Drug design, Discovery and development .

Drug Design, Discovery and development

1. Drug design, discovery and development Presented by : Group 03 Organic Chemistry-VII ( CHEM-412) Presented To: Dr. Ghulam Mustafa Department of Chemistry 1

2. Group Members: Hajra Shafaq ( 20011507-026) Soaybah Nawaz ( 20011507-030) Fatima Nadeem (20011507-031) Sana Eman Riaz ( 20011507-038) Sharqa Fatima ( 20011507-041) 2

3. Drug design by synthesis: Presented to: Dr. Ghulam Mustafa Presented by: Hajra Shafaq Roll no. : 20011507-026 BS VIII (Morning) University of Gujrat Hafiz Hayat Campus

4. Contents Introduction to drugs * Sources of drug * Formulation of drug Drug Design classification * Ligand-based drug design * Structure-based drug design 3 . Route for synthesis of various drugs * Rosiglitazone * Etoricoxib * Imatinib 4

5. Drugs’ Introduction: Any substance that is used to prevent, diagnose, treat, or relieve symptoms of a disease or abnormal condition. Drugs can also affect how the brain and the rest of the body work and cause changes in mood, awareness, thoughts, feelings, or behavior. Ref: Introduction to medicinal chemistry by Graham L. Padrick c hapter 1; page 1 5

6. Sources of Drugs: Ref: Introduction to medicinal chemistry by Graham L. Padrick chapter 1 page 1 6

7. Natural Drug Sources: 7 Ref: https://www.researchgate.net/figure/Drugs-developed-from-natural-sources-their-biological-sources-chemical-structures and_fig1_346625792

8. Synthetic Source: Synthetic materials are made by chemically changing the starting substances to create a material with different characteristics. Synthetic cannabinoids. Phenethylamines. Synthetic cathinones. Tryptamines. Piperazines. Novel benzodiazepines. Ref: Introduction to medicinal chemistry by Graham L. Padrick chapter 1 page 1 8

9. Drug Design: Drug design , often referred to as  rational drug design  or simply rational design, is the inventive process of finding new medications based on the knowledge of a biological target. The drug is most commonly an organic small molecule that activates or inhibits the function of a biomolecule such as a protein, which in turn results in a therapeutic benefit to the patient. In the most basic sense, drug design involves the design of molecules that are complementary in shape and charge to the biomolecular target with which they interact and therefore will bind to it. Ref: https://drugdesign.org/chapters/synthesis-of-drugs/ retrieved at 23/05/2024 9

10. Drug Design Classification: 10

11. Ligand Based Drug Design : Ligand based drug design is the indirect method for the designing of the therapeutic drugs. It is based on the understanding of ligand that binds with the target. Ligand based drug design makes use of the molecular structure of the ligands where the structure of the target is not known. Ref: https://drugdesign.org/chapters/synthesis-of-drugs/ retrieved at 23/05/2024 11

12. Structure based drug design is also referred to as direct drug design. It is based on the knowledge of the 3D structure of the receptor molecule obtained through Nuclear Magnetic Resonance (NMR) or X-ray crystallography. It deals with the known target molecules. Thus, the understanding of the structure of the target, the drug can be designed based on the selective binding sites of the target which results in maximum drug target interaction . Structure Based Drug Design: Ref: https://drugdesign.org/chapters/synthesis-of-drugs/ retrieved at 23/05/2024 12

13. Drug formulation Pharmaceutical formulation is the multistep process where the active drug is mixed with all other components by considering the factors of particle size, polymorphism, pH, and solubility and becomes the final beneficial medicinal product with following mixture: Active ingredients Diluents Binders Lubricating agents Wetting agents and Flavors are also added. Ref: Introduction to medicinal chemistry by Graham L. Padrick page 53,54 & 203,204 13

14. Route for synthesis: 14

15. Synthesis of Rosiglitazone Rosiglitazone is used to treat a type of diabetes mellitus called type 2 diabetes. It may be used alone or with other medicines such as metformin or sulfonylurea agents. Rosiglitazone is used together with a proper diet and exercise to help control blood sugar levels. Rosiglitazone is member of the so-called thiazolidinedione class of type-2 diabetes drugs. This pharmaceutical agent act as binders to the peroxisome proliferator-activated receptors that upon activation migrate to the DNA to regulate the transcription of specific genes which control the metabolism of carbohydrates and fatty acids. Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 15

16. The structures of pioglitazone and rosiglitazone show common structural features bearing a distal pyridine ring linked to the thiazolidinedione pharmacophore Rosiglitazone Structure: Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 16

17. Disadvantages: One of the safety concerns identified before approval was fluid retention. Moreover, the combination of rosiglitazone with insulin resulted in a higher rate of congestive heart failure. In Europe there were contraindications for use in heart failure and combination with insulin. It is banned because it causes heart failure. Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 17

18. Route of Synthesis: In rosiglitazone the pyridine unit is introduced via an S N Ar reaction between  N - methylethanolamine and 2-chloropyridine which in turn is readily prepared by chlorination of 2-pyridone with phosphorous oxychloride . The resulting primary alcohol  is then subjected to a second S N Ar reaction with 4-fluorobenzaldehyde . A Knoevenagel condensation of the aldehyde functionality in compound  with thiazolidinedione  in the presence of a catalytic amount of piperidinium acetate reportedly leads to the exclusive formation of the desired  Z -isomer product. Interestingly, the newly installed double bond was efficiently reduced using magnesium in methanol thus circumventing catalyst poisoning issues pertaining to the thiazolidinedione moiety as experienced using other reducing systems. Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 https://www.chemistrylearner.com/knoevenagel-condensation.html 18

19. Mechanism: Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 19

20. These belong to a family of medicines called non-steroidal anti-inflammatory drugs. Etoricoxib helps to reduce the pain and swelling in the joints and muscles of people 16 years of age and older with osteoarthritis, rheumatoid arthritis, ankylosing spondylitis and gout. Etoricoxib is a selective inhibitor of cyclooxygenase-2 (COX-2), an enzyme involved in pain and inflammation. It is a member of the COX-2-selective ( coxib ) class of nonsteroidal anti-inflammatory drugs (NSAIDs). It is reported to show a 160-fold selectivity for COX-2 over COX-1 and so it is hoped that it will not display long term side effects such as gastric ulceration, common to non-selective COX inhibitors Etoricoxib: Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 20

21. Route of S ynthesis : In many syntheses the presence of aryl–aryl linkages commands the use of Pd -mediated cross coupling reactions which dictates access to functionalised pyridines as starting materials. Howeochel has recently reported an approach to forming the first aryl–aryl C–C bond by a directed lithiation of a pyridine followed by conversion to its organozinc derivative. This intermediate then undergoes a high-yielding Negishi cross-coupling reaction with an arylbromide . After acidic hydrolysis of the phosphoramidate directing group the resulting pyridone  is subjected to a sequence of chlorinations rendering a suitably functionalised coupling partner for a final Stille coupling to yield etoricoxib. Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 21

22. M echanism: Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 22

23. Imatinib : Imatinib is a 2-phenylamino-pyrimidine derivative protein that is a medication used to manage and treat chronic myelogenous leukemia, gastrointestinal stromal tumors, and other malignancies. It is in the tyrosine-kinase inhibitors class of drugs. Imatinib is Novartis’ tyrosine kinase inhibitor used for the treatment of chronic myeloic leukaemia . In a patented route the aldol product  undergoes a condensation reaction with guanidine  in basic media to give the 2-aminopyrimidine. Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 23

24. After generating the functional pyrimidine core a hydrazine-mediated reduction of the nitro group in the side chain was conducted with Raney-Nickel as the catalyst. Amide formation with 4-chloromethylbenzoyl chloride and a direct displacement of the benzylic chloride with  N - methylpiperazine complete this synthesis of imatinib in excellent overall yields. COND’ Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 24

25. M echanism: Ref: https://www.beilstein-journals.org/bjoc/articles/9/265 25

26. Computer Aided Drug Design: Presented to: Dr. Ghulam Mu s tafa Presented by: Sana Eman Riaz Roll no. : 20011507-038 BS VIII (Morning) University of Gujrat Hafiz Hayat Campus

27. Contents Computer-Aided Drug Design: > Workflow of CADD > History of CADD > Major steps involved 2. Various Approaches in CADD: > Pharmacophore Modelling > Molecular Docking > Scoring Function > Target and Phenotypic approach > De Novo Approach 3. Advantages 27

28. Drug Design: Drug design is the inventive process of finding new medications based on the knowledge of a biological target . Ref:   https://www.researchgate.net/figure/Classification-of-drug-design-methods_fig1_354195731 28

29. Computer-Aided Drug Design : Computer-aided drug design (CADD) includes finding, developing and analyzing medicines and related biological active compounds by computer methodologies. The use of CADD methodologies speeds up the early stages of chemical development while guiding and speeding up drug discovery. https://www.sciencedirect.com/science/article/abs/pii/B9780128022207000053​ 29

30. Work Flow Of CADD: 30 30

31. History of CADD: 1960’s - Viz - review the target - drug interaction 1980’s- Automation - high throughput target/drug selection  1980’s- Databases (information technology) - combinatorial libraries 1980’s- Fast computers – docking 1990’s- Fast computers - genome assembly - genomic based target selection 2000’s- Vast information handling – pharmacogenomics 31

32. Major Steps Involved: https://youtube.com/@biocue?si=zVkTW89D3Rg9LIJn 32

33. COND’ Fig: Areas of Computer-aided drug discovery https://www.researchgate.net/figure/Computer-Aided-Drug-Design-Each-rectangular-box-shows-the-usage-area-of-CADD-Its_fig2_366697950 33

34. Ligand based drug design (Indirect drug design): Ligand based drug design is based on the knowledge of other molecules that bind to the biological    target of interest so as to derive a pharmacophore. The most popular approaches for ligand-based drug design are the  QSAR method and pharmacophore modeling .  https://www.jubilantbiosys.com/services/ligand-based-drug-discovery/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975775/#:~:text=Basics%20of%20QSAR,particular%20chemical%20or%20biological%20proces s. 34

35. Structure Based Drug Design: Structure based drug design is based on the knowledge of the three-dimensional structure of the biological target. Using the structure of the biological target, candidate drugs that are predicted to bind with high affinity and selectivity to the target may be designed https://www.slideshare.net/mojdehy/de-novo-drug-design-62885386 35

36. COND’ https://www.researchgate.net/figure/Workflow-of-structure-based-drug-design-SBDD_fig1_325095935 36

37. Pharmacophore modeling in CADD Pharmacophore modeling is most often applied to virtual screening in order to identify molecules triggering the desired biological effect. For this purpose, researchers create a pharmacophore model (query) that most likely encodes the correct 3D organization of the required interaction patterns.  The pharmacophore models can be used to identify possible interactions of drugs with drug-metabolizing enzymes by matching the equivalent chemical groups of test molecules to those of drug molecules. https://www.dovepress.com/pharmacophore-modeling-advances-limitations-and-current-utility-in-dru-peer-reviewed-fulltext-article-JRLCR 37

38. COND’ Fig: Four different situations for the pharmacophore search https://www.researchgate.net/figure/Four-different-situations-for-the-pharmacophore-search-Notes-The-figure-shows-the-four_fig3_268151894 38

39. Molecular Docking in CADD: Molecular docking is a method which analyses the conformation and orientation (referred together as the “pose”) of molecules into the binding site of a macromolecular target. Searching algorithms generate possible poses, which are ranked by scoring functions thereby. The first step in a docking calculation is to obtain the target structure, which commonly consists of a large biological molecule (protein, DNA or RNA). https://en.wikipedia.org/wiki/Docking_%28molecular%29 39

40. Molecular Docking: Fig: Molecular Docking https://www.mdpi.com/1422-0067/20/18/4574 40

41. Scoring functions in CADD: Scoring functions have been used to predict the strength of intermolecular interactions between two proteins or between proton and DNA. Different types used are: Shape and chemical complementary Scoring Empirical scoring Force field scoring Knowledge based s coring function Consensus scoring Fig: Scoring of a molecule https://www.youtube.com/@IaNiusha 41

42. Target & phenotypic approach : Different approaches to drug discovery. (A): A target-based approach aims to identify a hit to a known target using a biochemical screen. (B): A phenotypic-based approach identifies hits based on their effect in a cell-based assay, e.g., their ability to induce apoptosis or growth arrest, without necessarily knowing the compound's biochemical target and its role in disease biology. https://www.researchgate.net/figure/Different-approaches-to-drug-discovery-A-A-target-based-approach-aims-to-identify-a_fig1_355910395 42

43. De Novo Approach : Fig: De Novo drug design Approach through Artificial Intelligence https://www.slideshare.net/mojdehy/de-novo-drug-design-62885386 43

44. Advantages: Fast Cost Saving Efficient https://youtube.com/@bocsciences2547?si=fK7M7-nzPZRwUrN1 44

45. Drug Discovery & Lead compound Identification and Optimization Presented to: Dr. Ghulam Mustafa Presented by: Soaybah Nawaz Roll no. : 20011507-030 BS VIII (Morning) University of Gujrat Hafiz Hayat Campus

46. Contents: Drug Discovery - Background and process -Absorption, Distribution, Metabolism, Excretion, Toxicity   (ADMET) profile Stages of drug discovery - Identification of target - Validation of target - Lead compound identification - Lead compound optimization Various approaches in drug discovery Drug characterization, formulation & development 46

47. Background: Many early drugs, such as the analgesic morphine , are natural products derived from plants and just happen to interact with a molecular target ( Opioid receptor in Central Nervous System ) in the human body. Since the 1970s a variety of peptides and proteins have been discovered which act as the body’s own analgesics ( enkephalins and endorphins). Enkephalins are small peptides in CNS while endorphins are peptides produced by Central Nervous System and Pituitary glands Nitric oxide acts as a chemical messenger. 47 Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body

48. Background: For the first time, medicinal chemistry is faced with new targets, but with no lead compounds to interact with them. Such targets have been defined as orphan receptors , Example: Protein-G Receptor The challenge is now to find a chemical that will interact with each of these targets This was one of the main driving forces behind the development of combinatorial and parallel synthesis Combinatorial is the systematic combination of building blocks while parallel synthesis is the multi-reaction occurring simultaneously to form a single compound from the precursor 48 Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body

49. Drug Discovery Process: Drug discovery process basically is a patient-oriented science, where researchers strive to improve the existing drugs ( e.g., Omeprazole is used for treatment of acidity by the inhibition of proton pump inhibitors like H + , K + channel while Esomeprazole have greater activity of acid suppressing) or invent a totally new chemical entity, which should be ideally more potent than any existing drug of a similar category.  If not, then at least it should be safer than those existing. This process is a very time consuming and expensive activity. It takes nearly 12-14 years for the discovery of a single drug.   Failure at any stage would mean a huge loss for the company 49 Ref:     https://www.intechopen.com/chapters/37166   Promising Pharmaceutical edited by Purusotam Basnet – Chapter 2 pg 21-23

50. Drug Discovery Ref:   https://novalix.com/drug-discovery/hit-to-lead/    50

51. ADMET Profile: 51 Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body

52. ADMET Profile: Absorption: It is the process of transferring a drug from its site of administration to the bloodstream. Distribution: When a drug is absorbed into the bloodstream, it can be carried throughout the body. This process is defined as a distribution and reversible process. Metabolism: The drug is not readily metabolized. Drugs are removed from the body either unchanged through the kidneys and bile, or they may undergo chemical changes that allow them to be more easily excreted. 52 Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body

53. COND’… Excretion: The drug is not readily secreted. Basically, drug excretion is a mechanism of eliminating a drug from the body. The greatest proportion of drugs are excreted through kidneys but there are some others route for eliminating such as lungs, milk, sweat, tears, skin, or saliva Toxicity : The drugs may not affect all others tissue or cell. Drugs toxicity is also called Adverse Drug reaction (ADR).Drugs become toxins when a patient has accumulated overdose of drugs or drugs combine with other drugs that leads to the adverse effect like breathing suppression, lowers oxygen levels and finally fatal 53 Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body

54. Paracetamol ADME/T profile : Ref: Paracetamol – Pharmacokinetics (unil.ch) , Acetaminophen: Uses, Interactions, Mechanism of Action | DrugBank Online 54

55. Ideal Feature of A Drug: A drug must have the following ideal features : Drug must be safe and effective Drug should have good bioavailability Drug must be metabolically stable and with a long half-life Drug should be nontoxic with minimal or no side effects Drug should have selective distribution to target tissues or disease state 55 Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body

56. Stages of Drug Discovery: 56 Ref:     https://www.intechopen.com/chapters/37166   Promising Pharmaceutical edited by Purusotam Basnet – Chapter 2 pg 21-23

57. Identification of Biological Target: A diseased state, may hence, be identified by, either the abnormal biochemical functioning or, over or underproduction of some of the intermediates. Example: uncontrolled cell division leads to tumor formation. Hence, the most important and most common biological targets for drug discovery are either enzymes regulating the biochemistry or the receptors through which many hormones and endogenous effectors show their response. For example, inhibition of human dihydrofolate reductase, by methotrexate, brought under control the growth of tumor in humans. Dihydrofolate is used in DNA synthesis and repairing. DHF is converted to Tetrahydrofolate by folate mechanism and THF is helpful in nucleotide synthesis 57 Ref:     https://www.intechopen.com/chapters/37166   Promising Pharmaceutical edited by Purusotam Basnet – Chapter 2 pg 21-23

58. Validation of target molecule: Once the target is identified, it becomes necessary to confirm, that the correct target has been identified. Validation also helps researchers to identify any secondary target that the drug may bind to, which may lead to any sort of unwanted or adverse reaction. Ideally the drug candidate should be such that it binds to a single target only , but this seldom happens. Thus, binding to other targets, apart from the correct target leads to unwanted pharmacological actions . These cannot be completely avoided. It can be minimized to negligible extent. 58 Ref:     https://www.intechopen.com/chapters/37166   Promising Pharmaceutical edited by Purusotam Basnet – Chapter 2 pg 21-23

59. COND’… G-protein coupled receptors  (GCPRs) are the most common and the major targets where a drug binds. Hence, over 30% of drugs in market are modulators of GP. In vitro cell-based mechanistic studies can be used to reveal regulative characteristics of targets and the pathways in which they are involved.  Reproducibility : Once a drug target is identified, whether it be via a specific technique or from review of literature, the first step is to repeat the experiment to confirm that it can be successfully reproduced. 59 Ref:     https://www.intechopen.com/chapters/37166   Promising Pharmaceutical edited by Purusotam Basnet – Chapter 2 pg 21-23

60. Identification of Lead Compound : A lead compound is the one that has basic structural requirements for exhibiting the desired action. This means that, a lead compound has many structural spaces for further development of the structure, to give a compound with further enhanced action. Screening is a technique, which helps to identify the lead compound out of the many synthesized compounds or those compounds which are collected from the natural source.  The various other techniques involved in lead identification are virtual screening,  NMR-based screening and chemical genetics. 60 Ref:     https://www.intechopen.com/chapters/37166   Promising Pharmaceutical edited by Purusotam Basnet – Chapter 2 pg 21-23

61. Characteristics of Lead: Drug ability (preliminary toxicity) Synthetic feasibility Select mechanistic assays In vitro assessment of drug resistance and efflux potential Evidence of in vivo efficacy of chemical class Pharmacokinetics/Toxicity of chemical class known based on preliminary toxicity or in silico studies. Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body 61

62. Optimization of Lead: The chemists in close collaboration with the pharmacologists will carefully study the structure-activity relationship and will synthesize such other derivatives, so as to get a compound with the best possible desired activity. The various other approaches for lead optimization are Structure-Based Drug Design (SBDD), Quantitative Structure-Activity Relationship (QSAR) and Computer-Assisted Drug Design (CADD). All such approaches generate a huge amount of data, so as to assist the chemist in optimizing the lead to the best possible structure, with best possible desired action. 62 Ref:     https://www.intechopen.com/chapters/37166   Promising Pharmaceutical edited by Purusotam Basnet – Chapter 2 pg 21-23

63. Various Approaches in Drug Discovery: Drug discovery via Random screening of synthetic compounds or chemicals and natural products. Example: Accidental discovery of Penicillin by Alexander Flaming when he was working with Staphylococcus bacteria, the petri dish containing bacteria got contaminated by mold, later discovered as Penicillium notatum  Drug discovery via metabolic studies. Example : Statin (Lovastatin0 development used to lower Cholesterol level,  by inhibition of HMG-CoA reductase. The biosynthesis of cholesterol involves a complex process involving multiple enzymes. The rate limiting step is the conversion of HMG-CoA to mevalonate , catalyzed by HMG-CoA reductase   Ref:  https://pharmacyconcepts.in/wp-content/uploads/2022/06/Drug-Design.pdf   63

64. Various Approaches in Drug Discovery: Drug discovery via Novel compounds preparation based on the known structures of biologically active , natural substances of plant and animal origin, i.e., lead skeleton. Example: Aspirin synthesis from lead skeleton Salicin , primary metabolite of salicylic acid, naturally present in willow bark and inhibit Cyclo-oxygenase ) Drug discovery via Preparation of structural analogs of lead with increasing biological activity and Application of bio isosteric principle. Example:  Omeprazole is a racemic mixture of its two enantiomers  where s-enantiomer is more effective in inhibiting acid secretion while Esomeprazole is s-enantiomer of omeprazole, and it is more effective) 64 Ref:  https://pharmacyconcepts.in/wp-content/uploads/2022/06/Drug-Design.pdf  

65. Analog Design : Analog design is most fruitful in the study of pharmacologically active molecules that are structurally specific: their biological activity depends on the nature and the details of their chemical structure. Bioisosteric replacement strategy has been fruitful in design of psychoactive agents, by use of the antidepressant dibenzoazepine derivative Imipramine as the lead. The structural similarity between imipramine and the phenothiazine antipsychotics (typified by chlorpromazine is apparent). 65 Ref:  https://pharmacyconcepts.in/wp-content/uploads/2022/06/Drug-Design.pdf  

66. Bioisosteric Replacement 66 Ref:  https://pharmacyconcepts.in/wp-content/uploads/2022/06/Drug-Design.pdf  

67. Molecular Modification in Analog Design : In analog design, molecular modification of the lead compound can involve one or more of the following strategies: Bioisosteric replacement (e.g., Imipramine and chlorpromazine) Alteration of ring size  (e.g., Imipramine and chlorpromazine) Alteration of stereochemistry, or design of geometric isomers (or) stereoisomers   (e.g., Imipramine and chlorpromazine) Design of fragments of the lead molecule that contain the pharmacophoric group via bond disconnection (e.g., development of Acetaminophen from Acetanilide) 67 Ref:  https://pharmacyconcepts.in/wp-content/uploads/2022/06/Drug-Design.pdf  

68. Drug Characterization: Molecule is characterized by its size, shape, strength, weakness, use, toxicity, and biological activity after showing a promising therapeutic activity. The drug product is categorized according to its route of administration. A description of the drug product qualitative/quantitative composition provides a list of all ingredients, including solvents used in the manufacture of the drug product. 68 Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body

69. Drug Formulation: Formulations can be categorized according to the route of administration and include: Oral Rectal Vaginal Inhalation Topical Transdermal Parenteral drug Pharmaceutical development information provides the scientific rationale for the formulation development approach through to the final development and justification of a suitable dosage. 69 Ref:  https://pharmacyconcepts.in/wp-content/uploads/2022/06/Drug-Design.pdf             https://images.app.goo.gl/QTThGQje3EymS45n9  

70. Research for Development: Once researchers identify a promising compound for development, they conduct experiments to gather information on: How it is absorbed, distributed, metabolized, and excreted Its potential benefits and mechanisms of action The best dosage and best way of administration Side effects (often referred to as toxicity) How it affects different groups of people (such as by gender, race, or ethnicity) differently How it interacts with other drugs and treatments Its effectiveness as compared with similar drug 70 Ref:     https://gsconlinepress.com/journals/gscbps/content/drug-design-discovery-and-development-and-their-safety-or-efficacy-human-body

71. Preclinical and clinical trials of drugs Presented to: Dr. Ghulam Mustafa Presented by: Fatima Nadeem Roll no. : 20011507-031 BS VIII (Morning) University of Gujrat Hafiz Hayat Campus

72. Contents 1. Preclinical trial Toxicity testing Metabolism testing Formulation testing Stability testing 2. Clinical trials Phase-I Phase-II Phase-III Phase-IV 3. References 72

73. 1. Preclinical trials Preclinical trial is a term that simply refers to any research about a drug that use for treatment of a disease that occurs before it is tested by human volunteers. It starts with:   In vitro tests which utilize isolated cells or tissues.   In vivo testing on living organism such as animals to examine any effects of drug and to identify potential carcinogens.  73

74. 1.1 Toxicity testing Drug testing over a short period of time The drug is tested for acute toxicity by administering sufficiently large doses in vivo to produce a toxic effect or death over a short period of time. Drug testing over a period of month Further studies on acute toxicity then take place over a period of months, where the drug is administered to laboratory animals at a dose level expected to cause toxicity but not death. Blood and urine samples are analyzed over that period. 74

75. 1.1 Toxicity testing Drug testing over a period of year Finally, long-term toxicology tests are carried out over a period of years at lower dose levels to test the drug for chronic toxic effects, carcinogenicity, mutagenicity, and reproduction abnormalities.  75

76. 1.1.1 Therapeutic index The toxicity of a drug is measured by therapeutic index.  The ratio of LD 50 (the lethal dose required to kill 50% of a group of animals) to ED 50 (the dose required to produce the desired effect in 50% of test animals) is known as the therapeutic ratio or therapeutic index.   LD 50 : ED 50   Figure 1.1: Comparison of therapeutic and lethal dose curves 76

77. 1.1.2 In vivo and In vitro test LD values and therapeutic ratios are not the best indicators of a drug’s toxicity. Toxicity testing should include:   In vitro In vivo is Latin word for “within the glass.” It  utilize isolated cells or tissues.  In vivo tests In vivo is Latin word for “within the living.” It refers to tests, experiments, and procedures that researchers perform in or on a whole living organism. 77

78. 1.1.2 In vivo and In vitro test Figure1.2: Structure of UK 47265 and Flucanazole For example, the antifungal agent UK 47265 is tested in in vivo tests on mice, dogs, and rats showed that it had liver toxicity and was potentially teratogenic. The Fluconazole (analogue) discovered as useful drug .   78

79. 1.1.3 Dose level  Another aim of toxicity testing is to discover what dose levels are likely to be safe for future clinical trials.  The toxic properties in test animals may differ from those ultimately observed in humans.  For example, clinical trials were started for the antiviral agent fialuridine  after it had passed toxicity tests on animals results in kidney and liver damage in human.  Figure 1.3: Fialuridine structure 79

80. 1.2 Drug metabolism studies In order to carry out such studies, it is necessary to synthesize the drug with an isotopic label, such as deuterium ( 2 H or D), carbon-13 ( 13 C), tritium ( 3 H or T), or carbon-14 ( 14 C) and in vitro and in vivo tests can be carried out. In vivo tests are carried out by administering the labelled drug to a test animal, then taking blood and urine samples for analysis to see if any metabolites have been formed. In vitro drug metabolism studies can also be carried out using perfused liver systems, liver microsomal fractions, or pure enzymes.   80

81. 1.3 Formulation studies Formulation studies involve developing a preparation of the drug which is both stable and acceptable to the patient.  For example, for orally taken drugs, this usually involves incorporating the drug into a tablet or a capsule by considering some factors such as size, taste, and solubility of drug. 81

82. 1.4 Stability studies Stability studies are carried out to test whether temperature, humidity, ultraviolet light, and visible light have any effect. It is also important to check whether there are any unwanted interactions between the drug and the container.  For example , several batches of Paracetamol had to be withdrawn from the market in 2009 because they had a musty smell and caused nausea and stomach pains. It was discovered that the batches were contaminated with the breakdown product of a fungicide that had been applied to the wooden pallets used to transport packaging materials.  82

83. 2. Clinical trials Clinical trials involve testing the drug on human volunteers and patients. Phases of clinical trials: Phase-I  Phase-II Phase-III Phase-IV 83

84. 2.1 Phase I Phase I studies take about a year .  It involve 100–200 volunteers .  They are carried out on healthy human volunteers. It involves the evaluation of drug’s safety, its pharmacokinetics, and the dose levels.  For example, drugs intended for Alzheimer’s disease are tested on healthy, elderly volunteers to test the drug’s pharmacokinetics.  Bioavailability studies are carried out that refers to the fraction of administered drug that reaches the blood supply in a set period of time.  84

85. 2.2 Phase II Phase II studies generally last about two years and may start before phase I studies are complete.  They are carried : To study whether the drug has the therapeutic property claimed. to study the pharmacokinetics and short-term safety of the drug. To define the best dose level.  Phase II trials can be divided into early and late studies ( IIa and IIb respectively).  85

86. 2.2 Phase II  Initial trials (phase  IIa )  involve a limited number of patients to see if the drug has any therapeutic effect.  Later studies (phase IIb)  involve a larger numbers of patients. They are usually carried out as double-blind, placebo-controlled studies. This means that the patients are split into two groups where one group receives the drug, and the other group receives a placebo(inactive substance).  In this trial neither the researcher nor the participants knows which treatment are receiving to overcome placebo effect(psychological effect). This makes the results of the study less likely to be biased . 86

87. 2.2 Phase II Figure 1.4: Double blind experiment  Ref: https://practicalpie.com/experimenter-bias/ 87

88. 2.3 Phase III Phase III studies normally take about three years and can be divided into phases IIIa and IIIb . These studies may begin before phase II studies are completed. The drug is tested in the same way as in phase II, using double-blind procedures, but on a much larger sample of patients. Phase IIIa studies establish whether the drug is really effective or not. If the drug succeeds in passing phase IIIa, it can be registered.  Phase IIIb studies are carried out after registration, but before approval. They involve a comparison of the drug with those drugs that are already established in the field. 88

89. 2.4 Phase IV The drug is now placed on the market and can be prescribed, but it is still monitored for effectiveness and for any rare or unexpected side effects. For example, the β-blocker practolol had to be withdrawn after several years of use because some patients suffered blindness and even death. Figure 1.5: Structure of  β- blocker Proctolol 89

90. Drug Regulatory Approval & Post Marketing Serveillance : Presented to: Dr. Ghulam Mustafa Presented by: Sharqa Fatima Roll no. : 20011507-041 BS VIII (Morning) University of Gujrat Hafiz Hayat Campus

91. Contents: Drug Regulatory Approval Purpose Regulatory Authorities Process of drug approval 2. Post Marketing Drug Surveillance History and I mportance Methods of Reporting Challenges 91

92. Drug Regulatory Approval The process of obtaining approval from regulatory authorities to market and sell a new drug or biological product. Purpose: To ensure the safety and efficacy of drugs for human use. Ensures public health and safety. Encourages innovation and development of new drugs. Provides a framework for drug development and commercialization. Facilitates international collaboration and harmonization . 92 Pharmaceutical industry - Drug Regulation, Approval | Britannica

93. Regulatory Authorities To Ensure safety and efficacy in pharmaceutical development most governments have developed regulatory agencies to oversee development and marketing of drug products. FDA (US Food and Drug Administration) EMA (European Medicines Agency) MHRA (UK Medicines and Healthcare products Regulatory Agency) WHO (World Health Organization) DRAP (Drug Regulatory Authority of Pakistan). Postmarketing surveillance - Wikipedia 93

94. Process of Drugs Approval Pre-IND Meeting : A meeting between the FDA and a sponsor (a pharmaceutical company or researcher) requested by the sponsor and is held before submitting an Investigational New Drug (IND) application. The purpose of the meeting is to: Discuss the development plan of drug. Obtain the FDA's any concerns or issues they may have for plan. Understand the FDA's regulatory requirements and specific guidelines. Identify any pitfalls that could delay or prevent approval. Establish a relationship with the FDA that facilitate open communication throughout the development process. An introduction to Medicinal Chemistry By Graham L. Patrick 5th edition (2013) page 283 94

95. 2) IND Application: Investigational New Drug (IND) Application is a request to the FDA to conduct clinical trials on a new drug in humans. IND should contain information about drug’s: Chemistry Manufacture and quality control Pharmacology and pharmacokinetics Toxicology FDA reviews the IND application and approve it if safety of drug, sponsor’s expertise and therapeutic benefits of drug are in compliance with standards. An introduction to Medicinal Chemistry By Graham L. Patrick 5th edition (2013) page 282 95

96. 3) Clinical Trial Process: 96 Regulatory Requirements For New Drug Approval | PPT (slideshare.net)

97. 4) NDA Application: A New Drug Application (NDA) is a request to the FDA to approve a new drug for marketing.  It is a comprehensive submission that provides all the necessary information about the drug. FDA new drug approval process. Regulatory Requirements For New Drug Approval | PPT (slideshare.net) 97

98. 5) Review and Approval: Before approval, review includes following objectives (1)  Evaluation of safety and efficacy data from animal and clinical trials. To ensure that the  drug is  safe and effective  for its intended use and its benefits outweigh its risks. (2)  Licensing and inspection of manufacturing facilities and distribution channels to assure that drugs are not contaminated. (3) Monitoring of adverse drug reactions for investigational and marketed drugs. (4) Quality control of drug promotion and advertising to assure that safety and efficacy claims are accurate and the drug's labeling is complete. If the NDA application is approved, the sponsor can market the drug in the United States. If rejected, the sponsor must address the FDA's concerns and resubmit the application. Pharmaceutical industry - Drug Regulation, Approval | Britannica 98

99. Post Marketing Servillance : Introduction: Post-marketing surveillance (PMS)  is monitoring of drug  safety and efficacy after regulatory approval. The goal is to identify and mitigate potential risks, ensure  safe and effective use of drug after it has been released on  the market.  It is a part of pharmacovigillince . 99 Postmarket surveillance: a review on key aspects and measures on the effective functioning  of the United Kingdom and Canada - PMC (nih.gov)

100. Phase-4 of clinical trials: Post Marketing Survelliance is fourth phase of clinical trials as: Evaluation is done in real clinical setting. Patient population are larger in number and have  different or complex medical conditions as compared to earlier phases. Role: Information about benefit and risk of drug. Undesired effect is noticed. 100 Postmarket surveillance: a review on key aspects and measures on the effective functioning in the context of the United Kingdom and Canada - PMC (nih.gov)

101. History: T he concept of PMS gained momentum in the 1960s, particularly after the thalidomide disaster. Thalidomide tragedy:  The drug was introduced in the late 1950s and was widely prescribed to treat morning sickness in   pregnant women.  It was found to cause severe birth defects (limb deformities).  This led to a global outcry and highlighted the need for more effective drug monitoring. Establishment of national drug regulatory agencies to oversee drugs approval, marketing, and safety monitoring. Pharmaceutical industry - Drug Regulation, Approval | Britannica 101

102. Importance Ensures public health and safety. Identifies rare or long-term side effects. Information about ADRs (Adverse Drug Reactions) is obtained. Supports informed prescribing and patient decisions. May detects new uses of drug. Helps manufacturer to optimize the quality of product. Updates product labels and safety information. 102 The Importance of Post-Marketing Surveillance - DistillerSR

103. Methods Spontaneous reporting systems e.g., FDA MedWatch Healthcare professionals and patients report adverse events. Reports are voluntary and may be biased. Under-reporting is a common issue. 2. Active surveillance systems Electronic health records (EHRs) and claims data. Active monitoring and data analytics. More comprehensive than spontaneous reporting. MedWatch: The FDA Safety Information and Adverse Event Reporting Program 103

104. Cont... 3. Observational studies  Cohort studies: follow group of patients over time. Case-control studies: compare patients with and without adverse events Provide real-world evidence   4. Randomized Controlled Trials (RCTs) Gold standard for evaluating drug safety and efficacy as it reduces biasness. Controlled environment and randomization. Time-consuming and resource-intensive. 104 PMS (post marketing surveillance) | PPT (slideshare.net)

105. How post marketing reports get to FDA: 105 PMS (post marketing surveillance) | PPT (slideshare.net)

106. FAERS (FDA Adverse Event Reporting System) Collects and analyzes reports to identify potential safety signals and trends. Disseminates safety information to healthcare professionals and patients as well as facilitates communication.  Supports regulatory decisions on drug labeling, warnings. Initiate recalls or market withdrawals. Questions and Answers on FDA's Adverse Event ReportingSystem   (FAERS) | FDA 106

107. FAERS Strengths The FDA Adverse Event Reporting System (FAERS) has several strengths : It is a useful tool for the FDA to look for new safety concerns that might be related to a marketed product. It uses data mining, mathematical tool to identify the product-event  combinations. Gives a safety signal to at-risk population after ADR reporting. It develops well documented case series and take regulatory actions even product withdrawal when necessary . 107 A Standardized Dataset of a Spontaneous Adverse Event Reporting System - PMC (nih.gov)

108. Examples of drug withdrawal: Drug name  Withdrawn Usage Remarks Tetrazepam 2013 Anticonvulsant, muscle relaxant . Serious cutaneous reactions like skin rashes etc. Alatrofloxacin 2006  Floroquinolone antibiotic. Serious hepatotoxicity leading to liver transplant or death. Rofecoxib 2004 Was used to treat  rheumatoid arthritis. Risks for heart attack and stroke were increased. Tienilic acid 1982 Diuretic agent Used to treat hypertension. Damaged liver cells in 1 out of every 10,000 patients. Hepatitis risks. 108 An introduction to Medicinal Chemistry By Graham L. Patrick 5th edition (2013) page 279 List of withdrawn drugs - Wikipedia

109. Structures of Withdrawn Drugs Tetrazepam Alatrofloxacin Rofecoxib Tienilic acid 109

110. Challenges in PMS: Underreporting and biased reporting. Data quality and accuracy issues. Timely communication and response challenges. Balancing safety and efficacy with patient access. Active surveillance and data analytics. Regular updates and communication. Collaborative efforts (industry, regulators, healthcare professionals). Patient-centered approach Best Practices in PMS: 110 Post marketing surveillance of suspected adverse drug reactions through spontaneous reporting: current status, challenges and the future - PubMed (nih.gov)