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No significant new drugs have been approved for Irritable
Bowel Syndrome (IBS) for at least a decade. Current medications
tend to address only certain aspects of the syndrome, and
some of them are associated with unpleasant side effects.
Several companies are therefore developing more effective
and safer drugs to control both the motility disturbances
and pain in IBS.
New
Drugs near to Launch
IBS
sufferers can be divided into three types:
- Diarrhea
Predominant
- Constipation
Predominant
- Mixed
Glaxo
Wellcome’s Lotronex, a 5HT3 antagonist, was recommended
for approval by an FDA panel in November 1999 for use in
women with IBS for whom diarrhea is a predominant symptom.A
regulatory submission is expected in Europe in 2000.
Novartis’
Zelmac, a partial agonist of 5HT4 receptors, is in phase
III trials for constipation-dominant IBS and is expected
to be filed in both the USA and Europe by the end of 1999.
Zelmac could be approved and launched by Q3 2000, around
6-9 months after Lotronex.
Though
they have slightly different modes
of action, both Zelmac and Lotronex have been shown
to be extremely effective in controlling the predominating
symptoms of IBS - recurrent abdominal pain and disrupted
colonic motility.
Positioning
of Drugs in the Market
Dr
James Niedel, director of science & technology at Glaxo
Wellcome, told IMS Health that he viewed Zelmac as being
complementary to Lotronex, since Lotronex will be targeted
at diarrhea-predominant IBS and Zelmac at constipation-predominant
IBS.
Regarding
piboserod from SmithKline Beecham, currently in phase II
trials, Dr Niedel said that, if proven to work, piboserod
would be a direct competitor to Lotronex (SB claims that
it could be effective in all types of IBS). Brokers at Lehman
Brothers are anticipating peak sales of $950 million for
Lotronex in 2008 and peak sales of $750 million for Zelmac
Drugs
Predilection for Women
One
of the peculiarities of Lotronex is that it works only in
women. When questioned about the nature of this by IMS Health,
Dr Niedel stated, "We assume that physiology is universal.
However, we have no doubt that Lotronex works dramatically
in women and not in men." As to why this difference
exists, Dr Niedel suggested that it could be neurogenic.
Zelmac, on the other hand, appears to be equally effective
in both men and women (although 80% of the patients studied
have been female).
See
R&D Focus
for profiles of IBS and other pipeline drugs.
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