Atazanavir use during pregnancy

1 April 2011. Related: Antiretrovirals, Pregnancy.

On 4 February 2011, FDA approved new labeling for atazanavir (Reyataz) to include dosing recommendations for treatment of HIV-1 infection during pregnancy and postpartum period.

The major revisions to the package insert are summarised below. Other, minor changes to the package insert and patient package insert were made for consistency.

Dosing during pregnancy and the postpartum period

Reyataz should not be administered without ritonavir
Reyataz should only be administered to pregnant women with HIV-1 strains susceptible to atazanavir
For pregnant patients, no dose adjustment is required for Reyataz with the following exceptions:

For treatment-experienced pregnant women during the second or third trimester, when Reyataz is coadministered with either an H2-receptor antagonist or tenofovir, Reyataz 400 mg with ritonavir 100 mg once daily is recommended. There are insufficient data to recommend a Reyataz dose for use with both an H2-receptor antagonist and tenofovir in treatment-experienced pregnant women.

No dose adjustment is required for postpartum patients. However, patients should be closely monitored for adverse events because atazanavir exposures could be higher during the first 2 months after delivery [See Use in Specific Populations (8.1) and Clinical Pharmacology (12.3).]

Risk summary

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.

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.

Clinical pharmacology in pregnancy

The pharmacokinetic data from HIV-infected pregnant women receiving atazanavir/ritonavir were included in Table 17 of the package insert.

Below is a summary of the data contained in the table. 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 2843% higher during the postpartum period (412 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.

Please refer to the full label for details.

http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm

Source: FDA listserve (04 Feb 2011).

Reference:

Reyataz (atazanavir) label revised, adding dosing recommendations for pregnancy and postpartum period.
http://www.fda.gov/ForConsumers/ByAudience/ForPatientAdvocates/HIVandAIDSActivities/ucm242383.htm