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Randomized, Controlled, Double-Blind Multicenter Comparison
of the Efficacy and Tolerability of Ziprasidone and Olanzapine
in Acutely Ill Inpatients With Schizophrenia or Schizoaffective
Disorder
George M. Simpson, M.D., Ira D. Glick, M.D., Peter J. Weiden,
M.D., Steven J. Romano, M.D., and Cynthia O. Siu, Ph.D.
Am J Psychiatry 161:1837-1847, October 2004
This is a study that compares both the effectiveness and
side effects of two second generation antipsychotics: Olanzapine
(Zyprexa, by Eli Lilly) and Ziprasidone (Geodon, by Pfizer).
The authors state that there have not been very many direct
comparisons between the newer drugs but that each drug seems
to have various side effects labeled on them.
The study was set up very well to help eliminate confounding
variables (things that can alter a study other than what
one is looking for.) It is a double-blind (neither the patient
or the people working on the study know what drug the patient
is on), randomized (anyone is equally likely to get one
drug or the other), and it takes place throughout the US
to help eliminate regional differences. The authors used
a number of common rating scales to asses for changes in
symptoms both positive symptoms and negative symptoms. They
also looked at weight gain (body mass index), insulin levels
(to see of increased risk of diabetes) and cholesterol levels.
However, the authors only looked at 6 weeks worth of data
so long-term implications of these data are hard to decipher
and can only at best be inferred.
The results showed that both groups were the same with
respect to the number of patients who dropped out of the
study because the drug did not work. However, ultimately,
a statistically significant number of patients dropped out
from the ziprasidone group vs the olanzapine group, however
the reasons are not made clear (lost to followup or withdrawn
consent perhaps.) This may or may not be clinically meaningful.
Having patients withdraw early from a study potentially
can distort results and lead to statistical confusion and
less accurate results depending on how the lost patients
are tabulated.
The main results of the study showed that both drugs had
approximately equal efficacy on treating the core symptoms
of schizophrenia. Where thedifferences were seen was primarily
in side effects. This is where the withdrawal of patients
makes things difficult as well as the short duration of
the study. The side effects looked at were weight gain,
cholesterol changes and diabetes parameters. Many of these
things take time to develop and while a change in six weeks
is suggestive of future problem it does not necessarily
speak to the long term significance. However, this study
showed that olanzapine had a more serious side effect profile
than ziprasidone which is something that many people have
noted over recent years. They also showed that cardiac conduction
defects often attributed to ziprasidone were not clinically
seen here.
Overall, does this mean that olanzapine is a bad medication
compared to ziprasidone? Well, this is one case where it
is definitely helpful to see who sponsored this study: Pfizer,
who makes ziprasidone (geodon) in the US. Ziprasidone has
had a lower market share since coming onto the market several
years ago. While there may be many reasons for this, perhaps
this study was done to help bolster ziprasidone's position
in the marketplace. Regardless of intention, data is data
(statistical manipulation aside) and this is important information.
However, it cannot be denied that olanzapine does have
severe metabolic side effects that should be considered
when one starts on an antipsychotic. If someone you know
is already on one of these or another, this study is not
enough to warrant a change, especially if the medication
is working. However, it does point out again the importance
of maintaining a close eye on the overall health of someone
with schizophrenia and not settling for merely the reduction
of symptoms to be enough when one is taking care of such
a patient.
This study was supported by Pfizer Inc. (maker of Geodon
which is the tradename for ziprasidone).
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