AUA 2013: Newer OAB agent viable alternative to antimuscarinics

May 7, 2013

Data from a recent multicenter study provide new evidence that the beta-3 adrenoceptor agonist mirabegron (Myrbetriq) appears to be a viable alternative in patients with overactive bladder (OAB) who are poor responders to antimuscarinic agents or intolerant of their adverse events.

Data from a recent multicenter study provide new evidence that the beta-3 adrenoceptor agonist mirabegron (Myrbetriq) appears to be a viable alternative in patients with overactive bladder (OAB) who are poor responders to antimuscarinic agents or intolerant of their adverse events.

“At all doses, mirabegron revealed a very low incidence of typical antimuscarinic side effects and a statistically significant benefit for OAB symptoms over placebo,” said first author Victor Nitti MD, of New York University Langone Medical Center, New York.

In a pooled analysis of three phase III randomized, double-blind, placebo-controlled, 12-week studies, which assessed three doses of mirabegron (25, 50, and 100 mg) in patients with OAB, Dr. Nitti reviewed the incidence of adverse events commonly associated with the use of antimuscarinics. One study arm used tolterodine extended release (Detrol LA), 4 mg, as an active control. All three studies had exactly the same methodology and inclusion and exclusion criteria.

The incidence of common antimuscarinic-associated adverse events was generally low across the treatment groups. However, incidence of dry mouth was five times higher in the tolterodine treatment group (50/495 patients; 10.1%) versus the mirabegron group (54/2,736 patients; 2.0%) and the placebo group (29/1,380 patients; 2.1%). There was no increase in side effects with increasing mirabegron dosage, and there was no significant difference between doses.

Pruritus had a fivefold higher occurrence rate in the tolterodine group (7/495 patients; 1.4%) versus the mirabegron group (7/2,736 patients; 0.3%) and the placebo group (5/1,380 patients; 0.4%). Incidences of dry mouth and pruritus in the mirabegron groups were similar to that in the placebo group. Urinary retention was higher in both the tolterodine group (3/495 patients; 0.6%) and placebo group (6/1,380 patients; 0.4%) compared with mirabegron-treated patients (1/2,736 patients; <0.1%).

Dr. Nitti is a consultant and investigator for Astellas.