Xofigo (radium Ra 223 dichloride) is a prescription drug used to treat prostate cancer that’s spread to your bones. It comes as a liquid solution given as an injection into a vein, typically once every 4 weeks.

Xofigo is used in adults to treat prostate cancer that’s metastasized (spread to your bones). It’s used for this purpose when:

  • surgery to lower your testosterone level isn’t working
  • bone metastases are causing symptoms such as bone pain
  • the cancer hasn’t spread to other areas of your body apart from your bones

The active ingredient in Xofigo is radium Ra 223 dichloride. (An active ingredient is what makes a drug work.) Xofigo belongs to a group of drugs called radiopharmaceuticals.

This article describes the dosages of Xofigo, as well as its strength and how it’s given. To learn more about Xofigo, see this in-depth article.

This section describes the usual dosages of Xofigo. Keep reading to learn more.

What is Xofigo’s form?

Xofigo comes as a liquid solution in single-dose vials. The drug is given as an intravenous (IV) infusion (an injection into a vein given over time) by a healthcare professional.

What strength does Xofigo come in?

Xofigo comes in single-dose vials that contain 1,100 kilobecquerel (kBq) of radioactivity per milliliter (mL) of liquid solution at the reference date.*

* kBq is the unit of measurement for radioactivity. The reference date means the date and time the radioactivity measurement was taken. Since the radioactivity of Xofigo goes down over time, your doctor will factor this in when calculating your dosage of the drug.

What are the usual dosages of Xofigo?

The information below describes dosages that are commonly used or recommended. Your doctor will prescribe the dosage of Xofigo that provides the desired effect based on your body weight.

Dosage for prostate cancer

The typical Xofigo dosage for adults with prostate cancer that’s metastasized is based on your body weight in kilograms (kg). For reference, 1 kg equals about 2.2 pounds (lb).

Xofigo dosage is 55 kBq per kg of body weight. Xofigo’s radioactivity concentration is based on 1,100 kBq/mL at the reference date. A healthcare professional will calculate your dosage, factoring in the reference date for any loss of radium 223.

You’ll receive each Xofigo dose as an IV infusion given by a healthcare professional in a hospital or clinic. Each infusion lasts approximately 1 minute. You’ll receive an infusion once every 4 weeks, for a total of six infusions.

Is Xofigo used long term?

No, Xofigo is usually administered six times, once every 4 weeks. The safety and effectiveness of Xofigo when used for more than six doses is not known.

If you have questions about how long you’ll need Xofigo treatment, talk with your doctor.

The dosage of Xofigo you’re prescribed may depend on several factors. These include:

  • your body weight
  • Xofigo’s radioactivity concentration based on the reference date
  • Xofigo’s decay (loss of radiation)
  • other medications you’re taking

Xofigo comes as a liquid solution given as an IV infusion over the course of 1 minute by a healthcare professional at a clinic or hospital. You’ll receive an infusion once every 4 weeks, for a total of six infusions.

If you have questions about your dosage of Xofigo, talk with your doctor.

If you miss an appointment for a Xofigo infusion, call your doctor’s office as soon as possible to reschedule the missed dose. It’s important to stay on track with your Xofigo infusions to most effectively treat your condition.

If you need help remembering your appointments, try downloading a reminder app on your phone.

Below are answers to some commonly asked questions about Xofigo’s dosage.

Is Xofigo’s dosage similar to that of Xtandi or Zytiga?

No, it’s not. Xofigo (radium Ra 223 dichloride), Xtandi (enzalutamide), and Zytiga (abiraterone acetate) are all used to treat certain types of prostate cancer. But the forms the drugs come in, their dosages, and how often they’re taken or given differ.

Xofigo is a radiopharmaceutical that’s given as an IV infusion by a healthcare professional in a clinic or hospital every 4 weeks for six doses.

Xtandi is a type of hormone therapy that blocks the effects of testosterone. It belongs to a group of drugs called androgen receptor inhibitors. Xtandi comes as an oral tablet. The dosage is typically 160 mg taken once daily, which is usually taken long term.

Zytiga is a type of hormone treatment that lowers testosterone levels. It belongs to a group of drugs called CYP17 inhibitors. It comes as both coated and uncoated tablets you swallow. The usual dosage is 1,000 mg taken once per day. It may be used as a long-term treatment for prostate cancer.

Your doctor will prescribe the drug and the dosage that’s right for you. Talk with them to learn more about how these drugs compare.

How long does it take for Xofigo to start working?

Xofigo starts to work within 10–15 minutes of receiving a dose. But because of how it works, you likely won’t notice it working right away. You’ll receive a total of six doses, one every 4 weeks. You may notice an improvement in your symptoms (such as bone pain) after a few weeks of treatment.

Your doctor will monitor you during treatment to be sure the drug is working to treat your condition. Talk with them if you have other questions about what to expect with Xofigo.

The sections above describe the usual dosage provided by the manufacturer of Xofigo. If your doctor recommends this drug, they’ll prescribe the dosage that’s right for you. Talk with them if you have questions or concerns about your current dosage. Here are some examples of questions you may want to ask:

  • Can my dosage of Xofigo change if I lose weight between treatments?
  • Would I receive more than six Xofigo infusions if my condition hasn’t improved?
  • How does the dosage of Xofigo compare with the dosage of other medications prescribed for metastatic prostate cancer?

To learn more about Xofigo, see these articles:

To get information on different conditions and tips for improving your health, subscribe to any of Healthline’s newsletters. You may also want to check out the online communities at Bezzy. It’s a place where people with certain conditions can find support and connect with others.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.