IVIg change for CIDP and MMN treatment

What does the change in IVIg product mean for CIDP and MMN patients?

In July 2023 the NZ Blood Bank will begin to switch IVIg product from Intragam P 6% solution to Privigen NZ 10% solution. Both products are manufactured by CSL Behring from donated NZ plasma. The active ingredient in both products is the same but there are slight differences in the stabilizers used leading to an improved shelf life and easier storage for Privigen.  Many CIDP and MMN patients who are being treated with IVIg are worried that this might affect their treatment. So, what does this change really mean for these patients?

1. Why is the NZ Blood Service switching from Intragam to Privigen? There are several reasons for the switch. Firstly, CSL Behring wants to have their production facility aligned with other facilities internationally. Secondly, because Privigen is a more concentrated solution of immunoglobulin (Ig) than Intragam a smaller volume can be delivered to administer the same dose of the active Ig. The higher concentration may also allow subcutaneous (under the skin rather than into a vein) delivery in some individuals. Finally, Privigen can be stored at room temperature and for longer periods of time, making it easier, and therefore less expensive, to store the product.
2. Are the 2 products equally effective? The active component in the 2 products is identical, apart from the concentration and they should have identical beneficial effects in CIDP and MMN patients. I am not aware of any head-to-head studies testing this but there is no reason to suspect that there would be any difference in efficacy.
3. Are the 2 products equally safe and tolerable? The only difference in the products is the concentration of the active component and the stabilizing chemical. Because the Ig concentration is higher in Privigen it is possible that some infusion reactions could be more noticeable, particularly headache, but the rare serious adverse effects such as allergic reactions, and blood clots should not differ between products.
4. Will there be any difference in the infusion protocol? When patients are first switched from Intragam to Privigen, the manufacturer’s recommendation is that the initial infusion rate should be no more than 0.3 ml/kg body weight/hour. After the 1^st hour the infusion rate can be increased. It is almost certain that the prescribing neurologist will adhere to this infusion schedule so that the duration of each infusion will be longer than the current duration with Intragam. Once it has been established that a patient is tolerating the new product the prescribing neurologist may permit a faster initial infusion rate and a faster escalation of the rate but that will be determined by individual prescribers based on individual patients’ reaction to the infusion.