This article presents BEPO®, an in situ forming depot (ISFD) technology mediated by a solvent-exchange mechanism. The matrix of the in situ formed drug delivery depot is composed of the combination of a diblock (DB) and a triblock (TB) polyethylene glycol-polyester copolymer. This combination offers a broad capability to tune the release of a wide variety of drugs to the desired pharmacokinetics. The work described in the present article demonstrates that the delivery rate and profile can be adjusted by changing the composition of either TB or DB or the relative ratio between them, among other parameters. It has been shown that the polymeric composition of the formulation has a substantial impact on the solvent exchange rate between the organic solvent and the surrounding aqueous medium which subsequently determines the internal structure of the resulting depot and the delivery of the therapeutic cargo. This has been demonstrated studying the in vitro release of two model molecules: bupivacaine and ivermectin. Formulations releasing these drugs have been administered to animal models to show the possibility of delivering therapeutics from weeks to months by using BEPO® technology.
Keywords: Bioresorbable; In situ forming depot; Long acting injectable; PEG-PDLLA block copolymers.
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