Effect of implant formation on drug release kinetics of in situ forming implants.

In situ forming implants are attractive long-acting implant dosage forms due to their: i) ability to control drug release; ii) simple manufacturing process; and iii) minimally invasive administration. In situ forming implants are typically made of a drug, solvent, and a biocompatible polymer that controls drug release. Once injected in the subcutaneous tissue, they form solid depots through solvent/non-solvent exchange and phase separation of the biodegradable polymer (such as poly (lactic-co-glycolic acid), PLGA and poly (lactic acid), PLA).

Flow-through cell-based in vitro release method for triamcinolone acetonide poly (lactic-co-glycolic) acid microspheres.

The main objective of the current research was to develop a compendial flow-through cell apparatus based in vitro release testing method for sustained-release triamcinolone acetonide-loaded poly (lactic-co-glycolic) acid (PLGA) microspheres. Media-based and instrument-based parameters, such as surfactant type, concentration, media volume, flow rate, and testing temperature, were investigated. In addition, a detailed exploration was performed to reveal polymer degradation encompassing pore formation, channeling, and triamcinolone acetonide release from microspheres using freeze-fracture scanning electron microscopy.

Sterilization of Drug-Loaded Composite Coatings for Implantable Glucose Biosensors.

Background: An anti-inflammatory drug-loaded composite coating (dexamethasone-loaded poly (lactic-co-glycolic acid) [PLGA] microspheres/polyvinyl alcohol [PVA] hydrogel) was previously developed to counter the foreign body reaction to a fully implantable continuous glucose monitoring biosensor. The long-term sensor functionality was ensured in the presence of the drug-loaded composite coating thus facilitating better diabetes control and management. In order to advance such a drug-device combination product toward clinical testing, addressing sterilization remains a key step due to the heterogeneity of the product components.

Sterilization of implantable polymer-based medical devices: A review.

This review article is focused on the sterilization techniques used for polymer-based implantable medical devices as well as the regulatory aspects governing sterile medical devices. Polymeric materials are increasingly used in implantable devices due to their biodegradable and biocompatible nature. Patients and medical staff often prefer long-term implantable devices and these can be achieved using high molecular weight polymers.

Foreign Body Reaction to Subcutaneous Implants.

Subcutaneously implanted materials trigger the host's innate immune system, resulting in the foreign body reaction. This reaction consists of protein adsorption on the implant surface, inflammatory cell infiltration, macrophage fusion into foreign body giant cells, fibroblast activation and ultimately fibrous encapsulation. This series of events may affect the function of subcutaneous implants, such as inhibition of drug diffusion from long-acting drug delivery depots and medical device failure.

Drug Distribution in Microspheres Enhances Their Anti-Inflammatory Properties in the Gottingen Minipig.

The foreign body reaction (FBR), one of the body's defense mechanisms against foreign materials, results in loss of implant biocompatibility. A popular strategy to prevent FBR is the constant release of dexamethasone in the tissue surrounding the implant. However, FBR prevention has not been sufficiently studied in large animal models, which offer a better representation of the human subcutaneous tissue physiology.