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Catherine White and Michael Bartlett
of the UGA College of Pharmacy are looking at methods of drug delivery that
will effectively control the spread of HIV/AIDS to infants during pregnancy.
Their findings could be of major significance globally and specifically to
the large number of pregnant HIV-positive women in Africa who are in danger
of spreading the disease to their newborn babies.
Drug therapies for pregnant women in the United States often include a four-drug
combination given throughout pregnancy to decrease the viral load in the mother
and inhibit transmission of the virus to the fetus. Additional drugs may be
administered during labor and delivery. Alternatively, in Third World countries,
drug therapy is only begun at the onset of labor due to the expense and limited
availability of the drugs. Since the viral load of the mother cannot be affected
at that time, White and Bartlett are looking at which drugs or combination
of drugs will provide the most protection for the fetus. If some drug compounds
work better, then medical personnel might be able to stretch the drugs to achieve
the greatest effect.
Additionally, White and Bartlett are exploring the mechanisms by which the
drugs are transported through the placenta. By conducting studies in animal
models and in cell culture, they can look at passive and active transport methods.
Rats are being used as test subjects since they have multiple fetuses and transporters
similar to those in humans.
In this study, pregnant rats are injected with drugs and drug combinations
that are normally used to treat HIV patients. Drug concentrations are measured
over an eight-hour period in maternal plasma, the placenta, the fetus and amniotic
fluid. Since much research of this type has already been done on plasma levels,
the UGA scientists are paying more attention to drug measurements in tissues.
Drugs are studied individually first and then in combination. Some of the testing
samples in rats are so small that they only have one chance to measure, said
Bartlett, particularly for amniotic fluid, which might be only one drop.
They hope to determine whether a drug has an affinity for a specific transporter
and whether drugs compete for transporters through cell culture studies. “If
we see an effect in cell culture, then we will need to determine if it also
happens in the animal model,” said Bartlett.
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Pharmacy
professors Catherine White and Michael Bartlett are exploring how drugs are
transported through the placenta so they can find drug therapies that will
help prevent the transmission of HIV/AIDS from mothers to their babies during
pregnancy and childbirth.
