Albumin binding probe for extending the lifetime of drugs. Most polypeptide drugs, in particular non-glycosylated proteins of molecular mass less than 50 kDa, are short-lived species in vivo having circulatory half lives of 5-20 min. Drug association with endogenous albumin may be suitable for designing an approach to protract the action in vivo of, potentially, any short-lived peptide/protein drug. In doing so two principal obstacles must be overcome: (1) following its conjugation, the probe introduced into a peptide or a protein should have sufficient affinity to albumin to manifest prolonged action in vivo, and (2) in case such covalent introduction results in an inactive product, the latter should be capable to undergo slow reactivation at physiological conditions. The present invention relates to engineering prolonged-acting prodrugs employing an albumin-binding probe that undergoes slow hydrolysis at physiological conditions.
Since albumin is long-lived in vivo, drugs and endogenous substances that tightly associate with it have lower clearance rates than that of the unbound substances, and exhibit prolonged lifetime profiles in vivo. The present invention is based on a concept according to which a long chain fatty acid (LCFA) like albuminbinding compound is covalently linked to a short-lived amino-containing drug to form a non-covalent drug conjugate capable of associating with albumin in vivo, i.e., a long-lived prodrug that gradually releases the pharmacologically active constituent. This approach has been successfully implemented with several drugs (e.g. insulin, exendin and gentamicin).