Design, Synthesis, and Pharmacokinetics of a Bone-Targeting Dual-Action Prodrug for the Treatment of Osteoporosis

J Med Chem. 2017 Aug 24;60(16):7012-7028. doi: 10.1021/acs.jmedchem.6b00951. Epub 2017 Aug 10.

Abstract

A dual-action bone-targeting prodrug has been designed, synthesized, and evaluated for in vitro and in vivo metabolic stability, in vivo tissue distribution, and rates of release of the active constituents after binding to bones through the use of differentially double-labeled derivatives. The conjugate (general structure 7) embodies the merger of a very potent and proven anabolic selective agonist of the prostaglandin EP4 receptor, compound 5, and alendronic acid, a potent inhibitor of bone resorption, optimally linked through a differentially hydrolyzable linker unit, N-4-carboxymethylphenyl-methyloxycarbonyl-leucinyl-argininyl-para-aminophenylmethylalcohol (Leu-Arg-PABA). Optimized conjugate 16 was designed so that esterase activity will liberate 5 and cathepsin K cleavage of the Leu-Arg-PABA element will liberate alendronic acid. Studies with doubly radiolabeled 16 provide a proof-of-concept for the use of a cathepsin K cleavable peptide-linked conjugate for targeting of bisphosphonate prodrugs to bone and slow release liberation of the active constituents in vivo. Such conjugates are potential therapies for the treatment of bone disorders such as osteoporosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alendronate / analogs & derivatives*
  • Alendronate / chemical synthesis
  • Alendronate / metabolism
  • Alendronate / pharmacology*
  • Animals
  • Bone Density Conservation Agents / chemical synthesis
  • Bone Density Conservation Agents / metabolism
  • Bone Density Conservation Agents / pharmacology*
  • Bone Resorption / drug therapy
  • Bone and Bones / metabolism*
  • Cathepsin K / metabolism
  • Dipeptides / chemical synthesis
  • Dipeptides / metabolism
  • Dipeptides / pharmacology*
  • Diphosphonates / chemical synthesis
  • Diphosphonates / metabolism
  • Diphosphonates / pharmacology*
  • Drug Design
  • Drug Stability
  • Female
  • Humans
  • Osteoporosis / drug therapy
  • Prodrugs / chemical synthesis
  • Prodrugs / metabolism
  • Prodrugs / pharmacology*
  • Rats, Sprague-Dawley
  • Receptors, Prostaglandin E, EP4 Subtype / agonists
  • Tritium

Substances

  • Bone Density Conservation Agents
  • Dipeptides
  • Diphosphonates
  • PTGER4 protein, human
  • Prodrugs
  • Ptger4 protein, rat
  • Receptors, Prostaglandin E, EP4 Subtype
  • Tritium
  • CTSK protein, human
  • Cathepsin K
  • Ctsk protein, rat
  • Alendronate