Analysis of initial burst in PLGA microparticles.
BACKGROUND
This review addresses recent advances in the understanding of the mechanisms that underlie burst release and strategies developed to control burst from poly(lactide-co-glycolide) (PLGA) microparticle formulations. While the initial burst release of drug is not always detrimental, excessive drug release in the burst phase may be toxic, and irregularity in the amount of drug released (e.g., from batch to batch) is not acceptable. Many drugs that are good candidates for sustained release treatments are not miscible in PLGA and common microparticle processing solvents, and, as a result, suffer from excessive initial burst release.


OBJECTIVE
The aim of this review is to provide an update on research to understand the mechanisms that underlie burst release of drugs from PLGA microparticles, and strategies developed to control burst.


METHODS
This review focuses on literature published since 2004.


RESULTS
Strategies to control burst release fall into two general categories. First are efforts to improve the miscibility of drug and polymer by altering the composition of the formulation, for example by altering the salt form of the drug. Secondly, processing methods may be altered (increasing the rate of solvent removal, for example) to prevent drug-polymer separation. The goal of most strategies is to reduce or eliminate burst release, so that the encapsulated drug may be maximally retained in the delivery system for long-term delivery.
South Carolina College of Pharmacy, Department of Pharmaceutical and Biomedical Sciences, Columbia, SC 29205, USA. allison@cop.sc.edu
S Dean
SD
Allison
D002626:Chemistry, Pharmaceutical; D004058:Diffusion; D016503:Drug Delivery Systems; D005079:Excipients / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry*; D008863:Microspheres; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D016062:Porosity; D012995:Solubility
D005079:Excipients; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid