Drug Design / drug discoveryWhat’s a drug?A substance that treats/cure a disease.A small molecule that interacts with a target, (often protein involved in the diseaseprocess; activator/inhibitor)Drug discovery:The process of finding such a small molecule – combination of approachesDrug discovery or drug design?In principle: “Design” is more rational and targeted, and “discovery” is moreserendipitous. But design and discovery share a lot and are ~ synonymous in apharmaceutical context.
Drug discovery marketGigantic economic importance: 10 years & $200 to $1,900 million to develop a drug 25 new molecules /yearin millions US$ Revenue R&D incomeJohnson & Johnson 53,324 7,125 11,053Pfizer 48,371 7,599 19,337GlaxoSmithKline 42,813 6,373 10,135Novartis 37,020 5,349 7,202Sanofi-Aventis 35,645 5,565 5,033Hoffmann–La Roche 33,547 5,258 7,318AstraZeneca 26,475 3,902 6,063Merck & Co. 22,636 4,783 4,434Abbott Laboratories 22,476 2,255 1,717Wyeth 20,351 3,109 4,197 > $340 billion http://en.wikipedia.org/wiki/List_of_pharmaceutical_companies Intense scientific activity: very interdisciplinary approach
The drug discovery and design workflow: Target identification Discovery and design (hit/lead/optimisation) Biology: assay (binding/activity; inChemistry: synthesis vitro / in vivo,) drug development: Pharmacology / testing
The long and winding road to drug discovery Computational chemistry /Molecular modeling useful across the pipeline, but very different techniques aim for success, but if not: fail early, fail cheap
Role of Computers• In early 90’s there was a deal of optimism that computer’s will play a major role in the improvement of drug design.• It reduced at-least 5 year’s of research duration.
Computer aided drug design(CADD)• Computer aided drug design is a specialized discipline that uses computational methods to stimulate drug receptor interactions.• CADD technique are dependent on bioinformatics tools, databases & applications.
What is QSAR?• QSAR depict an attempt to correlate structural property of compounds with biological activities.• Such developments have provided a sound basis for the generation of 3D Quantitative Structure Activity Relationship (QSAR) for further refinement of the ligand molecule in terms of chemical structure so as to improve biological activity.• Such physiochemical descriptors which indulge parameters to account for hydrophobicity, electronic properties, steric effects, etc. can be determined by computational methods.
Two pathways to drug discovery / drug design Structure-based Structure-based don’t know receptor, know receptor, known ligands don’t known ligands ? What will be happy in there?Protein/ligand interactions Statistical analysis of what group(s)structure/biophysics are important for biological activitydocking
Structure basedUses protein structure directlyCADD: Protein-ligand docking
Ligand based• Binding of ligand to the receptor may include hydrophobic, electrostatic and hydrogen bonding interactions. -Derive information from ligand structures -Protein structure not always available • 40% of all prescription pharmaceuticals target GPCRs -Protein structure has large degree of flexibility • Structure deforms to accommodate ligands or gross movements occur on binding