How Does Zytiga Work?

Zytiga (Abiraterone Acetate) works by blocking an enzyme called CYP17A1 that your body needs to make testosterone — a hormone that fuels prostate cancer cell growth.

If you've been prescribed Zytiga or you're researching treatment options for advanced prostate cancer, understanding how the drug works can help you feel more confident about your treatment. This guide explains Zytiga's mechanism of action in plain, easy-to-understand language.

What Zytiga Does in Your Body

To understand how Zytiga works, it helps to know a little about prostate cancer and testosterone.

The Testosterone Connection

Prostate cancer cells need testosterone (and other androgens) to grow and multiply. That's why one of the main approaches to treating prostate cancer is to lower testosterone levels — a strategy called androgen deprivation therapy (ADT).

Standard ADT works by stopping the testicles from making testosterone. This can be done with medications (GnRH analogs) or surgery (orchiectomy). But here's the problem: testosterone isn't only made in the testicles. Your adrenal glands and even prostate tumor cells themselves can also produce small amounts of androgens.

In castration-resistant prostate cancer, the cancer has figured out how to keep growing even with very low testosterone levels — often by using these alternative androgen sources.

How Zytiga Blocks Testosterone Production

This is where Zytiga comes in. Zytiga targets an enzyme called CYP17A1 (also known as 17α-hydroxylase/C17,20-lyase). This enzyme is essential for making androgens in:

• The testicles
• The adrenal glands
• Prostate tumor tissue

By blocking CYP17A1, Zytiga shuts down testosterone production at all three sources — not just the testicles. This gives it an advantage over standard ADT alone.

The result: testosterone and other androgen levels drop even further, starving prostate cancer cells of the fuel they need to grow.

Why Prednisone Is Required

Because Zytiga blocks hormone production in the adrenal glands, it also affects the production of cortisol — a hormone your body needs for blood pressure regulation, immune function, and stress response. To compensate, Zytiga is always prescribed with Prednisone (5 mg twice daily), a low-dose corticosteroid that replaces the missing cortisol.

This is also why your doctor monitors your potassium levels and blood pressure regularly — the hormonal changes from Zytiga can cause side effects in these areas.

How Long Does Zytiga Take to Work?

Zytiga begins lowering testosterone levels within hours of the first dose. However, measuring its clinical effectiveness takes longer:

• PSA levels (prostate-specific antigen, a marker used to track prostate cancer) may begin to decrease within the first few weeks of treatment.
• Imaging improvements (shrinking tumors, slowed progression) are typically assessed after 3 to 6 months of treatment.
• Symptom relief — Some patients notice improvements in cancer-related pain or other symptoms within weeks, while others may take longer.

Your oncologist will monitor your progress with regular blood tests and imaging scans to determine how well Zytiga is working for you.

How Long Does Zytiga Last?

Zytiga is taken once daily, and it needs to be taken continuously as long as it's working and you're tolerating it well. There isn't a set duration — your doctor will keep you on Zytiga as long as your cancer is responding to treatment.

The duration of response varies widely. In clinical trials, many patients benefited from Zytiga for months to years. Your oncologist will track your PSA, imaging results, and symptoms to decide when to continue, adjust, or change treatment.

If Zytiga stops working, your doctor may recommend switching to a different treatment such as Enzalutamide (Xtandi), Darolutamide (Nubeqa), or chemotherapy with Docetaxel.

What Makes Zytiga Different from Other Prostate Cancer Drugs?

There are several medications used to treat advanced prostate cancer. Here's how Zytiga compares:

Zytiga vs. Enzalutamide (Xtandi)

Both are oral medications for metastatic prostate cancer, but they work differently:

• Zytiga blocks testosterone production (by inhibiting CYP17A1).
• Enzalutamide blocks testosterone from binding to receptors on cancer cells (androgen receptor inhibitor).

Zytiga requires Prednisone; Enzalutamide does not. Both are effective, and the choice often depends on your overall health, other medications, and your oncologist's recommendation.

Zytiga vs. Docetaxel

Docetaxel is a chemotherapy drug given by IV infusion. Zytiga is an oral tablet taken at home. Docetaxel works by a completely different mechanism (disrupting cell division). Zytiga is generally better tolerated, though some patients may eventually need chemotherapy if hormonal treatments stop working.

Zytiga vs. Apalutamide (Erleada) and Darolutamide (Nubeqa)

These are newer androgen receptor inhibitors approved for different stages of prostate cancer. Like Enzalutamide, they block testosterone at the receptor level rather than blocking production.

Final Thoughts

Zytiga is a powerful treatment that goes beyond standard hormone therapy by blocking testosterone production at all sources — the testicles, adrenal glands, and tumor tissue. This makes it especially effective for advanced prostate cancer that continues to progress despite initial hormone treatment.

If you've been prescribed Zytiga, learn about proper dosing and how to take it, understand the side effects to watch for, and check your drug interactions. And if you need help finding it, Medfinder can help you locate Zytiga in stock near you.