Gabapentin, an antiepileptic agent, significantly reduces the frequency and intensity of hot flashes in men who take androgen deprivation therapy for prostate cancer, according to results of a phase III study presented at the annual meeting of the American Society of Clinical Oncology.

“To my knowledge, this is the first nonhormonal treatment of hot flashes in men, where results from a placebo-controlled trial are positive enough to support that a nonhormonal medication can be used to help some of our patients,” said the study’s lead investigator, Mayo Clinic oncologist Charles Loprinzi, MD.

The 223 men (mean age, 70 years; at least 14 hot flashes per week) were randomized into one of four arms for 28 days: placebo, 300 mg daily gabapentin, increasing dosage to ceiling of 600 mg daily, and increasing dosage to 900 mg daily.

Using a scale from 1 to 4, patients recorded the daily number of mild, moderate, severe, and very severe hot flashes. Researchers found median frequency and score decreased between 22 to 27 percent in the placebo group, 23 to 30 percent in the 300 mg group, 32 to 34 percent in the 600 mg group, and 44 percent to 46 percent in the 900 mg arm.

The highest dose used in the study was less than one third of the dose that can be used to treat seizures, Loprinzi said, leaving room for possible improvements in effect against hot flashes with an increase in dosage. His research team may explore that idea in the future.

Gabapentin reduced the frequency and intensity of hot flashes by up to 46 percent compared with placebo, and gabapentin was associated with fewer side effects than placebo.

“This [gabapentin] provides an immediate clinical option that has not been previously available for treatment of hot flash side effects, and it is a welcome one,” concluded Loprinzi.