tegaserod and renzapride

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders and it is characterized by episodes of abdominal pain and altered bowel functions. The specific bowel disturbances of diarrhea, constipation or an alternation between the two defines the IBS subtypes of diarrhea-predominant, constipation-predominant, and mixed or alternating IBS. Because of the abnormalities in bowel states associated with each IBS subtype, it is not likely that one agent would successfully treat all three subtypes. As a result, clinical trials have focused, for the most part, on one IBS subtype. Over the past 2 decades very few agents have achieved regulatory approval for the treatment of IBS. In the present article we review publications reporting on phase 2 and phase 3 studies evaluating agents to potentially be used in the treatment of patients with IBS.

Topics: Alprostadil; Benzamides; Biphenyl Compounds; Bridged Bicyclo Compounds, Heterocyclic; Carbolines; Dose-Response Relationship, Drug; Gastrointestinal Agents; Humans; Indoles; Irritable Bowel Syndrome; Lubiprostone; Peptides; Phenylalanine; Phloroglucinol; Randomized Controlled Trials as Topic; Rifamycins; Rifaximin

Recent research has provided new information about drugs that could be used to treat functional motility disorders. Promotility drugs accelerate gastric emptying or colonic transit and these properties may contribute to their efficacy in treating symptoms associated with gastroparesis, functional dyspepsia or constipation. 5-Hydroxytryptamine4 receptors are targets for drugs (tegaserod, renzapride) that treat symptoms in constipated irritable bowel syndrome patients and in gastroparesis. Drugs acting at motilin (erythromycin) and cholecystokinin-1 (dexloxiglumide) receptors accelerate gastric emptying. Dexloxiglumide might be useful in the treatment of functional dyspepsia particularly that associated with lipid intake. Alvimopan is a mu-opioid receptor antagonist that does not cross the blood brain barrier. Alvimopan is effective in treating postsurgical ileus and perhaps opiate-induced bowel dysfunction. Successes and failures of recent efforts to develop promotility agents revealed opportunities and challenges for developing new promotility drugs. The pharmacological properties of partial agonists might be exploited to develop effective promotility drugs. However, opposing actions of promotility agents on motility (increased contraction vs decreased accommodation) limit the clinical efficacy of drugs with these opposing actions. Selection of appropriate patient populations for evaluation of new drugs is also critical.

Topics: Animals; Benzamides; Bridged Bicyclo Compounds, Heterocyclic; Cholecystokinin; Gastrointestinal Diseases; Gastrointestinal Motility; Humans; Indoles; Motilin; Receptors, Serotonin, 5-HT4; Serotonin; Serotonin Antagonists; Serotonin Receptor Agonists

This study examined whether the drug-receptor-binding sites of 5 selected human 5-HT(4) receptor splice variants [h5-HT4(a), h5-HT4(b), h5-HT4(c), h5-HT4(d) and h5-HT4(g)] display preferential affinities towards agonists. The agonists selected on the basis of chemical diversity and clinical relevance were: 5-HT4 benzamides, renzapride, zacopride and prucalopride; the benzimidazolones, DAU 6236 and BIMU 1; the aromatic ketone, RS67333, and the indole carbazimidamide tegaserod. The rank order of affinities ranging across the splice variants was: tegaserod (pKi: 7.38-7.91) > or = Y-36912 (pKi: 7.03-7.85) = BIMU 1 (pKi: 6.92-7.78) > or = DAU 6236 (pKi: 6.79-7.99) > or = 5-HT (pKi: 5.82-7.29) > or = 5-MeOT (pKi: 5.64-6.83) > or = renzapride (pKi: 4.85-5.56). We obtained affinity values for the 5-HT4(b), (d) and (g) variants for RS67333 (pKi: 7:48-8.29), prucalopride (pKi: 6.86-7.37) and zacopride (pKi: 5.88-7.0). These results indicate that the ligands interact with the same conserved site in each splice variant. Some splice variants have a higher affinity for certain agonists and the direction of selectivity followed a common trend of lowest affinity at the (d) variant. However, this trend was not evident in functional experiments. Our findings suggest that it may be possible to design splice variant selective ligands, which may be of relevance for experimental drugs but may be difficult to develop clinically.

Topics: Aniline Compounds; Animals; Benzamides; Benzimidazoles; Benzofurans; Binding Sites; Binding, Competitive; Bridged Bicyclo Compounds, Heterocyclic; Chlorocebus aethiops; COS Cells; Cyclic AMP; Dose-Response Relationship, Drug; Humans; Indoles; Kinetics; Ligands; Piperidines; Protein Isoforms; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin Antagonists