The guanylate cyclase-C receptor agonist linaclotide (Linzess – Abbvie/Ironwood) was first approved by the FDA in 2012 for treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation in adults. The drug has now been approved for treatment of functional constipation in patients 6-17 years old. Linaclotide is the only drug to be approved in the US for treatment of functional constipation.

The Vibrant orally administered vibrating capsule (Vibrant Gastro), an FDA-cleared medical device, is now available by prescription for treatment of adults with chronic idiopathic constipation (CIC) who have not experienced relief of their bowel symptoms by using laxative therapies at the recommended dosage for at least one month. It is the first drug-free treatment to be authorized by the FDA for this indication.

Irritable bowel syndrome (IBS) is a common disorder characterized by recurrent abdominal pain and altered bowel habits, often accompanied by bloating.IBS is classified according to the predominant bowel symptom as IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), mixed type (IBS-M), or unclassified (IBS-U). Alterations in the microbiome, stress responses, sensory and motor function of the gut, and host genetic factors may be contributing factors. Since the exact cause of IBS is unknown, the goal of treatment is symptom control.

The FDA has approved the 5-HT4 receptor agonist prucalopride (Motegrity – Shire) for treatment of chronic idiopathic constipation (CIC) in adults. Prucalopride is the only drug currently approved in the US for treatment of CIC that stimulates colonic peristalsis. It has been available in Europe and Canada for several years.

View the Expanded Table: Some Drugs for Chronic Idiopathic Constipation

Tegaserod maleate (Zelnorm), a 5-HT₄ receptor partial agonist that increases gastrointestinal (GI) motility, was approved by the FDA in 2002 for short-term treatment of irritable bowel syndrome with constipation (IBS-C) in women and in 2004 for treatment of chronic idiopathic constipation (CIC) in adults <65 years old.

In 2007, the manufacturer (Novartis) complied with an FDA request to stop marketing the drug based on an unpublished retrospective analysis of clinical trials in IBS-C and other GI motility disorders that showed a higher rate of ischemic cardiovascular events (including cardiovascular death, nonfatal myocardial infarction [MI], and nonfatal stroke) in patients who took tegaserod than in those who took placebo. Among more than 11,600 patients treated with tegaserod for 1-3 months, 13 (0.11%) had a confirmed ischemic event compared to only 1 (0.01%) of more than 7000 patients who received placebo.1

The mechanism by which tegaserod could cause cardiovascular ischemia is unknown; 5-HT₁ receptor agonists used to treat migraine, such as sumatriptan (Imitrex, and others), can constrict coronary arteries, and tegaserod has some affinity for 5-HT₁ receptors.1

Based on a re-examination of the data that led to withdrawal of tegaserod and the continued need for a drug with this mechanism of action to treat IBS-C, an FDA advisory committee recommended approval of a supplemental new drug application from a new sponsor (Sloan). The drug is now approved only for treatment of IBS-C in women <65 years old and is contraindicated in patients with a history of MI, stroke, transient ischemic attack, or angina.

Prucalopride (Motegrity), a selective 5-HT₄ receptor agonist recently approved by the FDA for treatment of CIC, will be reviewed in a future issue. It has less affinity for 5-HT₁ receptors than tegaserod.2

1. In brief: tegaserod withdrawn. Med Lett Drugs Ther 2007; 49:40.
2. J Tack et al. Systematic review: cardiovascular safety profile of 5-HT₄ agonists developed for gastrointestinal disorders. Aliment Pharmacol Ther 2012; 35:745.

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The FDA has approved the opioid receptor antagonist naldemedine (Symproic – Shionogi) for treatment of opioid-induced constipation (OIC) in adults with chronic noncancer pain. Naldemedine is the third oral peripherally-acting mu-opioid receptor antagonist (PAMORA) to be approved for this indication; naloxegol (Movantik) and methylnaltrexone (Relistor) were approved earlier.

The FDA has approved plecanatide (Trulance – Synergy), a guanylate cyclase-C receptor agonist, for treatment of chronic idiopathic constipation (CIC) in adults. Linaclotide (Linzess), another guanylate cyclase-C receptor agonist, and lubiprostone (Amitiza), a chloride channel activator, were approved earlier for treatment of CIC in adults.

Irritable bowel syndrome (IBS) is a common disorder characterized by chronic, intermittent abdominal pain or discomfort and altered bowel habits. It is subtyped according to the predominant bowel symptom as IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), mixed type (IBS-M), or unclassified (IBS-U). Since the exact cause of IBS is unknown, the goal of treatment is symptom control.

The FDA has approved naloxegol (Movantik – AstraZeneca), a pegylated derivative of the opioid antagonist naloxone, for oral treatment of opioid-induced constipation in adults with chronic noncancer pain. It is the only oral opioid antagonist approved for this indication in the US.

The FDA has approved use of lubiprostone (Amitiza) for treatment of opioid-induced constipation in adults with chronic non-cancer pain. The drug was previously approved for chronic idiopathic constipation and irritable bowel syndrome with constipation.

Linaclotide (lin´´ a kloe´ tide; Linzess – Ironwood/Forest), a guanylate cyclase-C receptor agonist, was recently approved by the FDA for oral treatment of chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation (IBS-C) in adults. It is the second drug approved for this indication; lubiprostone (Amitiza), a metabolite of prostaglandin E1, was the first.

Web sites and blogs are advising patients that periodic "cleansing" of the colon is necessary to rid the body of toxins.

The FDA has approved subcutaneous injection of methylnaltrexone (Relistor - Wyeth/Progenics), a selective mu-opioid receptor antagonist, for treatment of opioid-induced constipation in patients with advanced illness (such as incurable cancer or end-stage chronic obstructive pulmonary disease) who are receiving palliative care.

Lubiprostone (Amitiza), which was previously approved for treatment of chronic idiopathic constipation in adults, has now also been approved in a lower dose for use in women with irritable bowel syndrome with constipation (IBS-C). Since tegaserod (Zelnorm) has been withdrawn from the market,2 lubiprostone is the only drug approved by the FDA for treatment of this common condition.

Tegaserod maleate (Zelnorm – Novartis), a partial serotonin 5-HT4 receptor agonist that increases gastrointestinal motility, was approved by the FDA in 2002 for short-term treatment of constipation-predominant irritable bowel syndrome in women,1 and in 2004 for treatment of chronic constipation in adults ≤65 years old. Its efficacy has not been impressive statistically, but according to Medical Letter consultants some patients with slow-transit constipation have benefited from taking the drug. Diarrhea has been its main adverse effect.2

The FDA now has requested that the manufacturer stop marketing the drug based on an unpublished postmarketing analysis of earlier clinical trials that showed a higher rate of serious cardiovascular events (including angina, myocardial infarction and stroke) in patients who took tegaserod compared to placebo. Among more than 11,600 patients treated with tegaserod for 1-3 months, 13 (0.11%) had a confirmed ischemic event compared to only 1 patient (0.01%) among more than 7000 treated with placebo. The mechanism by which tegaserod would cause cardiovascular ischemia is unknown; serotonin 5-HT₁ receptor agonists used to treat migraine, such as sumatriptan (Imitrex), can constrict coronary arteries, and tegaserod has some affinity for 5-HT₁ receptors.3

Tegaserod may still be available, possibly through a special access program, for patients who do not have other treatment options.

1. Tegaserod maleate (Zelnorm) for IBS with constipation. Med Lett Drugs Ther 2002; 44:79.

2. Drugs for irritable bowel syndrome. Treat Guidel Med Lett 2006; 4:11.

3. AJ Busti et al. Tegaserod-induced myocardial infarction: case report and hypothesis. Pharmacotherapy 2004; 24:526.

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The FDA has approved lubiprostone (Amitiza - Sucampo/Takeda), a chloride channel activator, for treatment of chronic idiopathic constipation in adults. The only other prescription drug approved by the FDA for this indication (in 2004 for adults <= 65 years old) is tegaserod (Zelnorm), a partial agonist of serotonin that is also approved for constipation-predominant irritable bowel syndrome in women. Of course, numerous over-the-counter products are available for treatment of constipation.

Irritable bowel syndrome (IBS) is a common disorder, occuring in about 15% of the US population; it is 2-3 times more frequent in women than in men. IBS is characterized by chronic abdominal pain or discomfort and altered bowel habits.

Tegaserod maleate (teg a ser' od; Zelnorm - Novartis), a serotonin derivative, has received FDA approval for short-term treatment of women with irritable bowel syndrome (IBS) whose primary symptom is constipation. Alosetron (Lotronex), which was withdrawn previously because of toxicity, will soon be available again for women with severe diarrhea-predominant IBS (Medical Letter 2002; 44:67).