Impact of osmolality on burning sensations during and immediately after intramuscular injection of 0.5 ml of vaccine suspensions in healthy adults

A randomised placebo controlled double-blind cross-over trial was performed on twenty healthy adults to assess the effect of osmolality (300, 600, 850 and 1100 mOsm) on local tolerance of an intramuscular injection (0.5 mi) o f five suspensions containing the same components as the excipients of a co mbined Diphtheria-Tetanus-acellular Pertussis-inactivated Poliomyelitis-Hae mophilus influenzae type b paediatric vaccine (DtacP-IPV-Hib, PENTAVAC (TM) ). The results did not show any dose-effect relationship between burning or pain sensations and the different osmolalities tested. Although mild and n ot clinically relevant, these sensations seemed to occur more frequently fo llowing injection of an isotonic saline solution (P < 0.05). Thus, the osmo lality of vaccine like suspensions does not appear to be a potential cause of local pain or burning sensation after their administration. (C) 2001 Els evier Science Ltd. All rights reserved.