The discovery of tadalafil: a novel and highly selective PDE5 inhibitor. 1: 5,6,11,11a-tetrahydro-1H-imidazo[1',5':1,6]pyrido[3,4-b]indole-1,3(2H)-dione analogues

J Med Chem. 2003 Oct 9;46(21):4525-32. doi: 10.1021/jm030056e.

Abstract

Starting from ethyl beta-carboline-3-carboxylate (beta-CCE), 1, a modest inhibitor of type 5 phosphodiesterase (PDE5), a series of functionalized tetrahydro-beta-carboline derivatives has been identified as a novel chemical class of potent and selective PDE5 inhibitors. Optimization of the side chain on the hydantoin ring of initial lead compound 2 and of the aromatic ring on position 5 led to the identification of compound 6e, a highly potent and selective PDE5 inhibitor, with greater selectivity for PDE5 vs PDE1-4 than sildenafil. Compound 6e demonstrated a long-lasting and significant blood pressure lowering effect after iv administration in the spontaneously hypertensive rat model but showed only moderate oral in vivo efficacy.

MeSH terms

  • 3',5'-Cyclic-GMP Phosphodiesterases / antagonists & inhibitors*
  • Animals
  • Blood Pressure / drug effects
  • Carbolines / chemical synthesis*
  • Carbolines / pharmacology*
  • Cattle
  • Cyclic GMP / biosynthesis
  • Cyclic Nucleotide Phosphodiesterases, Type 5
  • Drug Design
  • Hydantoins / chemical synthesis
  • Hydantoins / pharmacology
  • Indicators and Reagents
  • Isomerism
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism
  • Phosphodiesterase Inhibitors / chemical synthesis*
  • Phosphodiesterase Inhibitors / pharmacology*
  • Rats
  • Rats, Inbred SHR
  • Structure-Activity Relationship
  • Tadalafil

Substances

  • Carbolines
  • Hydantoins
  • Indicators and Reagents
  • Phosphodiesterase Inhibitors
  • Tadalafil
  • 3',5'-Cyclic-GMP Phosphodiesterases
  • Cyclic Nucleotide Phosphodiesterases, Type 5
  • Pde5a protein, rat
  • Cyclic GMP