Biochemical and pharmacokinetic characterisation of two PEGylated variants of dipetarudin.

Dipetarudin was coupled to polyethylene glycol (PEG)-5000 residues in order to improve its pharmacokinetic profile and to enhance its anticoagulant efficacy. The resulting compounds, mono- and di-PEGylated dipetarudin were purified by gel filtration. Mono-PEGylated dipetarudin exhibited similar activity like its non-conjugated equivalent both in vitro and in vivo. However, di-PEGylated dipetarudin showed longer distribution and elimination half-lives and higher area under the time-concentration curve in comparison with the unmodified inhibitor which may be attributed to decreased renal clearance. Futhermore, ratio k(12)/k(21) decreased when the number of PEG chains coupled to dipetarudin increased. It means that the inter-compartment transfer of dipetarudin, characterised by a fast distribution and a high retention in the peripheral compartment, is reverted by coupling to PEG. Thus, the transfer of mono-PEGylated dipetarudin between these compartments is similar in both senses and the transfer of di-PEGylated dipetarudin is slower from vascular to extravascular compartment than vice versa. Our results show that di-PEGylated dipetarudin produces a better and longer anticoagulant effect than unmodified dipetarudin which is a desirable attribute for future therapeutic application.