P&T Portfolio - Zelnorm

HEALTH-SYSTEM EDITION
P&T PORTFOLIO

Generic name

Tegaserod

Proprietary name/manufacturer

Zelnorm/Novartis

FDA-approved indication

Tegaserod is approved for the short-term treatment of women with constipation-predominant IBS.

Pharmacology

Tegaserod is a selective partial agonist at the serotonin-4 (5-HT₄) receptor and possesses gastrointestinal prokinetic activity. Growing evidence suggests 5-HT plays a pivotal role in the maintenance of overall GI motor function. Activation of 5-HT₄ receptors in the GI tract by tegaserod stimulates the peristaltic reflex and intestinal secretion, in addition to inhibiting visceral sensitivity. Tegaserod, 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 drug has minimal to no binding affinity for 5-HT₃, dopamine, muscarinic, histamine (H₁), opioid, or alpha-1 or alpha-2 adrenergic receptors.

Pharmacokinetics

Efficacy

The approval of tegaserod was based on the results of three 12-week, multicenter, controlled clinical trials involving 2,470 women with constipation-predominant IBS. The primary efficacy end point in these studies was the subject's global assessment (SGA) of relief of IBS symptoms overall. Secondary end points included the individual symptoms of abdominal pain/discomfort and bloating. Study results showed that the proportion of patients responding to tegaserod therapy after one month ranged from 31%-35%, compared with 17%-22% for the placebo group. After three months of therapy, the proportion of responders was 39%-44% for tegaserod patients, compared with 28%-39% for placebo patients. In addition, tegaserod-treated patients experienced less abdominal pain/discomfort and bloating and had an increase in the number of bowel movements per week compared with placebo patients during the study period. Comparative studies with other agents used for the treatment of IBS are not available.

Contraindications

• Severe renal impairment

• Moderate or severe hepatic impairment

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

• Known hypersensitivity to the drug or any of its excipients

Warnings

• Patients currently experiencing or frequently experience diarrhea

• Discontinue in patients with new or sudden worsening of abdominal pain

Adverse effects

The most common adverse effects, occurring in 5%- 15% of patients, were headache, abdominal pain, diarrhea, nausea, flatulence, and back pain.

Less common adverse effects, occurring in 1%-4% of patients, were dizziness, accidental trauma, migraine, arthropathy, and leg pain.

Dose

6 mg orally twice a day before meals for four to six weeks (an additional four to six weeks can be considered for those patients who respond)

Conclusion/comments

Tegaserod is a 5-HT₄ agonist that has demonstrated efficacy in the short-term treatment of women with IBS whose primary bowel symptom is constipation. Tegaserod is a prokinetic agent that enhances motility throughout the GI tract, reducing the abdominal pain, bloating, and constipation associated with constipation- predominant IBS. Clinical studies have shown that the proportion of patients responding to tegaserod are greater at month one than month three, suggesting that efficacy may decrease over time. Efficacy beyond 12 weeks has not been studied. Novartis is also planning to study its potential use for GERD, chronic constipation, and functional dyspepsia.

Published September 2002. Content based on medical literature and product information available at that time.

P&T Portfolio - Zelnorm.

Drug Topics

2002;20:HSE23.