varicella-zoster immune globulin (VZIG)

Available forms
Available by prescription only
Injection: 10% to 18% solution of the globulin fraction of human plasma, which contains 125 units of varicella-zoster virus antibody in 2.5 ml or less

Indications and dosages
 Passive immunization of susceptible patients, primarily immunocompromised patients after exposure to varicella (chickenpox or herpes zoster). Adults and children: 125 units per 10 kg of body weight I.M., to maximum of 625 units. Higher doses may be needed in immunocompromised adults.

Pharmacodynamics
Postexposure prophylaxis: Provides passive immunity to varicella-zoster virus.

Pharmacokinetics
Absorption: Administered I.M.
Distribution: No information available.
Metabolism: No information available.
Excretion: No information available.

Contraindications and precautions
Contraindicated in patients with thrombocytopenia, coagulation disorders, immunoglobulin A deficiency, or history of severe reaction to human immune serum globulin or thimerosal.

Interactions
Drug-drug. Corticosteroids, immunosuppressants: May interfere with immune response to this immune globulin. Whenever possible, avoid using these drugs during postexposure immunization period.
Live-virus vaccines (such as those for measles, mumps, rubella): Drug may interfere with immune response. Don’t administer live-virus vaccines within 2 weeks before or 3 months after VZIG. If you must administer VZIG with a live-virus vaccine, confirm seroconversion with follow-up serologic testing.

Adverse reactions
CNS: malaise, headache, fever.
CV: chest tightness.
GI: GI distress.
GU: nephrotic syndrome.
Musculoskeletal: myalgia.
Respiratory: respiratory distress.
Skin: rash, discomfort at injection site.
Other: anaphylaxis, angioedema.

Effects on lab test results
None reported.

Overdose and treatment
No information available.

Special considerations
 ALERT Have epinephrine solution 1:1,000 available to treat allergic reactions.
• For maximum benefit, administer VZIG within 96 hours of presumed exposure.
• Although usually used only in children younger than age 15, VZIG may be administered to adults, if needed.
• VZIG is recommended primarily for immunodeficient patients younger than age 15 and certain infants exposed in utero, although use in other patients (especially immunocompromised patients of any age, normal adults, pregnant women, and premature and full-term infants) should be considered on a case-by-case basis. Not routinely recommended for use in immunocompetent pregnant women because chickenpox is much less severe than in immunosuppressed patients. Moreover, vaccine won’t protect fetus. VZIG isn’t for use in immunodeficient patients with history of varicella, unless immunosuppression is caused by bone marrow transplantation.
• Administer only by deep I.M. injection, never I.V. Use gluteal muscle in infants and small children and deltoid or anterolateral thigh in adults and larger children. For patients weighing more than 10 kg (22 lb), give no more than 2.5 ml at a single injection site.
• Monitor patient for immediate postadministration reactions, including anaphylaxis.
• After I.M. absorption, persistence of antibodies is unknown, but protection should last at least 3 weeks. Protection is sufficient to prevent or lessen severity of varicella infections.
Breast-feeding patients
• It isn’t known if VZIG appears in breast milk. Use cautiously in breast-feeding women.

Patient education
• Advise patient that the chance of contracting AIDS or hepatitis from VZIG is very small.
• Inform patient that some pain, swelling, and tenderness may occur at injection site. Acetaminophen may be taken to alleviate these minor effects.
• Encourage patient to immediately report severe reactions, including decreased urine output, sudden weight gain, fluid retention, or shortness of breath.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use