Overactive bladder syndrome - fesoterodine

Overactive bladder syndrome is an inability to hold urine in the bladder at will, and around 10% of the population over the age of 40 is affected.

Antimuscarinic agents are used to reduce bladder contractions, which improves the ability to retain urine, and reduces both the frequency of visits to the toilet and the number of episodes of incontinence. However, the efficacy of existing drug treatments could be better, and there are numerous drug-drug interaction problems. So new agents that are more effective and do not interact with other drugs are needed.

A new agent is being developed by Schwarz Pharma. Fesoterodine, formerly known as SPM 907, is an antimuscarinic agent, and has great potential as a once daily therapy for overactive bladder syndrome.

In a Phase I clinical trial to investigate its pharmaco-kinetics, 24 healthy male volunteers were randomised to receive a single oral dose of 4, 8 or 12mg fesoterodine.¹ Maximum plasma levels were reached five hours after administration, and mean half-life ranged from 7.3 to 8.9 hours.

Another trial has also been carried out to look at the influence of ethnic origin on its pharmacokinetics.² Single oral doses of 8mg were given to 16 healthy Caucasian and black African subjects. It was safe and well tolerated, and no variations in pharmacokinetics were observed between the ethnic groups.

A double blind randomised placebo-controlled trial has also taken place.³ Healthy volunteers were given multiple ascending oral doses of fesoterodine of 4, 8, 12, 20 and 28mg or placebo once a day for three days. Doses of 12mg and above gave increased residual urinary volume.

At higher doses other antimuscarinic effects such as a mild to moderate increase in heart rate and decreased salivary secretion were observed. Phase III trials are well under way.