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Medical Areas: Gastroenterology | Family Medicine | Infections and Infectious Diseases
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Lotronex (alosetron HCL) Tablets
The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
Approval Status: Approved February 2000
Treatment Area: For non-constipated women with IBS who experience diarrhea as their predominant bowel symptom
Lotronex was approved for treatment of women with Irritable
Bowel Syndrome (IBS) whose predominant bowel symptom is diarrhea
and who are non-constipated. The drug treats multiple symptoms of
the common disorder, including abdominal pain, urgency, stool
frequency, and stool consistency. It was generally well tolerated
in clinical studies. (See below for a list of possible side
The approval for treatment of women addresses the fact that 70%
of IBS sufferers in the U.S. are female. It also reflects clinical
studies that specifically indicate benefits for females.
IBS is one of the most common medical disorders in the U.S.,
affecting approximately 20% of all adults, yet the cause of IBS is
still unknown. The syndrome is manifested by a range of chronic
gastrointestinal symptoms, such as recurrent abdominal pain and
discomfort, and diarrhea and/or constipation.
Although the safety and effectiveness of Lotronex in men has not
yet been determined, research in this area is being conducted.
Earlier clinical trials indicated that alosetron is influenced by
gender, in that alosetron concentrations were 27% lower in males
than in females.
In two placebo-controlled studies, the efficacy of Lotronex at
various doses was investigated in females. In each study 71% of the
patients had diarrhea-predominant IBS, while the majority of the
remaining population had IBS symptoms alternating between diarrhea
and constipation. Only 1% and 2% of the women in studies 1 and 2,
respectively, had constipation-predominant IBS.
Results of both studies showed that 1 mg of Lotronex
administered twice daily was significantly more effective than
placebo in relieving a variety of symptoms of IBS in women. The
drug at that dose relieved abdominal pain and discomfort, decreased
the proportion of days with urgency, decreased stool frequency, and
produced firmer stools.
In study 1, women experienced relief within one week of
commencing the study drug. In study 2, this relief began within
four weeks. In both studies, effects of the drug were maintained
over the course of treatment. Furthermore, in both cases, after
discontinuation of the treatment, there was no significant
difference between women who had taken the drug and women who had
taken the placebo.
Acute ischemic colitis was infrequently reported in patients
Constipation was experienced by 28% of patients taking the drug.
The constipation was mild to moderate, and primarily required only
laxatives, fiber, or brief interruption of therapy in order to
treat the symptom. 10% of patients experiencing constipation as a
side effect could not continue with twice-daily dosing. Women with
constipation-predominant IBS should not take Lotronex.
All other adverse effects were experienced in less than 8% of
the population, with most side effects affecting only 1-3%, always
only 1-2% more than placebo. Some of these effects include:
- Allergic rhinitis
- Throat and tonsil discomfort and pain
- Bacterial ear, nose, and throat infections
- Gastrointestinal discomfort and pain
- Abdominal discomfort and pain
- Gastrointestinal gaseous symptoms.
- Viral gastrointestinal infections
- Dyspeptic symptoms
- Abdominal distention
- Sleep disorders
- Depressive disorders
Mechanism of Action
Alosetron is a potent and selective 5-HT3 receptor antagonist.
5-HT3 receptors are nonselective cation channels that are
extensively distributed on enteric neurons in the human
gastrointestinal tract, as well as other peripheral and central
locations. Activation of these channels and the resulting neuronal
depolarization affect the regulation of visceral pain, colonic
transit, and gastrointestinal secretions, processes that relate to
the pathophysiology of irritable bowel syndrome (IBS). 5-HT3
receptor antagonists such as alosetron inhibit activation of
non-selective cation channels which results in the modulation of
the enteric nervous system…(FDA Label)
Visit Glaxo Wellcome's own IBS information web site,
page is a comprehensive reference guide and interactive site
especially for IBS sufferers.
Also, visit the Glaxo Wellcome, Inc. web site to learn more
about Lotronex and about other products, research, and services
provided by the company that developed this drug.
To interact with others that suffer from the disorder, visit the
IBS Self Help Group web site:
This site also has valuable links about medical research and
developments related to Irritable Bowel Syndrome.