Formation of ondansetron polymorphs

We used differential scanning calorimetry, infrared spectrophotometry and H -1 nuclear magnetic resonance imaging to search for polymorphs of ondansetr on. Samples were tested under different conditions of temperature, pulveriz ation and pH, and in different solvents. The factors identified as able to cause the formation of polymorphs were heating to different temperatures fo r different times, and the use of ethanol and methanol as solvents. (C) 199 9 Elsevier Science B.V. All rights reserved.