Compliance with USP osmolarity labeling requirements.

In view of the USP requirement that the label of certain parenteral products contain the osmolarity of the solution, actual and theoretical osmolarity values for six preparations were determined, and the extent of any deviation was noted. Osmolarity values were determined experimentally by osmometry and converted to osmolarity values for six products: Calcium Chloride Injection USP, Dextrose Injection USP, Mannitol Injection USP, Potassium Chloride Injection USP, Sodium Bicarbonate Injection USP, and Sodium Chloride Injection USP. Theoretical values were calculated according to a standard equation based on the mass of the substance per liter of solution. The most substantial deviations between actual and theoretical osmolarity values occurred with the calcium chloride, sodium bicarbonate, potassium chloride and dextrose solutions. It is proposed that the technology for making osmotic measurements which exists in the industrial setting should be used to provide clinical practitioners with accurate and actual values. It is also urged that the USP specify a procedure for measuring osmolality and calculating actual osmolarity.