1. Dr. Basavaraj K. Nanjwade M.Pharm., Ph.D
Drug Design: Discovery, Development and Delivery – Regulatory Requirements
Dr. Basavaraj K. Nanjwade M.Pharm., Ph.D
Associate Professor
Department of Pharmaceutics
KLE University
BELGAUM –
Cell No:
21 April 2009
GCP Workshop, NIMS Hyderabad

2. GCP Workshop, NIMS Hyderabad
Drug Design
21 April 2009
GCP Workshop, NIMS Hyderabad

3. GCP Workshop, NIMS Hyderabad
Drug Design
Drug design is the approach of finding drugs by design, based on their biological targets. Typically a drug target is a key molecule involved in a particular metabolic or signalling pathway that is specific to a disease condition or pathology, or to the infectivity or survival of a microbial pathogen.
Other approaches may be to enhance the normal pathway by promoting specific molecules in the normal pathways that may have been affected in the diseased state.
In medicine, biotechnology and pharmacology, drug discovery is the process by which drugs are designed
21 April 2009
GCP Workshop, NIMS Hyderabad

4. GCP Workshop, NIMS Hyderabad
Drug Design
1. Rational Drug Design
2. Computer-assisted Drug Design (CADD)
3. Neural network in Drug Design
21 April 2009
GCP Workshop, NIMS Hyderabad

5. GCP Workshop, NIMS Hyderabad
Rational Drug Design
The industry now has the research tools to pursue rational Drug Design successfully, but a new hurdle is being raised:finding a way to generate data and manage our knowledge of disease that maximizes the value of that knowledge
1. Molecular properties
2. Receptor-Based modeling
3. Numerical methods
21 April 2009
GCP Workshop, NIMS Hyderabad

6. Refining the understanding of pathogenesis
Rational Drug Design
Refining the understanding of pathogenesis
21 April 2009
GCP Workshop, NIMS Hyderabad

7. Investigating complex systems increases knowledge return
Rational Drug Design
Investigating complex systems increases knowledge return
21 April 2009
GCP Workshop, NIMS Hyderabad

8. Computer-assisted Drug Design (CADD)
Drug design is a three-dimensional puzzle where small drug molecules, ligands, are adjusted to the binding site of a protein.
The factors which affect the protein-ligand interaction can be characterized by using molecular docking and different quantitative structure-activity relationships (QSAR) methods
21 April 2009
GCP Workshop, NIMS Hyderabad

9. Computer-assisted Drug Design (CADD)
In CoMFA map the colored fields describe how molecular structure can be modified to increase biological activity (CoMFA-Comparative molecular field analysis)
21 April 2009
GCP Workshop, NIMS Hyderabad

10. Computer-assisted Drug Design (CADD)
CADD most commonly used tool to model biological system is molecular dynamics
The model of a receptor refined with molecular dynamics simulations
21 April 2009
GCP Workshop, NIMS Hyderabad

11. Computer-assisted Drug Design (CADD)
3D models of membrane receptors can be refined and validated in a realistic lipid-water-salt environment using molecular dynamics simulations
21 April 2009
GCP Workshop, NIMS Hyderabad

12. Computer-assisted Drug Design (CADD)
Virtual screening is a computational technique to find novel drug candidates.
Data from virtual screening can be used to develop predictive models in order to optimize ADMET properties of the candidate molecules.
The ultimate goal of this procedure is to find investing lead molecules that are worth for further drug research and synthesis.
21 April 2009
GCP Workshop, NIMS Hyderabad

13. Computer-assisted Drug Design (CADD)
New potent inhibitor for the Human Sirutuin Type 2 enzyme was found using a virtual screening technique
21 April 2009
GCP Workshop, NIMS Hyderabad

14. Neural network in Drug Design
This is the most latest technique being applied to discover new drugs. It works on the same principles as the neural networks found in the human brain.
This technique makes use of Computer Artificial Intelligence, whereby a computer learns by itself, how to approach a target drug molecule and improves its iterations by itself.
This technique can be applied to solve complex drug calculations. Desktop computers as well as Super-Computers both are employed for Neural Networks Drug research.
21 April 2009
GCP Workshop, NIMS Hyderabad

15. GCP Workshop, NIMS Hyderabad
Applications
1. Find interesting lead molecules quickly
2. Predicting properties and activities of untested molecules
3. Propose compounds for synthesis
4. Validate models of receptor binding sites
5. Optimize pharmacokinetic properties of compound
21 April 2009
GCP Workshop, NIMS Hyderabad

16. GCP Workshop, NIMS Hyderabad
Drug Discovery
21 April 2009
GCP Workshop, NIMS Hyderabad

17. GCP Workshop, NIMS Hyderabad
Drug Discovery
In medicine, biotechnology and pharmacology, drug discovery is the process by which drugs are discovered
The process of drug discovery involves the identification of candidates, synthesis, characterization, screening, and assays for therapeutic efficacy.
21 April 2009
GCP Workshop, NIMS Hyderabad

18. Important DRUG Targets
Focused Areas of Research
Metabolic
Gastrointestinal
Dermatology
Ophthalmic
Neurological/
Pyschotherapeutic
Inflammatory/
Immune-related
Important DRUG Targets
Infectious Disease
Microbial/Viral
Oncology/
Cancer
Cardiovascular/
Blood Disorder
Musculoskeletal
Respiratory
21 April 2009
GCP Workshop, NIMS Hyderabad

19. GCP Workshop, NIMS Hyderabad
Drug Discovery Pathway
Preclinical Studies
Primary Screening
[Hits]
Selection of
candidate drug
ADME
Discovery
&
Development
Efficacy
Preformulations
Stability Studies
Safety
Toxicology
Leads
21 April 2009
GCP Workshop, NIMS Hyderabad

20. Drug Discovery Process
1. What is an ideal drug?
(Given by mouth and has a beneficial effect {safe & efficacious} in only ~ 50% !)
2. What is a promising drug candidate?
(Most site specific with best combination of target affinity, highest bioavailability and lowest toxicity)
3. How is a ‘lead’ drug candidate screened for ideal
characteristics?
(Study of the in vitro ADME/Tox- drug transport , absorption, metabolism, etc)
[Toxicity & pharmacokinetics: In vivo ]
21 April 2009
GCP Workshop, NIMS Hyderabad

21. Drug Discovery Pipeline
Exploratory Research
Discovery
Development
Proteomics
Diagnostics
Peptide Mass
Expression
Fingerprinting
Profiling
Fractionate
Mass
Protein
Spec
Validated
Targets
Pathway
Mapping
Lead
Lead
Pre-clinical
Clinical
Protein
Identification
Optimization
Protein-
protein
Interactions
Structure
Genotyping
Hot
Drug
ADME
Human
H-UHTS
Genome
SNP
M-HTS
L-MTS
Leads
Candidates PK
Trials
Sequencing
Discovery
Functional
Genomics
Primary
Secondary
Lab &
Clinical
Protein
Gene
Combichem
Screening
Screening
Animal Tests
Validation
Expession
Localization
Synthesis
Genomics
Compound
Profiling
Production
Library
Drug Discovery
Natural
Compounds
21 April 2009
GCP Workshop, NIMS Hyderabad

22. Drug Discovery Process
Exploratory
Drug Discovery
Drug Development
Compound library generation
Combichem
New
Drug
Target
Identification
Qualification
Validation
Lead
Optimization
Preclinical
Development
Clinical
NDA
Clinical
Trials
&
monitoring
Assay
Development
Discovery Center
w/primary & secondary screening
& Pre-ADME
In vitro & in-vivo ADMET
Functional and ADMET screening assays becoming more important earlier in the screening process.
21 April 2009
GCP Workshop, NIMS Hyderabad

23. GCP Workshop, NIMS Hyderabad
“Real drug “pipeline”
A – Absorption
Solubility
Stability
Dissolution
Drug Transport
D- Distribution
Plasma Protein Binding assays
(PPB)
Targets
“Permeability”
Drug
Drug
Drug
21 April 2009
GCP Workshop, NIMS Hyderabad

24. Overview of Solubility Screening Assay Protocol
1. Compound from library is added to buffer and mixed in plate.
2. Precipitated compound is filtered out.
3. Filtrate containing soluble compound is analyzed versus standards.
21 April 2009
GCP Workshop, NIMS Hyderabad

25. Value of Solubility and Permeability for Absorption
For a particular dose level and permeability value, the solubility must be above a certain level to assure oral bioavailability.
21 April 2009
GCP Workshop, NIMS Hyderabad

26. Cell Membrane Transport Mechanisms
Transcellular
Paracellular
Active Transport
Active Efflux
21 April 2009
GCP Workshop, NIMS Hyderabad

27. Membrane structure & transport
Membranes are two-dimensional solutions of oriented lipids and globular proteins that are mobile in the plane of the membrane – fluid-mosaic model
Membrane transport is mediated by specific integral membrane proteins – ion channels, porins, transporters (passive), pumps (active)
Integral membrane proteins have common structural features – predominantly transmembrane a helices
21 April 2009
GCP Workshop, NIMS Hyderabad

28. Ion channels are membrane spanning proteins
21 April 2009
GCP Workshop, NIMS Hyderabad

29. Opening and closing of channels requires conformational change
21 April 2009
GCP Workshop, NIMS Hyderabad

30. Flux of ions through the channels is passive
Extracellular
Intracellular
21 April 2009
GCP Workshop, NIMS Hyderabad

31. GCP Workshop, NIMS Hyderabad
Drug Development
21 April 2009
GCP Workshop, NIMS Hyderabad

32. GCP Workshop, NIMS Hyderabad
Drug Development
Drug development or preclinical development is defined in many pharmaceutical companies as the process of taking a new chemical lead through the stages necessary to allow it to be tested in human clinical trials, although a broader definition would encompass the entire process of drug discovery and clinical testing of novel drug candidates.
21 April 2009
GCP Workshop, NIMS Hyderabad

33. Drug Discovery Pathway
Preclinical Studies
Primary Screening
[Hits]
Selection of
candidate drug
ADME
Discovery
&
Development
Efficacy
Preformulations
Stability Studies
Safety
Toxicology
Leads
21 April 2009
GCP Workshop, NIMS Hyderabad

34. Drug Development Process
21 April 2009
GCP Workshop, NIMS Hyderabad

35. Reasons for Attrition in Drug
Development
21 April 2009
GCP Workshop, NIMS Hyderabad

36. Barriers of Drug Reaching Target
Stomach
pH2
Intestine
pH3-8
Blood
Kidneys
Tissues
Liver
Cell
Target PV
Phase I and II
Metabolic stability
Metabolite ID
Stability
Enzymatic
Plasma
stability
Permeability
Passive
Transporters
Log D
Cell Exposure
Stability
Acidic buffer
Stability
Acidic enzymatic
buffer
Renal Extraction
Log D
Protein binding
RBC uptake
Solubility
pKa
Permeability
Passive
P-gp efflux
Transportes
Log D
Stability
CYP3A metabolic stability
21 April 2009
GCP Workshop, NIMS Hyderabad

37. GCP Workshop, NIMS Hyderabad
Candidate Selection: Building “Developability” in Preclinical Profiling
Lead
(active molecule)
Physical properties
Metabolism
Potency
Potency
Best leads
Physical / chemical
properties
Biopharmaceutics
Selectivity
Metabolism
Selectivity LO
(optimized molecule)
21 April 2009
GCP Workshop, NIMS Hyderabad

38. Stability in Physiological Conditions
Duodenum
Stomach
Ascending colon
Descending colon
Jejunum
Ileum
Small intestine
Transverse
colon
Rectum
pH =
pH = 5 - 7
pH = 8
Blood = 7.4
21 April 2009
GCP Workshop, NIMS Hyderabad

39. GCP Workshop, NIMS Hyderabad
Solubility, Permeability, Chemical and Metabolic Stability Affects Oral Bioavailability
Portal
Vein
Membrane
Transfer
Liver
Extraction
Solid
Drug
Dissolution
Drug in
Solution
Absorbed
Drug
Systemic
Circulation
Solubility
Permeability
Metabolism
21 April 2009
GCP Workshop, NIMS Hyderabad

40. Physico-chemical profile of NCEs
21 April 2009
GCP Workshop, NIMS Hyderabad

41. Successful Drug = Activity + Property
Optimization
Activity
Pharmacology
Property
Pharmaceutical Profiling
In vitro
Solubility
Permeability
BBB & Pgp
Log P & pKa
Metabolism
P450 Inhibition
Stability
Pharmacokinetics
In vivo
Enzyme
Receptor
Cell-based assay
Animal Model
Redesign
21 April 2009
GCP Workshop, NIMS Hyderabad

42. Drug Development Process
21 April 2009
GCP Workshop, NIMS Hyderabad

43. GCP Workshop, NIMS Hyderabad
Drug Delivery
21 April 2009
GCP Workshop, NIMS Hyderabad

44. GCP Workshop, NIMS Hyderabad
Drug Delivery
Drug delivery is the method or process of administering a pharmaceutical compound to achieve a therapeutic effect in humans or animals
Drug Delivery technologies are patent protected formulation technologies that modifies drug release profile, absorption, distribution and elimination for the benefit of improving product efficacy & safety and patient convenience & compliance
21 April 2009
GCP Workshop, NIMS Hyderabad

45. GCP Workshop, NIMS Hyderabad
Drug Delivery
Most common methods of delivery include the preferred non-invasive peroral (through the mouth), topical (skin), transmucosal (nasal, buccal/sublingual, vaginal, ocular and rectal) and inhalation routes
21 April 2009
GCP Workshop, NIMS Hyderabad

46. GCP Workshop, NIMS Hyderabad
Drug Delivery
Many medications such as peptide and protein, antibody, vaccine and gene based drugs, in general may not be delivered using these routes because they might be susceptible to enzymatic degradation or can not be absorbed into the systemic circulation efficiently due to molecular size and charge issues to be therapeutically effective
protein and peptide drugs have to be delivered by injection.
21 April 2009
GCP Workshop, NIMS Hyderabad

47. GCP Workshop, NIMS Hyderabad
Drug Delivery
Current efforts in the area of drug delivery include the development of targeted delivery in which the drug is only active in the target area of the body (for example, in cancerous tissues) and in which the drug is released over a period of time in a controlled manner from a formulate
21 April 2009
GCP Workshop, NIMS Hyderabad

48. Context – Drug Delivery
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GCP Workshop, NIMS Hyderabad

49. Context – Drug Delivery
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GCP Workshop, NIMS Hyderabad

50. Drug Delivery - Markets
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GCP Workshop, NIMS Hyderabad

51. GCP Workshop, NIMS Hyderabad
Drug Delivery Systems
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GCP Workshop, NIMS Hyderabad

52. Regulatory Requirements
21 April 2009
GCP Workshop, NIMS Hyderabad

53. India (Ministry of Health & Family Welfare)
1. If the drug or its metabolites is related to a known carcinogen
2. Two species should be used for carcinogenicity studies
3. At least 3-dose level should be used
4. A control group should always be included
21 April 2009
GCP Workshop, NIMS Hyderabad

54. United States ( FDA’s Centre for Drug Evaluation & Research)
1. Microbial mutagenicity test
2. In vitro mammalian cell mutagenicity test
3. Mammalian chromosome test in vitro
4. In vitro mammalian cell transformation assay
5. Cytogenetic tests in vivo (e.g. bone marrow micronucleus test, liver unscheduled DNA synthesis [UDS] test).
6. Further in vivo test selection is left to the applicant
21 April 2009
GCP Workshop, NIMS Hyderabad

55. European Community (The Commission of the European Union)
1. An in vitro test for gene mutation in bacteria
2. An in vitro test for gene mutation in eukaryotic test system (mammalian cells)
3. An in vitro test for chromosomal aberration
4. An appropriate in vivo assay (usually test for chromosomal aberration)
21 April 2009
GCP Workshop, NIMS Hyderabad

56. Japan ( Ministry of Health & Welfare)
1. Bacterial reversion test
2. In vitro chromosomal aberration test
3. In vivo micronuleus test
Additional tests
(i) Continuous treatment for 24 and 48 hours with and without S9 mix..
(ii) Pulse treatment for 6 hours (with and without S9 mix) followed by sampling at 24 hours.
(iii) Chromosome preparation for the presence of polyploid cells
(iv) Use of single sex (male) in rodent micronucleus test
21 April 2009
GCP Workshop, NIMS Hyderabad

57. Canada (Health Protection Branch)
1. Salmonella/microsome assay.
2. Mammalian in vitro chromosome aberration assay.
3. Mammalian in vivo assay (either metaphase or micronucleus test).
4. Positive in vivo results may need additional in vivo germ cell assay
21 April 2009
GCP Workshop, NIMS Hyderabad

58. ICH (Regulatory authorities of EU, Japan & USA)
1. A test for gene mutation in bacteria.
2. In vitro chromosomal damage with mammalian cells or an in vitro tk assay.
3. In vitro test for chromosomal damage using rodent haemopoietic cells.
Additional test:
(i) Measurement of DNA adducts.
(ii) DNA – strand breaks
(iii) DNA repair or recombination
21 April 2009
GCP Workshop, NIMS Hyderabad

59. GCP Workshop, NIMS Hyderabad
THANK YOU FOR YOUR
ATTENTION
21 April 2009
GCP Workshop, NIMS Hyderabad