How is IV gammaglobulin used as an immunomodulator in rheumatic diseases?
- • Available formulations: multiple suppliers; solution concentrations vary from 3% to 12% Ig; cost is $100 to $300/g.
- • Dosage: 1 to 2 g/kg administered over 1 to 5 days.
- • Side effects: headache (2%–20%), flushing, chest tightness, back pain/myalgias, fever, chills, nausea, diaphoresis, hypotension, aseptic meningitis, clot, leukopenia, serum sickness.
- • Follow-up: creatinine 24 hours after infusion if baseline renal insufficiency.
- • Precautions: anaphylactic reaction in patients with hereditary IgA deficiency (1/700 patients); transmission of infectious agents (rare).
Some side effects of gammaglobulin are avoided by premedicating patients with acetaminophen and diphenhydramine hydrochloride (Benadryl) or hydrocortisone sodium succinate (Solu-Cortef) and by slowing the rate of infusion. Infusion is started at 30 mL/hour and increased to a maximum of 250 mL/hour (sometimes higher). Patients who get migraine headaches may benefit from premedication with sumatriptan. Avoid sucrose-containing IVIG (Carimune), which can cause acute renal failure. Avoid sugar-containing IVIG in diabetics. Use isoosmolar IVIG (240–300 mOsm/kg) to reduce the chance of clot. Use IVIG preparations (Privigen, Gammagard S/D) containing low IgA levels in IgA-deficient patients. In a patient who is not IgA-deficient, Gamunex-C (10%) may be best tolerated.