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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Alosetron
Generic Name
Alosetron
Active Ingredient
AlosetronCategory
Other
Salt Form
Hydrochloride
Variants
3
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 1 mg/1 | TABLET | ORAL | 63629-2518 |
| 1 mg/1 | TABLET | ORAL | 70756-701 |
| .5 mg/1 | TABLET | ORAL | 70756-702 |
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Alosetron, you must consult a qualified healthcare professional.
Detailed information about Alosetron
Alosetron is a potent 5-HT3 receptor antagonist specifically indicated for women with severe diarrhea-predominant irritable bowel syndrome (IBS-D) who have failed conventional therapy.
The dosing of alosetron must be carefully managed to balance efficacy with the risk of severe constipation. According to the FDA-approved labeling, the standard starting dose for women with severe IBS-D is 0.5 mg taken twice daily. This low starting dose is intended to minimize the risk of constipation. Patients should remain on this 0.5 mg twice-daily regimen for at least four weeks. If the symptoms are adequately controlled at this dose, the patient should continue with 0.5 mg twice daily. If the symptoms are not adequately controlled after four weeks and the patient has tolerated the medication well without constipation, the healthcare provider may increase the dose to 1 mg twice daily. The maximum recommended dose is 1 mg twice daily. If symptoms are not controlled after 4 weeks of the 1 mg twice-daily dose, the medication should be discontinued, as it is unlikely to provide benefit.
Alosetron is not approved for use in pediatric patients. The safety and effectiveness of alosetron in children and adolescents under the age of 18 have not been established. Due to the risk of serious gastrointestinal complications, its use in this population is generally avoided.
Specific dosage adjustments for patients with renal impairment have not been formally established. Since only 1% of the drug is excreted unchanged in the urine, mild to moderate renal impairment is not expected to significantly alter the clearance of alosetron. However, caution is always advised in patients with end-stage renal disease.
Alosetron is extensively metabolized by the liver. In patients with mild to moderate hepatic impairment (Child-Pugh scores 5-9), the exposure to alosetron can increase significantly. Therefore, extreme caution is required. Alosetron is strictly contraindicated in patients with severe hepatic impairment (Child-Pugh score >9) because of the increased risk of toxicity and the drug's influence on gut motility.
While no specific dose adjustment is required for the elderly based on age alone, clinical data suggest that older patients may be at a higher risk for complications arising from constipation. Healthcare providers typically monitor elderly patients more frequently during treatment.
Alosetron can be taken with or without food. However, consistency is key; if you choose to take it with food, you should do so every time. The tablets should be swallowed whole with a full glass of water. It is generally recommended to take the doses approximately 12 hours apart (e.g., morning and evening). You must read the Medication Guide provided by your pharmacist each time you refill your prescription, as it contains critical safety information regarding the REMS program. Store the tablets at room temperature, away from moisture and heat.
If you miss a dose of alosetron, skip the missed dose and take your next scheduled dose at the regular time. Do not double the dose to catch up. Taking two doses at once significantly increases the risk of developing severe constipation.
There is limited information regarding acute overdose with alosetron. Symptoms of overdose are likely to be an extension of the drug's pharmacological effects, primarily severe constipation and potentially ischemic colitis. If an overdose is suspected, contact a poison control center or seek emergency medical attention immediately. Treatment is generally supportive, focusing on monitoring for bowel obstruction or ischemia.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking the medication without medical guidance, unless you develop constipation or signs of ischemic colitis.
The most frequently reported side effect of alosetron is constipation. Clinical trial data indicate that approximately 25% to 30% of patients taking alosetron will experience constipation. In most cases, this occurs within the first month of treatment and is often mild and transient. However, for some, it can become severe. Other common side effects include:
These effects are reported by a smaller percentage of patients but are still clinically relevant:
Alosetron is a high-alert medication due to its potential for life-threatening gastrointestinal complications. It is strictly indicated only for women with severe IBS-D who have failed other therapies. Patients must be capable of understanding the risks and adhering to the strict monitoring requirements. If you develop constipation at any point, you must stop the medication immediately and contact your doctor. Resuming the medication after constipation has resolved should only be done under strict medical supervision.
According to the FDA-approved label (2024), alosetron has been associated with serious gastrointestinal adverse reactions, some of which have resulted in death. These reactions include ischemic colitis and serious complications of constipation (such as obstruction, ileus, impaction, toxic megacolon, and bowel perforation).
Alosetron must NEVER be used in patients with the following conditions due to the risk of life-threatening complications:
Alosetron is classified as Pregnancy Category B under the older FDA system. This means that animal reproduction studies (in rats and rabbits) have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women. Because animal studies are not always predictive of human response, alosetron should be used during pregnancy only if clearly needed. There is no known data regarding the use of alosetron in fertility treatments. If you become pregnant while taking alosetron, notify your healthcare provider immediately to discuss the risks and benefits of continuing therapy.
It is not known whether alosetron is excreted in human milk. However, because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. If a nursing mother takes alosetron, the infant should be closely monitored for signs of constipation or gastrointestinal distress.
Alosetron is not approved for use in children. The gastrointestinal system of a child is still developing, and the risk of severe complications like ischemic colitis or toxic megacolon is considered too high relative to the potential benefits. Clinical trials have not established a safe or effective dose for any pediatric age group.
Alosetron is a potent and selective antagonist of the 5-hydroxytryptamine (5-HT) type 3 receptor. These receptors are ligand-gated ion channels found extensively on enteric neurons throughout the gastrointestinal tract. In the gut, 5-HT3 receptors play a pivotal role in regulating visceral pain signaling and intestinal motility. By binding to these receptors, alosetron inhibits the activation of these neurons by serotonin. This results in a reduction in the sensation of abdominal pain (visceral afferent inhibition) and a significant slowing of colonic transit time. Unlike other 5-HT3 antagonists used for chemotherapy-induced nausea, alosetron has a higher affinity and slower dissociation rate from the receptor, which may explain its specific efficacy in the lower GI tract.
The pharmacodynamic effect of alosetron is most clearly seen in its effect on colonic transit. In healthy volunteers and patients with IBS-D, alosetron increases the time it takes for material to move through the colon. It also increases the consistency of the stool (making it firmer). There is a clear dose-response relationship, where higher doses lead to greater slowing of the gut. The onset of effect on stool consistency can be seen within 1 to 2 weeks of starting therapy. Tolerance to the effects of alosetron has not been observed in long-term clinical trials.
Common questions about Alosetron
Alosetron is specifically used to treat women with severe diarrhea-predominant irritable bowel syndrome (IBS-D). It is reserved for patients whose symptoms have lasted for at least six months and who have not responded to conventional treatments. The medication helps reduce the frequency of bowel movements, decrease the sense of urgency, and alleviate abdominal pain. Because of its potential for serious side effects, it is not used for mild IBS or for other types of bowel disorders. It is only available through a restricted program because it requires careful medical supervision.
The most common side effect of alosetron is constipation, which affects about one-quarter to one-third of all patients. In most cases, this constipation is mild and manageable, but it can become severe in some individuals. Other common side effects include nausea, abdominal discomfort, and headaches. Patients are instructed to stop the medication immediately if they become constipated. It is vital to monitor your bowel habits daily while taking this drug to ensure safety. If constipation occurs, you must notify your healthcare provider before taking another dose.
There is no direct chemical interaction between alcohol and alosetron that has been documented in clinical studies. However, alcohol is a known gastrointestinal irritant and can trigger or worsen symptoms of IBS-D in many people. Consuming alcohol may make it more difficult for you and your doctor to determine if the medication is working effectively. Furthermore, excessive alcohol use can affect liver function, which is where alosetron is metabolized. It is generally recommended to limit or avoid alcohol to better manage your IBS symptoms.
Alosetron is considered a Category B medication, meaning animal studies have not shown harm to the fetus, but there is limited data in pregnant humans. Because the safety in human pregnancy is not fully established, it should only be used if the potential benefit to the mother significantly outweighs the potential risk to the fetus. If you are pregnant or planning to become pregnant, you must discuss this with your doctor. Most physicians will look for alternative ways to manage IBS symptoms during pregnancy. Breastfeeding is also generally discouraged while taking alosetron as it is unknown if the drug passes into breast milk.
Most patients begin to see an improvement in their IBS-D symptoms within 1 to 2 weeks of starting alosetron. The first sign of improvement is usually a decrease in the frequency of bowel movements and an increase in stool firmness. Abdominal pain and urgency typically begin to improve around the same time. If you do not see any significant improvement after 4 weeks of taking the maximum dose (1 mg twice daily), the medication is unlikely to work for you. In such cases, your doctor will likely discontinue the treatment. It is important to be patient but also to keep a symptom diary during the first month.
Yes, you can stop taking alosetron suddenly without experiencing physical withdrawal symptoms, as it is not an addictive medication. In fact, if you develop constipation or signs of ischemic colitis, you must stop taking it immediately without waiting for a doctor's instruction. However, if the medication was successfully controlling your IBS-D, your symptoms like diarrhea and pain will likely return within a week or two of stopping. Always inform your healthcare provider if you decide to stop the medication for reasons other than side effects. They may want to suggest an alternative management plan.
If you miss a dose of alosetron, you should simply skip that dose and wait until your next regularly scheduled dose. Do not take two doses at once to make up for the one you missed. Doubling the dose significantly increases the risk of developing severe constipation, which is the most dangerous side effect of the drug. Consistency is important for managing IBS, so try to take your medication at the same times each day. Setting a phone alarm or using a pillbox can help you stay on track with your twice-daily schedule.
Weight gain is not a recognized or common side effect of alosetron. Clinical trials did not show a significant difference in weight changes between patients taking alosetron and those taking a placebo. If you experience rapid weight gain while taking this medication, it is more likely related to other factors, such as changes in diet or other medications. Some patients may find they can eat a wider variety of foods once their diarrhea is controlled, which could indirectly affect weight. However, the drug itself does not alter metabolism in a way that promotes fat storage.
Alosetron has several important drug interactions that you must be aware of. It should never be taken with fluvoxamine, an antidepressant, as this can dangerously increase alosetron levels in your blood. You should also be cautious when taking it with other drugs that cause constipation, such as opioid pain relievers or certain antihistamines. Always provide your healthcare provider with a complete list of all prescriptions, over-the-counter drugs, and herbal supplements you are using. Your doctor will check for interactions with the CYP450 enzyme system, which processes alosetron in the liver.
Yes, alosetron is available as a generic medication. The brand name version is Lotronex, but several manufacturers now produce the generic alosetron hydrochloride tablets. Both the brand and the generic versions are subject to the same strict REMS (Risk Evaluation and Mitigation Strategy) program requirements. This means that regardless of whether you receive the brand or the generic, your doctor and pharmacist must be enrolled in the safety program. The generic version is typically more cost-effective for patients while providing the same clinical efficacy and safety profile.
Other drugs with the same active ingredient (Alosetron)
Rare but reported side effects include:
> Warning: Stop taking Alosetron and call your doctor immediately if you experience any of these symptoms. Do not take another dose until you have spoken with your healthcare provider.
Long-term use of alosetron requires ongoing vigilance. There is no evidence that alosetron causes permanent changes to the gut anatomy, but the risk of severe constipation remains as long as the drug is being taken. Patients on long-term therapy should have their bowel habits reviewed regularly by their healthcare provider to ensure the benefit continues to outweigh the risks.
Alosetron carries an FDA Black Box Warning, the most serious type of warning. The warning highlights that alosetron has been associated with serious gastrointestinal adverse events, some resulting in death. These include:
Because of these risks, alosetron is only available through the Lotronex REMS program. Patients must sign a Patient-Physician Agreement before starting the medication, acknowledging they understand these risks.
Report any unusual symptoms to your healthcare provider immediately. Early detection of complications is critical for a positive outcome.
There are no specific laboratory tests (like blood counts or kidney tests) required solely for alosetron monitoring. However, the most important "monitoring" is the patient's self-assessment of bowel habits. Healthcare providers will typically schedule follow-up appointments at 2 weeks and 4 weeks after initiation to evaluate for constipation. In patients with liver disease, periodic liver function tests (LFTs) may be performed to ensure the drug is being metabolized safely.
Alosetron does not typically cause sedation or cognitive impairment. Most patients can safely drive or operate machinery. However, if you experience dizziness or fatigue as a side effect, you should avoid these activities until you know how the medication affects you.
There is no known direct interaction between alcohol and alosetron. However, alcohol can be a significant trigger for IBS symptoms in many patients. Excessive alcohol use may also stress the liver, potentially affecting the metabolism of alosetron. It is generally advised to limit alcohol consumption while managing severe IBS-D.
If alosetron is discontinued because symptoms have not improved after 4 weeks of the 1 mg twice-daily dose, there is no requirement for a tapering schedule. There is no known withdrawal syndrome associated with stopping alosetron. However, if the drug was effective, symptoms of IBS-D (diarrhea and pain) are likely to return within 1 to 2 weeks of stopping the medication.
> Important: Discuss all your medical conditions with your healthcare provider before starting Alosetron. Your full GI history is essential for safety.
Alosetron is not known to interfere with common laboratory tests, including blood chemistry, hematology, or urinalysis. It does not affect the results of stool tests for occult blood, though the drug itself is used in patients where such tests should have already been performed to rule out other pathologies.
When a potential interaction is identified, the management strategy usually involves:
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. Even over-the-counter cold medicines can sometimes contain ingredients that affect gut motility.
These conditions require a careful risk-benefit analysis by a specialist:
There is no documented cross-sensitivity between alosetron and other 5-HT3 antagonists (like ondansetron). However, if a patient has had a severe allergic reaction to any component of the Lotronex tablet, they should not take the medication.
> Important: Your healthcare provider will evaluate your complete medical history before prescribing Alosetron. Be honest about your history of constipation or any "mini-strokes" of the bowel you may have experienced.
In clinical trials, approximately 8% of patients were 65 years of age or older. While the efficacy of alosetron in the elderly appears similar to that in younger patients, the risk of serious complications from constipation is significantly higher. Elderly patients often have decreased intestinal motility and may be taking other medications that contribute to constipation. Healthcare providers are advised to use extreme caution when prescribing alosetron to patients over 65 and to monitor them more frequently for any changes in bowel habits.
No formal studies have been conducted in patients with renal impairment. However, given that renal clearance of the unchanged drug is a minor pathway (1%), it is unlikely that renal impairment will significantly affect the pharmacokinetics of alosetron. No dose adjustment is typically recommended for mild to moderate renal disease, but data for patients on dialysis are unavailable.
As the liver is the primary site of alosetron metabolism, hepatic function is a critical factor in its safety. In patients with mild to moderate hepatic impairment, the area under the curve (AUC) of alosetron can increase by up to 60%. This increases the risk of side effects. For patients with severe hepatic impairment (Child-Pugh score >9), the drug is strictly contraindicated as it has not been studied and the risk of toxicity is unacceptably high.
> Important: Special populations require individualized medical assessment. Always inform your doctor if you are planning a pregnancy or have underlying liver issues.
| Parameter | Value |
|---|---|
| Bioavailability | 50% - 60% |
| Protein Binding | 82% |
| Half-life | 1.5 hours |
| Tmax | 1 hour |
| Metabolism | CYP2C9, 3A4, 1A2 |
| Excretion | Renal 74%, Fecal 26% |
Alosetron is classified as a 5-HT3 receptor antagonist. While it shares a class with anti-emetics like ondansetron, dolasetron, and palonosetron, its unique pharmacokinetic profile and tissue distribution make it the only member of this class currently indicated specifically for the treatment of IBS-D. It is often grouped under the broader category of "GI Motility Modifiers" or "Visceral Analgesics."