Influence of plasticizers and drugs on the physical-mechanical properties of hydroxypropylcellulose films prepared by hot melt extrusion

Hydroxypropylcellulose (HPC) films containing drugs or hydrophilic or hydro phobic plasticizers were prepared by a hot melt extrusion process. Polyethy lene glycol 8000 (PEG 8000) 2%, triethyl citrate (TEC) 2%, acetyltributyl c itrate (ATBC) 2%, and polyethylene glycol 400 (PEG 400) 1% were the plastic izing agents studied. In addition, either hydrocortisone (HC) 1% or chlorph eniramine maleate (CPM) 1% was incorporated into the films as a model drug. The physical-mechanical properties of the films that were investigated inc luded tensile strength (TS), percentage elongation (%E), and Young's modulu s (YM). Differential scanning calorimetry (DSC) was utilized to determine g lass transition temperatures (T-g's). These parameters were studied as a fu nction of time and temperature. The glass transition temperatures initially decreased with the inclusion of the drugs and plasticizers. However, after 6 months aging, films containing PEG 400 and HC showed a marked increase i n T-g. The films containing PEG 400 showed physical-mechanical instability in all parameters studied All extruded films exhibited a mar ked decrease i n TS in contrast to a large increase in %E when testing was performed perpe ndicular to flow versus in the direction of flow. In addition, a consistent film of HPC in the absence of drugs or plasticizers could not be extruded due to the excessive stress on the equipment. Although the theoretical perc entage of CPM on aging remained fairly constant over the processing tempera ture ranges in this study, the HC levels remaining in the extruded films du ring storage were a function of time and temperature.