Pegfilgrastim is a myeloid growth factor that stimulates neutrophil precursors and can be used to decrease infection risk associated with neutropenia. However pegfilgrastim may induce back and leg pain in 20-50% of patients. No intervention has been consistently successful in treating or preventing this pain.~The exact mechanism of pegfilgrastim-induced pain is unknown but may be related to histamine-mediated inflammation. Several case reports and anecdotal reports have suggested efficacy of antihistamines for this indication.~This study will have two parts. In the first part (Observational Phase), patients receiving pegfilgrastim will be surveyed to document the incidence of significant pegfilgrastim-induced back and leg pain. In the second part (Treatment Phase), patients who previously experienced such pain will be randomized to receive a 7-day course of either the antihistamine loratadine or placebo to determine whether pegfilgrastim-induced back and leg pain can be prevented with this intervention.
The purpose of this study is to determine the incidence of pegfilgrastim-induced back and leg pain and to determine whether the antihistamine loratadine can prevent pegfilgrastim-induced back and leg pain.