Imfinzi (durvalumab) is a prescription drug that treats certain lung and other cancers. The drug comes as a liquid solution that a healthcare professional injects into a vein. You receive this infusion every 2–4 weeks.

Imfinzi is given to adults to treat:

Imfinzi may be prescribed alone or together with other therapies that treat certain types of cancer. These therapies include chemotherapy (traditional drugs prescribed to treat cancer), radiation therapy, or other medications.

The active ingredient in Imfinzi is durvalumab. (An active ingredient is what makes a drug work.)

Imfinzi belongs to a group of drugs called immunotherapy agents.

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

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

What is Imfinzi’s form?

Imfinzi is available as a liquid solution that a healthcare professional gives as an intravenous (IV) infusion. This is an injection given into your vein over a period of time.

What strengths does Imfinzi come in?

Imfinzi comes in two strengths:

  • 500 milligrams (mg) in 10 milliliters (mL) of sterile water for injection
  • 120 mg in 2.4 mL of sterile water for injection

What are the usual dosages of Imfinzi?

Your dosage of Imfinzi depends on several factors. These include the condition being treated, your body weight, and other factors. You’ll receive Imfinzi every 2, 3, or 4 weeks by itself or with other medications. Your doctor will prescribe the recommended dosage that provides the desired effect.

The information below describes dosages that are commonly prescribed or recommended. Your doctor will recommend the dosage that’s right for you.

Dosage for small cell lung cancer (SCLC)

Typical Imfinzi dosages for adults with extensive-stage SCLC are as follows. Dosages in mg are based on weight in kilograms (kg). For reference, 1 kg is about 2.2 pounds (lb).

  • If weight is greater than or equal to 30 kg (about 66 lb): Every 3 weeks, you’ll receive 1,500 mg of Imfinzi with two chemotherapy drugs as an IV infusion. This will continue for four cycles, or about 16 weeks. Then every 4 weeks, you’ll receive 1,500 mg of Imfinzi alone.
  • If weight is less than 30 kg (about 66 lb): Every 3 weeks, you’ll receive 20 mg per kg (mg/kg) of Imfinzi with two chemotherapy drugs as an IV infusion. This will continue for four cycles, or about 16 weeks. Then every 2 weeks, you’ll receive 10 mg/kg of Imfinzi alone.

As an example, if a person weighs 70 kg (about 154 lb), their dose of Imfinzi would be 1,500 mg throughout treatment. But if a person weighs 29 kg (about 64 lb), their dosage of Imfinzi would be 580 mg every 3 weeks and then 290 mg every 2 weeks.

Dosage for biliary tract cancer

For adults with biliary tract cancer, typical dosages of Imfinzi are based on body weight, as follows. Dosages in mg are based on weight in kg. For reference, 1 kg is about 2.2 lb.

  • If weight is greater than or equal to 30 kg (about 66 lb): Every 3 weeks, you’ll receive 1,500 mg of Imfinzi with a chemotherapy medication. This will continue for up to eight cycles, or up to about 24 weeks. Then, every 4 weeks, you’ll receive 1,500 mg of Imfinzi alone.
  • If weight is less than 30 kg (about 66 lb): Every 3 weeks, you’ll receive 20 mg/kg of Imfinzi with a chemotherapy medication. This will continue for up to eight cycles, or up to about 24 weeks. Then, every 4 weeks, you’ll receive 20 mg/kg of Imfinzi alone.

As an example, if a person weighs 60 kg (about 132 lb), their dose of Imfinzi would be 1,500 mg throughout treatment. But if a person weighs 29 kg (about 64 lb), their dose of Imfinzi would be 580 mg throughout treatment.

You’ll receive Imfinzi treatment until your cancer worsens or the medication’s side effects become unmanageable.

Dosage for liver cancer

For adults with hepatocellular carcinoma (liver cancer), typical dosages of Imfinzi are based on body weight, as follows. Dosages in mg are based on weight in kg. For reference, 1 kg is about 2.2 lb.

  • If weight is greater than or equal to 30 kg (about 66 lb): On day 1 of the first cycle,* you’ll receive 1,500 mg of Imfinzi with a single dose of another medication. Then, every 4 weeks, you’ll receive 1,500 mg of Imfinzi alone.
  • If weight is less than 30 kg (about 66 lb): On day 1 of the first cycle,* you’ll receive 20 mg/kg of Imfinzi with another medication. Then, every 4 weeks, you’ll receive 20 mg/kg of Imfinzi alone.

* A cycle is when medications are scheduled, followed by a period of rest.

As an example, if a person weighs 60 kg (about 132 lb), their dose of Imfinzi would be 1,500 mg throughout treatment. But if a person weighs 29 kg (about 64 lb), their dosage of Imfinzi would be 580 mg throughout treatment.

You’ll receive Imfinzi treatment until your cancer worsens or the medication’s side effects become unmanageable.

Dosage for non-small cell lung cancer (NSCLC)

Stage 3 NSCLC that cannot be removed with surgery

The typical Imfinzi dosages for adults with stage 3 NSCLC that cannot be removed with surgery are as follows. Imfinzi is given alone. Dosages in mg are based on weight in kg. For reference, 1 kg is about 2.2 lb.

  • If weight is greater than or equal to 30 kg (about 66 lb): Your doctor may prescribe one of two dosages. Every 2 weeks, you’ll receive 10 mg/kg of Imfinzi. Or every 4 weeks, you’ll receive 1,500 mg of Imfinzi.
  • If weight is less than 30 kg (about 66 lb): Every 2 weeks, you’ll receive 10 mg/kg of Imfinzi.

As an example, if a person weighs 70 kg (about 154 lb), they’d receive one of two Imfinzi dosages. They’d receive either 700 mg every 2 weeks or 1,500 mg every 4 weeks. But if a person weighs 29 kg (about 64 lb), their dosage of Imfinzi would be 290 mg every 2 weeks.

This dosage continues until your cancer worsens or you experience serious side effects. Or it might continue until you’ve received treatment for a maximum of 12 months.

NSCLC that has spread to other parts of the body (metastasized)

The typical Imfinzi dosages for adults with NSCLC that has metastasized are as follows. Imfinzi is given together with other therapies. Dosages in mg are based on weight in kg. For reference, 1 kg is about 2.2 lb.

  • If weight is greater than or equal to 30 kg (about 66 lb): Every 3 weeks, you’ll receive 1,500 mg of Imfinzi together with tremelimumab-actl and a chemotherapy medication. This will continue for four treatment cycles. Then every 4 weeks, you’ll receive 1,500 mg of Imfinzi. At week 16 of treatment, you’ll receive a fifth dose of tremelimumab-actl along with 1,500 mg of Imfinzi.
  • If weight is less than 30 kg (about 66 lb): Every 3 weeks, you’ll receive 20 mg/kg of Imfinzi together with tremelimumab-actl and a chemotherapy medication. This will continue for four treatment cycles. Then every 4 weeks, you’ll receive 20 mg/kg of Imfinzi. At week 16 of treatment, you’ll receive a fifth dose of tremelimumab-actl along with 20 mg/kg of Imfinzi.

For example, if a person weighs 70 kg (about 154 lb), their dose of Imfinzi would be 1,500 mg throughout treatment. If a person weighs 29 kg (about 64 lb), their dose of Imfinzi would be 580 mg throughout treatment.

Is Imfinzi prescribed long term?

It may be. The length of your treatment often depends on how your body responds to it. It also may depend on how manageable the side effects of Imfinzi are.

Your doctor will discuss your treatment plan and how long you’re likely to need Imfinzi.

Dosage adjustments

Imfinzi doesn’t have dosage adjustments for any conditions. But some people may have certain serious side effects from Imfinzi. In these cases, your doctor may stop Imfinzi treatment temporarily or permanently.

During treatment, your doctor will monitor you and adjust your infusion rate if needed. That means they’ll adjust how fast you receive your infusion of Imfinzi.

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

  • the type and severity of the condition you’re receiving the drug to treat
  • other medications you may be taking or receiving
  • your weight

You’ll receive Imfinzi injections at a clinic or a hospital.

Imfinzi comes as a liquid solution that you receive by IV infusion. This is an injection into your vein over a period of time, given by a healthcare professional. An Imfinzi infusion typically lasts 60 minutes.

If you miss an appointment to receive a dose of Imfinzi, call your doctor’s office as soon as possible to reschedule. They’ll reschedule your dose and adjust your future appointments if needed.

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

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

Are Imfinzi’s dosages similar to the dosages of Keytruda?

No, they’re not. But both Imfinzi and Keytruda (pembrolizumab) treat certain types of cancer. And both come as liquid solutions for IV infusion by a healthcare professional.

The doses in mg and how often you receive them also differ for both medications. For example, Imfinzi infusions are generally every 2, 3, or 4 weeks. Keytruda infusions are every 3 weeks or every 6 weeks.

Your doctor will prescribe the drug and the dosage that’s right for you. To learn more about how these two drugs compare, talk with your doctor.

How long does it take for Imfinzi to start working?

Imfinzi starts to work after your first dose. Your doctor will monitor you during treatment to check whether the drug is working to treat your condition. The length of treatment depends on individual factors. These include your body’s response to Imfinzi treatment, your type of cancer, and other medications you may be taking.

If you have other questions about what to expect from your Imfinzi treatment, talk with your doctor.

The sections above describe the usual Imfinzi dosages provided by the drugmaker. If your doctor recommends Imfinzi for you, they’ll prescribe the dosage that’s right for you.

Talk with your doctor if you have questions or concerns about your current dosage.

Here are some examples of questions you may want to ask your doctor:

  • If I miss a dosage cycle of Imfinzi, will I have to start again?
  • Does my risk of Imfinzi side effects depend on my dosage?
  • What are my options if I find my Imfinzi dosage unmanageable?

To learn more about Imfinzi, see these articles:

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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.