Behaviour of HPMC compacts investigated using UV-imaging

TY - JOUR

T1 - Behaviour of HPMC compacts investigated using UV-imaging

AU - Pekka Pajander, Jari

AU - Baldursdottir, Stefania G.

AU - Rantanen, Jukka

AU - Østergaard, Jesper

PY - 2012/5/10

Y1 - 2012/5/10

N2 - The aim of the study was to visualize the behaviour of the hydroxypropyl methylcellulose (HPMC) in a buffer solution using UV imaging. The obtained results were related to rheological measurements in order to gain insight into critical polymer properties affecting drug release. Two viscosity grades of HPMC, 15 cP and 50 cP, were used. The behaviour of the polymer at the surface of the compact was observed by UV-imaging at 214 nm for 90 min in a stagnant buffer solution and in presence of flow. Steady shear and oscillatory shear measurements were conducted to determine the rheological characteristics. Three distinctive phases could be detected by real-time UV-imaging of the HPMC; gel formation due to water penetration, further expansion of the gel into solution and finally steady conditions, where a critical polymer concentration that can withstand the shear forces without eroding was observed. The critical concentration corresponded to the rheologically determined gel point, which is the lowest concentration where a 3D-network is obtained. Higher viscosity grade HPMC swelled more rapidly and lead to a thicker gel layer, which was more resistant towards the shear forces due to the applied flow. The results showed that UV imaging is suitable for obtaining both qualitative and quantitative information on polymer behaviour.

AB - The aim of the study was to visualize the behaviour of the hydroxypropyl methylcellulose (HPMC) in a buffer solution using UV imaging. The obtained results were related to rheological measurements in order to gain insight into critical polymer properties affecting drug release. Two viscosity grades of HPMC, 15 cP and 50 cP, were used. The behaviour of the polymer at the surface of the compact was observed by UV-imaging at 214 nm for 90 min in a stagnant buffer solution and in presence of flow. Steady shear and oscillatory shear measurements were conducted to determine the rheological characteristics. Three distinctive phases could be detected by real-time UV-imaging of the HPMC; gel formation due to water penetration, further expansion of the gel into solution and finally steady conditions, where a critical polymer concentration that can withstand the shear forces without eroding was observed. The critical concentration corresponded to the rheologically determined gel point, which is the lowest concentration where a 3D-network is obtained. Higher viscosity grade HPMC swelled more rapidly and lead to a thicker gel layer, which was more resistant towards the shear forces due to the applied flow. The results showed that UV imaging is suitable for obtaining both qualitative and quantitative information on polymer behaviour.

KW - Former Faculty of Pharmaceutical Sciences

U2 - 10.1016/j.ijpharm.2012.02.034

DO - 10.1016/j.ijpharm.2012.02.034

M3 - Journal article

C2 - 22387216

SN - 0378-5173

VL - 427

SP - 345

EP - 353

JO - International Journal of Pharmaceutics

JF - International Journal of Pharmaceutics

IS - 2

ER -