Design, Synthesis, and Pharmacokinetic Evaluation of Phosphate and Amino Acid Ester Prodrugs for Improving the Oral Bioavailability of the HIV-1 Protease Inhibitor Atazanavir

J Med Chem. 2019 Apr 11;62(7):3553-3574. doi: 10.1021/acs.jmedchem.9b00002. Epub 2019 Apr 2.

Abstract

Phosphate and amino acid prodrugs of the HIV-1 protease inhibitor (PI) atazanavir (1) were prepared and evaluated to address solubility and absorption limitations. While the phosphate prodrug failed to release 1 in rats, the introduction of a methylene spacer facilitated prodrug activation, but parent exposure was lower than that following direct administration of 1. Val amino acid and Val-Val dipeptides imparted low plasma exposure of the parent, although the exposure of the prodrugs was high, reflecting good absorption. Screening of additional amino acids resulted in the identification of an l-Phe ester that offered an improved exposure of 1 and reduced levels of the circulating prodrug. Further molecular editing focusing on the linker design culminated in the discovery of the self-immolative l-Phe-Sar dipeptide derivative 74 that gave four-fold improved AUC and eight-fold higher Ctrough values of 1 compared with oral administration of the drug itself, demonstrating a successful prodrug approach to the oral delivery of 1.

MeSH terms

  • Administration, Oral
  • Amino Acids / chemistry*
  • Animals
  • Area Under Curve
  • Atazanavir Sulfate / administration & dosage
  • Atazanavir Sulfate / chemical synthesis
  • Atazanavir Sulfate / chemistry*
  • Atazanavir Sulfate / pharmacokinetics*
  • Biological Availability
  • Drug Design*
  • Esters
  • HIV Protease Inhibitors / administration & dosage
  • HIV Protease Inhibitors / chemical synthesis
  • HIV Protease Inhibitors / chemistry*
  • HIV Protease Inhibitors / pharmacokinetics*
  • Humans
  • Phosphates / chemistry*
  • Prodrugs / administration & dosage
  • Prodrugs / chemical synthesis
  • Prodrugs / chemistry*
  • Prodrugs / pharmacokinetics*

Substances

  • Amino Acids
  • Esters
  • HIV Protease Inhibitors
  • Phosphates
  • Prodrugs
  • Atazanavir Sulfate