Comparison of fluoxetine and duloxetine hydrochloride therapeutic effects on patients with constipation-predominant irritable bowel syndrome

As few randomized clinical trials have verified the efficacy of selective and norepinephrine reuptake inhibitors in IBS, the current study made an inclusive comparison between them, and their effectiveness in IBS-C was proven.

Irritable bowel syndrome with constipation (IBS-C) is a functional bowel disorder characterized by changes in bowel movements and abdominal pain in the absence of identifiable structural abnormalities. Despite much progress in the treatment of other types of IBS, limited treatments are available for IBS-C.

The study population comprised 182 IBS-C patients who were randomly divided into 3 groups according to treatment type. One group was given 20 mg of dicyclomine and fluoxetine, the second group received dicyclomine along with duloxetine hydrochloride, and the third group received dicyclomine only for two months. The severity of symptoms was recorded by questionnaire at the beginning and end of the treatment.

Results: 

The average age and BMI of the patients were 28.5 ± 5.2 years and 25.2 ± 2.4 kg/m2, respectively. Duloxetine was more effective than fluoxetine in reducing flatulence (p=0.043), abdominal pain intensity (p≤0.046), and duration (p≤0.003), in increasing the quality of life (p≤0.046), and the frequency of fecal excretion in patients (p≤0.004).

Based on the study findings, fluoxetine and duloxetine had greater therapeutic effects on all symptoms of IBD than dicyclomine, with duloxetine, specifically, being more effective than fluoxetine. Further studies on larger groups are suggested to determine the best dosage and identify any potential side effects of these drugs.