CisaprideGastrointestinal AgentsGastric EmptyingGastrointestinal MotilityMetoclopramideGastroparesisDomperidoneMotilinReceptors, Serotonin, 5-HT4Gastrointestinal TransitPiperidinesDyspepsiaBenzyl CompoundsErythromycinSerotonin 5-HT4 Receptor AgonistsFumariaLaxativesViolaGastroesophageal RefluxSerotonin Receptor AgonistsAsclepiadaceaeGallbladder EmptyingConstipationPeristalsisBenzamidesSerotonin AntagonistsEsophagitis, PepticAntiemeticsSimethiconeStomachDefecationManometryMorpholinesDouble-Blind MethodCross-Over Studies