Abiraterone

1. Introduction

Abiraterone is an androgen biosynthesis inhibitor used for the treatment of prostate cancer. It works by inhibiting CYP17, an enzyme required for androgen synthesis, thereby reducing testosterone production in the adrenal glands, testes, and tumour cells.

2. Indications

  • Metastatic Castration-Resistant Prostate Cancer (mCRPC)
  • Metastatic Hormone-Sensitive Prostate Cancer (mHSPC) (In combination with prednisone/prednisolone)

3. Dosage

Adults (Prostate Cancer):

  • 1,000 mg (four 250 mg tablets) once daily
  • Given with prednisone or prednisolone 5 mg twice daily

Elderly:

  • No dose adjustment needed, but monitor for hypertension, liver function, and hypokalaemia.

Renal Impairment:

  • No dose adjustment required, but monitor renal function in severe impairment.

Hepatic Impairment:

  • Mild impairment (Child-Pugh A): No dose adjustment needed.
  • Moderate impairment (Child-Pugh B): Reduce dose or use with caution.
  • Severe impairment (Child-Pugh C): Contraindicated.

4. Administration

  • Take on an empty stomach (at least 1 hour before or 2 hours after a meal).
  • Swallow whole with water—do not crush or chew.
  • Prednisone/prednisolone must be taken alongside abiraterone to prevent adrenal insufficiency.

5. Forms Available

  • Tablets: 250 mg, 500 mg

6. Side Effects

6.1 Common Side Effects:

  • Hypertension
  • Hypokalaemia (low potassium)
  • Fluid retention
  • Fatigue
  • Joint pain
  • Increased liver enzymes (ALT, AST)

6.2 Less Common Side Effects:

  • Hot flashes
  • Dizziness
  • Diarrhoea

6.3 Rare but Serious Side Effects:

  • Adrenal Insufficiency (if prednisone is not taken correctly)
  • Severe hepatotoxicity
  • Cardiac events (arrhythmias, heart failure, myocardial infarction)
  • Fractures and osteoporosis (long-term use risk)

7. Warnings

  • Hepatotoxicity: Monitor liver enzymes (ALT, AST, bilirubin) before treatment and every 2 weeks for 3 months, then monthly.
  • Hypertension & Cardiovascular Risk: Can increase blood pressure, monitor regularly.
  • Hypokalaemia: Can lead to cardiac arrhythmias, monitor potassium levels.
  • Adrenal Insufficiency: Must be taken with prednisone/prednisolone to prevent adrenal suppression.

8. Precautions

  • Use with caution in heart disease (history of myocardial infarction, arrhythmia).
  • Monitor for osteoporosis in long-term users.
  • Caution in patients with diabetes—can affect blood glucose levels.

9. Interactions

  • CYP3A4 Inducers (e.g., rifampin, phenytoin): May reduce abiraterone levels.
  • CYP2D6 Substrates (e.g., metoprolol, codeine): Abiraterone may increase their effects.
  • Diuretics & ACE Inhibitors: Increased risk of hypokalaemia.
  • Warfarin & Other Anticoagulants: Increased bleeding risk—monitor INR.

10. Monitoring Parameters

  • Liver function (ALT, AST, bilirubin): Every 2 weeks for 3 months, then monthly.
  • Potassium levels: Every 2–4 weeks.
  • Blood pressure: Regular monitoring.
  • Cardiac function: In high-risk patients.

11. Use in Children

  • Not indicated for paediatric use.

12. Use in Pregnancy

  • Category X: Contraindicated in women (teratogenic).
  • Men should use effective contraception if their partner is pregnant or of childbearing potential.

13. Use in Elderly

  • No dose adjustment needed, but monitor blood pressure, liver function, and potassium levels.

14. Use in Kidney Disease

  • No dose adjustment required, but monitor renal function in severe impairment.

15. Use in Liver Disease

  • Mild impairment: No adjustment needed.
  • Moderate impairment: Reduce dose and monitor closely.
  • Severe impairment: Contraindicated.

16. Patient Counselling Points

  • Take on an empty stomach to ensure proper absorption.
  • Always take with prednisone/prednisolone to avoid adrenal insufficiency.
  • Monitor blood pressure and potassium levels regularly.
  • Report any signs of liver issues (yellowing of the skin, dark urine, fatigue).
  • Avoid grapefruit juice, as it may alter drug metabolism.

17. Table of Brand Names, Manufacturer, and Prices in USD

Brand NameManufacturerStrength/Dosage FormPrice (USD)
ZytigaJanssen250 mg, 500 mg Tablets$5,500 (30 tabs)
YonsaSun Pharma500 mg Tablets$5,000 (30 tabs)
Generic AbirateroneVarious250 mg, 500 mg Tablets$2,000 (30 tabs)

18. 15 FAQs (Frequently Asked Questions)

1. What is Abiraterone used for?
It is used for metastatic prostate cancer to reduce testosterone production.

2. How does Abiraterone work?
It inhibits CYP17, an enzyme needed for testosterone synthesis, slowing cancer growth.

3. How long does Abiraterone take to work?
It may take weeks to months to show full effects.

4. Why do I need to take prednisone with Abiraterone?
To prevent adrenal insufficiency and excess mineralocorticoid effects (hypertension, hypokalaemia).

5. Can I take Abiraterone with food?
No, it must be taken on an empty stomach for proper absorption.

6. Does Abiraterone cure prostate cancer?
No, but it prolongs survival and slows disease progression.

7. What are the main side effects?
High blood pressure, low potassium, liver dysfunction, and fluid retention.

8. Can I drink alcohol while taking Abiraterone?
Alcohol should be avoided, as it can worsen liver side effects.

9. How is Abiraterone monitored?
Regular blood tests for liver function, potassium, and blood pressure.

10. Can I stop taking Abiraterone if I feel better?
No, stopping can cause cancer to progress faster—consult your doctor first.

11. Can women take Abiraterone?
No, it is contraindicated in women, especially pregnant women.

12. Can Abiraterone be taken with chemotherapy?
Yes, it can be combined with docetaxel in advanced prostate cancer.

13. Does Abiraterone cause weight gain?
It may cause fluid retention, leading to weight changes.

14. What should I do if I miss a dose?
Take it as soon as you remember, but skip it if the next dose is soon—never double dose.

15. How should Abiraterone be stored?
Store at room temperature, away from moisture.