21 April 2009 GCP Workshop, NIMS Hydera bad 1 Drug Design: Discovery, Development and Delivery – Regulatory Requirements Dr. Basavaraj K. Nanjwade M.Pharm., Ph.D Associate Professor Department of Pharmaceutics KLE University BELGAUM – 590010 E-mail: [email protected]Cell No: 0091 9448716277
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21 April 2009GCP Workshop, NIMS Hyderabad1 Drug Design: Discovery, Development and Delivery – Regulatory Requirements Dr. Basavaraj K. Nanjwade M.Pharm.,
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21 April 2009 GCP Workshop, NIMS Hyderabad 1
Drug Design: Discovery, Development and Delivery –
• 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
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
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Rational Drug Design
Refining the understanding of pathogenesis
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Rational Drug Design
Investigating complex systems increases knowledge return
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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
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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)
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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
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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
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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.
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Computer-assisted Drug Design (CADD)
New potent inhibitor for the Human Sirutuin Type 2 enzyme was found using a virtual screening technique
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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.
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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
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Drug Discovery
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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.
1. Membranes are two-dimensional solutions of oriented lipids and globular proteins that are mobile in the plane of the membrane – fluid-mosaic model
2. Membrane transport is mediated by specific integral membrane proteins – ion channels, porins, transporters (passive), pumps (active)
3. Integral membrane proteins have common structural features – predominantly transmembrane helices
Membrane structure & transport
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Ion channels are membrane spanning proteins
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Opening and closing of channels requires conformational change
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Extracellular
Intracellular
Flux of ions through the channels is passive
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Drug Development
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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.
Candidate Selection: Building “Developability” in Preclinical Profiling
Lead (active molecule)
MetabolismSelectivity
Potency
LO
(optimized molecule)
Physical properties
Potency
Selectivity
Metabolism
Best leadsPhysical / chemical
propertiesBiopharmaceutics
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Duodenum
Stomach
Ascending colon
Descending colon
Jejunum
Ileum
Small intestine
Transverse colon
Rectum
pH = 1 - 3.5
pH = 5 - 7
pH = 8
Blood = 7.4
Stability in Physiological Conditions
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Solubility, Permeability, Chemical and Metabolic Stability Affects Oral Bioavailability
Solid
Drug
Drug in
Solution
Absorbed
Drug
Dissolution
Membrane
Transfer
Solubility Permeability
Systemic Circulation
Metabolism
Liver
Extraction
PortalVein
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Physico-chemical profile of NCEs
Permeability
pKa
Stability
PPB Log D
Polymorphism
Lipophilicity
Solubility
Integrity
Profile
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Successful Drug = Activity + Property
OptimizationActivity
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
In vitro
Animal Model
In vivo Redesign
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Drug Development Process
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Drug Delivery
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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
• 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
• 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.
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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
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Context – Drug Delivery
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Context – Drug Delivery
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Drug Delivery - Markets
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Drug Delivery Systems
NanoTechnology
DDS
Buccal DDS
Rectal DDS
Vaginal DDSPulmonary
DDS
Nasal DDS
Topical DDS
Parentral DDS
Oral DDS
DeliverySystems
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Regulatory Requirements
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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
India (Ministry of Health & Family Welfare)
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United States ( FDA’s Centre for Drug Evaluation & Research)
1. Microbial mutagenicity test2. In vitro mammalian cell mutagenicity
test3. Mammalian chromosome test in vitro4. In vitro mammalian cell transformation
assay5. 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
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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)
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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
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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
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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.