Background: An estimated 13 to 28 percent of adults have persistent or recurrent upper abdominal discomfort for which no pathology can be identified. Although the etiology of functional dyspepsia remains unknown, psychological factors are believed to play an important role. Miwa and colleagues studied the ability of tandospirone (not available in the United States), a partial 5-HT1A receptor agonist, to relieve symptoms, improve psychometric parameters, and enhance quality of life in patients with functional dyspepsia.
The Study: Study participants were recruited from outpatients attending six Japanese hospitals. Eligibility was based on reported symptoms that met Rome II criteria (principally epigastric pain and fullness, early satiety, anorexia, nausea or vomiting, and belching) plus absence of pathology on endoscopy. Patients taking prokinetic or acid-suppressing medications, anxiolytics, or gastric irritants such as nonsteroidal anti-inflammatory drugs were excluded. Baseline data included a modified Gastrointestinal Symptom Rating Scale (GSRS), the SF-8 quality-of-life questionnaire, and the State-Trait Anxiety Inventory (STAI).
A total of 150 participants were randomized to treatment with placebo or tandospirone citrate in a dosage of 10 mg three times per day for four weeks. The primary end point was the change in abdominal symptom score from baseline to the end of week 4.
Results: The 75 patients treated with tandospirone were comparable to the 75 patients in the placebo group in all important variables. The average age of patients was 46 years and the mean duration of symptoms was about one year. Approximately one third of patients reported alcohol consumption, and about 11 percent were current smokers.
Both groups of patients showed significant improvements in symptom scores over four weeks, although overall improvement was greater in the tandospirone-treated patients. Improvement was most pronounced in upper abdominal pain and discomfort. The proportion of patients responding to treatment increased over time in those assigned to tandospirone, from 5.5 percent at week 1 to 31.5 percent by week 4. In the placebo group, response rates remained below 15 percent throughout the study. Scores on the SF-8 and STAI scales improved in both groups with no statistical difference between groups. Subanalysis of patients who responded to treatment found greater improvement in STAI and several items on the SF-8 scores in patients taking tandospirone. The most common adverse effect was dizziness, which was reported by 6.7 percent of the tandospirone group and 2.7 percent of the placebo group.
Conclusion: The authors conclude that tandospirone is associated with a significant improvement in symptoms of functional dyspepsia, especially upper abdominal pain and discomfort. The limited impact on other symptoms and the differences in STAI scores between responders taking tandospirone and those in the placebo group suggest that the anti-anxiety effects of this drug may be more notable than its direct effect on gastric motility in relieving symptoms of functional dyspepsia.