May 23, 2017
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(alosetron hydrochloride) Tablets


Infrequent but serious gastrointestinal adverse events have been reported with the use of LOTRONEX (alosetron hydrochloride) . These events, including ischemic colitis and serious complications of constipation, have resulted in hospitalization, and rarely, blood transfusion, surgery, and death.

  • The Prescribing Program for LOTRONEX (alosetron hydrochloride) ™ was implemented to help reduce risks of serious gastrointestinal adverse events. Only physicians who have enrolled in based on their understanding of the benefits and risks, should prescribe LOTRONEX (see PRECAUTIONS: Prescribing Program for LOTRONEX (alosetron hydrochloride) ).
  • LOTRONEX (alosetron hydrochloride) is indicated only for women with severe diarrhea-predominant IBS who have not responded adequately to conventional therapy (see INDICATIONS AND USAGE). Before receiving the initial prescription for LOTRONEX (alosetron hydrochloride) , the patient must read and sign the Patient-Physician Agreement for LOTRONEX (see PRECAUTIONS: Information for Patients).
  • LOTRONEX (alosetron hydrochloride) should be discontinued immediately in patients who develop constipation or symptoms of ischemic colitis. Patients should immediately report constipation or symptoms of ischemic colitis to their physician. LOTRONEX (alosetron hydrochloride) should not be resumed in patients who develop ischemic colitis. Patients who have constipation should immediately contact their physician if the constipation does not resolve after LOTRONEX (alosetron hydrochloride) is discontinued. Patients with resolved constipation should resume LOTRONEX (alosetron hydrochloride) only on the advice of their treating physician.


The active ingredient in LOTRONEX Tablets is alosetron hydrochloride (HCl), a potent and selective antagonist of the serotonin 5-HT3 receptor type. Chemically, alosetron is designated as 2,3,4,5-tetrahydro-5-methyl-2-[(5-methyl-1H-imidazol-4-yl)methyl]-1H-pyrido[4,3-b]indol-1-one, monohydrochloride. Alosetron is achiral and has the empirical formula: C17H18N4O•HCl, representing a molecular weight of 330.8. Alosetron is a white to beige solid that has a solubility of 61 mg/mL in water, 42 mg/mL in 0.1M hydrochloric acid, 0.3 mg/mL in pH 6 phosphate buffer, and < 0.1 mg/mL in pH 8 phosphate buffer. The chemical structure of alosetron is:

LOTRONEX® (alosetron hydrochloride) Structural Formula Illustration

LOTRONEX (alosetron hydrochloride) Tablets are supplied for oral administration as 0.5-mg (white) and 1-mg (blue) tablets. The 0.5-mg tablet contains 0.562 mg alosetron HCl equivalent to 0.5 mg alosetron and the 1-mg tablet contains 1.124 mg alosetron HCl equivalent to 1 mg of alosetron. Each tablet also contains the 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.

What are the possible side effects of alosetron (Lotronex)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop taking alosetron and call your doctor at once if you have a serious side effect such as:

  • new or worsening stomach pain;
  • bleeding from your rectum or blood in your stools; or
  • fast or uneven heartbeats.

Less serious side effects may include:

  • mild stomach discomfort, bloating, or nausea;
  • mild constipation;
  • burping with heartburn;
  • rectal...

Read All Potential Side Effects and See Pictures of Lotronex »

What are the precautions when taking alosetron hydrochloride (Lotronex)?

Before taking alosetron, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: certain intestinal disorders (e.g., ileus, ischemic colitis, impaired intestinal circulation, constipation or its complications, obstruction, megacolon, stricture/adhesions, or perforation), Crohn's disease, ulcerative colitis, diverticulitis, severe liver disease, blood disorders (e.g., history of blood clots).

Before using this medication, tell your doctor your...

Read All Potential Precautions of Lotronex »

Last reviewed on RxList: 1/24/2017
This monograph has been modified to include the generic and brand name in many instances.

Lotronex - User Reviews

Lotronex User Reviews

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