About Zytiga (Abiraterone Acetate)

Zytiga is a prescription drug used in combination with prednisone, for the treatment of metastatic castration-resistant prostate cancer (mCRPC) in men. The drug works by regulating the production of androgens in the body. Zytiga was approved by the FDA for oral administration in the year 2011 and is being manufactured by Janssen Pharmaceuticals.

Active ingredient

The active ingredient of Zytiga is Abiraterone Acetate which is an inhibitor of an enzyme known as CYP17 (17α-hydroxylase/C17,20-lyase). Within the body, abiraterone acetate is converted into abiraterone which is an androgen biosynthesis inhibitor and inhibits CYP17.

CYP17 is imperative for androgen production in the body. By inhibiting CYP17, abiraterone inhibits testosterone production, which results in increased in mineralocorticoids production. Since prostate cancer is sensitive to androgens, androgen inhibition controls the spread of cancer¹.

Dosage information

Zytiga comes in the form of packs with a variable amount of tablets and strength. The recommended dose of Zytiga is 1000mg once daily which means for instance that 4 tablets of 250 mg of Zytiga should be taken to achieve a 1000 mg dose. This dose often considers taking it along with tablets of prednisone, often 5mg are prescribed to be taken twice daily. Always ask your doctor how exactly you should take your medication. In patients with moderate hepatic impairment, the recommended dose of Zytiga is 250mg per day.

The ideal way is to take the tablets with a little amount of water twice daily on an empty stomach. Zytiga should be taken at least 1 hour before or 2 hours after food. The tablets should be swallowed whole and should not be crushed or chewed.

Conditions treated by Zytiga

Zytiga is indicated for men suffering from metastatic castration-resistant prostate cancer (mCRPC) which pertains to the stage of prostate cancer when the cancer cells have metastasized beyond the prostate gland. The cancer spreads even if the testosterone levels fall below the castration levels. The drug is meant for the patients who have received chemotherapy with docetaxel.

Side effects

Following side effects have been observed with the use of Zytiga.

• Joint swelling or discomfort
• Hypokalemia (low potassium levels)
• Edema
• Muscle discomfort
• Hot flushing
• Dyspepsia
• Diarrhea
• Urinary frequency
• Nocturia
• Urinary tract infections
• Cough
• Upper respiratory tract infections
• Hypertension
• Arrhythmias

Warnings and Precautions

The following precautionary measures should be exercised with the use of Zytiga.

Contraindications

• Pregnancy

Precautions

• Since Zytiga increases the concentration of mineralocorticoids in the body, it should be carefully administered in patients with cardiovascular disorders since electrolyte derangement in such patients can lead to adverse cardiac events².
• Zytiga may alter normal electrolyte levels in the body. Your doctor should be doing regular bloodwork to monitor for any electrolyte abnormalities.
• Stress, infection or interruption of corticosteroid use can cause something known as adrenal insufficiency. Your physician should closely monitor for signs and symptoms of adrenal insufficiency
• Zytiga is hepatotoxic; therefore, its use with the drugs that are metabolized through the liver should be closely observed.
• Patients with severe hepatic impairment (Child Pugh class C) should not take Zytiga.
• Liver functions should be closely monitored during treatment with Zytiga.
• Zytiga should always be taken on an empty stomach since food can increase its absorption into the blood stream and can therefore increase the risk of adverse events associated with it.
• Patients receiving GnRH agonists should continue taking the drugs during treatment with Zytiga.
• Patients using Zytiga should use condoms or some other effective means of barrier protection during intercourse with women of childbearing age due to the potential risks to the fetus caused by Zytiga.
• The drug is not to be used in women.
• Zytiga is a category X drug. It is contraindicated in women who are or may become pregnant.
• Zytiga is not indicated for use in children.

Drug interactions

• CYP2D6 substrates : Thioridazine

Note: This list is not all inclusive

Frequently Asked Questions

What is Zytiga?

Zytiga is a prescription drug used as an adjunct to prednisone for the treatment of metastatic castration-resistant prostate cancer (mCRPC) in men.

How does Zytiga work?

The active ingredient of Zytiga is Abiraterone Acetate (acetyl ester of abiraterone) which is an inhibitor of CYP17. By inhibiting CYP17, abiraterone inhibits testosterone synthesis which helps control the spread of cancer.

How to store?

Always store Zytiga at room temperature between 15^oC to 30^oC, away from direct light, heat and moisture. Keep the drug out of reach of children.

Is there any alternative generic brand to Zytiga?

No, there is no alternative drug to Zytiga. The drug should be used exactly as prescribed by the doctor in precise dosage.

How and when to take Zytiga?

The most common dose of Zytiga is 1000mg once daily, which means that 4 tablets of Zytiga containing 250mg should be taken, along with 5mg of prednisone which is taken twice a day. Zytiga should be taken on an empty stomach, at least 1 hour before and 2 hours after food.

Why do doctors prescribe Zytiga?

Zytiga is commonly prescribed along with prednisone for the treatment of metastatic castration-resistant prostate cancer (mCRPC) for the patients who have received prior chemotherapy with docetaxel.

What is metastatic castration-resistant prostate cancer?

Metastatic castration-resistant prostate cancer (mCRPC) refers to the stage of prostate cancer when the cancer cells have metastasized beyond the prostate gland even if the testosterone levels fall below the castration levels.

What if I overdose on Zytiga?

If you accidentally overdose on Zytiga, report to the nearest medical facility, call your healthcare provider or call the Poison Control Center at 1-800-222-1222 right away.

What if I miss a dose of Zytiga?

If you miss a dose, skip the missed dose and take your next dose at the regular scheduled time. Do not double up your dose to “catch up”.