peginterferon beta-1a (Plegridy)

What is Plegridy? What is Plegridy used for?

Peginterferon beta-1a (Plegridy) is a protein produced by recombinant DNA technology using genetically engineered Chinese Hamster Ovary Cells into which the human interferon beta genes have been introduced. It is used for treating multiple sclerosis (MS). It differs from interferon beta-1a by having polyethylene glycol attached to the interferon molecules (peglated) that allow the interferon to remain in the body for longer times thus allowing less frequent dosing. Interferon beta-1a is designed to be identical to interferon beta that is naturally produced by various cells in the body. Interferon beta has antiviral properties and plays a role in regulating the immune response. The exact mechanism by which interferon beta-1a works in the body to treat MS is not known. Interferon beta-1a does not cure MS. Rather it helps to decrease the number of flare-ups and slows the occurrence of some of the physical disability that commonly occurs in the disease. Plegridy works in the same way and has similar side effects as other interferon beta-1a products such as Avonex and Rebif. However, it is given every 14 days versus once weekly or 3 times per week injections. The FDA approved Plegridy in August, 2014.

What brand names are available for Plegridy?


Is Plegridy available as a generic drug?


Do I need a prescription for Plegridy?


What are the side effects of Plegridy?

The most common side effects of interferon beta-1a are:

Flu-like symptoms are commonly experienced when patients first start taking interferon beta-1a. These symptoms can be managed with over-the-counter pain and fever reducers, and usually decrease or go away over time.

Stomach pain, an increase in liver enzymes, and blood disorders including a drop in the number of red blood cells, white blood cells, and platelets also occur.

Interferon beta-1a may also cause other serious side effects including seizures, suicidal thoughts or actions, liver disease, and serious allergic and skin reactions.


What Is Multiple Sclerosis? MS Symptoms, Causes, Diagnosis See Slideshow

What is the dosage for Plegridy?

The recommended dose of Plegridy is 125 mcg injected under the skin (subcutaneously) every 14 days.

Treatment is started at the lower dose of 63 mcg followed by a second injection of 94 mcg injection on day 15. The full dose of 125 mcg is administered for the third dose on day 29 and every 14 days thereafter.

The best sites to inject are the areas of the body that usually have more fatty tissue such as the thigh, back of the upper arm, and stomach. To avoid injury, patients are advised to change or rotate the injection sites.

Which drugs or supplements interact with Plegridy?

Combining interferon beta-1a with zidovudine (Retrovir) or hydroxyurea (Hydrea) may increase the risk of bone marrow suppression.

Is Plegridy safe to take if I'm pregnant or breastfeeding?

Use of peginterferon beta-1a has not been adequately evaluated in pregnant women. Due to the lack of conclusive safety data, peginterferon beta-1a should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus. Peginterferon beta-1a is classified as FDA pregnancy risk category C. This designation indicates fetal harm from the drug has been shown in animal studies, but information on effects in pregnant women is not clear.

It is not known if peginterferon beta-1a is excreted in breast milk. As many drugs enter breast milk and can potentially cause harm to the nursing infant, peginterferon beta-1a should be used cautiously in nursing mothers. 

What else should I know about Plegridy?

What preparations of Plegridy are available?

Plegridy is available in prefilled pens or syringes for subcutaneous injection.

Injection: 125 mcg/0.5 ml solution in single-dose prefilled syringe or single-dose prefilled pen.

Injection starter pack: containing 63 mcg/0.5 ml and 94 mcg/0.5 ml solution in single-dose prefilled pens or syringes.

How should I keep Plegridy stored?

Preferably peginterferon beta-1a should be stored refrigerated at a temperature from 2 C to 8 C (36 F to 46 F). Peginterferon beta-1a should be warmed to room temperature before injecting. If refrigeration is not available, peginterferon beta-1a can be stored from 2 C to 25 C (36 F to 77 F) for up to 30 days.


Peginterferon beta-1a (Plegridy) is a protein produced by genetically engineered cells used in the treatment of multiple sclerosis by mimicking the human protein and reducing physical disability. Side effects, drug interactions, and use during pregnancy should be reviewed prior to taking any medication.

Treatment & Diagnosis

Medications & Supplements

Subscribe to MedicineNet's General Health Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

FDA Prescribing Information