Vibegron (brand name: Gemtesa) is the latest drug used to treat overactive bladder that has been approved by the FDA in the USA. Gemtesa will be available in the US as prescription-only medication from April 2021. In this post, I will summarise:
- Licensed use and legal status of vibegron (US)
- It’s a mechanism of action
- The effectiveness of vibegron: summary of clinical trial
- vibegron vs mirabegron: what is the difference?
- Alternative drugs used in the treatment of overactive bladder in the UK
Vibegron – licensed use and legal status
Vibegron is used in the management of overactive bladder. Common symptoms of overactive bladder include:
- Difficulty in controlling bladder contractions
- Frequent urination – passing urine frequently in small volumes
- Difficulty in controlling the need for urination – sudden urgency for urination and leakage episodes)
- Waking up at night to pass urine
In the US, Vibegron (Gemtesa) is a prescription-only medication. Almost with certainty, vibegron would be classified as the prescription-only drug should it be approved in the UK and European market.
How does Vibegron work?
Vibegron is classified as a selective β3-adrenoreceptor agonist. Vibegron is the second β3-adrenoreceptor agonist licensed for the management of overactive bladder. The first one, mirabegron (brand name: Betmiga) is currently available in the UK.
β3-adrenoreceptor agonist affects the bladder’s contraction by acting on β3 receptors found in the urinary bladder. As a result, muscle contractions in the bladder are decreased (relaxation of the muscle), allowing to store more urine, hence reducing the need for frequent urination.
The effectiveness in controlling symptoms
The evidence for the effectiveness of vibegron in controlling of the overactive bladder the symptoms comes from clinical trials. When investigated for its efficacy, vibegron was found to reduce the number of urgency episodes, urge incontinence significantly (statistical significance). Vibegron also increased urination volume and a reduced number of micturitions (Staskin et al., 2020).
Overall it was concluded that treatment with Gemtesa is well tolerated and the drug has a ‘favourable’ safety profile.
The most common side effects experienced by patients taking Gemtesa during the clinical trial were (ibid):
- nausea, and
- upper respiratory tract infection
Vibegron vs mirabegron: what is the difference?
- Both drugs belong to the same class of drugs – β3-adrenoreceptor agonist, hence have the same mechanism of action.
- Both drugs come in forms of tablets.
- Mirabegron (Betmiga) is available as 25 and 50mg prolonged-release tablets (25mg or 50mg of mirabegron per tablet), whereas vibegron (Gemtesa) as 75mg tablet (each tablet contain 75mg of active ingredient).
- Both drugs are taken once daily to control symptoms of urinary frequency.
- Most common side effects for mirabegron (Betmiga) are urinary tract infections, headache, dizziness, tachycardia (rapid heart rate), nausea, constipation, diarrhoea (eMC, 2020). Although it seems that mirabegron has more common side effects, most of them were observed in post-marketing experience, after the launch of the drug to the public. Vibegron has not been available for public use yet.
- Most common side effects for Gemtesa: see the previous paragraph.
Alternative drugs in the treatment of overactive bladder
At the moment in the UK, mirabegron is not recommended as a first-line treatment drug. Mirabegron is reserved as an optional treatment in the symptoms of overactive bladder in patients whom (NICE, 2013):
- antimuscarinic drugs are contraindicated (not recommended)
- antimuscarinic drugs are ineffective
- antimuscarinic drugs cause unacceptable side-effects.
One would expect the same recommendation if vibegron becomes available in the UK.
Treatment options with antimuscarinic drugs in the UK for the management of overactive bladder:
- Trospium chloride
- Propiverine hydrochloride
eMC (2020). Summary of product characteristics: Betmiga 25 mg prolonged-release tablets. Available at: https://www.medicines.org.uk/emc/product/2977/smpc Accessed on 30/12/2020
NICE, (2013). Mirabegron for treating symptoms of overactive bladder. Available at: https://www.nice.org.uk/guidance/ta290/chapter/1-Guidance Accessed on 31/12/2020
Staskin D, Frankel J, Varano S, Shortino D, Jankowich R, Mudd PN Jr. International Phase III, Randomized, Double-Blind, Placebo and Active Controlled Study to Evaluate the Safety and Efficacy of Vibegron in Patients with Symptoms of Overactive Bladder: EMPOWUR. J Urol. 2020 Aug;204(2):316-324. doi: 10.1097/JU.0000000000000807. Epub 2020 Feb 18. PMID: 32068484. Available at: https://doi.org/10.1097/ju.0000000000000807 Accessed on 30/12/2020