 5 mg daily; Child-Pugh C: reduce dose to 2.5 mg daily, or consider alternate therapy.
Safety and efficacy not established in pediatric patients; no recommended dose.
For SEGA: 5 mg/m^2 orally once daily, adjusted to achieve everolimus trough concentrations of 5-15 ng/m L. Dose adjustments per AUC or tolerability. Not approved for other indications in children.
No specific dose adjustment required. Clinical studies included patients ≥65 years; increased risk of adverse effects such as hypertension, hypokalemia, and fatigue. Monitor renal function and electrolytes regularly.
No specific dose adjustment; start at recommended adult dose. Monitor for increased risk of infections, stomatitis, and metabolic effects due to age-related decline in organ function.
AKEEGA can cause severe and persistent hypertension, hypokalemia, and fluid retention due to mineralocorticoid excess, especially in patients with renal impairment. Monitor blood pressure, serum potassium, and fluid status regularly.
No black box warnings.
Hypertension, hypokalemia, and fluid retention due to mineralocorticoid excess,Adrenocortical insufficiency,Hepatotoxicity,Cardiovascular effects including QT prolongation,Bone marrow suppression (anemia, thrombocytopenia, neutropenia),Fetal harm if used during pregnancy
Non-infectious pneumonitis,Infections (including opportunistic infections),Hypersensitivity reactions including anaphylaxis,Angioedema,Renal failure,Impaired wound healing,Metabolic effects (hyperglycemia, dyslipidemia),Myelosuppression,Immunosuppression leading to increased risk of infections,Cases of fatal hemorrhage in patients with history of bleeding,Radiation sensitization and recall reactions, especially in patients with previous radiation therapy,Increased risk of pneumocystis jirovecii pneumonia (PJP) and other opportunistic infections; consider prophylaxis,Avoid live vaccines
Concomitant use with strong CYP3A4 inducers,Severe renal impairment (Cr Cl <30 m L/min) or end-stage renal disease,History of hypersensitivity to niraparib, abiraterone, or any excipient
Hypersensitivity to everolimus, sirolimus, or any component of the formulation
Avoid food and beverages containing grapefruit, grapefruit juice, Seville oranges, and starfruit as they inhibit CYP3A4 and may increase abiraterone exposure. Take AKEEGA on an empty stomach (no food for at least 1 hour before or 2 hours after). Avoid high-fat meals as they increase abiraterone absorption.
Avoid grapefruit, grapefruit juice, and Seville oranges (including marmalade) due to CYP3A4 inhibition increasing everolimus levels. Take consistently with or without food, but high-fat meals reduce absorption. Avoid St. John's wort.
AKEEGA (niraparib and abiraterone acetate) is contraindicated in pregnancy. Based on its mechanism of action and findings in animal studies, niraparib can cause fetal harm. Abiraterone acetate is also associated with fetal risks. First trimester exposure may cause embryofetal lethality and teratogenicity. Second and third trimester exposure may impair fetal adrenal function and androgen-dependent development.
Pregnancy Category D. Positive evidence of human fetal risk. Based on its mechanism of action (m TOR inhibitor) and animal studies, AFINITOR (everolimus) is embryotoxic and fetotoxic. First trimester exposure carries risk of structural anomalies; second and third trimester exposure may cause fetal growth restriction, oligohydramnios, and renal impairment. Use only if benefit outweighs risk.
No data on the presence of niraparib or abiraterone in human milk, effects on breastfed infants, or milk production. Due to the potential for serious adverse reactions, breastfeeding is not recommended during treatment and for at least 1 month after the last dose. M/P ratio is unknown.
No data on presence in human milk, effects on breastfed infant, or milk production. M/P ratio unknown. Breastfeeding is not recommended due to potential adverse effects on the developing immune system and growth.
No specific dose adjustments are established during pregnancy as AKEEGA is contraindicated. Pharmacokinetic changes in pregnancy (e.g., increased volume of distribution, altered hepatic metabolism) may necessitate dose adjustments if used inadvertently, but no data are available. If exposure occurs, cautious monitoring and individualized dosing are recommended.
No specific dose adjustments established for pregnancy. Pharmacokinetic changes in pregnancy (increased volume of distribution, altered hepatic metabolism) may reduce drug exposure; however, given the teratogenic risk, use during pregnancy should be avoided. If unavoidable, consider therapeutic drug monitoring if available and adjust dose to achieve target trough concentrations (typically 3-8 ng/m L for transplant indications; for oncology, refer to specific protocol).
AKEEGA (niraparib and abiraterone acetate) is indicated for BRCA-positive metastatic castration-resistant prostate cancer. Monitor for myelosuppression (CBC at baseline and monthly), hypertension (BP weekly for first month then monthly), hypokalemia, and hepatotoxicity (LFTs at baseline and monthly). CYP3A4 inhibitors increase abiraterone exposure; avoid strong inhibitors or reduce dose. Corticosteroid co-administration (prednisone 5 mg BID) is required to manage mineralocorticoid excess. Niraparib may cause fetal harm; confirm pregnancy status before initiation.
Monitor renal function and blood glucose regularly; Afinitor (everolimus) can cause non-infectious pneumonitis, so obtain baseline chest imaging and assess for new or worsening respiratory symptoms. Adjust dose for moderate hepatic impairment (Child-Pugh B). Avoid live vaccines during treatment.
Take tablets on an empty stomach, at least 1 hour before or 2 hours after a meal.,Swallow tablets whole; do not crush or chew.,Avoid grapefruit, grapefruit juice, Seville oranges, and starfruit during treatment.,Use effective contraception during treatment and for 4 months after the last dose for females and 3 months for males.,Report signs of bone marrow suppression: fever, bruising, bleeding, or unusual tiredness.,Report symptoms of high blood pressure: severe headache, blurred vision, or chest pain.,Take prednisone exactly as prescribed; do not stop abruptly.,Avoid pregnancy; discuss fertility preservation options before starting treatment.,Take missed doses if within 12 hours of scheduled time; otherwise skip and resume next day.,Store at room temperature; keep in original container.
Take Afinitor at the same time each day, consistently either with or without food.,Avoid grapefruit, grapefruit juice, and Seville oranges during treatment.,Report any new or worsening cough, chest pain, or difficulty breathing immediately.,Monitor for signs of infection such as fever, chills, or sore throat; avoid large crowds and sick individuals.,Use effective contraception during treatment and for 8 weeks after stopping.,Do not crush or chew tablets; swallow whole with a glass of water.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about AKEEGA vs AFINITOR, answered by our medical review team.
AKEEGA is a Antineoplastic Combination that works by Niraparib is a poly (ADP-ribose) polymerase (PARP) inhibitor that inhibits PARP-1, PARP-2, and PARP-3, leading to DNA damage repair inhibition and apoptosis in BRCA-mutated cells. Abiraterone acetate is a prodrug converted to abiraterone, a CYP17A1 inhibitor that suppresses androgen biosynthesis in testicular, adrenal, and prostate tumor tissues.. AFINITOR is a mTOR Inhibitor Antineoplastic that works by Inhibitor of mammalian target of rapamycin (m TOR), specifically the m TORC1 complex, by binding to the FKBP-12 protein, reducing cell proliferation, angiogenesis, and glucose uptake.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between AKEEGA and AFINITOR depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of AKEEGA is: Recommended dose: 240 mg (niraparib) / 500 mg (abiraterone acetate) orally once daily with or without food.. The standard adult dose of AFINITOR is: 10 mg orally once daily for advanced breast cancer, neuroendocrine tumors, and renal cell carcinoma; 10 mg orally once daily for subependymal giant cell astrocytoma (SEGA) in adults; 5 mg/m^2 orally once daily for SEGA in pediatric patients (titrated to trough levels 5-15 ng/m L).. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between AKEEGA and AFINITOR in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. AKEEGA is classified as Category C. AKEEGA (niraparib and abiraterone acetate) is contraindicated in pregnancy. Based on its mechanism of action and findings in animal studies, niraparib can cause fetal harm. Abirate. AFINITOR is classified as Category C. Pregnancy Category D. Positive evidence of human fetal risk. Based on its mechanism of action (mTOR inhibitor) and animal studies, AFINITOR (everolimus) is embryotoxic and fetotoxi. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.