Effect of refrigeration of the antiemetic Cerenia (maropitant) on pain on injection.

Injection pain has been associated with veterinary use of the antiemetic maropitant (Cerenia, Pfizer Animal Health). Cerenia is formulated using sulphobutylether-beta-cyclodextrin to bind maropitant and mitigate injection pain. The objective of this study was to determine whether the temperature of Cerenia alters binding between maropitant and sulphobutylether-beta-cyclodextrin and affects injection pain. Binding decreased as temperature increased, and Cerenia-elicited injection pain increased at warmer drug temperatures. These data suggest that the amount of free unbound maropitant increases with temperature and that injection pain increases with temperature in a similar fashion. Clinically, these studies suggest that injection of refrigerated Cerenia may significantly reduce or eliminate pain associated with SC injection of Cerenia.