Drug Design


Drugs work by interacting with target molecules in our body and altering their activity in a way that is beneficial to our health

A drug may function by either stimulating the activity of its target (agonists) or by blocking or inhibiting the activity of its target (antagonists)

Rational Drug Design

Rational drug design involves determining the structure and function of a target molecule and using this information to develop effective drug treatments

It involves the following steps:

  • Disease conditions are researched to identify specific biological target molecules - as these molecules are usually proteins, this involves proteomics
  • Structural information is determined using methods such as X-ray crystallography or nuclear magnetic resonance (NMR) imaging
  • Online databases are referenced to identify chemical compounds most likely to interact favourably with the desired target molecule
  • Treatment compounds can then be developed using molecular modelling software designed to optimise and improve the identified chemical analogs
  • The designed drug can then be synthesised (using combinatorial chemistry) and tested in animal and clinical trials to determine its therapeutic value
  • Some of the drugs designed by this process include Relenza (for influenza), Indanivir (for HIV), Gleevec (for leukemia) and Viagra


One of the first drugs produced by rational drug design was Relenza, which was designed to treat the spread of infection of the influenza virus

  • Relenza was developed by identifying molecules most likely to interact with neuraminidase
  • Neuraminidase is a virus-produced enzyme that is needed to release newly formed virions from an infected cell
  • It cleaves the haemagglutinin glycoprotein which anchors the virion to the infected cell's surface, thereby mediating its release
  • By blocking the active site of neuraminidase (i.e. competitive inhibition), Relenza inhibits the spread of infection

Overview of the Treatment of Influenza by Relenza