Hyqvia is an immune globulin therapy used to treat two conditions: primary immunodeficiency (PI) in adults and children ages 2 and older, and chronic inflammatory demyelinating polyneuropathy (CIDP) as maintenance therapy in adults. Both conditions involve a malfunctioning immune system, but in very different ways. PI leaves the body unable to fight infections effectively, while CIDP is a condition where the immune system attacks the nerves.
Primary Immunodeficiency
Primary immunodeficiency refers to a group of more than 400 disorders where the immune system doesn’t produce enough protective antibodies on its own. People with PI get frequent, severe, or unusual infections that healthy immune systems would handle without trouble. Hyqvia works by delivering concentrated antibodies (immunoglobulin G, or IgG) collected from donated human plasma directly into the body, essentially replacing what the immune system can’t make.
For PI, the typical dose ranges from 300 to 600 mg per kilogram of body weight, given once every 3 to 4 weeks after an initial ramp-up period. That ramp-up starts with weekly infusions at lower volumes and gradually increases the amount and stretches out the interval, giving the body time to adjust to larger doses.
CIDP Maintenance Therapy
Chronic inflammatory demyelinating polyneuropathy is a neurological condition in which the immune system damages the protective coating around nerves, called myelin. This leads to progressive weakness, numbness, and impaired movement, often in the legs and arms. Immune globulin therapy helps by modulating the immune response and reducing the ongoing nerve damage.
Hyqvia is approved specifically for maintenance therapy in CIDP, meaning it’s used to keep the condition stable after initial treatment has brought symptoms under control. It is not intended as a first-line treatment to stabilize someone during an acute flare.
How Hyqvia Differs From Other Immune Globulin Therapies
What sets Hyqvia apart from other subcutaneous immune globulin products is an added enzyme called recombinant human hyaluronidase. This enzyme temporarily loosens the connective tissue under the skin, allowing much larger volumes of fluid to be absorbed from a single infusion site. Standard subcutaneous immune globulin infusions typically require weekly injections at multiple sites because the tissue can only absorb small amounts at a time.
Hyqvia can deliver a full therapeutic dose at just one infusion site, up to every four weeks. That’s a significant practical difference for people who would otherwise need weekly infusions or regular trips to an infusion center for intravenous treatment. Most patients can self-administer Hyqvia at home once they’ve been trained, which reduces the disruption to daily life considerably.
The maximum volume per infusion site is 600 mL, and patients weighing 40 kg (about 88 pounds) or more can receive up to 1,200 mL total per infusion day across multiple sites. If that volume is too much for one session, doses can be split across multiple days with 48 to 72 hours between infusions to let the body absorb the fluid.
Common Side Effects
The most common reaction is pain at the infusion site, reported by roughly 40 to 48% of patients in clinical trials. Other local reactions include redness at the site (17 to 21%), itching (8 to 19%), and swelling (11 to 12%). These tend to be most noticeable during the first few infusions and often improve as the body adjusts.
Systemic side effects, meaning reactions that affect the whole body, are also common in the first 72 hours after an infusion:
- Headache: 30 to 35% of patients
- Nausea: 7 to 22%
- Fatigue: 12 to 18%
- Fever: 13 to 15%
- Diarrhea: 7 to 10%
- Chills or dizziness: 5 to 8%
Children under 16 experienced vomiting more often than adults (15% vs. 4%), while adults reported higher rates of nausea (22% vs. 7%).
Serious Risks
Hyqvia carries an FDA boxed warning for thrombosis, which is the formation of blood clots in veins or arteries. This risk applies to all immune globulin products, not just Hyqvia. People at higher risk include those who are older, have a history of blood clots, have cardiovascular risk factors, use estrogen-based medications, or have been immobile for extended periods. Blood clots can also occur in people with no known risk factors, which is why staying well-hydrated before and after infusions is important.
Aseptic meningitis syndrome is another recognized risk. This involves severe headache, neck stiffness, drowsiness, sensitivity to light, and nausea, typically starting within hours to two days after an infusion. It resolves within several days once treatment is paused, and it does not involve a bacterial or viral infection despite mimicking meningitis symptoms.
Who Can Use Hyqvia
For primary immunodeficiency, Hyqvia is approved for adults and children ages 2 and older. For CIDP, it is approved only for adults. Patients typically start Hyqvia after being stabilized on intravenous immune globulin or another subcutaneous product, then transition to Hyqvia with a dose calculated to maintain the same blood levels of protective antibodies they were achieving with their previous treatment. If blood levels drift too high or too low after switching, the dose can be adjusted based on body weight and the gap between the target and actual antibody levels.