Chronic inflammatory demyelinating polyneuropathy (CIDP) is thought to be an autoimmune condition. When you have CIDP, your immune system sees your nerves as foreign and attacks them. The attack causes inflammation and damage to the protective coating around your nerves (myelin sheath). Damaged myelin can lead to muscle weakness and sensory problems, such as your ability to feel sensations like touch.
CIDP may start as a pattern of weakness that slowly develops in the muscles of the hips, shoulders, hands, and feet on both sides of the body. Other symptoms may include numbness, tingling, fatigue, and trouble walking. The symptoms may slowly worsen over time, or they may come and go.
Starting treatment early for CIDP can help maintain your mobility and independence. Common medicines prescribed for CIDP are steroids (corticosteroids) and intravenous immune globulin (IVIG). One IVIG option is Privigen (immune globulin intravenous, human).
The FDA has approved Privigen to help improve nerve symptoms and movement problems in adults with CIDP. This article covers frequently asked questions about using Privigen for CIDP.
How Does Privigen Work for CIDP?
The exact way Privigen works is not completely understood. Like other IVIG medicines, Privigen contains antibodies collected from the plasma of carefully selected donors in the United States. These antibodies help regulate your immune system and may reduce its attack on your nerves.
Privigen may help improve nerve function and ease muscle weakness in your arms and legs.
How Is Privigen Different From Other IVIG Medicines?
Privigen is similar to other IVIG medicines but has unique differences. One key difference is that Privigen is made with proline to stabilize the medicine. Proline is a natural amino acid made in the body and found in foods such as dairy, meat, and eggs.
This stabilizer allows Privigen to be stored at room temperature and comes ready to use, whereas some other IVIG products require refrigeration and must be diluted before infusion.
Unlike some other IVIG products, Privigen does not contain sugar or sucrose, which can be important for people with certain health problems or sensitivities. It has a low IgA content, making it suitable for most people, but those with a known IgA deficiency should discuss potential risks with their health care provider. Also, since Privigen contains proline, it should not be used if your blood test results show that you have too much proline in your blood (hyperprolinemia).
How Is Privigen Administered for CIDP?
Privigen is given as an IV infusion (through a needle into a vein) by a health care professional. Infusions may be given at a hospital, clinic, or doctor's office, or sometimes at home under supervision.
Your health care provider will calculate your dose and let you know your treatment plan. Here is the typical Privigen dosing schedule:
- Treatment starts with a high (loading) dose, aimed at getting your symptoms under control. This dose is given very slowly to help lower the risk of bad reactions.
- Induction dose: 2 grams per kilogram (g/kg) of body weight, given over two to five days.
- After that, you may continue to receive maintenance doses to keep your symptoms under control.
- Maintenance dosage: 1 g/kg given every three weeks, either as one infusion in a single day or divided into two doses over two days.
During and after each Privigen infusion, a health care professional will monitor your blood pressure, heart rate, and temperature. Tell your health care provider right away if you have chest pain, shortness of breath, severe headache, back pain, or swelling in your legs during or after your infusion.
If you start to have a reaction (such as trouble breathing) or changes in your vital signs (such as fever or increased blood pressure), your infusion may be slowed or stopped. If you start feeling better, your health care provider may resume your Privigen infusion at a slower rate and will continue to monitor you closely.
How Was Privigen Studied for CIDP?
A clinical trial called PRIMA tested the effectiveness of Privigen for improving symptoms in adults with CIDP.
Here are some details about the 28 adults who took part in the study:
- There were 18 men and 10 women.
- All participants were White.
- 13 people had previously been treated with IVIG (“IVIG-pretreated”), and 15 people had not received IVIG before (“IVIG-untreated”).
- Median age: 58 years, with a range of 22-79 years (Median is the middle point when looking at everyone’s ages from youngest to oldest.)
- Median body weight: 83 kg (about 183 pounds), ranging from 50 to 118 kg (110-260 pounds)
- Median inflammatory neuropathy cause and treatment (INCAT) disability score at baseline: 3.5, with a range of 3-4.5 (INCAT is a 10-point disability scale that measures how well a person can use their arms and legs for daily activities such as walking, dressing, or gripping objects.)
- Most participants (about 43%) had been living with CIDP for 2-10 years before joining the study.
People were not allowed to join the study if they had other types of nerve problems (neuropathy), other major health issues affecting their kidneys, liver, or blood, or if they had recently received other immune-modifying treatments.
The study was open-label, meaning the people in the study knew they were receiving Privigen. All participants were given a loading dose followed by maintenance treatment every three weeks for up to seven doses. The participants also had a checkup at baseline and every three weeks to see if their symptoms improved.
The main goal of the study was to see how well Privigen worked. To determine how well it worked, the researchers kept track of the number of people whose symptoms improved on the INCAT 10-point scale. The researchers also looked at other measures, such as overall muscle strength.
A response was defined as having at least a one-point improvement on the INCAT score between the start of the study and week 25.
What Are the Main Benefits of Privigen for CIDP Based on the Study?
Privigen met the study goal, with 61% of participants showing meaningful improvement in their ability to use their arms and legs for daily activities such as walking, dressing, or gripping objects.
Other PRIMA study results:
- 77% of IVIG-pretreated participants responded to Privigen treatment, while 47% of IVIG-untreated participants had a response.
- Median INCAT score improved from 3.5 to 2.5.
Your results may differ from those seen in clinical studies. Talk with your health care provider about whether Privigen is right for you and what to expect from treatment.
Are There Additional Potential Benefits of Privigen for CIDP Based on Studies?
In addition to improving overall arm and leg function (based on the INCAT score), many participants in the PRIMA study also experienced improvements in grip strength of both hands.
The Medical Research Council (MRC) sum score, which measures overall muscle strength, also improved by nearly seven points.
These findings show that Privigen can help some people improve their grip or muscle strength. This improvement may help people do daily activities more easily. But individual results can vary.
How Long Does It Take to Work for CIDP?
Some people may notice improvement as soon as three weeks after starting Privigen. This is based on the PRIMA study, where the median time to improvement was 7.5 weeks. In this study, people who were new to IVIG treatment improved at a slower rate (around 4.5 months), while those who had used IVIG therapies before improved faster (about three weeks).
Is Privigen a Long-Term Treatment for CIDP?
Privigen has been studied for use in CIDP for up to six months. Some people who respond to treatment during this time may not need ongoing maintenance therapy to stay symptom-free. Your health care provider will decide how long you should continue treatment based on how well you respond and whether you still need it.
Can I Receive Privigen at Home?
Privigen is given as an IV infusion (into a vein) by a health care professional. It can be given at a hospital, an outpatient clinic, or sometimes as a home infusion. A nurse or other health care professional will closely monitor you for side effects during and after each infusion.
Some people need to get Privigen at a hospital if they need closer monitoring or have had serious reactions in the past. Because hospitals can expose people to infections, it may be safer for some individuals to receive Privigen in an outpatient clinic or at home. Your health care provider will review your medical history, treatment response, and insurance coverage to decide which setting is best for you.
Note: Privigen is FDA-approved for the IV infusion route only. However, in some cases, Privigen or other IVIG medicines may be given under the skin (subcutaneous infusion/SCIG) for people who respond well to IV therapy. This is considered an off-label use of Privigen. Your health care provider can let you know whether this is an option for you.
Is There Any Cost Assistance Available?
A cost assistance program is available from the maker of Privigen, CSL Behring. It may lower the amount you pay. Whether you qualify to enroll may depend on what type of insurance you have or if you are uninsured. Visit this website from the drugmaker for more information about Privigen costs and copay savings. You can also contact the drugmaker at 877-355-4447 to connect with a representative for financial support information and other resources.
