An in vitro study of the release capacity of the local anaesthetics from siloxane matrices

Abstract

Aims. In the field of anaesthesia and intensive care, the controlled release systems capable of delivering constantly local anaesthetics are of interest because of the advantages brought to pain management. In this paper we presented the release profiles by usage of siloxane matrices of two common local anaesthetics, lidocaine and bupivacaine, analysed in vitro.Methods. The siloxane matrices were obtained in accordance with the methods described in the specialized literature, tetraethoxysilane (TEOS) and tetramethoxysilane (TMOS) were used as precursors. Lidocaine and bupivacaine were encapsulated in the synthesized gels. The controlled release was performed in vitro artificial systems in which temperature (30°C, 36.5°C, 40°C) and pH (6, 7, 8) have varied.Results. Following the analysis of the artificial systems similar profiles were highlighted for both local anaesthetics. Statistically significant differences were identified (p < 0.05) for systems where the release occurred at temperatures above 36.5°C. There were no statistically significant differences regarding the influence of pH, the type of the entrapped anaesthetic or the type of the precursor used in the synthesis of siloxane matrices.Conclusions. According to this experimental study, the pH, the type of precursor or the type of anaesthetic does not statistically influence the release profile from the studied system. In conclusion, these systems are promising for obtaining pharmaceutical preparations which can be used in current clinical practice. Several studies on controlled release siloxane systems should be carried out both in vitro and in vivo in order to exclude possible toxicity and histopathological effects.