Evaluation of Two Dextrose-Based Directly Compressible Excipients

The objectives of this research were to evaluate the physical properties and compaction behavior of two dextrose-based directly compressed excipients. Anhydrous theophylline (10% w/w) was used as a drug model, Emdex and or Maltrin M510 (89.5% w/w) were used as diluent, and magnesium stearate (0.5% w/w) was used as lubricant. Direct compression and wet granulation methods were used for preparing the compacts. In general, the wet granulation method reduced the density of the mixture and consequently its flow rate compared to the mixture prepared only by solid-solid mixing. All formulations were compressed at four different compressional forces and at a target weight of 450 mg +/- 5%. Tablets obtained were different in physical properties and mechanical strength based on type of excipient used and methods of tablet preparation (direct compression versus wet granulation). Compacts prepared from Maltrin M510 had a longer disintegration time and slower drug release than compacts of the same composition but prepared with Emdex. Disintegration time and drug dissolution from tablets containing Maltrin M510 as diluent and prepared by wet granulation appeared to be controlled by a "gel" layer formation around the tablets and not by the tablets porosity. This study demonstrates that full characterization of excipients is needed because a different manufacturing process for the same excipients may produce differences in the pharmaceutical products.