Continuous release of rh-interferon alpha-2a from triglyceride matrices.

The use of biodegradable polymeric matrices as controlled release systems is known to be associated with various drawbacks. The objective of this study was to develop an alternative delivery system based on triglycerides, thereby aiming for sustained continuous protein release. Tristearin implants containing lyophilised rh-interferon alpha-2a (IFN-alpha) and varying amounts of polyethylene glycol 6000 (PEG) were prepared by compression. Release studies exhibited that more than 90% of the incorporated IFN-alpha can be liberated in a continuous way over 1 month from systems containing 10% PEG. Integrating hydroxypropyl-beta-cyclodextrin (HP-beta-CD) into the matrices proved to stabilise IFN-alpha and led to a higher and faster protein release due to solubilising effects. The protein was released in virtually monomeric form. Scanning electron microscopy (SEM) and mercurial porosimetry revealed the matrices forming an interconnected pore network.