February 4, 2011
On February 4, 2011, FDA approved new labeling for Reyataz (atazanavir) to include dosing recommendations for treatment of HIV-1 infection during pregnancy and postpartum period. The major revisions to the package insert are summarized below. Other, minor changes to the package insert and patient package insert were made for consistency.
Summary of Revisions:
DOSAGE AND ADMINISTRATION
Dosing During Pregnancy and the Postpartum Period:
Atazanavir has been evaluated in a limited number of women during pregnancy and postpartum. Available human and animal data suggest that atazanavir does not increase the risk of major birth defects overall compared to the background rate. Nevertheless, because the studies in humans cannot rule out the possibility of harm, Reyataz should be used during pregnancy only if clearly needed.
Cases of lactic acidosis syndrome sometimes fatal and symptomatic hyperlactatemia have occurred in pregnant women using Reytaz in combination with nucleoside analogues. Nucleoside analogues are associated with an increased risk of lactic acidosis syndrome.
Hyperbilirubinemia occurs frequently in patients who take Reyataz, including pregnant women. All infants, including neonates exposed to Reyataz in-utero, should be monitored for the development of severe hyperbilirubinemia during the first few days of life.
Dosing During Pregnancy and the Postpartum Period:
Clinical Trials: In clinical trial AI424-182, REYATAZ/ritonavir (300/100 mg or 400/100 mg) in combination with zidovudine/lamivudine was administered to 41 HIV-infected pregnant women during the second or third trimester. Among the 39 women who completed the study, 38 women achieved an HIV RNA <50 copies/mL at time of delivery. Six of 20 (30%) women on REYATAZ/ritonavir 300/100 mg and 13 of 21 (62%) women on REYATAZ/ritonavir 400/100 mg experienced hyperbilirubinemia (total bilirubin greater than or equal to 2.6 times the upper limit of normal). There were no cases of lactic acidosis observed in clinical trial AI424-182.
Atazanavir drug concentrations in fetal umbilical cord blood were approximately 12-19% of maternal concentrations. Among the 40 infants born to 40 HIV-infected pregnant women, all had test results that were negative for HIV-1 DNA at the time of delivery and/or during the first 6 months postpartum. All 40 infants received antiretroviral prophylactic treatment containing zidovudine. No evidence of severe hyperbilirubinemia (total bilirubin levels greater than 20 mg/dL) or acute or chronic bilirubin encephalopathy was observed among neonates in this study. However, 10/36 (28%) infants (6 greater than or equal to 38 weeks gestation and 4 less than 38 weeks gestation) had bilirubin levels of 4 mg/dL or greater within the first day of life.
Lack of ethnic diversity was a study limitation. In the study population, 33/40 (83%) infants were Black/African American, who have a lower incidence of neonatal hyperbilirubinemia than Caucasians and Asians. In addition, women with Rh incompatibility were excluded, as well as women who had a previous infant who developed hemolytic disease and/or had neonatal pathologic jaundice (requiring phototherapy).
Additionally, of the 38 infants who had glucose samples collected in the first day of life, 3 had adequately collected serum glucose samples with values of <40 mg/dL that could not be attributed to maternal glucose intolerance, difficult delivery, or sepsis.
Antiretroviral Pregnancy Registry Data: As of January 2010, the Antiretroviral Pregnancy Registry (APR) has received prospective reports of 635 exposures to atazanavir-containing regimens (425 exposed in the first trimester and 160 and 50 exposed in second and third trimester, respectively). Birth defects occurred in 9 of 393 (2.3%) live births (first trimester exposure) and 5 of 212 (2.4%) live births (second/third trimester exposure). Among pregnant women in the U.S. reference population, the background rate of birth defects is 2.7%. There was no association between atazanavir and overall birth defects observed in the APR.
12.3 Clinical Pharmacology
The pharmacokinetic data from HIV-infected pregnant women receiving REYATAZ Capsules with ritonavir were included in Table 17 of the package insert.
Below is a summary of the data contained in the table. Of note, limited data were available during 2nd trimester (n=5); whereas during the 3rd trimester and postpartum period 20 and 34 subjects, respectively were available.
In the 2nd trimester the Cmax, AUC and Cmin values were 3078.85 ng/mL, 27657.1 ng·h/mL and 538.70 ng/mL, respectively.
In the 3rd trimester the Cmax, AUC and Cmin values were 3281.46 ng/mL 34251.5 ng·h/mL and 668.48 ng/mL), respectively.
During Postpartum the Cmax, AUC and Cmin values were 5721.21 ng/mL, 61990.4 ng·h/mL and 1462.59 ng/mL, respectively.
Atazanvir peak concentrations and AUCs were found to be approximately 28-43% higher during the postpartum period (4-12 weeks) than those observed historically in HIV-infected, non-pregnant patients. Atazanavir plasma trough concentrations were approximately 2.2-fold higher during the postpartum period when compared to those observed historically in HIV-infected, non-pregnant patients.
The complete revised label will be posted soon at Drugs@FDA.