- Oxybutynin significantly improves hot-flash frequency and severity and QoL, according to data from ACCRU study SC-1603.
Why this matters
- Hot flashes are associated with decreased QoL and premature discontinuation of breast cancer treatment.
- Oxybutynin does not interfere with the metabolism of tamoxifen.
- 150 women experiencing hot flashes ≥28 times a week >30 days were randomly assigned to receive twice-daily 2.5 mg (n=51) or 5 mg (n=50) oral oxybutynin or placebo for 6 weeks.
- 62% were receiving tamoxifen or an aromatase inhibitor.
- Weekly hot flash diary, Hot Flash Related Daily Interference Scale (HFRDIS), and symptom experience questionnaire.
- 113 patients had postbaseline data compared with placebo (n=38):
- Patients receiving 2.5 mg (n=40) had lower mean hot flash score (−10 vs −5.1; P=.003) and greater reduction in average weekly hot flashes (−4.6 vs −2.3; P=.002).
- Patients receiving 5 mg (n=35) had lower mean hot flash score (−16.2 vs −5.1; P<.001 and greater reduction in average weekly hot flashes vs p>
- HFRDIS showed improvement related to work, social and leisure activities, sleep, relations, and overall QoL with 2.5 mg, plus life enjoyment and mood with 5 mg.
- Significant adverse effects included dry mouth, abdominal pain, and difficulty urinating at both doses, and dry eyes, confusion, diarrhea, and headaches with 5 mg.
- Funding: Breast Cancer Research Foundation.
- Dr. Leon-Ferre reported receiving travel support from Immunomedics.
- No data on long-term toxicity.