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Study on the Effects of Venlafaxine and Gut Microbiome in Patients with Major Depressive Disorder

Verified siteRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial focuses on studying Major Depressive Disorder, a common mental health condition characterized by persistent feelings of sadness and loss of interest. The study will use a medication called Venlafaxine, which is commonly prescribed to help alleviate symptoms of depression. The purpose of the study is to explore how the community of bacteria in the gut, known as the gut microbiome, is related to the effectiveness of depression treatment and any side effects experienced.

Participants in the study will begin a new treatment with Venlafaxine and will be monitored to see how their gut microbiome changes in response to the medication. The study aims to find out if these changes in the gut bacteria are linked to improvements in depression symptoms and any side effects that may occur. Additionally, the study will look at how the levels of the medication in the blood might influence these changes and the overall effectiveness of the treatment.

The study will take place over a period of time, with participants being observed for changes in their symptoms and gut microbiome. The goal is to better understand the relationship between the gut microbiome and depression treatment, which could lead to more effective ways to manage the condition in the future.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Introduction to the trial

    Upon joining the study, the patient will receive an overview of the trial's purpose, which is to explore the relationship between gut bacteria and the effectiveness of depression treatment.

    The patient will be informed about the medication venlafaxine, which is an antidepressant taken orally.

  2. Step 2

    Medication administration

    The patient will begin taking venlafaxine as prescribed. The dosage and frequency will be determined by the healthcare provider based on individual needs.

    The medication is part of the treatment for major depressive disorder and aims to relieve symptoms and monitor side effects.

  3. Step 3

    Monitoring and assessments

    Throughout the trial, the patient will undergo regular assessments to monitor changes in depression symptoms and any side effects experienced.

    These assessments will also include evaluating changes in the gut microbial profile, which may be influenced by the medication.

  4. Step 4

    Blood plasma level evaluation

    The patient will have blood samples taken to measure therapeutic blood plasma levels. This helps in understanding how the drug is absorbed and its impact on gut bacteria and treatment effectiveness.

  5. Step 5

    Completion of the trial

    The trial is expected to conclude by December 31, 2025. At the end of the study, the patient will receive a summary of their participation and any relevant findings related to their treatment.

Who can join the trial?

5 criteria

  • Must be **18 years old or older**.
  • Must have a main diagnosis of **unipolar depression**, which is a type of depression that does not include mood swings from high to low.
  • Must need a prescription for an **antidepressant**, which is a medication used to help improve mood and relieve symptoms of depression.
  • Must be starting a new treatment with an **SSRI/SNRI or TCA antidepressant**. These are different types of antidepressants that work in various ways to help improve mood.
  • Must have already tried one or more antidepressants without success or experienced side effects.
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Investigated drugs

  • Fluoxetine

    is a medication commonly used to treat depression. It works by increasing the levels of serotonin, a natural substance in the brain that helps maintain mental balance. In this trial, it is used to evaluate its effectiveness in relieving symptoms of depression and its interaction with gut microbiota.

  • Sertraline

    is another medication used to treat depression. It also works by affecting serotonin levels in the brain. This trial examines how sertraline helps alleviate depression symptoms and its relationship with the gut microbial community.

  • Citalopram

    is a medication that treats depression by increasing serotonin levels in the brain. The trial investigates its role in symptom relief and its effects on gut microbiota in patients with depression.

  • Escitalopram

    is similar to citalopram and is used to treat depression by enhancing serotonin activity in the brain. The study aims to understand its effectiveness in symptom relief and its interaction with gut bacteria.

  • Paroxetine

    is a medication used to manage depression by boosting serotonin levels in the brain. This trial explores its impact on depression symptoms and its association with the gut microbiome.

What is already known about the treatment

Fluoxetine – Fluoxetine is typically administered orally in the form of capsules or tablets. It is a well-established medication in the treatment of depression, with extensive documentation in medical literature. The primary use of Fluoxetine is to treat major depressive disorder, among other conditions. It works by increasing the levels of serotonin, a neurotransmitter, in the brain, which helps improve mood and emotional state. Fluoxetine is classified as a selective serotonin reuptake inhibitor (SSRI).

Investigated diseases

Major Depressive Disorder – This is a mental health condition characterized by persistent feelings of sadness, hopelessness, and a lack of interest or pleasure in activities. It can affect how a person thinks, feels, and handles daily activities, such as sleeping, eating, or working. The disorder often involves changes in appetite and sleep patterns, fatigue, and difficulty concentrating. Emotional symptoms may include feelings of worthlessness or excessive guilt. Physical symptoms can also manifest, such as unexplained aches and pains. The progression of the disorder can vary, with symptoms lasting for weeks, months, or even longer if untreated.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-518101-18-02Protocol codeNL79264.091.21Estimated enrolment25 patientsSponsorStichting Radboud University Medical Center

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