Study of poloxamer 188 and polyethylene glycols influence on in situ systems thermoreversible properties

Relevance. Poloxamers are the most promising polymers in modern pharmaceutical development due to their ability to make a sol-gel phase transition under physiological conditions and provide a sustained release, so these polymers are ideal for creating thermoreversible in situ drug delivery systems. Complexes with other polymers are created to give optimal characteristics to such systems. Aim. Study of poloxamer 188 and polyethylene glycols influence on in situ systems thermoreversible properties (gelation temperature, viscosity). Material and methods. Commercial samples of poloxamer 407, poloxamer 188 and polyethylene glycols from BASF company were used. Experimental compositions were obtained by dispersing the components in purified water on IKA C-mag HS 7 digital magnetic stirrer (IKA, Germany) and subsequent gel structuring in a refrigerator. The gelation temperature was measured once a week for 12 months, from the moment the sample in a polymer container removed from the storage place, settled and then was immersed in the ODA-LQ40 ultrasonic bath (ODA, Russia) in the heating mode. As an indicator of the gelation temperature, the values determined with an increase of sample dynamic viscosity in the process of mixing using a measuring thermal probe were taken. The stability of the indicator was described using statistical analysis. For the most stable compositions with optimal temperatures rheological properties were studied on a coaxial rotational viscometer Lamy Rheology RM 220 (Lamy, France). Results. In long-term tests, a direct dependence of the average gelation temperature on the concentration of poloxamer 188 was revealed. It was shown the addition of polyethylene glycol 1500 not only increase the gelation temperature, but also positively affects its stability. Also, rheological characteristics were studied. Conclusions. The effect of poloxamer 188 and polyethylene glycol 1500 on the gelation temperature and its stability during long-term storage, as well as the promise of these polymers for the pharmaceutical development of in situ thermoreversible systems, was shown in our study.