Tegaserod
Novartis' brand name Zelnorm (tegaserod) had originally received approval from the US FDA in 2002 for the treatment of irritable bowel syndrome with constipation (IBS-C). It was, however, voluntarily withdrawn from widespread use in the US market in 2007 after concerns arose over the possibility that tegaserod could potentially cause dangerous cardiovascular events in patients. Since then, closer evaluations of the original data suggesting such cardiovascular risk have resulted in the limited reintroduction or 're-approval' of tegaserod for treatment of IBS-C specifically in female patients less than 65 years of age and whom are considered to be at a lower risk of a cardiovascular event than the broader population. Zelnorm (tegaserod) by Sloan Pharma subsequently gained re-approval in April of 2019. Nevertheless, tegaserod remains un-approved in certain regions.  Despite the relative complications involved in its history of regulatory approval, ever since its first introduction in 2002 tegaserod remains the only therapy for IBS-C that possesses the unique mechanism of action of acting on serotonin-4 (5-HT(4)) receptors in smooth muscle cells and in the gastrointestinal wall to facilitate actions like esophageal relaxation, peristaltic gut movement, and natural secretions in the gut, among others.