What antidepressant is recommended in someone with significant anxiety and co-morbid Irritable Bowel Syndrome (IBS) (diarrhea subtype) and functional gut disorder?

From the Guidelines

For someone with significant anxiety, comorbid Irritable Bowel Syndrome (diarrhea subtype), and functional gut disorder, a tricyclic antidepressant (TCA) such as amitriptyline or nortriptyline is recommended as the first-line treatment. This recommendation is based on the most recent and highest quality study available, which suggests that TCAs are effective in managing both anxiety symptoms and gut-related issues in patients with IBS 1. Amitriptyline can be started at a low dose of 10-25 mg at bedtime, gradually increasing to 25-50 mg if needed and tolerated. TCAs have anticholinergic and antispasmodic properties that help reduce intestinal motility, which is particularly beneficial for diarrhea-predominant IBS. They also modulate pain perception in the gut through effects on serotonin and norepinephrine pathways.

Some key points to consider when prescribing TCAs for IBS include:

• Starting with a low dose and gradually increasing as needed and tolerated
• Monitoring for side effects such as dry mouth, constipation, and sedation, which can actually be advantageous in this clinical scenario
• Considering alternative options such as SSRIs or SNRIs if TCAs are not tolerated or effective
• Continuing treatment for at least 4-6 weeks before assessing efficacy, and if beneficial, maintaining for 6-12 months before considering gradual tapering

It's also important to note that the American Gastroenterological Association (AGA) suggests against using SSRIs for patients with IBS, due to low certainty in the evidence 1. However, SSRIs may be considered as an alternative option if symptoms do not respond to TCAs, particularly if a mood disorder is suspected 1.

In terms of specific dosing and treatment duration, the evidence suggests that TCAs can be effective at low doses, and that treatment should be continued for at least 4-6 weeks before assessing efficacy 1. Overall, the use of TCAs in patients with IBS and anxiety symptoms is supported by the most recent and highest quality evidence available.

From the Research

Antidepressant Recommendations for IBS and Functional Gut Disorder

• For patients with significant anxiety and co-morbid Irritable Bowel Syndrome (IBS) (diarrhea subtype) and functional gut disorder, tricyclic antidepressants (TCAs) are recommended, especially for those with disturbed sleep patterns 2.
• Selective serotonin reuptake inhibitors (SSRIs) such as paroxetine, fluoxetine, or sertraline may also be beneficial for patients with IBS and mild to moderate co-morbid depression 2, 3.
• Buspirone, a 5-HT1A agonist, may be useful for patients with functional dyspepsia and IBS, as it enhances gastric accommodation and reduces postprandial symptoms 4.
• Venlafaxine, a serotonin norepinephrine reuptake inhibitor, may also be effective in reducing sensations to distension and improving gastric accommodation, but its use is limited by adverse effects 4.

Considerations for Antidepressant Use

• Antidepressants appear to be more effective in treating patients with anxiety or depression, and larger prospective trials are needed to assess their clinical and pharmacodynamic effects on gut sensorimotor function 4, 5.
• A meta-analysis of randomized controlled trials found that antidepressants, including TCAs and SSRIs, are efficacious in reducing symptoms in IBS patients, with a relative risk of symptoms not improving of 0.66 (95% CI 0.57-0.76) 5.
• Psychological therapies, such as cognitive behavioral therapy, relaxation therapy, and hypnotherapy, may also be effective treatments for IBS, although the quality of the evidence is limited 5.
• The treatment effects of antidepressants and psychological therapies may be overestimated due to issues with trial design, including lack of blinding 5, 6.