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Timothy Tracy
Pharmacy |
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New Grant
Timothy Tracy recently received a $982,425 grant to
study how the body processes drugs-findings that could
decrease dangerous drug interactions. He hopes to develop
a set of rules that will predict how certain drugs will
behave in the body. Ultimately, these rules will reduce
or eliminate the need to pull drugs from the market
because of unforeseen drug interactions. The discoveries
could also increase the number of new drugs brought
to market because manufacturers will better understand
drug interactions. Ultimately, this knowledge will save
lives.
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When a physician writes
a prescription for a patient, the dose is often based on studies
that until recent years have been conducted exclusively on healthy
men. This could pose a problem for women, whose bodies process medications
differently than men's. Pregnant women are of even greater concern,
as their bodies metabolize different drugs at different rates during
each trimester. As healthy women are now included in dosing studies,
researchers at the University of Minnesota are looking at the unique
needs of pregnant women.
Timothy Tracy, a professor in the Department of Experimental and
Clinical Pharmacology, has published findings that will help pregnant
women receive the right dose of medication to manage chronic conditions
such as diabetes, depression, or HIV during each stage of pregnancy.
Tracy notes that a pregnant woman's ability to metabolize medications
depends on the stage of pregnancy and the medication taken-dosages
can't be determined by a one-size-fits-all approach. "The dose
a woman needs in pregnancy may need to be changed throughout her
pregnancy," he says.
Researchers knew pregnant women needed to have their medications
adjusted, but they didn't know by how much and whether to increase
or decrease dosages. Tracy's findings show that dosage adjustments
depend on the stage of pregnancy and the medication."You can't
treat all medications the same," Tracy says.
"You can't say 'She's pregnant so we automatically have to
increase or decrease the medication.'"
In the study, pregnant women were given two drugs known to be safe
during pregnancy-caffeine and dextromethorphan, a cough suppressant
that is available without a prescription. These are considered "marker
drugs" since they are broken down by specific enzymes in the
body. Pregnant women were given the drugs three times: Between the
14th and 18th weeks, between the 24th and 28th weeks, and between
the 36th and 40th weeks of pregnancy. They were also given the drugs
between six and eight weeks after giving birth.
Three enzymes in the body metabolize about 80 percent of medications-including
caffeine and dextromethorphan. Tracy studied the concentration of
these drugs after they were ingested to determine whether metabolism
of medication increased or decreased throughout pregnancy.
Tracy found pregnant women's metabolism of some medications increases
or decreases only once during pregnancy, while metabolism of other
medications continues to increase or decrease as pregnancy progresses.
The change depends on which enzyme the body uses to metabolize the
drug. Researchers can now correlate the findings to the 80 percent
of medications metabolized by these enzymes. That means more accurate
and safer dosing guidelines for medications women need to manage
their chronic conditions as their bodies change during pregnancy.
The findings from Tracy's research were published in the February
issue of the American Journal of Obstetrics and Gynecology.
Asking the right questions, giving
complete answers
In another study, Tracy looked at the disparity between information
pregnant women give their physicians about medication use and what
drugs they actually take. According to the study, what information
women perceive as important to tell their obstetrician and what
the physician deems important are often two different things. Throughout
the study, researchers interviewed 700 pregnant women using a three-tiered
process. "We asked what prescription medications are you taking
and why, what over-the-counter medications and why, and what herbal
medications are you taking and why," says Tracy. Then they
asked what medications the patient would take for a headache and
other common conditions. The interviewer finished by listing additional
medications to jog the patient's memory. At each stage of the questioning,
most patients remembered additional medications that they take regularly.
The study's findings show that both patients and physicians need
to be aware of the importance of sharing and obtaining accurate
information, especially in assessing drug interactions. "We
need to make it such that we can make the best decisions for your
health," says Tracy.
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