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°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.

Key Words:

• Poly(EAD:SA 1:1)
• Gentamicin sulfate
• Implant
• Injection‐molding
• Heat treatment
• In vitro properties
• Copolymer molecular weights
• Mechanical properties
• Drug‐release profiles