Fat-free Albumin as a Novel Drug Delivery System
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The search for effective drug delivery systems is one of the major challenges in drug formulation especially for biopharmaceuticals such as proteins, and peptide-based drugs and vaccines. A procedure has been developed whereby human serum albumin (HSA) can be used as a delivery vehicle for these biomolecules using its role as main fatty acid carrier. Using essentially fatty acid free HSA (HSAff) it is possible to form stable complexes with lipidic chain compounds (lipo-compounds). Two lipo-compounds have been used to develop this system, a novel antimicrobial lipopeptide and γ-amino-n-butyric acid, GABA, conjugated with an alkyl chain, lipo-GABA, in both cases C8 and C14 alkyl chain lengths were evaluated. The HAS–lipo compound complex had a mutual stabilizing effect on both the HSA and the lipo-compound. The protease enzyme study showed that the alkyl chains of these lipo-compounds bound to HSAff confer a similar if not greater biostability than caprylic acid shown by CD and importantly, the bound lipopeptide was stabilized by the HSA shown by mass spectrometry. Heat stability studies at 60°C over 10 h also confirmed that the lipo-HSA complexes confer stability and provide a method of preparing sterile formulation for therapeutic use. No further increased in stability of the lipo-compounds when HSA containing fatty acid (HSAfa) was used. With the antimicrobial lipopeptide, there was enhanced activity with HSAff formulation suggesting increased biostability and bioavailability of compounds. These finding allowed us to develop a simple and effective way of delivering lipo-compounds using fatty acid free HSA as the carrier.