Osmolality of parenteral solutions

Osmolality-concentration profiles for individual and mixed solute systems are presented. Linear relationships between osmolality and concentration held true in all systems examined at concentrations below 0.2 molal levels. At higher concentrations, linearity existed only in select systems. Deviations from linearity can be greater or less than extrapolated values. In view of the need to determine an osmolarity conversion factor for each parenteral formulation and the many errors possible in the use of these values, adoption of osmolality values for labeling parenteral products rather than osmolarity, as stipulated in USP XIX-NF XIV third supplement, strongly recommended.