- If the Rh status of the baby is not known at 72 hours, administer WinRho
®SDF to the mother at 72 hours after delivery. If more than 72 hours have elapsed, administer as soon as possible up to 28 days after delivery.
- If WinRho
®SDF is administered early in pregnancy for amniocentesis and chorionic villus sampling (before 34 weeks), then administer WinRho
®SDF repeatedly at 12-week interval to maintain adequate levels of passively acquired anti-Rh.
IncompatibleTransfusion
Table 3: Incompatible Transfusion Dosing Guidelines| Indication | Dose (dose in either IU or mcg)
| Frequency |
Incompatible Transfusion (intravenous or intramuscular) | Begin treatment within 72 hours of exposure |
| Intravenous |
| If exposed to Rh
0(D)-Positive
Whole Blood | 45 IU per ml blood | 9 mcg per ml blood | Every 8 hours |
| If exposed to Rh
0(D)-Positive
Red Blood Cells | 90 IU per ml cells | 18 mcg per ml cells |
| Administer this dose until total dose has been administered | 3000 IU | 600 mcg | Every 8 hours |
| Intramuscular |
| If exposed to Rh
0(D)-Positive
Whole Blood | 60 IU per ml blood | 12 mcg per ml blood | Every 12 hours |
| If exposed to Rh
0(D)-Positive
Red Blood Cells | 120 IU per ml cells | 24 mcg per ml cells |
| Administer this dose until total dose has been administered | 6000 IU | 1,200 mcg | Every 12 hours |
For incompatible transfusion or massive fetal hemorrhage, treatment must occur within 72 hours and dose may be intravenous or intramuscular, based on the volume of blood or cells replaced.
Treatment of ITP
The safety of WinRho
®SDF was evaluated in clinical trials (n=161) in children and adults with acute and chronic ITP and adults and children with ITP secondary to HIV. Overall, 417 adverse events were reported by 91 patients (57%). The most common adverse events were headache (14% of the patients), fever (11% of the patients) and asthenia (11% of the patients). A total of 117 adverse drug reactions were reported by 46 patients (29%). Headache, chills, and fever were the most common related adverse events (
Table 5). With respect to safety profile per administration, 60/848 (7%) of WinRho
®SDF infusions had at least one adverse reaction. The most common adverse reactions were headache (19 infusions; 2%), chills (14 infusions; < 2%), and fever (9 infusions; 1%).
Table 5: Adverse Drug Reactions with an Incidence ≥ 5% of Patients| Body System | Adverse Event | All Studies | Children | Adults |
| # of Patients (%) |
| Body as a Whole | Headache | 18 (11) | 8 (11) | 10 (12) |
| Chills | 13 (8) | 4 (5) | 9 (10) |
| Fever | 9 (6) | 5 (7) | 4 (5) |
| Asthenia | 6 (4) | 2 (3) | 4 (5) |
| Infection | 4 (3) | 4 (5) | 0 (0) |
| Nervous System | Dizziness | 6 (4) | 2 (3) | 4 (5) |
In four clinical trials of patients treated with the recommended initial intravenous dose of 250 IU/kg (50 mcg/kg), the mean maximum decrease in hemoglobin was 1.70 g/dL (range: +0.40 to -6.1 g/dL). At a reduced dose, ranging from 125 to 200 IU/kg (25 to 40 mcg/kg), the mean maximum decrease in hemoglobin was 0.81 g/dL (range: +0.65 to -1.9 g/dL). Only 5/137 (3.7%) of patients had a maximum decrease in hemoglobin of greater than 4 g/dL (range: -4.2 to -6.1 g/dL).
Suppression of Rh Isoimmunization
In the clinical trial of 1,186 Rh
o(D)-negative pregnant women, no adverse reactions were reported to Rh
o(D) IGIV.
Risk Summary
For the treatment of ITP, there is no human data or animal data available to establish the presence or absence of drug-associated risk.
When administered to pregnant women in a clinical trial to evaluate WinRho
®SDF for suppression of Rh isoimmunization [
see Clinical Studies(
14.2)] following dosing regimens similar to
Table 2[
see Dosing and Administration(
2.1)], WinRho
®SDF was not shown to harm the fetus or newborn.
12
Risk Summary
There is no information regarding the presence of WinRho
®SDF in human milk, the effect on the breastfed infant, and the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for WinRho
®SDF and any potential adverse effects on the breastfed infant from WinRho
®SDF or from the underlying maternal condition.
Treatment of ITP and Suppression of Rh Isoimmunization
In post-marketing spontaneous reporting, there has been a limited number of medication error reports related to dosage calculations in which higher doses than that recommended for WinRho
®SDF were administered (doses > 60 mcg/kg). Signs and laboratory findings of overdosage in Rh positive (ITP) patients have included hemoglobin decreases in excess of 1.2 g/dL. For the suppression of Rh isoimmunization, hemolytic reactions have been reported in cases of mis-matched blood transfusions where very large doses of WinRho
®SDF were administered.
In one ITP case report that involved an overdose due to confusion between mcg and international unit (IU), a patient with significant co-morbidities developed IVH and had a fatal outcome. In the event of overdose, monitor patients closely for signs and symptoms of hemolysis and initiate symptomatic and supportive treatment.
Treatment of ITP
WinRho
®SDF has been shown to increase platelet counts in non-splenectomized, Rh
o(D)-positive patients with ITP. Platelet counts usually rise within one to two days and peak within seven to 14 days after initiation of therapy. The mechanism of action is not completely understood, but is thought to be due to the formation of anti-Rh
o(D)-coated RBC complexes, which are preferentially removed by the reticuloendothelial system, particularly the spleen. This results in Fc receptor blockade, thus sparing antibody-coated platelets.
9,10
Suppression of Rh Isoimmunization
The mechanism by which Rh
o(D) immune globulin suppresses immunization to Rh
o(D)-positive RBCs is not completely understood.
WinRho
®SDF when administered within 72 hours of a full-term delivery of a Rh
o(D)-positive infant by a Rh
o(D) negative mother will reduce the incidence of Rh isoimmunization from 12-13% to 1-2%. The 1-2% is, for the most part, due to isoimmunization during the last trimester of pregnancy. When treatment is given both antenatally, at 28-weeks gestation, and postpartum, the Rh immunization rate drops to about 0.1%.
13,14
When 600 IU (120 mcg) of WinRho
®SDF is administered to pregnant women, passive anti-Rh
o(D) antibodies are not detectable in the circulation for more than six weeks and therefore a dose of 1,500 IU (300 mcg) should be used for antenatal administration.
IM versus IV Administration (Lyophilized Powder)
In a clinical study involving Rh
o(D)-negative volunteers, two subjects received 600 IU (120 mcg) WinRho
®SDF by intravenous (IV) administration and two subjects received this dose by intramuscular (IM) administration. Peak levels (36 to 48 ng/mL) were reached within two hours of IV administration and peak levels (18 to 19 ng/mL) were reached at five to 10 days after IM administration. Although no statistical comparisons were made, the calculated areas under the curve were comparable for both routes of administration. The t
½for anti-Rh
o(D) was about 24 days following IV administration and about 30 days following IM administration.
Lyophilized Powder versus Liquid Formulation
In two comparative pharmacokinetics studies, 101 volunteers were administered the liquid or lyophilized formulation of WinRho
®SDF intravenously (n=41) or intramuscularly (n=60). The formulations were bioequivalent following IV administration based on area under the curve to 84 days and had comparable pharmacokinetics following IM administration. The average peak concentrations (C
max) of anti-Rh
o(D) for both formulations were comparable following IV or IM administration and occurred within 30 minutes or 2-4 days of administration, respectively. Both formulations also had similar elimination half-lives (t
½) following IV or IM administration.
Childhood Chronic ITP
In an open-label, single arm, multicenter study, 24 non-splenectomized, Rh
o(D)-positive children with ITP of greater than six-months duration were treated initially with 250 IU/kg (50 mcg/kg) WinRho
®SDF [125 IU/kg (25 mcg/kg) on days 1 and 2, with subsequent doses ranging from 125 to 275 IU/kg (25 to 55 mcg/kg)]. Response was defined as a platelet increase to at least 50,000/mm
3and a doubling of the baseline. Nineteen of 24 patients responded for an overall response rate of 79%, an overall mean peak platelet count of 229,400/mm
3(range 43,300 to 456,000), and a mean duration of response of 36.5 days (range 6 to 84).
15
Childhood Acute ITP
A multicenter, randomized, controlled trial comparing WinRho
®SDF to high dose and low dose Immune Globulin Intravenous (Human) (IGIV) and prednisone was conducted in 146 non-splenectomized, Rh
o(D)-positive children with acute ITP and platelet counts less than 20,000/mm
3. Of 38 patients receiving WinRho
®SDF [125 IU/kg (25 mcg/kg) on days 1 and 2], 32 patients (84%) responded (platelet count ≥ 50,000/mm
3) with a mean peak platelet count of 319,500/mm
3(range 61,000 to 892,000), with no statistically significant differences compared to other treatment arms. The mean times to achieving ≥ 20,000/mm
3or ≥ 50,000/mm
3platelets for patients receiving WinRho
®SDF were 1.9 and 2.8 days respectively. When comparing the different therapies for time to platelet count ≥ 20,000/mm
3or ≥ 50,000/mm
3, no statistically significant differences among treatment groups were detected, with a range of 1.3 to 1.9 days and 2.0 to 3.2 days, for IGIV and prednisone respectively.
16,17
Adult Chronic ITP
Twenty-four non-splenectomized Rh
o(D)-positive adults with ITP of greater than six-months duration and platelet counts < 30,000/mm
3or requiring therapy were enrolled in a single-arm, open-label trial were treated with 100 to 375 IU/kg (20 to 75 mcg/kg) WinRho
®SDF [mean dose 231 IU/kg (46.2 mcg/kg)]. Twenty-one of 24 patients responded (increase ≥ 20,000/mm
3) during the first two courses of therapy for an overall response rate of 88% with a mean peak platelet count of 92,300/mm
3(range 8,000 to 229,000).
18,19
ITP Secondary to HIV Infection
Eleven children and 52 adults, who were non-splenectomized and Rh
o(D)-positive, with all Walter Reed classes of HIV infection and ITP, with initial platelet counts of ≤ 30,000/mm
3or requiring therapy, were treated with 100 to 375 IU/kg (20 to 75 mcg/kg) WinRho
®SDF in an open label trial. WinRho
®SDF was administered for an average of 7.3 courses (range 1 to 57) over a mean period of 407 days (range 6 to 1,952). Fifty-seven of 63 patients responded (increase ≥ 20,000/mm
3) during the first six courses of therapy for an overall response rate of 90%. The overall mean change in platelet count for six courses was 60,900/mm
3(range -2,000 to 565,000), and the mean peak platelet count was 81,700/mm
3(range 16,000 to 593,000).
18-20