WRITER: Amy Couteé
CONTACT: DAVE PEDERSEN
283 Medical Laboratories
Iowa City IA 52242
(319) 335-8032; fax (319) 335-8034
Study provides doctors with method to determine most effective drug
IOWA CITY, Iowa -- While most people believe that more is better, a
University of Iowa psychiatrist offers proof that it is not always true.
Taking more of a medication that didn't work the first time is often
common practice, both among physicians and self-medicators. However, a
study by Dr. William Coryell, UI professor of psychiatry, may lead psychiatrists
to reconsider how they prescribe drugs for schizophrenia and other mental
The study, published in the January 1998 issue of the American Journal
of Psychiatry, revealed that increasing a commonly used medication for
patients with schizophrenia when the initial dosage is ineffective may
not be the best way to go.
Coryell studied the effects that different doses of haloperidol, an
antipsychotic medication marketed as Haldol, had on schizophrenic patients.
He found that a patient's plasma level may enable doctors to determine
if an increased or decreased dose would be more effective in easing symptoms.
According to Coryell, the study findings can help guide doctors toward
getting better results when prescribing drugs. It provides a way of determining
the best dose for each patient.
By looking at the various plasma levels of 66 schizophrenic patients
and comparing the drug's effectiveness on each patient, Coryell determined
that haloperidol could be more effective for certain patients when administered
in smaller doses rather than a larger one.
Haloperidol is one of the most commonly prescribed conventional drugs
for schizophrenia and works to relieve the "positive" symptoms
of the disease, such as hallucinations and delusions. Newer, atypical antipsychotic
drugs have been developed to improve schizophrenia's "negative"
symptoms, which include blunted affect, lack of drive and lack of sociability.
Typically, when the first prescription dose of haloperidol does not
improve a schizophrenic patient's condition, doctors respond by increasing
the dosage. If the higher dose does not produce better results, the doctor
has to look for an alternative treatment. The key, according to Coryell,
is to make the drug more effective the first time by finding out specifically
what dosage will be most beneficial while causing the fewest side effects.
"The idea is that if you exceed a certain blood plasma level it
may increase the side effects of the drug but not the benefits," Coryell
The side effects of haloperidol and other antipsychotics are drowsiness
and movement disorders, usually stiffness and tremors, and a lack of facial
To test the theory that plasma levels can determine an optimal dose,
Coryell gave the 66 patients fixed doses of haloperidol and watched for
decreases in symptoms. A simple blood test was done to determine each patient's
plasma levels. The patients with higher plasma levels showed less improvement
after taking the haloperidol. These patients who experienced less improvement
were randomly reassigned to one of two groups. One was given a higher dose,
the other a lower dose of the drug. Those whose dosages were lowered experienced
significantly more improvement than those whose dosages were increased.
"The high plasma levels may be interfering with the benefits of
the drug," Coryell says.
If the plasma levels of patients seeking drug therapy is determined,
doctors have a better chance of prescribing the best dose the first time.
This could save patients time and money, and more importantly, deliver