Arena, Eisai Diet Drug Less Concentrated In Human Brain Than Rat
August 02 2011 - 07:29AM
Dow Jones News
Arena Pharmaceuticals Inc. (ARNA) and Eisai Co. (ESALY, 4523.TO)
said that a study of the diet pill lorcaserin showed that the drug
seems to concentrate in the human brain less than it does in
rats.
The data is part of the companies' work to respond to Food and
Drug Administration concerns that led to the pill being rejected
for approval last year. The agency requested multiple sets of new
data including studies related to breast cancer and brain cancer
occurring in rats, and more information on heart-related risk.
The company said that the effort to address other FDA concerns
is ongoing.
Arena conducted the study by measuring lorcaserin concentrations
in human cerebrospinal fluid and then seeing how that compared to
the amount of the drug in blood plasma.
The company used an "apparent consistent relationship" of the
amount of lorcaserin in the brain in relation to the spinal fluid
of mice, rats and monkeys. That ratio was used to predict the
corresponding amount of the drug in the human brain using the
spinal fluid measurements.
Using the new data and previous information, Arena estimates
that human brain exposure to the drug is 1.7 times the plasma
concentration at normal dose. In rats with a much higher dose, but
which didn't have brain cancer, the ratio was 24 times.
Arena noted that its estimates in the study are based on
"certain assumptions and extrapolations" and the FDA may have
different findings when looking at the raw data. The agency also
may not view the company estimates as "reliable or predictive of
the safety margin," Arena said in a statement.
-By Thomas Gryta, Dow Jones Newswires; 212-416-2169;
thomas.gryta@dowjones.com
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