Synthesis, metabolism and cellular permeability of enzymatically stable dipeptide prodrugs of acyclovir

Int J Pharm. 2008 Sep 1;361(1-2):118-24. doi: 10.1016/j.ijpharm.2008.05.024. Epub 2008 Jun 23.

Abstract

The objective of this study was to synthesize and evaluate novel enzymatically stable dipeptide prodrugs for improved absorption of acyclovir. l-Valine-l-valine-acyclovir (LLACV), l-valine-d-valine-acyclovir (LDACV), d-valine-l-valine-acyclovir (DLACV) and d-valine-d-valine-acyclovir (DDACV) were successfully synthesized. The uptake and transport studies were conducted on a Caco-2 cell line. Buffer stability and metabolism of the prodrugs in Caco-2, rat intestine and liver homogenates were studied. Structure and purity of the all compounds were confirmed with LC-MS/MS and NMR spectroscopy. Uptake and transport of [(3)H] glycylsarcosine was inhibited by all prodrugs except DDACV. DLACV and DDACV exhibited no measurable degradation in Caco-2 homogenate. Except DDACV other three prodrugs were hydrolyzed in rat intestine and liver homogenates. The order of permeability across Caco-2 was LDACV>LLACV>DDACV>DLACV. A linear correlation between the amount of prodrug transported and over all permeability of acyclovir was established. This study shows that the incorporation of one d-valine in a dipeptide did not abolish its affinity towards peptide transporters (PEPT). Moreover, it enhanced enzymatic stability of prodrug to a certain extent depending on the position in a dipeptide conjugate. This strategy improved both the cellular permeability and the amount of intact prodrug transported which would enable targeting the nutrient transporters at blood ocular barrier (BOB).

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acyclovir / chemistry
  • Acyclovir / pharmacokinetics*
  • Animals
  • Antiviral Agents / chemistry
  • Antiviral Agents / pharmacokinetics*
  • Biological Transport
  • Blood-Aqueous Barrier / metabolism
  • Caco-2 Cells
  • Dipeptides / chemistry
  • Dipeptides / pharmacokinetics
  • Humans
  • Hydrolysis
  • Intestinal Mucosa / metabolism
  • Liver / metabolism
  • Male
  • Membrane Transport Proteins / metabolism
  • Permeability
  • Prodrugs / chemistry
  • Prodrugs / pharmacokinetics*
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Antiviral Agents
  • Dipeptides
  • Membrane Transport Proteins
  • Prodrugs
  • peptide permease
  • Acyclovir