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General Information
Vowst (fecal microbiota spores, live-brpk) is a microbiota-based therapeutic.
Vowst is specifically indicated to prevent the recurrence of Clostridioides difficile infection (CDI) in individuals 18 years of age and older following antibacterial treatment for recurrent CDI (rCDI).
Vowst is supplied as capsules for oral administration.
Prior to taking the first dose
- Complete antibacterial treatment for recurrent CDI 2 to 4 days before initiating treatment with Vowst .
- Drink 296 mL (10 oz) magnesium citrate, on the day before and at least 8 hours prior to taking the first dose of Vowst .
- Do not eat or drink, except for small amount of water, for at least 8 hours prior to taking the first dose.
Dosing regimen
- The dosage of Vowst is 4 capsules taken orally once daily for 3 consecutive days.
- Take each dose (4 capsules) on an empty stomach prior to the first meal of the day.
Mechanism of Action
Vowst (fecal microbiota spores, live-brpk) is a bacterial spore suspension in capsules for oral administration. The administration of fecal microbiota is thought to restore the gut microbiome to prevent further episodes of CDI.
Vowst is manufactured from human fecal matter sourced from qualified donors. Human fecal matter donations are routinely tested for a panel of transmissible pathogens. Donors do not have dietary restrictions with respect to potential food allergens. The spore suspension is generated by treating fecal matter with ethanol to kill organisms that are not spores, followed by filtration steps to remove solids and residual ethanol. Each capsule of Vowst contains between 1x106 and 3x107 Firmicutes spore colony forming units in 92 ± 4% (w/w) glycerol in saline.
Side Effects
Adverse effects associated with the use of Vowst may include, but are not limited to, the following:
- abdominal distension
- fatigue
- constipation
- chills
- diarrhea
Clinical Trial Results
The FDA approval of Vowst was based on a randomized placebo-controlled multi-center study. The primary objective was to demonstrate the reduction of CDI recurrence with Vowst. Enrolled participants were 18 years of age or older and had a confirmed diagnosis of recurrent CDI (with a total of ≥3 episodes of CDI within 12 months). Participants were required to have symptom resolution, defined as <3 unformed stools in 24 hours for 2 or more consecutive days prior to randomization, following 10 to 21 days of standard-of-care antibacterial treatment with vancomycin or fidaxomicin. Participants were stratified by antibacterial received (vancomycin or fidaxomicin) and age (<65 years or ≥65 years) and randomized 1:1 to receive a dose of Vowst or placebo once daily for 3 consecutive days. The day prior to starting the assigned treatment regimen, participants were required to drink 296 mL (10 oz) of magnesium citrate.
All participants fasted for at least 8 hours before taking the first dose of Vowst. Participants were also required to continue fasting for 1 hour after the first day of treatment with Vowst. For Days 2 and 3, Vowst was taken in the morning before breakfast.
The intent-to-treat population included 182 participants.
The primary efficacy endpoint was CDI recurrence through 8 weeks after completion of treatment. Participants were assessed for recurrence, which was defined as ≥3 unformed stools per day for 2 consecutive days with continued diarrhea until antibacterial treatment was initiated, a positive C. difficile test on a stool sample determined by a toxin assay, and assessment by the Investigator that the clinical condition of the participant warranted antibacterial treatment. Through 8 weeks after treatment, CDI recurrence in Vowst-treated participants was lower compared to that in placebo-treated participants (12.4% compared to 39.8%).
Through 12 weeks after treatment, the recurrence rates for Vowst and placebo recipients were 18.0% and 46.2% (43/93), respectively. Through 24 weeks after treatment, recurrence rates for Vowst and placebo recipients were 21.3% and 47.3%, respectively.