Differential scanning calorimetric characterization of pharmaceutical powder blend uniformity in a laboratory-scale V-blender

• A novel DSC method was reported for assessment of powder mixing uniformity.
• Sample analysis was very quick with only 5 to 10 mg of samples.
• Sample analysis did not require any solvent or chemicals.
• The results were reliable and accurate when compared to a UV method.

Testing of powder blend uniformity is one of the important steps during formulation development and routine commercial production of pharmaceutical products. Pharmaceutical industries heavily rely on chemical analysis by UV or HPLC for the same. However, the chemical methods are time consuming, need a few grams of powder sample, and they are not green in nature. The objective of this research is to explore the use of DSC as an alternative of UV analysis to assess the powder blend uniformity of a binary mixture of metformin hydrochloride and HPMC (5:95 w/w) at 50% and 60% occupancy of a laboratory-scale V-blender. Samples were withdrawn at 5, 10, 15, and 20 min intervals each of the top, middle, and bottom positions of the blender. Samples from all three locations at all time-points were found to have similar concentrations by both methods with the maximum RSD below 26%. Percent of metformin HCl recovery from the powder mixture after 20 min was comparable to the DSC method (2.68 ± 0.22% and 2.29 ± 0.14% at 50% and 60% occupancy, respectively) and UV method (2.66 ± 1.10% and 2.60 ± 0.32% at 50% and 60% occupancy levels, respectively). DSC, after a careful evaluation of drug and excipient specific interaction, can be considered as an alternative of pharmacopoeial spectrophotometric or chromatographic methods for powder blend uniformity assessment at various stages of pharmaceutical product development and its commercial production.

A binary powder mixture of metformin hydrochloride and HPMC with a ratio of 5:95 w/w was mixed in a laboratory scale V-blender for 20 min at 50% and 60% occupancy. Powder samples were withdrawn from the top, middle, and bottom positions of a laboratory-scale V-blender at 5, 10, 15, and 20 min intervals. The powder samples were analyzed by a DSC method and the results were confirmed by a UV method. The results obtained by the DSC method were reliable and accurate as the UV method. The DSC method should be further investigated as an alternative to chemical methods like UV or HPLC.Figure optionsDownload as PowerPoint slide