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Newer antidepressants and gabapentin for hot flashes: a discussion of trial duration

Loprinzi, Charles L. MD1; Diekmann, Brent BS1; Novotny, Paul J. MS1; Stearns, Vered MD2; Sloan, Jeff A. PhD1

doi: 10.1097/gme.0b013e31819c46c7

Objective: Information regarding the ideal length of hot flash trials is scarce. In the literature, hot flash trial durations have commonly varied from 4 to 12 weeks. This article is devoted to providing scientific data to better ascertain how long it is necessary to conduct hot flash trials with newer centrally acting agents.

Methods: Individual participant data were collected from all known published, through December 2007, randomized, placebo-controlled, double-blinded clinical trials regarding the use of newer antidepressants and gabapentin for hot flash relief. Trials that studied periods longer than 4 weeks were included for this project. Profile analysis was applied to the hot flash activity longitudinal data for each study individually, allowing a comparison of data collected for 6 to 12 treatment weeks versus data collected for only 4 treatment weeks.

Results: Ten studies were identified, five of them fulfilled the eligibility criteria for this investigation, three evaluating gabapentin, and two newer antidepressants. Flatness tests from a profile analysis did not provide any evidence that hot flash activity increased or decreased between week 4 and time periods up to 12 weeks.

Conclusions: Changes in hot flash scores from newer antidepressants and gabapentin are apparent within 4 weeks of therapy. Available data indicate that hot flash treatment efficacy, compared with that of placebo, remains stable for up to 12 weeks of follow-up.

A pooled analysis of individual patient data obtained from five published clinical trials evaluating gabapentin or one of the newer antidepressants was conducted. These trials, which had hot flash data during a baseline week, at 4 weeks, and also at 6 to 12 weeks, supported that results seen at 4 weeks were similar to what was seen at 6 to 12 weeks.

From the 1Mayo Clinic, Rochester, MN; and 2Johns Hopkins School of Medicine, Baltimore MD.

Received October 24, 2008; revised and accepted January 6, 2009.

Financial disclosure/conflicts of interest: Dr. Loprinzi is an investigator and consultant for P&G Pharmaceuticals, a cosultant to Astra Zenica, Novartis, Acrux, a recipient of research grant support form Asta Zenica, Novartis, Acrux and a recipient of honoraria from Organon Australia.

Address correspondence to: Charles L. Loprinzi, MD, Mayo Clinic, Rochester MN. E-mail:

©2009The North American Menopause Society