Pathophysiology as a basis for understanding symptom complexes and therapeutic targets.

Sensorimotor disorders of the stomach, small intestine and colon have a limited repertoire of clinical manifestations, and there is the potential for more than one mechanism to lead to symptoms. In many recent clinical trial programs of novel agents in neurogastroenterology, the emphasis has been primarily on symptom assessment of broad groups of patients identified by the Rome criteria. Drugs of potential value have fallen by the wayside with this approach. We propose the current paradigm is partly to blame; physiological testing should provide the basis for identifying more homogeneous populations and therapeutic targets within functional bowel disease, and this applies to the upper and lower gut. Here we summarize the evidence that certain biomarkers can, in a limited fashion, be used to predict the success of an experimental medicine in common disorders of gastrointestinal function, including the irritable bowel syndrome and functional dyspepsia. Although the current evidence is limited and is most convincingly demonstrated with examples of transit measurements (for loperamide, alosetron, tegaserod and piboserod), we perceive this paradigm that studies using validated and responsive biomarkers have an important role to play in drug development.