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Lotronex: Full Drug Profile

Medically reviewed by Min Clinic Staff | Updated: January 2026

Lotronex - General Information

Lotronex is a 5-HT3 antagonist used for the management of severe diarrhoea-predominant irritable bowel syndrome (IBS) in women only. Lotronex has an antagonist action on the 5-HT3 receptors of the enteric nervous system of the gastrointestinal tract.

 

Pharmacology of Lotronex

Lotronex is a potent and selective antagonist of the serotonin 5-HT3 receptor type. Activation of these receptors affects the regulation of visceral pain, colonic transit, and GI secretions. By blocking these receptors, alosetron is able to effectively control IBS.

 

Lotronex for patients

Patients should be fully counseled on and understand the risks and benefits of LOTRONEX before an initial prescription is written. The patient may be educated by the enrolled physician or a healthcare provider under a physicianís direction.

PHYSICIANS MUST:

  • Counsel patients for whom LOTRONEX is appropriate about the benefits and risks of LOTRONEX and discuss the impact of IBS symptoms on the patientís life.
  • Give the patient a copy of the Medication Guide, which outlines the benefits and risks of LOTRONEX, and instruct the patient to read it carefully. Answer all questions the patient may have about LOTRONEX. The complete text of the Medication Guide is printed at the end of this document.
  • Review the Patient-Physician Agreement for LOTRONEX with the patient, answer all questions, and give a copy of the signed agreement to the patient
  • .
  • Provide each patient with appropriate instructions for taking LOTRONEX.

Copies of the Patient-Physician Agreement for LOTRONEX and additional copies of the Medication Guide are available by contacting GlaxoSmithKline at 1-888-825-5249 or visiting www. lotronex.com.

PATIENTS WHO ARE PRESCRIBED LOTRONEX SHOULD BE INSTRUCTED TO:

  • Read the Medication Guide before starting LOTRONEX and each time they refill their prescription.
  • Not start taking LOTRONEX if they are constipated.
  • Immediately discontinue LOTRONEX and contact their physician if they become constipated, or have symptoms of ischemic colitis such as new or worsening abdominal pain, bloody diarrhea, or blood in the stool. Contact their physician again if their constipation does not resolve after discontinuation of LOTRONEX. Resume LOTRONEX only if their constipation has resolved and after discussion with and the agreement of their treating hysician.
  • Stop taking LOTRONEX and contact their physician if LOTRONEX does not adequately control IBS symptoms after 4 weeks of taking 1 mg twice a day.

MEDICATION GUIDE

LOTRONEX® (LOW-trah-nex) Tablets
(alosetron hydrochloride)

Before using LOTRONEX for the first time, you should:
  • Understand that LOTRONEX has serious risks for some people.
  • Read and follow the directions in this Medication Guide.
  • Sign a Patient-Physician Agreement with your doctor.

Read this Medication Guide carefully before you sign the Patient-Physician Agreement. You must sign the Patient-Physician Agreement before you start LOTRONEX. Read the Medication Guide you get with each refill for LOTRONEX. There may be new information. This Medication Guide does not take the place of talking with your doctor.

1. What is the most important information I should know about LOTRONEX?

LOTRONEX is a medicine only for some women with severe chronic IBS whose:

  • main problem is diarrhea and
  • IBS symptoms have not been helped enough by other treatments.

A. Some patients have developed serious bowel side effects while taking LOTRONEX. Serious bowel (intestine) side effects can happen suddenly, including the following two:

  1. Serious complications of constipation: About 1 out of every 1,000 women who take LOTRONEX may get serious complications of constipation. These complications may lead to a hospital stay, and in rare cases, blood transfusions, surgery, and death. People who are older, who are weak from illness, or who take other constipating medicines may be more likely to have serious constipation problems with LOTRONEX.

  2. To lower your chances of getting serious complications of constipation do the following:

    • If you are constipated, do not start taking LOTRONEX.
    • If you get constipated while taking LOTRONEX, stop taking it right away and call your doctor.
    • If your constipation does not get better after stopping LOTRONEX, call your doctor again.
    • If you stopped taking LOTRONEX, do not start taking LOTRONEX again unless your doctor tells you to do so.
  3. Ischemic colitis (reduced blood flow to the bowel): About 3 out of every 1,000 women who take LOTRONEX over a 6-month period may get a serious problem where blood flow to parts of the large bowel is reduced. This is called ischemic colitis. The chance of getting ischemic colitis when you take LOTRONEX for more than 6 months is not known. Ischemic colitis may lead to a hospital stay, and in rare cases, blood transfusions, surgery, and death.

  4. To lower your chances of getting serious complications of ischemic colitis, stop taking LOTRONEX and call your doctor right away if you get:

    • new or worse pain in your stomach area (abdomen) or
    • blood in your bowel movements.

B. Is LOTRONEX right for you?

LOTRONEX may be right for you if all of these things are true about you:

  • Your doctor has told you that your symptoms are due to IBS.
  • Your IBS bowel problem is diarrhea.
  • Your IBS has lasted for 6 months or longer.
  • You tried other IBS treatments and they didnít give you the relief you need.
  • Your IBS is severe.

You can tell if your IBS is severe if at least 1 of the following is true for you:

  • You have lots of painful stomach cramps or bloating.
  • You often canít control the need to have a bowel movement, or you have ìaccidentsî where your underwear gets dirty from diarrhea or bowel movements.
  • You can't lead a normal home or work life because you need to be near a bathroom.

Enough testing has not been done to confirm LOTRONEX works in men or children under age 18.

C. There is a special prescribing program for LOTRONEX.

Only doctors who have signed up with the company that makes LOTRONEX should write prescriptions for LOTRONEX. As part of signing up, these doctors have said that they understand about IBS and the possible side effects of LOTRONEX. They have agreed to use a special sticker on all prescriptions for LOTRONEX, so the pharmacist will know that the doctors have signed up with the company.

You may be taught about LOTRONEX by your doctor or healthcare provider under a doctorís direction. Your doctor will ask you to sign a Patient-Physician Agreement after you read this Medication Guide for the first time. Signing the Agreement means that you understand the benefits and risks of LOTRONEX and that you have read and understand this Medication Guide.

2. What is LOTRONEX?

LOTRONEX is a medicine only for some women with severe chronic IBS whose:

  • main problem is diarrhea and
  • IBS symptoms have not been helped enough by other treatments.

LOTRONEX does not cure IBS, and it may not help every person who takes it. For those who are helped, LOTRONEX reduces lower stomach area (abdominal) pain and discomfort, the sudden need to have a bowel movement (bowel urgency), and diarrhea from IBS. If you stop taking LOTRONEX, your IBS symptoms may return within 1 or 2 weeks.

3. Who should not take LOTRONEX?

LOTRONEX is not right for everyone. Do not take LOTRONEX if any of the following apply to you:

  • Your main IBS problem is constipation or you are constipated most of the time.
  • You have had a serious problem from constipation.
  • You have had serious bowel blockages.
  • You have had blood flow problems to your bowels, such as ischemic colitis.
  • You have had blood clots.
  • You have had Crohnís disease, ulcerative colitis, or diverticulitis.
  • You do not understand this Medication Guide or the Patient-Physician Agreement, or you are not willing to follow them.
  • You are allergic to LOTRONEX or any of its ingredients.
  • You are taking fluvoxamine (LUVOX)

If you are constipated now, do not start taking LOTRONEX.

4. What should I talk about with my doctor before taking LOTRONEX?

Talk with your doctor:

  • about the possible benefits and risks of LOTRONEX.
  • about how much of a problem IBS is in your life and what treatments you have tried.
  • about any other illnesses you have and medicines you take or plan to take. These include prescription and non-prescription medicines, supplements, and herbal remedies. Certain illnesses and medicines can increase your chance of getting serious side effects while taking LOTRONEX. Other medicines may interact with how the body handles LOTRONEX.
  • if you are pregnant, planning to get pregnant, or breastfeeding.

5. How should I take LOTRONEX?

  • Take LOTRONEX exactly as your doctor prescribes it. You can take LOTRONEX with or without food.
  • Begin with 0.5 mg two times a day for 4 weeks to see how LOTRONEX affects you. You and your doctor may
  • Check with your doctor 4 weeks after starting LOTRONEX:


    • If you try 0.5 mg two times a day for 4 weeks, it may not control your symptoms. If you do not get constipation or other side effects from LOTRONEX, your doctor may increase your dose up to 1 mg two times a day.
    • If 1 mg two times a day does not work after 4 weeks, LOTRONEX is not likely to help you. You should stop taking it and call your doctor.
  • If you miss a dose of LOTRONEX, just skip that dose. Do not take 2 doses the next time. Wait until the next time you are supposed to take it and then take your normal dose.
  • Follow the important instructions in the section ìWhat is the most important information I should know about LOTRONEX?î about when you must stop taking the drug and when you should call your doctor.
  • If you see other doctors about your IBS or side effects from LOTRONEX, let the doctor who prescribed LOTRONEX know.

6. What are the possible side effects of LOTRONEX?

Constipation is the most common side effect among women with IBS who take LOTRONEX. Some patients have developed serious bowel side effects while taking LOTRONEX. Read the section ìWhat is the most important information I should know about LOTRONEX?î at the beginning of this Medication Guide for information about the serious side effects you may get with LOTRONEX.

This Medication Guide does not tell you about all the possible side effects of LOTRONEX. Your doctor or pharmacist can give you a more complete list.

7. General information about the safe and effective use of LOTRONEX

Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. If you have any questions or concerns about LOTRONEX, ask your doctor. Do not use LOTRONEX for a condition for which it was not prescribed. Do not share your medicine with other people. It may harm them.

Your doctor or pharmacist can give you more information about LOTRONEX that was written for healthcare professionals. You can also contact the company that makes LOTRONEX (toll free) at 1-888-825-5249 or at www.lotronex.com.

8. What are the ingredients of LOTRONEX?

Active Ingredient: alosetron hydrochloride

Inactive Ingredients: lactose (anhydrous), magnesium stearate, microcrystalline cellulose, and pregelatinized starch. The white film-coat for the 0.5-mg tablet contains hypromellose, titanium dioxide, and triacetin. The blue film-coat for the 1-mg tablet contains hypromellose, titanium dioxide, triacetin, and indigo carmine.

This Medication Guide has been approved by the US Food and Drug Administration.

 

PATIENT-PHYSICIAN AGREEMENT FOR LOTRONEX

LOTRONEX (alosetron hydrochloride) is only for women with severe irritable bowel syndrome (IBS) whose main problem is diarrhea and who did not get the relief needed from other treatments. LOTRONEX has not been shown to help men with IBS or patients under age 18.

My doctor, or a healthcare provider under a doctorís direction, answered my questions about treatment with LOTRONEX. I have read and I understand the Medication Guide for LOTRONEX, and

  • I understand that some patients using LOTRONEX have had serious bowel conditions (ischemic colitis and complications of constipation). I understand that these serious conditions can happen suddenly, and that they may lead to a hospital stay, and in rare cases, blood transfusions, surgery, and death. I also understand that certain patients may be more likely to develop a serious bowel condition while taking LOTRONEX. These include older patients, those who have other health problems and those who take other medicines that may cause constipation.


  • My doctor and I agree that my IBS is severe and that other treatments have not given me the relief that I need. I also agree that I meet all of the requirements described in the section of the Medication Guide ìWhat is the most important information I should know about LOTRONEX?î I understand that these requirements help to make sure that LOTRONEX is used only by patients who are likely to have more benefit from treatment than risk.


  • I donít have any problems listed in the section of the Medication Guide ìWho should not take LOTRONEX?î that prevents me from taking LOTRONEX.
  • I will follow instructions in the Medication Guide about:
    • telling my doctor, before taking LOTRONEX, about any illnesses I have, or other medicines I am taking or planning to take.
    • taking LOTRONEX exactly as my doctor prescribes it.
    • stopping LOTRONEX and calling my doctor right away if I get constipated, if I have new or worse pain in my abdomen, or if I see blood in my bowel movements.
    • calling my doctor again if the constipation I called about before has not gotten better.
    • not starting LOTRONEX again unless my doctor tells me to do so, if I stopped taking it because I got constipated.
    • talking with my doctor 4 weeks after starting LOTRONEX to recheck my IBS symptoms.
    • stopping LOTRONEX and calling my doctor if my IBS symptoms have not improved after 4 weeks of taking 1 mg 2 times a day.

I understand that LOTRONEX should be prescribed only by doctors who have signed up with the company that makes the drug. Doctors in the program must:

  • fully discuss the drugís benefits and risks with each patient.
  • sign this agreement with each patient before giving the initial prescription. It is not necessary to sign an agreement more than once.
  • use a special sticker on all LOTRONEX prescriptions so that pharmacists know the doctor has signed up.

If I see other doctors about my IBS or possible side effects from LOTRONEX, I will let the doctor who prescribed LOTRONEX know.

My signature below indicates I have read, understood, and agree with all the statements made above. I would like to begin treatment with LOTRONEX.

__________________________
Name of Patient (print)
__________________________
Signature		 _____________________
Date

SECTION FOR THE PHYSICIAN

I am enrolled in the Prescribing Program for LOTRONEX, and I will continue to follow the requirements of the Program.

I, or a healthcare provider under a physician's direction, have given the patient named above:

  • a copy of the Medication Guide for LOTRONEX, and instructed the patient to read it carefully before signing this Agreement, and to take it home.
  • counseling about the benefits and risks of LOTRONEX.
  • appropriate instructions for taking LOTRONEX.
  • answers to all of the patientís questions about treatment with LOTRONEX.
  • a prescription for LOTRONEX that has the program sticker affixed on it to alert pharmacists I am enrolled in the Prescribing Program for LOTRONEX.

The patient signed the Patient-Physician Agreement in my presence after I counseled the patient, asked if the patient had any questions about treatment with LOTRONEX, and answered all questions to the best of my ability.

__________________________
Name of Physician (print)
__________________________
Signature		 _____________________
Date

After the patient and the physician sign this Patient-Physician Agreement, give a copy to the patient and put the original signed form in the patientís medical record.

PRESCRIBING PROGRAM FOR LOTRONEXTM:
PHYSICIAN ENROLLMENT FORM

The Prescribing Program for LOTRONEX was implemented to help reduce risks of serious gastrointestinal adverse events, some fatal, associated with this medicine. The program is intended to help physicians and their patients understand the benefits and risks of treatment with LOTRONEX in order to make fully informed decisions.

I wish to participate in the Prescribing Program for LOTRONEX (PPL) and acknowledge that I have read the complete Prescribing Information for LOTRONEX and understand and will follow the requirements of the PPL described below.

  • For safety reasons, LOTRONEX is approved only for women with severe, diarrhea-predominant irritable bowel syndrome (D-IBS) who have:
    • Chronic IBS symptoms (generally lasting for 6 months or longer),
    • had anatomic or biochemical abnormalities of the gastrointestinal tract excluded, and
    • not responded adequately to conventional therapy.

    • Diarrhea-predominant IBS is severe if it includes diarrhea and one or more of the following:

    • Frequent and severe abdominal pain/discomfort
    • Frequent bowel urgency or fecal incontinence
    • Disability or restriction of daily activities due to IBS
  • Physicians who enroll in the PPL should be able to diagnose and manage IBS, ischemic colitis, constipation, and complications of constipation, or refer patients to a specialist as needed.
  • Patients considering treatment with LOTRONEX must be educated on the benefits and risks of the drug, given a copy of the Medication Guide, instructed to read it, and encouraged to ask questions. The patient may be educated by the enrolled physician or a healthcare provider under a physicianís direction.
  • After reviewing the Medication Guide prior to the initial prescription, the physician and the patient must both sign the Patient-Physician Agreement form. The original signed form must be placed in the patientís medical record, and a copy given to the patient.
  • Program stickers must be affixed to all prescriptions for LOTRONEX (i.e., the original and all subsequent prescriptions). Stickers will be provided as part of the GlaxoSmithKline Prescribing Program for LOTRONEX. Refills are permitted to be written on prescriptions.
  • All prescriptions for LOTRONEX must be written and not transmitted by telephone, facsimile, or computer.
  • Prescribers must report all serious adverse events with LOTRONEX to GlaxoSmithKline at 1-888-825-5249 or to the Food and Drug Administration at 1-800-FDA-1088.

__________________________
Name of Physician (print)
__________________________
Signature		 _____________________
Date
DEA Number _____________________
Office Address: _____________________
_____________________
_____________________
Office Phone Number: _____________________
Office Fax Number: _____________________

Upon enrollment, you will receive a prescribing kit for LOTRONEX with the complete Prescribing Information, Prescribing Program for LOTRONEX stickers, multiple copies of the Medication Guide and Patient-Physician Agreement for LOTRONEX, and instructions for ordering additional supplies of Program materials.

You only need to enroll once, and you are under no obligation to prescribe LOTRONEX.

If you have any questions, please call the Prescribing Program for LOTRONEX at 1-888-825-5249 or visit www.lotronex.com.

TO ENROLL, VISIT WWW.LOTRONEX.COM OR PHONE 1-888-825-5249 OR COMPLETE THIS FORM IN ITS ENTIRETY AND MAIL OR FAX TO THE FOLLOWING ADDRESS:

Prescribing Program for Lotronex
Customer Response Center
Five Moore Drive
PO Box 13398
Research Triangle Park, NC 27709-3398
Fax Number: 1-866-698-7582


GlaxoSmithKline
Research Triangle Park, NC 27709
©2005, GlaxoSmithKline
All rights reserved.

 

Lotronex Interactions

Because alosetron is metabolized by a variety of hepatic CYP drug-metabolizing enzymes, inducers or inhibitors of these enzymes may change the clearance of alosetron.

Fluvoxamine is a known strong inhibitor of CYP1A2 and also inhibits CYP3A4, CYP2C9, and CYP2C19. In a pharmacokinetic study, 40 healthy female subjects received fluvoxamine in escalating doses from 50 to 200 mg per day for 16 days, with coadministration of alosetron 1 mg on the last day. Fluvoxamine increased mean alosetron plasma concentrations (AUC) approximately 6-fold and prolonged the half-life by approximately 3-fold. Concomitant administration of alosetron and fluvoxamine is contraindicated.

Concomitant administration of alosetron and moderate CYP1A2 inhibitors, including quinolone antibiotics and cimetidine, has not been evaluated, but should be avoided unless clinically necessary because of similar potential drug interactions.

Ketoconazole is a known strong inhibitor of CYP3A4. In a pharmacokinetic study, 38 healthy female subjects received ketoconazole 200 mg twice daily for 7 days, with coadministration of alosetron 1 mg on the last day. Ketoconazole increased mean alosetron plasma concentrations (AUC) by 29%. Caution should be used when alosetron and ketoconazole are administered concomitantly. Coadministration of alosetron and strong CYP3A4 inhibitors, such as clarithromycin, telithromycin, protease inhibitors, voriconazole, and itraconazole has not been evaluated but should be undertaken with caution because of similar potential drug interactions. The effect of induction or inhibition of other pathways on exposure to alosetron and its metabolites is not known.

In vitro human liver microsome studies and an in vivo metabolic probe study demonstrated that alosetron did not inhibit CYP enzymes 2D6, 3A4, 2C9, or 2C19. In vitro, at total drug concentrations 27-fold higher than peak plasma concentrations observed with the 1-mg dosage, alosetron inhibited CYP enzymes 1A2 (60%) and 2E1 (50%). In an in vivo metabolic probe study, alosetron did not inhibit CYP2E1 but did produce 30% inhibition of both CYP1A2 and N-acetyltransferase. Although not studied with alosetron, inhibition of N-acetyltransferase may have clinically relevant consequences for drugs such as isoniazid, procainamide, and hydralazine. The effect on CYP1A2 was explored further in a clinical interaction study with theophylline and no effect on metabolism was observed. Another study showed that alosetron had no clinically significant effect on plasma concentrations of the oral contraceptive agents ethinyl estradiol and levonorgestrel (CYP3A4 substrates). A clinical interaction study was also conducted with alosetron and the CYP3A4 substrate cisapride. No significant effects on cisapride metabolism or QT interval were noted. The effect of alosetron on monoamine oxidases and on intestinal first pass secondary to high intraluminal concentrations have not been examined. Based on the above data from in vitro and in vivo studies, it is unlikely that alosetron will inhibit the hepatic metabolic clearance of drugs metabolized by the major CYP enzyme 3A4, as well as the CYP enzymes 2D6, 2C9, 2C19, 2E1, or 1A2.

Alosetron does not appear to induce the major cytochrome P450 (CYP) drug metabolizing enzyme 3A. Alosetron also does not appear to induce CYP enzymes 2E1 or 2C19. It is not known whether alosetron might induce other enzymes.

 

Lotronex Contraindications

LOTRONEX should not be initiated in patients with constipation.

LOTRONEX is contraindicated in patients with a history of the following:

  • chronic or severe constipation or sequelae from constipation
  • intestinal obstruction, stricture, toxic megacolon, gastrointestinal perforation, and/or adhesions
  • ischemic colitis, impaired intestinal circulation, thrombophlebitis, or hypercoagulable state
  • Crohnís disease or ulcerative colitis
  • diverticulitis
  • hypersensitivity to any component of the product

LOTRONEX should not be used by patients who are unable to understand or comply with the Patient-Physician Agreement for LOTRONEX.

Concomitant administration of alosetron with fluvoxamine is contraindicated. Fluvoxamine, a known strong inhibitor of CYP1A2, has been shown to increase mean alosetron plasma concentrations (AUC) approximately 6-fold and prolong the half-life by approximately 3-fold.

 

Additional information about Lotronex

Lotronex Indication: For the treatment of symptoms of irritable bowel syndrome in women whose primary symptom is diarrhea Mechanism Of Action: Lotronex 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. Drug Interactions: Not Available Food Interactions: Take without regard to meals.Absorption is decreased by about 25% when taken with meals. Generic Name: Alosetron Synonyms: Alosetron HCl Drug Category: Serotonin Antagonists; Gastrointestinal Agents Drug Type: Small Molecule; Approved; Withdrawn Other Brand Names containing Alosetron: Lotronex; Absorption: 50-60 % Toxicity (Overdose): Not Available Protein Binding: 82% Biotransformation: Hepatic, via microsomal cytochrome P450 (CYP) Half Life: 1.5 hours Dosage Forms of Lotronex: Tablet Oral Chemical IUPAC Name: 5-methyl-2-[(5-methyl-1H-imidazol-4-yl)methyl]-3,4-dihydropyrido[4,3-b]indol-1-one Chemical Formula: C17H18N4O Alosetron on Wikipedia: https://en.wikipedia.org/wiki/Alosetron Organisms Affected: Humans and other mammals