PARIS — Treatment with paroxetine led to a significant improvement in the clinical status of patients with irritable bowel syndrome in a randomized, placebo-controlled study with 74 patients.
Results from open-label studies had suggested that selective serotonin reuptake inhibitors might be beneficial for patients with irritable bowel syndrome (IBS), but this was the first double-blind, placebo-controlled study to test the hypothesis, Prakash S. Masand, M.D., said in a poster presentation at the 24th Congress of the Collegium Internationale Neuro-Psychopharmacologicum.
The study's primary efficacy end point was improvement in symptom severity based on a symptom diary. This analysis has not been completed. The current report focused on the study's two secondary efficacy end points: the percentage of patients with an increase of one or two points in their Clinical Global Impression-Improvement (CGI-I) scale score and the percentage of patients with a drop in their Clinical Global Impression-Severity (CGI-S) scale score of at least 1 point. The study was funded by GlaxoSmithKline, which markets paroxetine (Paxil).
The study enrolled patients aged 18-75 years old who met the modified Rome II criteria for IBS and had IBS symptoms for at least 1 year. The average age of the patients was 49 years old, 81% were women, and 75% were white, said Dr. Masand, director of the psychopharmacology consultation program at Duke University in Durham, N.C.
Of 92 patients screened, 76 met the entry criteria; 2 of these patients responded during the placebo run-in phase and so were excluded. The remaining 74 patients were randomized to treatment with 12·5-50 mg of controlled-release paroxetine per day or placebo. Treatment continued for 12 weeks and then patients were tapered off of treatment. The average was 33 mg/day.
During the study, five patients dropped out from the paroxetine group and four from the placebo group. The efficacy analysis was done on an intention-to-treat basis with the last observation carried forward for the dropouts.
With the efficacy criterion of an increase in the CGI-I score of 1 or 2 points, 26 patients in the paroxetine group met this standard (70%), compared with 15 in the placebo group (41%), a statistically significant difference, Dr. Masand reported. When the criterion of an improvement in the CGI-S scale of at least 1 point was used, 21 patients in the paroxetine group (57%) met this standard, compared with 10 (27%) in the placebo group, also a statistically significant difference.
Common adverse effects were drowsiness in 36% of patients treated with paroxetine and 24% on placebo, and female genital disorders in 26% of paroxetine patients and 12% of placebo patients.
Modified Rome II Symptom Criteria
At least 12 weeks or more, which need not be consecutive, in the preceding 12 months of abdominal discomfort or pain that has two out of three features:
▸ Relieved with defecation.
▸ Onset associated with a change in frequency of stool.
▸ Onset associated with a change in form (appearance) of stool.
Other symptoms that are not essential but support the diagnosis of IBS:
▸ Abnormal stool frequency (greater than three bowel movements/day or less than three bowel movements/wk).
▸ Abnormal stool form (lumpy/hard or loose/watery stool).
▸ Abnormal stool passage (straining, urgency, or feeling of incomplete evacuation).
▸ Passage of mucus.
▸ Bloating or feeling of abdominal distension.
Source: Dr. Masand