Nucala (mepolizumab)

What it is

Nucala (mepolizumab) is a biologic medicine that blocks interleukin-5 (IL-5) — the protein that tells the body to make eosinophils, a type of white blood cell. It was the first drug approved for EGPA (eosinophilic granulomatosis with polyangiitis), a rare type of vasculitis (inflammation of the blood vessels) in which eosinophils damage tissues such as the lungs, sinuses, skin, and nerves. By lowering eosinophil numbers, Nucala helps control EGPA and can allow steroid doses to be reduced. It is also used for severe eosinophilic asthma and certain other eosinophil-driven conditions.

Before starting

Before starting, we check your blood eosinophil count and review your history for parasite (helminth) infections — because eosinophils help fight parasites, an untreated parasite infection should be dealt with before eosinophils are lowered. We also review your steroid use carefully: if you take steroids for EGPA, they should not be stopped suddenly when Nucala begins, since abrupt steroid withdrawal can cause symptoms of its own; any taper is gradual and directed by your provider. Shingles has been reported in people taking Nucala, so we may discuss the shingles vaccine — vaccines work best when given before immune-modifying treatment is under way.

How it’s given

For EGPA, Nucala is given as three separate injections under the skin, one after another, once every 4 weeks, in our office. The EGPA dose is higher than the asthma dose because the tissue inflammation in EGPA needs the higher level. Visits are short, and you return to normal activities the same day. There is nothing to store or inject at home.

What to expect

Eosinophil counts drop quickly, but the results that matter — fewer EGPA flares, calmer asthma and sinus symptoms, and a gradual reduction in steroid dose — build over months; benefit is usually judged over 3–6 months. The most common side effects are headache, back pain, tiredness, and soreness where the injections were given. Allergic reactions are uncommon; seek urgent care for swelling of the face or tongue, widespread itchy rash, or difficulty breathing. Report a painful blistering rash promptly (possible shingles), and tell us about any new numbness, weakness, or worsening breathing, which can signal EGPA activity during a steroid taper.

Everyday guidance

Keep the monthly appointments on schedule — steady eosinophil control is what keeps EGPA quiet between visits. Do not change your steroid dose on your own; tapering is done in planned steps with your provider. Keep a brief symptom diary (breathing, sinuses, skin, tingling or numbness) to bring to visits — it helps us tell disease activity apart from everyday aches. Tell other clinicians you receive an eosinophil-lowering biologic. For questions or concerning symptoms, call (361) 400-7700.