Osmolality of Oral Drug Solutions and Suspensions

The osmolality values of a variety of commonly used drug solutions and suspensions were determined. A total of 58 commercially available drug solutions and suspensions and electrolyte solutions for oral use were analyzed. Samples of each product were diluted 1:10 to a total volume of 100 microL with sterile water for irrigation and mixed thoroughly. The osmolality of 10-microL aliquots of each diluted mixture was determined at least in duplicate by vapor pressure osmometry. Only six (10%) of the products had osmolality values that were less than or equal to 1000 mOsm/kg (i.e., similar to the values of commercially available enteral formulas). The other products had osmolality values ranging from 1,050 to 10,950 mOsm/kg. Since many drug solutions and suspensions are hypertonic compared with normal gastrointestinal secretions, inappropriate administration could cause adverse gastrointestinal effects in patients receiving enteral nutrition support.