Viscoelastic properties of a virucidal cream containing the monoglyceride monocaprin: Effects of formulation variables: A technical note

The viscoelastic properties of the cream formulations were tested by 2 methods (ie, increased stress and increased frequency tests). The rheology experiments indicate that the formulations are stable; they show resistance to external forces, as their elastic properties are sustained whether or not the magnitude or frequency of external forces are increased. The results show that rheological properties of the formulations are affected by the proportion of the oil phase and the amount of carbomer in the aqueous phase, but the effect of monocaprin is modest. Increasing carbomer amount increases viscosity and elasticity. Increasing the oil volume fraction increased the structural stability of the creams. The formulation containing monocaprin, which yielded the most viscoelastic structure was a cream containing 10% oil phase and 0.5% carbomer (Formulation 9)

Effect of Oppositely Charged Polymer and Dissolution Media on Rheology of Spray-Dried Ionic Complexes

The purpose of this research was to address the utility of rheological study in understanding the influence of oppositely charged polymers on release of naproxen sodium encapsulated in chitosan particles. The interaction between oppositely charged κ-carrageenan (κ-Ca) and chitosan leads to relatively higher gel strength, which is proportional to the ability to retard the drug release at acidic pH. The oscillatory tests within the linear viscoelastic range where the stress is proportional to the applied strain were performed on the hydrated sample matrices containing chitosan-naproxen sodium spray-dried complexes and k-Ca or hydroxypropyl methylcellulose (HPMC) in various ratios. It was observed that the effect of pH change on the dynamic moduli in spray-dried complexes containing κ-Ca was much stronger than that with HPMC reflecting presence of strong ionic interaction between κ-Ca and chitosan. The combination of oppositely charged polymers in different ratios proved to be useful in modulating the rheological properties of the hydrated formulations and their release-retarding properties. Dynamic moduli can be used to measure gel strength and are significant for the interpretation of oral sustained release spray-dried complexes