Effect of Postmolding Heat Treatment on In Vitro Properties of a Polyanhydride Implant Containing Gentamicin Sulfate

Abstract

A polyanhydride implant containing gentamicin sulfate was fabricated using a laboratory-scale injection-molding machine. After injection molding, the implants were subject to heat treatment at 60 degrees C for various time periods with or without nitrogen protection. The impact of this heat treatment on the in vitro properties of the implants including copolymer molecular weights, mechanical properties, and in vitro drug-release profiles was investigated. This heat treatment caused a drastic drop in the molecular weight of the copolymer. Heating without nitrogen protection resulted in the hardening of the implant, but heating in the presence of nitrogen rendered the implant less rigid. It was also found that a faster in vitro drug release profile was shown by implants heated without nitrogen protection and a pronounced slowing down in drug release was exhibited by implants heated with nitrogen protection.

Sustained-Release and Swelling Characteristics of Xanthan Gum/Ethylcellulose-Based Injection Moulded Matrix Tablets: in Vitro and in Vivo Evaluation

“…Demineralised water (900 mL) was used as dissolution medium and the paddle speed was set at 50 rpm, while the temperature of the medium was maintained at 37 ± 0.5 • C. Samples of 5 mL were withdrawn at specific time points (0. 5,1,2,4,6,8,12,16,20, and 24 h without media replacement) and spectrophotometrically assessed for MPT concentration at a wavelength of 222 nm by means of a double beam spectrophotometer (UV-1650PC; Shimadzu Benelux, Antwerpen, Belgium). The MPT content in the samples was determined by linear regression using a calibration curve between 0 and 0.1 g/L.…”

“…Hot melt extrusion (HME) in combination with injection moulding (IM) is commonly used to process thermoplastic polymers with the aid of heat and pressure into shape‐specific items 1. HME has received considerable interest within the pharmaceutical industry for the production of polymeric drug delivery systems such as mini‐tablets,2 milled extrudates,3 pellets,4 films,5 and implants,6 in order to manufacture immediate as well as sustained dosage forms. In contrast, the pharmaceutical applications of IM to prepare shape‐specific drug delivery systems have been very limited.…”