Pandya, K.J., Morrow, G.R., Roscoe, J.A., Zhao, H., Hickok, J.T., Pajon, E., … Flynn, P.J. (2005). Gabapentin for hot flashes in 420 women with breast cancer: A randomised double-blind placebo-controlled trial. Lancet, 366, 818–824.

Assess efficacy of gabapentin in controlling hot flashes in women with breast cancer

Patients were randomized to placebo, gabapentin 300 mg/day, or gabapentin 300 mg three times a day for eight weeks.

• Women with breast cancer having an average of two or more hot flashes per day (N = 420).
• Evaluable data for 371 patients at four weeks (119 placebo, 123 gabapentin 300 mg, and 129 gabapentin 900 mg) and 347 at eight weeks (113 placebo, 114 gabapentin 300 mg, 120 gabapentin 900 mg).
• Mean age: 55 years old
• Inclusion: Adult women with history of breast cancer and were having an average of two or more hot flashes per day; adjuvant tamoxifen use was permitted
• Exclusion: Currently receiving chemotherapy; use of venlafaxine, clonidine, or anticonvulsants not permitted; pregnancy, breastfeeding, use of steroidal contraception, coronary insufficiency, recent history of myocardial infarction, symptomatic cardiac disease, peripheral or cerebrovascular disease, stroke, syncope, or symptomatic hypotension; hepatic dysfunction (aspartate aminotransferase concentration above twice the upper limit of normal or bilirubin concentration above the upper limit of normal), renal dysfunction (serum creatinine concentration above 1–25 times the upper limit of normal); allergy to gabapentin

University community clinic oncology program

Randomized, double-blind, placebo-controlled multi-institutional trial.

• Hot flash diary one week prior to study and during weeks 4 and 8 of treatment
• Symptom inventory pretreatment, weeks 4 and 8 of treatment.

Decreases in hot flash severity scores between baseline and weeks 4 and 8, respectively were: 21% and 15% in the placebo group; 33% and 31% in the group assigned gabapentin 300 mg; and 49% and 46% in the group assigned gabapentin 900 mg. The differences between the groups were significant (p = 0.0001 at four weeks and p = 0.007 at eight weeks by analysis of covariance for overall treatment effect).

Gabapentin was effective in control of hot flashes at a dose of 900 mg/day but not at a dose of 300 mg/day.

• Long-term use of gabapentin not assessed 
• Withdrawal rate of 12% at four weeks and 17% at eight weeks