Prolonged injectable formulation of Nafarelin using in situ gel combination delivery system

The principal purpose of the present study was to prepare and characterize a complex drug delivery system consisting of Nafarelin-poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles (NPs) in combination with sodium alginate/poloxamer 407 in situ gel. Nafarelin-loaded PHBV NPs were prepared via double emulsion solvent evaporation technique. Box–Behnken Response Surface Methodology was utilized to optimize NPs. Mean particle size, polydispersity index (PDI), entrapment efficiency (EE), and drug loading (DL) of the optimized NPs were measured. Incorporation of Nafarelin within NPs was proven by differential scanning calorimetry (DSC). The combination delivery system (CDS) was prepared by adding Nafarelin-loaded PHBV NPs to sodium alginate/poloxamer 407 solution followed by physical mixing. Morphological properties of Nafarelin-loaded PHBV NPs and CDS were evaluated by SEM. Rheological properties were employed to investigate the effects of alginate concentration on sol–gel transition temperature. The release profile of Nafarelin from both PHBV NPs and CDS were individually assessed. The cumulative release percentage from CDS was significantly lower than Nafarelin released from PHBV NPs. Based on the favorable results in this study, the CDS consisting of sodium alginate/poloxamer 407 loaded with PHBV NPs could be a promising candidate for designing a long-lasting formulation of Nafarelin.