In final draft guidance NICE is recommending Astellas’s Betmiga (mirabegron) for the treatment of overactive bladder syndrome in patients for whom antimuscarinic drugs - the established treatment for the condition - are not suitable.

Professor Carole Longson, NICE health technology evaluation centre director, said: “Mirabegron represents a new class of drug treatment for OAB and is the first of its kind. Offering mirabegron as an option for treatment, with clear advice about its potential benefits and side effects will help improve quality of life for people living with this distressing condition.

“Having an over-active bladder can significantly affect physical, psychological and social well-being. The condition can cause people to find work and normal social activities difficult and some become so anxious about their symptoms that they find it hard to leave their homes. In frail older people, the condition is associated with an increased risk of falls, fractures and urinary tract infections.”

Astellas’s drug is a once daily oral _3-adrenoceptor agonist with a different mechanism of action compared to antimuscarinics, the current treatment standard.

These drugs work by binding to muscarinic receptors in the bladder and inhibiting involuntary bladder contractions, but Betmiga – known as Myrbetriq in the USA - works by stimulating the _3 receptors in the detrusor muscle of the bladder, causing relaxation of the bladder muscle during the storage phase of the micturition cycle.

Astellas says that this improves the storage capacity of the bladder without inhibiting bladder voiding.

For NICE, it all comes down to cost effectiveness and Betmiga was deemed to fall “well below” NICE’s £20,000 QALY limit when compared against Pfizer’s Detrusitol (tolterodine) 4mg, a standard, NICE-approved medicine for OAB.

But it has not been given a first-line approval as it can still only be used after the failure of standard medicines; this is however within the drug’s European licence remit. Final guidance on the drug is expected within the next month.

Astellas already has a drug available in the UK for urinary urgency and incontinence called Vesicare, which has reached blockbuster sales globally. Betmiga is designed as a successor to this drug, and Astellas will hope it too will reach the $1billion sales mark at its peak – and NICE’s approval will be a boost toward that goal. 

Overactive bladder syndrome is common; it’s estimated to affect one in six men and women aged 40 years and over and around five million people are thought to have OAB in England and Wales. Symptoms include an urgent need to go to the toilet, going to the toilet frequently, and sometimes accidentally leaking urine before you can get to the toilet.