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Zelnorm: Full Drug Profile

Medically reviewed by Min Clinic Staff | Updated: January 2026

Zelnorm - General Information

Zelnorm is a 5-HT4 agonist manufactured by Novartis and used for the management of irritable bowel syndrome and constipation. Its use was the only drug approved by the United States Food and Drug Administration to help relieve the abdominal discomfort, bloating and constipation associated with irritable bowel syndrome. On March 30, 2007, the U.S. Food and Drug Administration requested that Novartis withdraw Zelnorm from shelves. The FDA alleges a relationship between prescriptions of the drug and increased risks of heart attack or stroke. [Wikipedia]

 

Pharmacology of Zelnorm

Zelnorm is indicated for the short-term treatment of women with irritable bowel syndrome (IBS) whose primary bowel symptom is constipation. Irritable bowel syndrome with constipation and chronic idiopathic constipation are both lower gastrointestinal dysmotility disorders. Clinical investigations have shown that both motor and sensory functions of the gut appear to be altered in patients suffering from irritable bowel syndrome (IBS), while in patients with chronic idiopathic constipation, reduced intestinal motility is the predominant cause of the condition. Both the enteric nervous system, which acts to integrate and process information in the gut, and 5-hydroxytryptamine (5-HT, serotonin) are thought to represent key elements in the etiology of both IBS and idiopathic constipation. Approximately 95% of serotonin is found throughout the gastrointestinal tract, primarily stored in enterochromaffin cells but also in enteric nerves acting as a neurotransmitter. Serotonin has been shown to be involved in regulating motility, visceral sensitivity and intestinal secretion. Investigations suggest an important role of serotonin Type-4 (5-HT4) receptors in the maintenance of gastrointestinal functions in humans. 5-HT4 receptor mRNA has been found throughout the human gastrointestinal tract.

 

Zelnorm for patients

Zelnorm

(tegaserod maleate)

Tablets

(pronounced ZEL-norm, te-gas-a-rod mal- -ate)

Read this information carefully before you start taking Zelnorm (ZEL-norm). Read the information you get each time you get more Zelnorm. There may be new information. This information does not take the place of talking to your doctor about your medical condition or treatment.

What is the most important information I should know about Zelnorm?

If you get new or worse abdominal (stomach) pain, or blood in your stools, stop taking Zelnorm right away and tell your doctor. Your doctor may need to do tests to find out if you have a serious problem with your bowel that may require special treatment or hospitalization.

Sometimes Zelnorm causes diarrhea. Stop taking Zelnorm and call your doctor right away if you get so much diarrhea that you get lightheaded, dizzy, or faint.

What is Zelnorm?

Zelnorm is a medicine for:

  • the short-term treatment of women who have irritable bowel syndrome (IBS) with constipation (not enough or hard bowel movements) as their main bowel problem. Zelnorm does not work for all women who use it. Zelnorm has not been shown to work in men with IBS with constipation.
  • the treatment of patients less than 65 years of age with chronic idiopathic constipation. Chronic constipation means constipation lasting over 6 months. Idiopathic constipation means constipation not due to other diseases or drugs. Zelnorm has not been shown to work in patients with chronic idiopathic constipation who are 65 years of age or older. Zelnorm increases the movement of stools (bowel movement) through the bowels. Zelnorm does not cure IBS with constipation or chronic idiopathic constipation. For those with IBS with constipation who are helped, Zelnorm reduces pain and discomfort in the abdominal area, bloating, and constipation. For those with chronic idiopathic constipation, Zelnorm increases bowel movements, reduces straining, bloating and abdominal discomfort If you stop taking Zelnorm, your symptoms may return within 1 or 2 weeks.

Who should not take Zelnorm?

You should not start taking Zelnorm if:

  • You now have diarrhea or have diarrhea often.
  • You have bad kidney or liver disease.
  • You have ever had bowel obstruction (intestinal blockage), symptomatic gallbladder disease, or abdominal adhesions causing pain and/or intestinal blockage.
  • You are allergic to Zelnorm or any of its ingredients. The active ingredient in Zelnorm is tegaserod maleate. The inactive ingredients are listed at the end of this leaflet.

Zelnorm may not be right for you. Tell your doctor if you:

  • Are pregnant or plan to become pregnant. Zelnorm is not recommended for use by pregnant women.
  • Are breast-feeding. Do not breast-feed while you are taking Zelnorm. The drug is likely to pass into breast milk.
  • Are taking or planning to take any other medicines, including those you can get without a prescription.

How should I take Zelnorm?

  • You should take Zelnorm twice a day on an empty stomach shortly before you eat a meal, or as your doctor prescribes it.
  • For IBS with Constipation: You should take Zelnorm for 4 to 6 weeks to treat your IBS symptoms. If you feel better, your doctor may prescribe an additional 4 to 6 weeks of Zelnorm.
  • For Chronic Idiopathic Constipation: You should talk to your doctor regularly about whether you need to stay on Zelnorm.
  • If you miss a dose of Zelnorm, just skip that dose. Do not take two tablets to make up the missed dose. Instead, just wait until the next time you are supposed to take it and then take your normal dose.

What are the possible side effects of Zelnorm?

Headache and diarrhea were the most common side effects seen with Zelnorm.

Diarrhea was an occasional side effect of treatment with Zelnorm. Most people who got diarrhea had it during the first week after starting Zelnorm. Typically, diarrhea went away with continued therapy. If you get bad diarrhea, or if you get diarrhea together with bad cramping, abdominal pain, fainting, or dizziness, tell your doctor. Your doctor may tell you to stop taking Zelnorm or suggest other ways to manage your diarrhea.

There have been rare cases of rectal bleeding and severe abdominal pain in patients treated with Zelnorm. Some of these problems were related to insufficient blood flow to part of the bowel. It is not known if this was related to Zelnorm use.

In studies a very small number of patients were reported to have abdominal surgery. In IBS with constipation studies there were a few more reports of abdominal surgery in patients taking Zelnorm than in patients taking a sugar pill. Most of these were related to the gallbladder. It is not known if Zelnorm may increase your chance of abdominal surgery. Gallbladder surgery has been reported to occur more often in IBS patients than in the general population.

This list is not complete. Your doctor or pharmacist can give you a more complete list of possible side effects. Talk to your doctor about any side effects you may have.

General information about the safe and effective use of Zelnorm

Keep Zelnorm at room temperature. Do not use Zelnorm past the expiration date shown on the package.

Medicines are sometimes prescribed for conditions that are not mentioned in patient information leaflets. Do not use Zelnorm for a condition for which it was not prescribed. Do not give Zelnorm to other people, even if they have the same symptoms that you have. This leaflet summarizes the most important information about Zelnorm. For more information, talk with your doctor. You can ask your doctor or pharmacist for information about Zelnorm that is written for health professionals. You can also contact the company that makes Zelnorm at 1-866-427-6682 or www.zelnorm.com.

Inactive Ingredients

Zelnorm is available for oral use in the following tablet formulations:

  • 2 mg and 6 mg tablets (blister packs) containing the following inactive ingredients: crospovidone, glyceryl monostearate, hypromellose, lactose monohydrate, poloxamer 188, and polyethylene glycol 4000
  • 6 mg tablets (bottles) containing the following inactive ingredients: crospovidone, glyceryl behenate, hypromellose, lactose monohydrate, colloidal silicon dioxide.

 

Zelnorm Interactions

In vitro drug-drug interaction data with tegaserod indicated no inhibition of the cytochrome P450 isoenzymes CYP2C8, CYP2C9, CYP2C19, CYP2E1 and CYP3A4, whereas inhibition of CYP1A2 and CYP2D6 could not be excluded. However, in vivo, no clinically relevant drug-drug interactions have been observed with dextromethorphan (CYP2D6 prototype substrate), and theophylline (CYP1A2 prototype substrate). There was no effect on the pharmacokinetics of digoxin, oral contraceptives, and warfarin. The main human metabolite of tegaserod hydrogen maleate, 5-methoxyindole-3-carboxylic acid glucuronide, did not inhibit the activity of any of the above cytochrome P450 isoenzymes in in vitro tests.

Dextromethorphan

A pharmacokinetic interaction study demonstrated that co-administration of tegaserod and dextromethorphan did not change the pharmacokinetics of either compound to a clinically relevant extent. Dose adjustment of either drug is not necessary when tegaserod is combined with dextromethorphan. Therefore, tegaserod is not expected to alter the pharmacokinetics of drugs metabolized by CYP2D6 (e.g., fluoxetine, omeprazole, captopril).

Theophylline

A pharmacokinetic interaction study demonstrated that co-administration of tegaserod and theophylline did not affect the pharmacokinetics of theophylline. Dose adjustment of theophylline is not necessary when tegaserod is co-administered. Therefore, tegaserod is not expected to alter the pharmacokinetics of drugs metabolized by CYP1A2 (e.g., estradiol, omeprazole).

Digoxin

A pharmacokinetic interaction study with digoxin demonstrated that concomitant administration of tegaserod reduced peak plasma concentration and exposure of digoxin by approximately 15%. This reduction of bioavailability is not considered clinically relevant. When tegaserod is co-administered with digoxin dose adjustment is unlikely to be required.

Warfarin

A pharmacokinetic and pharmacodynamic interaction study with warfarin demonstrated no effect of concomitant administration of tegaserod on warfarin pharmacokinetics and pharmacodynamics. Dose adjustment of warfarin is not necessary when tegaserod is co-administered.

Oral Contraceptives

Co-administration of tegaserod did not affect the steady-state pharmacokinetics of ethinylestradiol and reduced peak concentrations and exposure of levonorgestrel by 8%. Tegaserod is not expected to alter the risk of ovulation in subjects taking oral contraceptives. No alteration in oral contraceptive medication is necessary when tegaserod is co-administered.

 

Zelnorm Contraindications

Zelnorm (tegaserod maleate) is contraindicated in those patients with:

• severe renal impairment

• moderate or severe hepatic impairment

• a history of bowel obstruction, symptomatic gallbladder disease, suspected sphincter of Oddi dysfunction, or abdominal adhesions

• a known hypersensitivity to the drug or any of its excipients

 

Additional information about Zelnorm

Zelnorm Indication: Provides relief from the symptoms of irritable bowel syndrome including chronic idiopathic constipation. Mechanism Of Action: Zelnorm is a 5-HT4 receptor partial agonist that binds with high affinity at human 5-HT4 receptors, whereas it has no appreciable affinity for 5-HT3 or dopamine receptors. It has moderate affinity for 5-HT1 receptors. Zelnorm, by acting as an agonist at neuronal 5-HT4 receptors, triggers the release of further neurotransmitters such as calcitonin gene-related peptide from sensory neurons. The activation of 5-HT4 receptors in the gastrointestinal tract stimulates the peristaltic reflex and intestinal secretion, as well as inhibits visceral sensitivity. Drug Interactions: Not Available Food Interactions: Not Available Generic Name: Tegaserod Synonyms: SDZ HTF 919; Tegaserod maleate Drug Category: Gastrointestinal Agents; Serotonin Agonists Drug Type: Small Molecule; Withdrawn; Investigational Other Brand Names containing Tegaserod: Zelmac; Zelnorm; Absorption: Rapidly absorbed after oral administration, with an absolute bioavailability of approximately 10%. Toxicity (Overdose): Oral LD50 in rat is 2000 mg/kg. Protein Binding: 98% Biotransformation: Tegaserod is metabolized mainly via two pathways. The first is a presystemic acid catalyzed hydrolysis in the stomach followed by oxidation and conjugation which produces the main metabolite of tegaserod, 5-methoxyindole-3-carboxylic acid glucuronide. The main metabolite has negligible affinity for 5-HT4 receptors in vitro. The second metabolic pathway of tegaserod is direct glucuronidation which leads to generation of three isomeric N-glucuronides. Half Life: 11 ± 5 hours Dosage Forms of Zelnorm: Tablet Oral Chemical IUPAC Name: 1-[[(Z)-[5-(hydroxymethyl)indol-3-ylidene]methyl]amino]-2-pentylguanidine Chemical Formula: C16H23N5O Tegaserod on Wikipedia: https://en.wikipedia.org/wiki/Tegaserod Organisms Affected: Humans and other mammals