Tegaserod-induced myocardial infarction: case report and hypothesis

Tegaserod for constipation-predominant irritable bowel syndrome

Tegaserod, a selective and partial agonist at the 5-hydroxytryptamine (5-HT [serotonin]) receptor subtype 4 (5-HT4), is the only United States Food and Drug Administration-approved drug for the treatment of constipation-predominant irritable bowel syndrome (IBS) in women. The drug's stimulation of 5-HT4 receptors on intestinal enterocytes increases peristaltic activity and fluid secretion into the gut lumen, facilitating stool passage. In addition, affinity of tegaserod for 5-HT4 receptors modulates visceral sensitivity, which helps alleviate abdominal pain associated with constipation-predominant IBS. The drug's pharmacokinetic and pharmacodynamic parameters do not differ significantly with age or sex. Tegaserod safely and effectively relieves overall gastrointestinal symptoms and abdominal discomfort and normalizes bowel habits in patients with constipation-predominant IBS. It is associated with few drug interactions. In clinical studies, tegaserod was well tolerated, and its adverse-effect profile was similar to that of placebo. Severe diarrhea, as well as abdominal pain, flatulence, headache, and nausea, were the most commonly reported events. Patients who experience severe diarrhea should discontinue the drug. With the data available, tegaserod remains an option for patients with constipation-predominant IBS.

The rationale, efficacy and safety evidence for tegaserod in the treatment of irritable bowel syndrome

A growing body of evidence implicates abnormal serotonergic regulation of gastrointestinal function in the pathogenesis of the irritable bowel syndrome (IBS). Drugs targeting this system are therefore attractive concepts. The partial 5-HT4 receptor agonist tegaserod might be predicted to have positive therapeutic effects on a constipated and uncomfortable gut. However, IBS runs a chronic, benign course and carries no associated mortality, so it is imperative that the safety profile of new pharmacological agents made available to physicians is exemplary. The authors review the evidence for 5-HT in the aetiology of IBS and its symptoms, and the data available concerning the partial 5-HT4 receptor agonist tegaserod, in terms of rationale, efficacy and safety.

Current pharmacological treatment of gastroparesis

The aetiology of gastroparesis differs between children and adults. During childhood, gastroparesis is quite rare, and is mostly seen in preterm infants, with either immaturity of the gastrointestinal tract, or when allergic to cow's milk protein. Acute, delayed gastric emptying may be observed following viral infections. In adults, most patients with gastroparesis are either idiopathic or of diabetic origin. As a consequence, approaches in the treatment of children and adults differ. Metoclopramide, domperidone, cisapride and erythromycin have all been studied. Evidence for benefit is strongest for the latter two drugs, although most studies have methodological shortcomings. From a paediatric perspective, it seems astonishing that more trials with erythromycin analogues have not been performed, as the few data available suggests that these analogues are more powerful, without the side effects of long-term, low-dose administration of antibiotics. Gastric electrical stimulation seems the most promising therapeutic option available at present.

Review of tegaserod in the treatment of irritable bowel syndrome

Tegaserod is a drug in a new class of compounds called aminoguanidine indoles and is structurally similar to serotonin (5-HT) with modifications that make the drug selective for the 5-HT(4) receptor. Tegaserod has a stimulatory effect on gastrointestinal (GI) motility that has been demonstrated in animal studies and in healthy adults. Tegaserod also increases GI secretion and reduces rectal sensitivity. Tegaserod is currently approved by the FDA for the treatment of women with constipation-predominant irritable bowel syndrome (C-IBS). Eight large Phase III clinical trials involving > 5000 IBS patients support the clinical efficacy of tegaserod in this group of patients. Patients who were treated with tegaserod had an overall improvement in IBS symptoms (Subject's Assessment of Global Relief) as well as in secondary end points, such as abdominal pain and discomfort, stool consistency, change in bowel movements and relief of bloating. Tegaserod was well-tolerated. The most common adverse reaction in clinical trials was diarrhoea, which was usually temporary and mild, although severe diarrhoea requiring hospitalisation has been rarely (< 1%) reported.