Injectable long-acting in situ forming systems for Radix Ophiopogonis polysaccharide

In the area of injectable long-acting formulations, the in situ forming system (ISFS) is an attractive alternative for its various superiorities. In this study, both hydrophilic and hydrophobic in situ forming systems, using Poloxamer and sucrose acetate isobutyrate (SAIB) or poly(d,l-lactide-co-glycolide) copolymer (PLGA) as carrier, respectively, were investigated for Radix Ophiopogonis polysaccharide (ROP), a natural anti-myocardial ischemic fructan. A reasonable and applicable range of formulations were selected from each carrier for in vivo study by investigating their rheological property. The results from in vivo evaluation show that relatively promising sustained behaviors were achieved by formulations 24% P407/10% P188, 40% PLGA30k/NMP, and 30% PLGA50k/NMP. Significant differences of drug release kinetics were observed between in situ thermally-induced Poloxamer-based hydrogels and in situ solvent exchange-induced hydrophobic PLGA depots. This suggests that different ISFS could be chosen to provide different application purpose for polysaccharide drugs. In the case of ROP, Poloxamer-based ISFS is promising for short-term acute therapies; however, PLGA-based ISFS might be promising for long-term precaution or/and cure of myocardial ischemia.