Leon-Ferre, R. A. et. al.

A randomized, double-blind, placebo-controlled trial of oxybutynin (Oxy) for hot flashes (HF): ACCRU study SC-1603.

Abstract GS6-02, San Antonio Breast Cancer Symposium, 2018.

Hot flashes can be debilitating for many women. Often a result of natural menopause, hot flashes are also a common side effect of tamoxifen and aromatase inhibitors. Women who take these medications as part of breast cancer treatment must often cope with this issue. Many women stop the therapy because of intolerable hot flashes. Medical remedies are used with variable success. Oxybutynin is one such remedy.

The investigators selected 150 women who were experiencing hot flashes. About two-thirds of the women were taking endocrine therapy for breast cancer. Each participant rated her hot flashes on a standardized scale. The group was then randomized to lower or higher dose Oxybutynin or placebo. The follow up period was 6 weeks.

The frequency and severity of hot flashes were significantly lower among the women who took Oxybutynin. The higher dose of the medication appeared to be associated with greater efficacy. Women who took Oxybutynin also reported better quality of life versus placebo.

Reported side effects included stomach pain, confusion, headaches, diarrhea, nausea, dry eyes, dry mouth, constipation and difficulty urinating. However, the rate of cessation of the drug due to adverse effects was equivalent across all three groups.

This study supports the use of Oxybutynin as an effective treatment for hot flashes, including those caused by endocrine therapy for breast cancer. Its side effects were not reported as severe. However, it must be kept in mind that the study period was short, and more significant side effects may appear with longer use. Some women will have contraindications to taking the medication. More investigation, with more women and over a longer time period, is warranted.