ABSTRACT
The objective of this study was to investigate the sustained release of a hydrophilic drug, montelukast (MK), from two biodegradable polymeric drug delivery systems, in situ implant (ISI) and in situ microparticles (ISM). N-Methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO), triacetin, and ethyl acetate were selected as solvents. The release of 10% (w/v) MK from both systems containing poly-lactic-co-glycolic acid (PLGA) as the biodegradable polymer was compared. Upon contact with the aqueous medium, the PLGA in ISI and ISM systems solidified resulting in implants and microparticles, respectively. The in vitro drug release from the ISI system showed marked difference from miscible solvents (NMP and DMSO) than the partially miscible ones (triacetin and ethyl acetate), and the drug release decreased with increased PLGA concentration. In the ISM system, the initial in vitro drug release decreased with decreased ratio of polymer phase to external oil phase. In vivo studies in rats showed that ISM had slower drug release than the drug release from ISI. Also, the ISM system when compared to ISI system had significantly reduced initial burst effect. In vitro as well as the in vivo studies for both ISI and ISM systems showed sustained release of MK. The ISM system is suitable for sustained release of MK over 4-week period with a lower initial burst compared to the ISI system. Stability studies of the ISI and ISM formulations showed that MK is stable in the formulations stored at 4°C for more than 2 years.
Subject(s)
Absorbable Implants , Acetates/administration & dosage , Lactic Acid/chemistry , Leukotriene Antagonists/administration & dosage , Polyglycolic Acid/chemistry , Quinolines/administration & dosage , Acetates/blood , Acetates/chemistry , Acetates/pharmacokinetics , Animals , Chemistry, Pharmaceutical , Cyclopropanes , Dimethyl Sulfoxide/chemistry , Drug Implants , Drug Stability , Injections, Intramuscular , Leukotriene Antagonists/blood , Leukotriene Antagonists/chemistry , Leukotriene Antagonists/pharmacokinetics , Male , Particle Size , Polylactic Acid-Polyglycolic Acid Copolymer , Pyrrolidinones/chemistry , Quinolines/blood , Quinolines/chemistry , Quinolines/pharmacokinetics , Rats, Sprague-Dawley , Solubility , Solvents/chemistry , Sulfides , Technology, Pharmaceutical/methods , Temperature , Triacetin/chemistryABSTRACT
The objective of this study is to formulate injectable, biodegradable sustained release in situ implant (ISI), and in situ microparticle (ISM) formulations of haloperidol. Factors affecting the in vitro drug release, pharmacokinetics, and stability of the formulations were investigated. The concentration of the polymer, poly(lactide-co-glycolide) acid (PLGA), and the type of solvents showed a pronounced effect on the in vitro drug release from the ISI and ISM formulations. The ISM formulation [20% PLGA in N-methyl-2-pyrrolidone (NMP)-peanut oil, 1:4] showed reduced maximum plasma concentration (60 versus 44 ng/mL) and longer release (30 days, plasma concentration of 8 ng/mL versus 20 days, plasma concentration of 6 ng/mL) compared with the ISI formulation (20% PLGA in NMP) after intramuscular injection in rats. The delivery of haloperidol can be extended further by changing the concentration, molecular weight, and lactide-to-glycolide ratio of the PLGA. These formulations can be easily administered by both intramuscular and subcutaneous injections. The shelf lives of both systems were found to be 2 years when stored at 4°C. Haloperidol can be formulated as an injectable ISI or ISM systems suitable for 1 month or longer release.
