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Injected vs. Infused Biologics: What’s the Difference?

Posted on May 03, 2021
Medically reviewed by
Ariel D. Teitel, M.D., M.B.A.
Article written by
Joan Grossman

Biologic drugs currently available for rheumatoid arthritis (RA) treatment must be taken by IV infusion or by subcutaneous (under the skin) injection. Some biologics that can be injected are also available for self-injection at home. If you’re new to biologics, you may wonder about the difference between injected and infused treatments and what to expect from each.

Why Are Biologics Injected or Infused?

Biologics are a particular type of disease-modifying antirheumatic drug (DMARD) made from biological cells and used in the treatment of autoimmune diseases like RA, psoriatic arthritis, psoriasis, and ankylosing spondylitis. Conventional DMARDs like methotrexate are sometimes taken with biologics.

Biologics are highly complex and sensitive compounds. They are made with genetically modified proteins designed to target specific areas of the immune system that overreact and cause inflammation, joint pain, and joint damage in people with RA. Compounds for biologic medications consist of large molecules that cannot be adequately absorbed in the digestive system if taken orally, which is why these medications must be taken by IV infusion or by injection.

Compound sensitivity, risk of degradation, and viscosity — or thickness of the fluid — are some of the factors that determine which biologic drugs must be infused, rather than injected. In addition, some biologic therapies require high doses that may not be appropriate for injection. These drugs will require IV infusions to be properly administered at the right dosage, usually in a clinical setting.

Classes of Biologics

There are four classes of biologic drugs that are available in various forms.

Tumor Necrosis Factor-Alpha Inhibitors

Tumor necrosis factor-alpha inhibitors (TNF inhibitors), such as Cimzia (certolizumab pegol), Enbrel (etanercept), and Humira (adalimumab), are only available for subcutaneous injection. Other TNF inhibitors, such as Remicade (infliximab), may be available by infusion.

B-Cell Inhibitors

B-cell inhibitors, such as Rituxan (rituximab), are only available for infusion.

Interleukin Inhibitors

Interleukin (IL) inhibitors, such as Actemra (tocilizumab) and Kineret (anakinra), are available for subcutaneous injection. Some interleukin inhibitors are also available for infusion.

Selective Costimulation Modulators

The selective costimulation modulator Orencia (abatacept) is available for both subcutaneous injection and infusion.

Read more about the different types of biologics for RA.

The Difference Between Infusion and Injection

Infusions and injections are different ways of delivering a biologic medication. An infusion uses a needle to administer a biologic drug directly into a vein for release into the blood system. Injected biologics are administered with a needle that releases the medication under the skin.

Some people with RA may experience quick relief when starting a biologic drug, but many biologics take time to start working, regardless of whether the drug is taken by infusion or injection. “The infusions take a while to work. For me, it took about two months to really kick in!” said one myRAteam member.

Infusions: What To Expect

To get an infusion, you will go to a medical facility and have an IV needle inserted into your hand or arm. The needle will deliver the medication from a tube attached to a bag that slowly releases the drug in drip over an allotted time to provide the necessary dosage. An infusion pump may be used to regulate the dosage of the biologic. Some biologic drug infusions take as little as 15 minutes, while others may take several hours.

An infusion is a relatively painless procedure, usually experienced only as a pinprick when the needle is inserted into a vein. It is not uncommon for people with RA to be wary of infusions, but many people adjust well to the procedure.

“I was resistant and scared of infusions at first, but was in enough misery to give it a try after going through so many drugs that worked, then stopped or had negative side effects,” one myRAteam member wrote. “I just had my monthly Orencia infusion today. I have been on and off it for years. It works well, and I have no side effects from it.”

Injections: What To Expect

Injections of biologics can be quickly administered with a syringe in a clinical setting, similar to other types of shots or vaccines. A subcutaneous injection uses a needle to release medication into the fatty tissue under the skin.

Many injectable biologics are now available for self-injection and can be safely taken at home. Self-injection is administered with prefilled syringes or auto-injectors — injection pens or e-devices — that come with the appropriate dose of medication.

Some people have a reaction at the injection site. Redness, itching, pain, or swelling are common reactions, and can usually be avoided by changing the method of injection. If you have a reaction from an injection, be sure to talk to your doctor about it.

Read more about getting started with biologics.

Advantages and Disadvantages

Your health care provider can explain the advantages and disadvantages of injections and infusions. You may have some choice about how to have your biologic therapy administered, depending on which biologic drug is recommended for you.

Scheduling Differences

Infusions must be administered in a clinical setting, and that can take time. Larger dosing by infusion allows some people to receive biologic treatment less frequently than treatment by injections.

“I’m trying to decide whether or not to request the possibility of monthly infusions vs. weekly injections,” a myRAteam member wrote. “I went the other way and did bimonthly infusions. Now I have biweekly shots,” another member responded.

Scheduling can vary considerably among biologics. Some biologics taken by infusion may be taken monthly or once every eight weeks. Rituxan (rituximab) is a biologic that can be administered with two infusions over two weeks, and then no treatment for at least six months.

Injection Choices

A number of biologics drugs available for injection can be taken safely by self-injection. Many people with RA prefer the convenience of self-injection, which can be taken in the comfort of one’s home and reduce the frequency of doctor’s office visits.

It may take time to adjust to self-injections, but for some people the effort is worth the convenience. As a myRAteam member wrote, “One hundred days into self-injections and today I got it on the first try. Here's to small victories!”

One member explained her experience with self-injection to someone who asked about the process: “I found self-injecting wasn't bad. I gave it in my upper leg. After a few times, it won't be a big deal.”

A fear of needles is a common reason some people avoid self-injection. “Don't talk about needles. I hate needles. The mere thought of a needle is devastating for me,” a member wrote. Another member had these encouraging words, “It will be scary the first time, but before you know it, you will be a pro.”

Read more about self-injection.

Discuss Your Options With Your Medical Team

Ask your rheumatologist and health care team any questions you have about injections and infusions if you are considering biologics as a treatment option. Biologic drugs can significantly improve symptoms in some people with RA, and understanding the options you have with infusions or injections of biologics may improve your experience with these drugs.

“I am so thankful the infusions are giving me my life back,” a myRAteam member wrote about her experience with biologics. Another member said, “I’m feeling a lot better after my Cimzia shot :)”

Talk With Others Who Understand

On myRAteam, the social network for people with rheumatoid arthritis and their loved ones, more than 147,000 members come together to ask questions, give advice, and share their stories with others who understand life with rheumatoid arthritis.

Are you living with rheumatoid arthritis? Do you have questions about injections or infusions? Share your experience in the comments below, or start a conversation by posting on your Activities page.

References

  1. Biologics — Arthritis Foundation
  2. Development Pathways for Subcutaneous Formulations of Biologics Versus Biosimilar Development — Expert Review of Precision Medicine and Drug Development
  3. Subcutaneous Delivery of High-Dose/Volume Biologics: Current Status and Prospect for Future Advancements — Drug Design, Development and Therapy
  4. Subcutaneous Administration of Biotherapeutics: An Overview of Current Challenges and Opportunities — Biodrugs
  5. Getting Biologic Infusions for Arthritis: 12 Common Questions, Answered — CreakyJoints
  6. Infusion Pumps — Making Healthcare Safer III: A Critical Analysis of Existing and Emerging Patient Safety Practices
  7. Effective Method for Drug Injection Into Subcutaneous Tissue — Scientific Reports
  8. Injection Site Reactions With the Use of Biological Agents — Dermatologic Therapy
  9. The Use of Biologics in Rheumatoid Arthritis: Current and Emerging Paradigms of Care — Clinical Therapeutics
  10. Rheumatoid Arthritis: A Brief Overview of the Treatment — Medical Principles and Practice
Ariel D. Teitel, M.D., M.B.A. is the clinical associate professor of medicine at the NYU Langone Medical Center in New York. Review provided by VeriMed Healthcare Network. Learn more about him here.
Joan Grossman is a freelance writer, filmmaker, and consultant based in Brooklyn, NY. Learn more about her here.

A myRAteam Member said:

Thank you great information, been on biologic, for 18 years , saved my life xo

posted 5 days ago

hug (3)

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