Washington, July 22 (ANI): Researchers including one of Indian origin have used hair and blood samples from three-month old infants born to HIV-positive mothers to measure the uninfected babies' exposure - both in the womb and from breast-feeding - to antiretroviral medications their mothers were taking.
According to researchers from the University of California, San Francisco (UCSF) and Makerere University in Uganda, the results are surprising.
"We found high levels of exposure to three antiretroviral medications in the hair samples of HIV uninfected infants at twelve weeks of life," Monica Gandhi, senior author of the study, said.
"From looking at plasma level data at the same time point, we believe that transfer of two of the medicines from mother to baby occurs exclusively in the womb and transfer of the third medication occurs both in the womb and through breastfeeding," she said.
The findings could lead to new ways to protect infants from HIV transmission and to better understand the development of toxicities and resistance to the drugs, the researchers said.
A single plasma level of a medication reflects drug exposure over approximately 24 hours. Measuring the concentrations of antiretrovirals in a small hair sample reveals exposure over the past month.
The team therefore measured both plasma and hair levels of medications in babies whose mothers were taking HIV medications to get a better idea of when drugs are being passed from mother to baby.
"Since foetuses start growing hair in the womb, hair sampling gives us an opportunity to examine exposures to drug before birth," Gandhi said.
In the study, the team took hair and blood samples from two groups of HIV-positive mothers, all of whom breast-fed their infants. For 45 mother/infant pairs, the mothers' antiretroviral regimens included a protease inhibitor, lopinavir, boosted by ritonavir, another antiretroviral medication.
The other 64 mothers were on an efavirenz-based regimen.
Infants in the lopinavir group had levels of the drug in their hair that measured 87 percent of the levels found in their mothers' hair. The levels of ritonavir were about 45 percent of the levels found in their mothers' hair.
When the researchers looked at the drug levels in the blood drawn from the mothers and infants at 12 weeks, they found the expected levels of lopinavir and ritonavir in the mothers, but none of either in the blood of the infants.
"The inability to find drug in the infants' blood at 12 weeks tells us that the lopinavir and ritonavir in their hair is not due to recent exposure, so breast-feeding did not transfer these drugs to the infants. Our conclusion is that the lopinavir and ritonavir were transferred to the babies in the womb, and lopinavir at quite a high level," Gandhi said.
In the efavirenz group, researchers found infant drug levels in hair samples that were about 40 percent of the levels found in their mothers.
Additionally, they found that infants had levels in their blood that were about 15 percent of what was found in their mothers.
These findings indicate a moderate transfer of efavirenz both in the womb and during breastfeeding said Gandhi.
"Our findings, as we verify them, will have important implications. One, being able to measure drug exposures of foetuses in the womb and during breast-feeding can help us understand how to better protect infants from HIV transmission from HIV-positive mothers during pregnancy, birth and after birth.
"Antiretroviral medications are delivered prophylactically to HIV-positive mothers and newborns to prevent transmission, and fetuses derive protection from transmission if their HIV-positive mothers are on an antiretroviral regimen.
"Second, the development of resistance to antiretroviral medications in infants is an important issue. HIV develops resistant mutations after fairly low levels of exposure to the class of medications to which efavirenz belongs,non-nucleoside transcriptase inhibitors (NNRTIs). Additionally, hair sampling for antiretroviral exposure levels will ultimately help us monitor toxicities associated with these medications in infants," she added.
The findings of the study were presented during the 4th International Workshop on HIV Pediatrics, Washington, D.C. (ANI)
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