1. Clinical Overview
Human Normal Immunoglobulin (HNIG) is a sterile, concentrated solution of purified immunoglobulin G (IgG) antibodies derived from pooled human plasma of thousands of healthy donors. It contains a broad spectrum of IgG antibodies against common pathogens, reflecting the donor population's immune status. The 5gm presentation is a high-dose formulation used for immunomodulation and antibody replacement. In India, it is prepared following WHO guidelines and DCGI regulations, undergoing rigorous viral inactivation/removal steps (solvent/detergent treatment, low pH incubation, nanofiltration).
| Onset | Duration | Bioavailability |
|---|---|---|
| Immunomodulatory effects begin within 24-48 hours. Antibody levels peak immediately post-infusion. | 3-4 weeks for antibody replacement. Immunomodulatory effects can last several weeks to months. | 100% via intravenous administration. |
2. Mechanism of Action
Mechanism is multifactorial: 1) REPLACEMENT: Provides passive immunity by supplying opsonizing and neutralizing antibodies against a wide range of bacterial and viral pathogens in immunodeficient patients. 2) IMMUNOMODULATION: In autoimmune/ inflammatory conditions, mechanisms include Fc receptor blockade on macrophages, modulation of cytokine production, neutralization of autoantibodies via anti-idiotypic antibodies, inhibition of complement activation, and acceleration of IgG catabolism which may lower pathogenic autoantibody levels.
3. Indications & Uses
- Primary Immunodeficiency Disorders (e.g., X-linked agammaglobulinemia, Common Variable Immunodeficiency, Severe Combined Immunodeficiency)
- Immune Thrombocytopenic Purpura (ITP) - for rapid elevation of platelet count
- Guillain-Barré Syndrome (as part of immunomodulatory therapy)
- Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) - for induction and maintenance therapy
- Kawasaki Disease - to prevent coronary artery aneurysms
4. Dosage & Administration
Adult Dosage: **Immunodeficiency:** 300-600 mg/kg every 3-4 weeks. **ITP:** 1 gm/kg/day for 1-2 days (or 400 mg/kg/day for 5 days). **CIDP:** 2 gm/kg divided over 2-5 days for induction, then 1 gm/kg over 1-2 days every 3 weeks for maintenance. **GBS:** 2 gm/kg divided over 2-5 days. **Kawasaki:** 2 gm/kg as a single infusion over 10-12 hours.
Administration: For 5gm vial: Reconstitute/dilute as per manufacturer's instructions (usually with 0.9% NaCl or provided diluent). Administer IV only. **START INFUSION SLOWLY:** 0.5 to 1.0 mL/kg/hr for first 30 min. If well-tolerated, gradually increase to a maximum of 3-4 mL/kg/hr (or per product-specific guidelines). Pre-medication with antihistamines/analgesics/steroids may be considered. Do not mix with other drugs. Use a separate infusion line.
5. Side Effects
Common side effects may include:
- Headache
- Pyrexia
- Chills
- Fatigue
- Nausea, Vomiting
- Back pain, Myalgia, Arthralgia
- Mild hypotension or hypertension
- Flushing, Tachycardia
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Live Attenuated Vaccines (e.g., MMR, Varicella, Yellow Fever) | Immunoglobulin may interfere with the immune response to the vaccine, rendering it ineffective. | Major |
| Other Immunosuppressants (e.g., high-dose corticosteroids, cyclophosphamide) | Additive immunosuppression may increase infection risk. In autoimmune conditions, effect may be synergistic. | Moderate |
| Loop Diuretics (e.g., Furosemide) | Concurrent use in renal impairment may increase risk of renal dysfunction. | Moderate |
| ACE Inhibitors | May increase risk of anaphylactoid reactions in patients receiving IVIG, especially those with IgA deficiency. | Moderate |
7. Patient Counselling
- Do report any history of allergies, especially to blood products, or IgA deficiency.
- Do inform your doctor about all medications and recent vaccinations.
- Do maintain good hydration before and after the infusion.
- Don't receive live vaccines for at least 3 months (up to 11 months for measles) after a high-dose IVIG infusion without consulting your doctor.
- Don't miss follow-up appointments for monitoring blood counts, renal function, or IgG levels.
8. Toxicology & Storage
Overdose: Symptoms of fluid overload (dyspnea, orthopnea, pulmonary edema), hyperviscosity (headache, blurred vision, neurological deficits), severe headache, aseptic meningitis, acute renal failure.
Storage: Store at +2°C to +8°C (refrigerate). Do not freeze. Protect from light. Keep in outer carton. The reconstituted/diluted product should be used immediately. If not used immediately, storage time and conditions before use are product-specific (consult package insert) but should not exceed 24 hours at 2-8°C. Do not use after the expiry date.