Vowst (oral FMT drug) for recurrent C. difficile infection


Vowst’s FDA approval for recurrent Clostridioides difficile (C. difficile) infection

Recurrent Clostridioides difficile infection (CDI) poses a significant healthcare challenge, often leading to high relapse rates and associated healthcare costs. Recent advancements include the FDA approval of Vowst, an oral fecal microbiota transplant (FMT) drug designed as a prophylactic therapy to prevent recurrent CDIs. Vowst aims to restore the disrupted gut microbiota, inhibit the germination of C. difficile spores, and promote microbiome repair. This article discusses the clinical trials, approval journey, and broader implications of Vowst’s introduction to the market.

Vowst: A Novel Therapeutic Approach

The introduction of Vowst marks a significant step in the management of CDI. Unlike traditional methods such as antibiotic therapy, Vowst utilizes a formulation of live fecal microbiota spores, which are administered orally. This method aligns with the shift towards using microbiota-based products to manage diseases associated with dysbiosis.

Vowst: Mechanism of Action

The mechanism of action of Vowst, the oral fecal microbiota transplant (FMT) drug approved for the prevention of recurrent Clostridioides difficile infection (CDI), involves several key steps that target the restoration and stabilization of the gut microbiota. Here’s how Vowst functions:

1. Restoration of Gut Microbiota

Vowst contains a formulation of live spores from fecal microbiota, specifically selected for their ability to re-establish a healthy balance within the gut. By reintroducing these spores into the intestinal tract, Vowst helps replenish the beneficial bacteria that may have been depleted due to antibiotic use or the initial CDI. This restoration is crucial as it helps re-establish the natural microbial community which plays a significant role in resisting pathogenic colonization, including that of C. difficile.

2. Inhibition of C. difficile Spore Germination

One of the direct targets of Vowst is the lifecycle of C. difficile, particularly the germination of its spores. C. difficile spores are the primary form of the bacterium that contribute to infection spread and recurrence. Vowst works by creating an environment in the gut that is unfavorable to the germination of these spores. This is achieved by manipulating the bile acid pool within the gut.

3. Manipulation of Bile Acid Metabolism

The gut microbiota influences bile acid metabolism significantly. In a healthy gut, the microbiota converts primary bile acids to secondary bile acids. Primary bile acids, such as cholic acid and chenodeoxycholic acid, can promote the germination of C. difficile spores. In contrast, secondary bile acids, such as lithocholic acid and deoxycholic acid, inhibit spore germination and the growth of C. difficile.

Vowst leverages this mechanism by promoting the conversion of primary bile acids into secondary bile acids. The spores in Vowst include species that possess the enzyme 7α-dehydroxylase, which is critical for this conversion process. By increasing the concentration of secondary bile acids, Vowst helps inhibit the growth and germination of C. difficile spores, thus reducing the risk of infection recurrence.

Clinical Observations

Clinical trials and studies of Vowst have shown that the introduction of these beneficial spores leads to a rapid and sustained modification of the gut microbiota. This alteration not only reduces the recurrence of CDI but also supports the overall health of the gut microbiome, making it less hospitable to C. difficile colonization. Measurements of bile acid concentrations in patients treated with Vowst have demonstrated significant shifts towards secondary bile acids, correlating with reduced rates of CDI recurrence.

In summary, the mechanism of action of Vowst in preventing recurrent CDI revolves around the strategic restoration of beneficial gut microbiota, inhibition of C. difficile spore germination through manipulation of bile acid metabolism, and the overall stabilization of the gut environment. This comprehensive approach addresses the underlying causes of CDI recurrence, offering a promising solution to a persistent healthcare challenge.

Clinical Trials and FDA Approval

Vowst underwent rigorous clinical trials, which demonstrated its efficacy in preventing recurrent CDI. The FDA approval was based on the positive outcomes from these trials, which highlighted its safety and effectiveness. The trials showed a significant reduction in recurrence rates among patients treated with Vowst compared to those receiving placebos.

How to take Vowst

Vowst is administered as an oral capsule, designed to be taken in a specific dosing regimen that optimizes its effectiveness for preventing recurrent Clostridioides difficile infection (CDI). Here’s how the dosing regimen is structured:

Dosing Schedule

Vowst is delivered in a regimen of four capsules taken once daily on an empty stomach. This regimen is continued for three consecutive days. The treatment begins within the first four days after the completion of antibiotic therapy for CDI, as this timing helps ensure that the Vowst capsules can effectively re-establish and stabilize the gut microbiota after antibiotic disruption.

Preparation for Dosing

Before starting the Vowst treatment, patients are required to undergo a bowel cleansing procedure. This preparation involves taking a cleansing agent such as magnesium citrate (approximately 300 mL, or 10 ounces) or, in cases of renal impairment, a 250 mL dose of a polyethylene glycol electrolyte solution. This bowel cleansing helps remove residual antibiotics and other substances that could inhibit the effectiveness of the microbiota contained within the Vowst capsules.

Importance of the Administration Protocol

The specific administration protocol for Vowst, including the pre-dosing bowel cleanse and the timing of capsule ingestion relative to the end of antibiotic treatment, is designed to maximize the probability of successful engraftment of the beneficial spores from the capsules into the patient’s intestinal tract. This process is critical for restoring the gut microbiota to a state that can resist further C. difficile infections.

This dosing regimen highlights the innovative approach of using oral capsules to deliver fecal microbiota therapy, providing a non-invasive and patient-friendly method compared to other FMT methods like colonoscopy or naso-duodenal tubes. The use of capsules significantly simplifies the administration of the treatment and reduces the discomfort and medical risks associated with more invasive procedures.

Economic Implications

The approval of Vowst is also significant from an economic perspective. While the upfront costs of FMT drugs like Vowst are high, they are justified by the potential reductions in hospitalizations and healthcare expenditures associated with recurrent CDIs. Economic analyses suggest that despite higher initial costs, the overall expenditure on healthcare can be reduced with effective management of CDI recurrences.

Future Prospects and Challenges

The journey of Vowst from development to market is a promising sign for the future of FMT-based therapies. However, challenges remain, such as understanding the long-term impacts of microbiota-based products and addressing potential variations in treatment efficacy among different populations. The success of Vowst and similar products will depend on ongoing research, adaptation of treatment protocols, and comprehensive pharmacovigilance to ensure safety and efficacy.


Vowst represents a groundbreaking advancement in the prevention of recurrent CDIs, with significant implications for patient care and healthcare economics. As the medical community continues to explore the potentials of FMT, products like Vowst are at the forefront of transforming therapeutic approaches to complex bacterial infections.

This article provides a thorough overview of the challenges and breakthroughs associated with developing new treatments for recurrent CDI, emphasizing the importance of innovative approaches like Vowst in changing the landscape of infectious disease management.

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Last update: 12 April 2024, 06:52


Gastroenterologist - Hepatologist, Thessaloniki

PhD at Medical School, Aristotle University of Thessaloniki, Greece

PGDip at Universitair Medisch Centrum Utrecht, The Netherlands

Ex President, Hellenic H. pylori & Microbiota Study Group