In situ forming microparticle system for controlled delivery of leuprolide acetate: Influence of the formulation and processing parameters

Injectable <i>In Situ</i> Forming Microparticles: A Novel Drug Delivery System

“…In vitro solidification and dissolution studies releaved that in situ forming microparticles prepared by using PLGA were spherical and had a smooth surface but a porous inner structure as seen in Figure 2A. Drug release from these ISMs [31] was occurred in two phases with a high initial release followed by an almost constant and slower release, as shown in Figure 3A. Drug release profiles obtained from ISMs prepared by using PLA were almost monophasic ( Figure 3B) compared to ISMs that contained PLGA ( Figure 3A).…”

“…The two syringes are coupled with a connector and emulsification can be achieved by pushing the content of syringe A into syringe B to and fro for 50 mixing cycles. At the end of this, the contents are pushed into one syringe, the connector is removed and a needle is attached, and is ready for use [19][20][31][32][33][34][35][36][37][38].…”

“…In both systems, leuprolide acetate and PLGA or PLA were dissolved in polar solvent NMP. Therefore existence of ionic interactions between polymer and drug was also possible and a stronger interaction in the presence of R 202H could impede drug loss from polymer solution and thus lead to a lower initial release [31].…”

“…The ISM systems were prepared as a combination of PLA-solvent phase dispersed into an external peanut oil phase. The solvent release from ISMs and in situ forming implants into phosphate buffer which influences polymer precipitation rate was investigated as a function of the type of Figure 3: (A) Influence of drug loading ( =10%; = 5%; ▲ = 2.5% ) on leuprolide release from ISMs containing %30 w/w RG 503H; and (B) Leuprolide release from ISMs at different drug loadings and polymer concentrations (x = 15% drug, 30% R 202H; = 10% drug, 30% R 202; = 10% drug, 40% R 202H; all % are given w/w) [31]. solvent (NMP, DMSO and 2-pyrrolidone), polymer concentration and polymer:oil phase ratio.…”

“…Thus, easier injectability and reduced pain has been achieved, compared to use of the polymer solutions (in situ implant systems). Additionally ISMs are multiparticulates, and thus minimize variations in implant morphology (after solidification) and provide more consistent and reproducible drug release profile [28][29][30][31][32][33][34].…”