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2011 Mar 3 - The use of potent anti-HIV therapy (commonly called ART or HAART) has greatly extended
the survival of HIV-positive people by helping to lower production of HIV and allowing the immune system to partially repair itself. ART has
additional benefits: for instance, HIV-positive women who take ART during pregnancy can significantly reduce the amount of HIV in their
blood (viral load) and, therefore, the risk of transmitting HIV to the fetus. These additional steps also help reduce the risk of
transmitting HIV to the infant:
- intravenous AZT (Retrovir, zidovudine) during delivery
- delivery of the baby via cesarian section
- oral AZT for the baby for the first six weeks of life
- use of baby formula rather than breastfeeding (as breast milk can transmit HIV)
In high-income countries today, among women who take ART exactly as directed and whose viral load is
suppressed, who also receive prenatal counselling and care and take the steps outlined above the chance of transmitting HIV to the
fetus can be reduced to less than two percent.
Enter atazanavir
Leading American HIV treatment guidelines, produced by the Department of Health and Human Services
suggest that the preferred regimen for pregnant HIV-positive women is:
lopinavir-ritonavir (Kaletra) + AZT (Retrovir, zidovudine) + 3TC (lamivudine).
This combination of drugs has been taken by many people living with HIV and its safety during pregnancy
for the mother as well as the fetus is well established. Treatment-experienced women who develop drug resistance may need to use other
anti-HIV drugs. One potential alternative to Kaletra that is being tested in pregnant HIV-positive women is the combination of
atazanavir (reyataz) and ritonavir (Norvir).
The U.S. Food and Drug Administration (FDA) has recently changed the prescribing information for the use
of atazanavir in HIV-positive treatment-experienced women who are pregnant. Below are key points from the FDA's update.
Dosing during pregnancy and postpartum:
- Atazanavir should only be taken with ritonavir.
- Atazanavir should only be taken by pregnant women whose strain of HIV-1 is susceptible to atazanavir.
Acid-reducing agents, such as cimetidine (Tagamet) and ranitidine (Zantac), belong to a class of drugs called
histamine 2 -receptor antagonists (H 2 -receptor antagonists). For pregnant HIV-positive women who use
H 2 -receptor antagonists with atazanavir or the anti-HIV drug tenofovir (Viread, also in Truvada and Atripla), the FDA recommends the following dose:
- atazanavir 400 mg and ritonavir (Norvir) 100 mg once daily.
The FDA does not have sufficient information to make a dose and schedule recommendation for the use of antazanavir-ritonavir when both an H 2 -receptor
antagonist and tenofovir are also used in pregnancy by treatment-experienced women.
The FDA notes that no dose adjustment is required during the first two months after the baby is delivered. However, the agency does state that
women "should be closely monitored for adverse events because [the concentration of atazanavir] could be higher during the first two months after delivery."
Risk summary
The FDA states that atazanavir has been "evaluated in a limited number of women during pregnancy and postpartum. Available human data suggest that atazanavir
does not increase the risk of major birth defects overall compared to the background rate. Nevertheless, because studies in humans cannot rule out the possibility of harm, atazanavir should be used during pregnancy only if clearly needed."
The FDA will eventually post this and other updates about the use of atazanavir in pregnant HIV-positive women at this location:
www.accessdata.fda.gov/scripts/cder/drugsatfda/
In Canada
Bristol-Myers Squibb, the manufacturer of atazanavir, has submitted similar changes for the prescribing information of this drug to Health Canada for approval.
-Sean R. Hosein
REFERENCES:
- Klein R and Struble K. HIV/AIDS Update - Reyataz (atazanavir) label revised, adding dosing recommendations for pregnancy and postpartum period. HIV/AIDS Update . U.S. Food & Drug Administration. 4 February, 2011.
- Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents . Department of Health and Human Services. January 10, 2011; 1-166.
Available at www.aidsinfo.nih.gov/ContentFiles/AdultandAdolescentGL.pdf. Accessed 7 February, 2011.
- von Linstow ML, Rosenfeldt V, Lebech AM, et al. Prevention of mother-to-child transmission of HIV in Denmark, 1994-2008. HIV Medicine . 2010 Aug;11(7):448-56. Epub 2010 Feb 8.
- Townsend CL, Cortina-Borja M, Peckham CS, et al. Low rates of mother-to-child transmission of HIV following effective pregnancy interventions in the United Kingdom and Ireland, 2000-2006. AIDS . 2008 May 11;22(8):973-81.
From Canadian AIDS Treatment Information Exchange (CATIE). For more information visit CATIE's Information Network at http://www.catie.ca
Source: CATIE: CANADIAN AIDS TREATMENT INFORMATION EXCHANGE
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