Thermal, mechanical and drug release characteristics of an acrylic film using active pharmaceutical ingredient as non-traditional plasticizer.

The objective of this study was to investigate thermal and mechanical properties as well as in vitro drug release of Eudragit® RL (ERL) film using chlorpheniramine maleate (CPM) as either active pharmaceutical ingredient or non-traditional plasticizer. Differential scanning calorimeter was used to measure the glass transition temperature (Tg) of 0-100% w/w CPM in ERL physical mixture. Instron testing machine was used to investigate Young's modulus, tensile stress and tensile strain (%) of ERL film containing 20-60% w/w CPM. Finally, a Franz diffusion cell was used to study drug release from ERL films obtained from four formulations, i.e. CRHP0/0, CRHP0/5, CRHP2/0 and CRHP2/5. The Tg of ERL was decreased when the weight percentage of CPM increased. The reduction of the Tg could be described by Kwei equation, indicating the interaction between CPM and ERL. Modulus and tensile stress decreased whereas tensile strain (%) increased when weight percentage of CPM increased. The change of mechanical properties was associated with the reduction of the Tg when weight percentage of CPM increased. ERL films obtained from four formulations could release the drug in no less than 10 h. Cumulative amount of drug release per unit area of ERL film containing only CPM (CRHP0/0) was lower than those obtained from the formulations containing traditional plasticizer (CRHP0/5), surfactant (CRHP2/0) or both of them (CRHP2/5). The increase of drug release was a result of the increase of drug permeability through ERL film and drug solubility based on traditional plasticizer and surfactant, respectively.

Plasticizing effect of ibuprofen induced an alteration of drug released from Kollidon SR matrices produced by direct compression.

The objectives of this study were to investigate the effect of storage temperature on drug release from matrices containing 10, 40 and 70% w/w ibuprofen in Kollidon® SR (KSR). The matrix tablets were produced by direct compression and then kept at 30 and 45 °C for 3 months. Drug release from the matrix tablets was examined after storage for 0, 1, 4 and 12 weeks. Scanning electron microscope was used to reveal physical appearance of the tablet surface at the respective time intervals. In addition, differential scanning calorimeter was used to investigate glass transition temperature (Tg) of ibuprofen in KSR at 0-100% w/w based on the principle of Gordon-Taylor equation. At 45 °C, the dissolution of ibuprofen in KSR as well as the coalescence of polymer particles were observed to be higher than those of storage at 30 °C. The physical state of ibuprofen dispersed in the polymeric matrix and degree of polymer coalescence led to the variation of drug release. The coalescence of polymer particles was a result of the polymer transition from glassy to rubbery state according to water absorption of KSR and plasticizing effect of ibuprofen. The reduction of the Tg of ibuprofen blended with KSR could be better described by the Kwei equation, a modified version of Gordon-Taylor equation.

Miscibility and interactions between 17beta-estradiol and Eudragit RS in solid dispersion.

Miscibility of 17beta-estradiol and Eudragit RS in solid dispersions was determined by modulated temperature differential scanning calorimetry (MTDSC). A reduction of the 17beta-estradiol melting point in Eudragit RS solid dispersions was observed by MTDSC using heating program I in which the maximum temperature in the first heating run was lower than the 17beta-estradiol melting point. The melting point depression of 17beta-estradiol in solid dispersions as a function of composition could be explained by the Nishi-Wang equation indicating an interaction between 17beta-estradiol and Eudragit RS in the system. A variation of glass transition temperature (T(g)) of 17beta-estradiol in Eudragit RS solid dispersion was observed by MTDSC using heating program II in which the maximum temperature in the first heating run reached the 17beta-estradiol melting point. In the second heating run of heating program II, 17beta-estradiol was in an amorphous form blended with Eudragit RS. The variation in T(g) of amorphous 17beta-estradiol blended with Eudragit RS could be explained by the Kwei equation, a modified version of the Gordon-Taylor equation. The parameter estimates from the Kwei equation were consistent with an interaction between 17beta-estradiol and Eudragit RS, which was due to inter-associated hydrogen bonding as deduced from the FTIR spectra of the blends.