Rheological and textural analysis as tools for investigation of drug-polymer and polymer–polymer interactions on the example of low-acyl gellan gum and mesalazine

Abstract

Purpose. In the performed study, the rheological and textural parameters of gellan-based hydrogels were investigated and their dependence on three factors was taken into consideration: ( i) The presence of the model drug, ( ii) The presence and type of the ionic crosslinking agent, and ( iii) the composition of the polymer network. The objective was to compare two analytical methods, regarded as complementary, and define to what extent the obtained results correlate with each other. Methods. The hydrogels contained low-acyl gellan gum or its mixtures with hydroxyethyl cellulose or κ-carrageenan. CaCl2 and MgCl2 were used as gelling agents. Mesalazine was used as a model drug. The rheological analysis included oscillatory stress and frequency sweeping. The texture profile analysis was performed to calculate texture parameters. Results. Placebo gels without the addition of gelling agents had the weakest structure. The drug had the strongest ability to increase the stiffness of the polymer network. The weakest structure revealed the placebo samples without the addition of gelling agents. Texture analysis revealed no significant influence of the drug on the strength of the gels, while rheological measurements indicated clear differences. Conclusions. It can be concluded that in the case of some parameters methods correlate, that is, the effect related to gelling ions. However, the rheological analysis seems to be more precise and sensitive to some changes in the mechanical properties of the gels.

Comparative Study of Polysaccharide-Based Hydrogels: Rheological and Texture Properties and Ibuprofen Release

“…In agreement with our observation with IBU, the authors reported in their works that the content of ketoprofen or indomethacin increased the shear stress of various hydrogels (Carbopol, HEC, sodium alginate, gellan gum). Analogically, the drug mesalazine showed the ability to increase the stiffness of the polymer network (acyl gellan gum) [ 36 ], as it was observed with IBU and the studied polysaccharide gels in our work.…”

“…However, the influence of the own drug presence in hydrogels and the subsequent influence of rheological parameters on the drug release was evaluated only in a few articles. The rheological and texture parameters of hydrogels (e.g., Carbopol, HEC, sodium alginate, gellan gum) were influenced by the presence of the drug, their viscosity was increased [ 35 , 36 ]. In some cases, the drug is reported to increase the stiffness of the polymer network.…”

“…In some cases, the drug is reported to increase the stiffness of the polymer network. The rheological parameters seem to be more precise and sensitive to some changes in the mechanical properties of the gels [ 36 ]. However, the data are scarce and a complex view on this topic is currently missing.…”

Mucoadhesive Polymeric Polyologels Designed for the Treatment of Periodontal and Related Diseases of the Oral Cavity

“…This disparity (identified as a statistical interaction in the ANOVA) may be, at least in part, due to competition between the drug and polymer for the non-aqueous solvent (in systems where the drug is dissolved) and the effect of suspended drugs on the flow properties. Therapeutic agents have been previously reported to affect the rheological properties of pharmaceutical gels and semi-solids [ 47 , 48 ]. For example, the authors demonstrated the interaction between chlorhexidine and polyacrylic acid in mucoadhesive semisolids and the effects on the rheological properties whenever chlorhexidine was dissolved and dispersed [ 47 ], whereas Gadziński et al reported increased elasticity of gellan-based hydrogels following the incorporation of mesalazine [ 47 ].…”

“…Therapeutic agents have been previously reported to affect the rheological properties of pharmaceutical gels and semi-solids [ 47 , 48 ]. For example, the authors demonstrated the interaction between chlorhexidine and polyacrylic acid in mucoadhesive semisolids and the effects on the rheological properties whenever chlorhexidine was dissolved and dispersed [ 47 ], whereas Gadziński et al reported increased elasticity of gellan-based hydrogels following the incorporation of mesalazine [ 47 ]. Conversely, the incorporation of lidocaine into gels of acrylamide/sodium acryloyldimethyl taurate copolymer significantly reduced gel elasticity through screening of the charge on the polymer chains and hence reducing polymer chain expansion through charge repulsion.…”