Lotronex contains the active ingredient alosetron hydrochloride, which is a selective antagonist of the serotonin 5-HT receptor type. It is available as oral tablets in 0.5 mg and 1 mg strengths. Key inactive ingredients include lactose, magnesium stearate, microcrystalline cellulose, and pregelatinized starch. The tablets are designed for oral administration.

How should I use this medication?

Take this medication by mouth with water. Take it as directed on the prescription label. You can take this medication with or without food. Do not use it more often than directed. Keep taking it unless your care team tells you to stop.

A special MedGuide will be given to you by the pharmacist with each prescription and refill. Be sure to read this information carefully each time.

Talk to your care team about the use of this medication in children. It is not approved for use in children.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

If you miss a dose, skip that dose. Do not take double or extra doses.

Where should I keep my medication?

Keep out of the reach of children and pets.

Store at room temperature between 20 and 25 degrees C (68 and 77 degrees F). Protect from light and moisture. Keep the container tightly closed. Get rid of any unused medication after the expiration date.

To get rid of medications that are no longer needed or have expired:

• Take the medication to a medication take-back program. Check with your pharmacy or law enforcement to find a location.
• If you cannot return the medication, check the label or package insert to see if the medication should be thrown out in the garbage or flushed down the toilet. If you are not sure, ask your care team. If it is safe to put it in the trash, take the medication out of the container. Mix the medication with cat litter, dirt, coffee grounds, or other unwanted substance. Seal the mixture in a bag or container. Put it in the trash.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible:

• Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
• Bowel blockage—stomach cramping, unable to have a bowel movement or pass gas, loss of appetite, vomiting
• Sudden or severe stomach pain, bloody diarrhea, fever, nausea, vomiting

Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):

• Constipation
• Nausea
• Stomach pain

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

• Blood clotting disorder
• Blood flow problems to your bowels, such as ischemic colitis
• Constipation
• Diverticulitis
• History of bowel blockage
• Inflammatory bowel disease, such as Crohn disease or ulcerative colitis
• Liver disease
• An unusual or allergic reaction to alosetron, other medications, foods, dyes, or preservatives
• Pregnant or trying to get pregnant
• Breastfeeding

What may interact with this medication?

Do not take this medication with any of the following:

• Antidiarrheal medications, such as diphenoxylate or loperamide
• Crofelemer
• Fluvoxamine
• Viloxazine

This medication may also interact with the following:

• Certain antibiotics, such as ciprofloxacin, enoxacin, clarithromycin, erythromycin, troleandomycin
• Certain antivirals for HIV or hepatitis
• Cimetidine
• Hydralazine
• Isoniazid, INH
• Medications for fungal infections, such as ketoconazole, itraconazole, voriconazole
• Opioid medications for pain
• Procainamide

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medication?

If you get constipated, serious side effects may occur. Do not take this medication if you are constipated. If you have constipation, new or worsening abdominal pain, bloody diarrhea, or blood in the stool, immediately stop taking this medication and contact your care team.

What are the most serious risks of this medication?

This medicine can cause serious, life-threatening complications of constipation. Risk factors are older age, being weak from illness, or taking other medicines that cause constipation. If you get constipated while taking this medicine, stop taking it right away and call your healthcare provider. If the constipation does not get better after stopping the medicine call your healthcare provider again. Do not start taking this medicine again unless your healthcare provider tells you to.

Taking this medicine could cause a decrease of blood flow to your bowels, called ischemic colitis. This is a serious, life-threatening complication and could lead to a hospital stay, blood transfusion, or surgery. Taking this medicine for longer than 6 months might increase the risk. Stop taking this medicine right away and call your healthcare provider if there is blood in your bowel movements, if you have new stomach pains, or if your stomach pain gets worse. Do not start taking this medicine again unless your healthcare provider tells you to.