Study details
The women randomized in ACCRU study SC-1603 had had hot flashes for at least 30 days and were experiencing at least 28 of them each week. Concurrent stable-dose antidepressants, gabapentin, and pregabalin were allowed, whereas concurrent potent anticholinergics were not. Two-thirds of the women were on tamoxifen or an aromatase inhibitor.
In addition to the dramatic reduction in hot flash scores seen with oxybutynin, the drug was associated with marked reductions in hot flash frequency: 30% with placebo versus 60% with oxybutynin 2.5 mg b.i.d. and 75% with oxybutynin 5 mg b.i.d. (P less than .01 across groups and for each dose compared with placebo), Dr. Leon-Ferre reported.
Most of the 10 domains on the Hot Flash-Related Daily Interference Scale were significantly more improved with both doses of oxybutynin relative to placebo. The exceptions were mood and life enjoyment, which were significantly more improved only with the higher dose, and concentration and sexuality, which were not significantly more improved with either dose.
Both doses of oxybutynin were overall well tolerated, according to Dr. Leon-Ferre. Each was associated with higher incidence of dry mouth, abdominal pain, and difficulty urinating relative to placebo, as expected from what is known about the drug. The higher dose had a greater incidence of dry eyes, episodes of confusion, diarrhea, and headache.
Dr. Leon-Ferre disclosed that he had no conflicts of interest. The study was funded by the Breast Cancer Research Foundation.
SOURCE: Leon-Ferre RA et al. SABCS 2018 Abstract GS6-02.