Rh_o(D) immune globulin, human (Rh_o[D] IGIM)

BayRho-D Full Dose, RhoGAM

Rh_o(D) immune globulin, human, microdose (Rh_o[D] IG Microdose)
BayRho-D Mini Dose, MICRhoGAM

Available forms
Available by prescription only
Injection: 300 mcg of Rh_o(D) immune globulin/vial (standard dose); 50 mcg of Rh_o(D) immune globulin/vial (microdose)

Indications and dosages
 Rh-positive exposure (full-term pregnancy or termination of pregnancy beyond 13 weeks’ gestation), threatened abortion. Women: Administer 1 vial I.M. for each 15 ml of estimated fetal packed RBC volume entering patient’s blood, as determined by a modified Kleihauer-Betke technique to determine fetal packed RBC volume. Usual (standard) dose after delivery of full-term infant is 1 vial; it must be given within 72 hours after delivery or miscarriage.
 If Rh_o(D) immune globulin is indicated before delivery, administer 1 vial (standard dose) at about 28 weeks’ gestation and give a second vial within 72 hours of delivery.
 Transfusion accidents. Premenopausal women: Consult blood bank or transfusion unit at once. The number of vials (standard dose) to administer is calculated via the following formula:
 
Number of vials = Volume of whole blood transfused × Donor unit hematocrit ÷ 15

Dose must be given within 72 hours.
 Termination of pregnancy (spontaneous or induced abortion or ectopic pregnancy) up to and including 12 weeks’ gestation. Women: 1 vial of microdose immune globulin I.M.; ideally, given within 3 hours but may give up to 72 hours after abortion or miscarriage.
 Amniocentesis or abdominal trauma during pregnancy. Women: Dosage varies based on extent of estimated fetomaternal hemorrhage.

Pharmacodynamics
Rh reaction prophylaxis: Suppresses the active antibody response and formation of anti-Rh_o(D) in Rh_o(D)-negative or D^u-negative individuals exposed to Rh-positive blood. Provides passive immunity to women exposed to Rh-positive fetal blood during pregnancy. Prevents formation of maternal antibodies (active immunity), which prevents hemolytic disease of the Rh-positive newborn in another pregnancy.

Pharmacokinetics
Absorption: No information available.

Contraindications and precautions
Contraindicated in Rh_o(D)-positive or D-positive patients and those previously immunized to Rh_o(D) blood factor. Also contraindicated in patients with anaphylactoid or severe systemic reaction to human globulin. Use extreme caution when giving to patients with immunoglobulin A deficiency because of increased risk of anaphylactoid reaction.

Interactions
Drug-drug. Live-virus vaccines (measles, mumps, rubella): Rh_o(D) immune globulin may interfere with immune response to vaccine. Don’t give live-virus vaccine within 3 months after Rh_o(D) immune globulin. If postpartum women receive both Rh_o(D) immune globulin and rubella virus vaccine within a 3-month period, serologic tests should be performed 6 to 8 weeks after vaccination to confirm seroconversion.

Adverse reactions
CNS: slight fever.
Skin: discomfort at injection site.

Effects on lab test results
None reported.

Overdose and treatment
No information available.

Special considerations
• Obtain thorough history of allergies and reactions to immunizations.
• Keep epinephrine solution (1:1,000) available to treat allergic reactions.
• Immediately after delivery, send a sample of infant’s cord blood to laboratory for typing and crossmatching and direct antiglobulin test. Infant must be Rh_o(D)-positive or D^u-positive. Confirm that mother is Rh_o(D)-negative and D^u-negative.
• For best results, Rh_o(D) immune globulin must be given within 72 hours of Rh-incompatible delivery, spontaneous or induced abortion, or transfusion.
• The microdose formulation is recommended for use after every spontaneous or induced abortion up to and including 12 weeks’ gestation unless mother is Rh_o(D)-positive or D^u-positive, she has Rh antibodies, or father or fetus is Rh-negative.
• Give I.M. in anterolateral aspect of upper thigh and deltoid muscle. Don’t give I.V.
• Rh_o(D) immune globulin hasn’t been linked to an increased frequency of AIDS. The immune globulin contains no HIV, and recipients develop no antibodies to HIV.
• Store product between 36° and 46° F (2° and 8° C). Don’t freeze.
Breast-feeding patients
• Immune globulins appear in breast milk. Safety in breast-feeding women hasn’t been established.

Patient education
• Inform patient that she is receiving this product because her blood has been exposed to the Rh-positive factor. Tell postpartum patient that her body will naturally develop antibodies to destroy this factor, which could threaten future Rh-positive pregnancies.
• Tell patient there is no known risk of HIV infection after receiving product.
• Tell patient that local pain, swelling, and tenderness at injection site may occur after vaccination. Recommend acetaminophen to ease minor discomfort.
• Tell patient to report headache, skin changes, or difficulty breathing.

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