Interaction of surfactants with poloxamers 338 and its effect on some properties of cream base

Abstract

The aim. Study of the interaction of surfactants with poloxamer 338 (P338) and the effect of P338 on the properties of cream bases.
 Materials and methods. Solutions of the surfactants and P338 as well as cream bases were under study. The average hydrodynamic diameter (Dh) and zeta potential (ζ‑potential) were determined by the light scattering intensity and electrophoretic mobility of micelles. The electron paramagnetic resonance (EPR) spectra of spin probes in micelles, solvents and bases were obtained; the type of spectrum, isotropic constant (AN), rotational correlation times (τ) and anisotropy parameter (ε) were determined. Liquids and cream bases were studied by capillary and rotational viscometry; the flow behaviour and yield stress (t0), dynamic and apparent viscosity (η) as well as the hysteresis (thixotropic) area (AH) were determined. The microstructure of the bases was examined by optical microscopy. The strength of adhesion (Sm) was assessed by the pull-off test, and the absorption of water was studied by dialysis.
 Results. Under the impact of P338 the hydrodynamic diameters of micelles formed by cationic, anionic and nonionic surfactants decreased as well as the absolute values of their ζ‑potential became lower, but the microviscosity of the micelle nuclei increased. There was also a change in the structure of the aggregates of surfactant with fatty alcohols; EPR spectra, which were superpositions characteristic for the lateral phase separation, converted into triplets that indicated the uniform distribution of lipophilic probes in the surfactant phase. When the content of P338 increased to 17 %, the rheological parameters of the bases increased drastically, the flow behaviour and the microstructure changed. The bases had the consistency of cream within temperature range from 25 °C to 70 °C and completely restored their apparent viscosity, which had decreased under shear stress. P338 enhances the adhesive properties of the bases. Due to their microstructure, cream bases have a lower ability to absorb water compared to a solution and gel containing 17 % and 20 % P338, respectively.
 Conclusions. The structure of surfactant micelles and aggregates of surfactants with fatty alcohols changed under impact of P338 due to the interaction of surfactants with P338. As a result of this interaction, at a sufficiently high concentration of P338, the microstructure and flow behaviour of bases changed, their rheological parameters, which remain high at temperatures from 25 °C to 70 °C, increased significantly, and water absorption parameters decreased. The bases with P338 were more adhesive

Study of the formation of micelles and their structure by the spin probe method

“…The dynamic viscosity of liquid paraffin (comparator liquid) was equal to 128 mPa•s at 25 °С, and τ ±1 of probe 2 was≈0.7 ns. By the calculations, the viscosity of the microenvironment of probe 2 in P338 associates was on average 2.2 times greater than the dynamic viscosity of liquid paraffin, which approximately corresponds to the viscosity of soft white paraffin [28]. In micelles of M20CE, the viscosity of the microenvironment of probe 2 was on average about 85 % of the dynamic viscosity of liquid paraffin.…”

“…Probe 2 in the micelles was in state of rapid rotation. The viscosity of its environment was about 2 times less than the viscosity of liquid paraffin (τ -1 ≈0.28 ns; τ ±1 ≈0.70 ns) [28]. Using of lipophilic probe 2 it was shown that there was BC concentration range, in which BC associates were formed before the CMC.…”

“…In micelles of M20CE, the viscosity of the microenvironment of probe 2 was on average about 85 % of the dynamic viscosity of liquid paraffin. These imputations are approximate, since liquid paraffin is an isotropic liquid, and the cores of micelles are anisotropic in viscosity [15,28]. Moreover, the dynamic properties of different segments of alkyl chains of spin probe 2 are different (Fig.…”

Effect of the composition of emulsifiers and the dispersion medium on the properties of bases for semi-solid preparations

“…5 % poloxamer 338, 20 % macrogol 1450 and 5 % macrogol 4000 were the thickening agents in these bases (Table 2) [13,15]. The fourth group consisted of liquid and cream with a mixed structure of dispersion medium (Table 3) [4].…”

“…However, the development of both novel drugs and generic/hybrid products is quite difficult, and specific problems arise on the way to their authorisation and production [2]. SSPs can represent a variety of dispersed systems with extremely complex structures [3,4]. SSPs are characterised by more complicated, interdependent relationships in their structure, physicochemical, biopharmaceutical properties and effectiveness as compared to solid dosage forms or parenteral preparations.…”