Cell Structure, Genetics & Human Genome

Basic Cell Structure and Genetics

• Human cells are the basic working units of living systems, containing one set of chromosomes from each parent
• DNA sequences contain all instructions for cell activities
• DNA consists of base pairs abbreviated as A, T, C, and G
• Mitochondria, the cell's powerhouse, generate 90% of the required energy for cellular function
• Mitochondria also possess their own small chromosomes

Chromosomes

• Chromosomes, made of DNA and protein, contain multiple genes
• Human cells contain 23 pairs of chromosomes, except for sperm and egg cells
• 22 pairs are autosomes numbered 1-22
• 1 pair are sex chromosomes (XX for females, XY for males)
• The function of chromosomes is to transmit DNA from one generation to another
• Diseases can result if there are abnormalities in the chromosome number or structure

Human Genome

• The human genome is the complete composition of genetic material within a cell
• Genomes contain all the information required for an individual's development and function
• The human genome contains approximately 3 billion nucleotides
• Genomes consist of 23 pairs of chromosomes and mitochondrial DNA

Genes

• Genes are specific base sequences that encode proteins
• Only about 5% of the human genome is protein-coding genes
• Human genome contains roughly 20,000-25,000 genes
• Depending on function and environmental factors, different genes activate in different cells

Genetic Diseases

• Genetic diseases mostly result from one or more mutations in a single gene
• Multiple mutations and environmental factors may influence diseases like diabetes and cancer

Types of Genetic Mutations

• Germline mutations occur in reproductive cells (sperm and eggs)
• Germline mutations can be inherited and passed to future generations
• Somatic mutations occur in non-reproductive cells after conception
• Somatic mutations are not inherited or passed to offspring
• Somatic mutations can lead to diseases like cancer

Categories of Genetic Diseases

• Hereditary diseases are caused by inherited mutations in single genes
• Multifactorial Genetic Inheritance Disorders are caused by multiple gene mutations plus environmental factors
• Mitochondrial disorders caused by mutations affecting mitochondria
• Chromosomal Abnormalities Disorders are caused by changes in chromosomes during cell division

Single Gene Disorders (Mendelian Inheritance)

• Mutations in a single gene cause monogenetic disorders
• Inheritance patterns include autosomal dominant, autosomal recessive and X-linked

Inheritance Patterns:

• Autosomal dominant inheritance needs only one defective gene copy
• Autosomal recessive inheritance needs two defective gene copies, one from each parent
• X-linked inheritance involves a defective gene on the X chromosome

Examples of Genetic Disorders

• Single-Gene Disorders:
  • Duchenne Muscular Dystrophy - X-linked recessive disorder causing muscle weakness
  • Huntington's Disease - autosomal dominant disorder causing nerve cell breakdown
• Chromosomal Disorders:
  • Down Syndrome (Trisomy 21) - presence of a third copy of chromosome 21
  • Turner Syndrome (45,X0) - absence or incompleteness of an X chromosome in females
  • Klinefelter Syndrome (47,XXY) - an extra X chromosome in males
• Mitochondrial Disorders:
  • Leigh Syndrome affects the central nervous system in children

Genome Editing vs Genetic Modification

• Genome Editing:
  • Increases the probability of a naturally possible mutation
  • Example: treating disease
• Genetic Modification:
  • Introduces genes that the organism did not originally have
  • Creates mutations impossible in nature
  • Example: glow-in-the-dark animals

Gene Therapy

• Gene therapy corrects genetic abnormalities by introducing functional genes into cells
• There are two approaches to gene therapy; non-integrating and integrating
  • Non-integrating gene therapy leaves the DNA separate from the genome, therefore not permanent
  • Integrating gene therapy makes the new gene becomes a permanent part of the genome

Genome Editing Therapies

• There are two types of genome editing therapies; In vitro and In vivo
  • In vitro involves removing, editing, and returning cells to the body
  • In vivo triggers mutations by introducing CRISPR-Cas directly into the body

Genetic Testing Considerations

• Companies like 23andMe keep genetic code permanently
• Genetic testing, like that done by the company 23andMe;
  • Provides benefits such as scientific discoveries about diseases
  • Creates concern about the commercial value of genetic data

Genetically Modified Organisms (GMOs)

• GMO are organisms whose DNA has been altered using genetic engineering
• GMO's modifications differ from traditional selective breeding, because it directly modifies DNA

Introduction to Gene Therapy

• Gene editing for disease dates back to 1950s after the discovery of DNA's double helix structure
• A fundamental concept of gene therapy involves identifying and fixing "molecular mistakes" in DNA to prevent or reverse genetic diseases
• Gene therapy has been considered an important concept in molecular genetics since the 1980s

FDA Definition and Types of Gene Therapy

• Human gene therapy is aimed at modifying gene expression or to alter biological properties of cells for therapeutic purposes
• Gene therapy works through three main mechanisms:
  • Replacing disease-causing genes with healthy copies
  • Inactivating malfunctioning genes
  • Introducing new or modified genes to treat diseases
• Various types of gene therapy products include:
  • Plasmid DNA
  • Viral vectors (modified viruses delivering genetic material)
  • Bacterial vectors
  • Human gene editing technology
  • Patient-derived cellular gene therapy products

Gene Therapy Core Challenges

• To effectively correct genetic mistakes, researchers needed to;
  • Create precise double-stranded breaks at specific locations in the 3+ billion base pairs of human genome
  • Ensure efficient repair using templates that replace "bad" sequences with "good" ones
  • Overcome difficulty of making precise breaks at only desired locations

CRISPR-Cas Gene Editing

• CRISPR-Cas9 uses RNA-DNA binding (not protein-DNA binding) to guide nuclease activity
• This innovation simplifies design and enables application to many target sequences
• CRISPR stands for "Clustered Regularly Interspaced Short Palindromic Repeats"
• CRISPR is derived from bacterial adaptive immune systems
• CRISPR has the potential to change genetic makeup of organisms and fix numerous genetic problems

Key CRISPR Scientists

• Jennifer Doudna and Emmanuelle Charpentier co-invented the CRISPR technique
• Doudna and Charpentier won the 2020 Nobel Prize in Chemistry for this groundbreaking work

FDA Approved Gene Therapies

Kymriah (2017) - First FDA-Approved Gene Therapy

• Approved for certain pediatric and young adult patients with acute lymphoblastic leukemia (ALL)
• Acute lymphoblastic leukemia (ALL) is a quickly progressing blood/bone marrow cancer and most common childhood cancer in the US
• ALL affects ~3,100 patients under 20 years yearly
• Kymriah targets B-cell ALL patients whose cancer didn't respond to initial treatment, about 15-20% of patients
• Kymriah's treatment process:
  • Patient's T-cells are collected
  • Cells are genetically modified to target specific cancer cells
  • The modified cells are reinfused into the patient to kill cancer cells

Sickle Cell Disease Treatments (2023)

• Casgevy and Lyfgenia are the first cell-based gene therapies for sickle cell disease
• They are approved for patients 12 years and older
• The process involves-
  • Collecting the patient's own blood stem cells
  • Modifying these cells
  • Myeloablative conditioning (high-dose chemotherapy) to prepare bone marrow
  • Reinfusion of modified cells is a one-time treatment
• Long-term studies continue to evaluate safety and effectiveness

CRISPR Challenges

• CRISPR may not always be sufficient for precise mutation repair required in some therapies
• The immune system may recognize Cas9 as foreign, causing rapid degradation
• There is potential for off-target effects: unintended mutations or unexpected deletions
• Cancer therapies are particularly challenging as they require targeting multiple mutations simultaneously

Prime Editing (PE)

• Prime Editing is a "search-and-replace" genome editing technology
• Prime Editing directly writes new genetic information into targeted DNA sites
• Prime Editing uses fusion protein ("prime" protein) consisting of catalytically impaired Cas9 endonuclease fused to engineered reverse transcriptase enzyme
• Prime editing guide RNA (pegRNA) identifies targets and provides replacement genetic information

How Prime Editing Works

• Prime editing mediates insertions, deletions, and base conversions without double-strand breaks or donor DNA templates
• It nicks the target site and extends new DNA sequence using pegRNA as a template
• The edited DNA then incorporates into the genome through endogenous cellular processes

Prime Editing Applications

• Prime Editing shows potential for treating genetic disorders
• It is still in developmental stages and needs improvement in editing efficiency and delivery strategies
• Prime Editing has not yet been used for clinical trials, but is proving successful in animal models of Duchenne muscular dystrophy and Phenylketonuria

Designer Babies: Ethics and Concerns

• A documentary raises questions about genetic modification in humans
  • Concerns include the privacy of genetic testing results and potential discrimination by employers and insurance companies
  • There are ethical questions about parents choosing genetic traits like gender, height, and intelligence for their children
  • Fundamental questions raised are about human identity, cloning, and the relationship between genetics and behavior

Xenotransplantation

• Xenotransplantation is defined as transplanting organs and tissues from non-human species to humans
• Xenotransplantation is a potential solution to the shortage of human organs for transplant
• Attempts have failed, such as those using baboon hearts
• Significant cultural barriers to acceptance exist
• There are animal welfare concerns, from developing animals specifically for organ harvesting

Stem Cell Therapy

• Stem cells are cells that can differentiate into various tissue types, like muscle, brain, blood, and skin
• Stem cell therapy has potential applications for treating spinal cord injuries, juvenile diabetes, Parkinson's, and Alzheimer's
• The most potent stem cells come from embryos and early fetuses
• There are ethical controversies around using embryos as stem cell sources
• Some researchers propose cloning techniques to increase stem cell material availability

Case Study: Jesse Gelsinger

• Jesse Gelsinger was a 17-year-old with ornithine transcarbamylase deficiency (OCTD), a rare genetic disease
  • OCTD prevents the breakdown of ammonia in the body, often causing a fatal outcome in infants
  • Jesse volunteered for a gene therapy trial using an adenovirus vector
  • Sadly, Jesse died four days after treatment in 1999

Key Ethical Issues in Gene Therapy: Informed Consent

• Informed consent follows the basic principle that patients must be fully informed and freely consent to participation
• Adults were chosen for OTC trial because they could better understand risks compared to parents of sick infants
• An investigation revealed that previous adverse reactions were not properly communicated to Gelsinger

Conflict of Interest

• Lead scientist Dr. James Wilson had financial interest in the adenovirus vector being tested
• Financial interests may influence research decisions and experimental protocols
• Jesse Gelsinger's case raises questions about researcher objectivity when they have stake in experimental outcomes

Subject Selection Ethics

• The case of Jesse Gelsinger also raises the question of whether to use relatively healthy adult volunteers vs. sick infants
• There are concerns about parents of sick newborns being able to truly provide informed consent under duress

Cloning vs. Genetic Engineering

• Cloning creates genetically identical copies of an organism, cell, or DNA sequence
  • Its verb form refers to the process of genetically engineering or cloning
• Genetic engineering alters an organism's genetic makeup by introducing foreign DNA
  • Genetic Engineering results in Genetically Modified Organisms (GMOs) and can modify various organisms including animals, plants, and microorganisms

Types of Cloning

Reproductive Cloning

• Reproductive cloning creates genetically identical, fully developed organisms from cells from another mature organism
• Reproductive cloning is a form of asexual reproduction
• Reproductive cloning is useful for propagating genetically modified organisms (GMOs)
• An example of reproductive cloning is Dolly the sheep

Therapeutic Cloning

• Therapeutic cloning produces embryonic stem cells for research and disease treatment
• The goal of therapeutic cloning is not to create cloned humans but to harvest stem cells
• Therapeutic cloning is useful for research and stem cell transplants to rebuild organs and cure diseases

Molecular Cloning

• Molecular cloning involves isolating and copying particular DNA segments for study
• It is used for research, making industrial and pharmaceutical proteins, gene therapy, and GMOs
• Molecular cloning involves introducing DNA into a cell where it doesn't belong

Therapeutic Cloning Details

• The goal of therapeutic cloning is to make stem cell lines compatible with patients to repair cells

Stem Cell Options:

Adult Stem Cells

• Adult stem cells are located in different body parts, such as bone marrow
• Adult stem cells can divide and both replace themselves and produce progeny cells
• Adult stem cells have limitations, as it is difficult to obtain and restricted in the types of cells they can form

Embryonic Stem Cells

• Embryonic stem cells are from early embryos with totipotent cells, so they can form any part of the developing body
• Pluripotent cells can be cultured indefinitely as stem cell lines
• Their source is from blastocysts from in vitro fertilization clinic surplus embryos
• Embryonic stem cells advantages are that they can be cultured indefinitely and they can form tissues that will not be rejected by the patient.
• A disadvantage of embryonic stem cells is that harvesting them requires embryo destruction

Induced Pluripotent Stem Cells (iPSCs)

• iPSCs are created by transforming adult differentiated cells with transcription factors
• An advantage of iPSCs is that there is no embryo destruction required
• A disadvantage of iPSCs is that there is a potential cancer risk when reintroduced
• Induced Pluripotent Stem Cells were discovered by Shinya Yamanaka and Sir John Gurdon, who received the Nobel Prize in 2021

Molecular Cloning Process

• Molecular cloning involves replicating DNA molecules to produce cells with identical DNA
• Its steps are Backbone generation, Insert generation, Isolation of insert and vector, Assembly of recombinant DNA, Transformation, Selection and screening, and Verification

Reproductive Cloning

• Technology to generate an animal with identical DNA as another existing animal

Advantages and Disadvantages of Reproductive Cloning

• Advantages;
  • Reduce the "unknown" element in selective breeding
  • Can control characteristics of the organism
• Disadvantages;
  • Identical populations are more vulnerable to environmental changes and pathogens
  • Low success rate, with 95-97% of attempts failing

Famous Cloning Examples

Dolly the Sheep

• Dolly was born at the Roslin Institute in Scotland
• Out of 277 attempts, only 29 embryos survived beyond 6 days
• Had three mothers: one provided the egg, another the DNA, and the third carried the embryo
• Dolly was created by Ian Wilmut
• Dolly lived from July 5, 1996 to February 14, 2003, she was euthanized due to progressive lung disease
• She raised questions about accelerated aging in clones

Other Cloning Examples

• The Pyrenean ibex was the first and only successful revival of an extinct species, although it died shortly after birth
• Commercial cloning applications include animal husbandry, medical research such as cancer-sniffing dogs, competition animals, pet cloning, and restoring endangered populations

Ethical Considerations for Human Cloning

• Cloned individuals would be physically identical but internally different due to environment and experiences
• Even identical twins with the same genome have different personalities and characteristics
• Cloning starts as a baby, not as an adult copy of the original
• Technical challenges include high failure rate and risk of genetic malformations

Healing vs. Regeneration

• Healing is the process that limits damage and prevents death from injury, where cells produce factors to stop bleeding, fight infection, and close wounds
• Healing only involves limited production of new cells mostly for scar formation
• Regeneration is a longer process that follows initial healing which involves producing large numbers of new cells of many different cell types
• Regeneration requires cells to essentially reenact development

Regeneration in Simple Animals

• Simple animals have more potent regenerative abilities than complex ones
• Differences can be explained by tissue complexity, the immune system complexity, and strategies for avoiding cancer

Hydra Regeneration

• Hydras constantly renew body cells
• Hydra cells migrate to different parts and assume different roles
• Hydras have specialized cells for nervous, digestive, and muscular functions
• They can reproduce by "budding" a new animal from the trunk
• When a Hydra is cut into pieces, each piece will regenerate a head and foot

Planaria Regeneration

• Planaria, also known as flatworms, have remarkable regenerative ability
• When a Planaria is cut in two, each fragment regenerates a complete animal
• Planaria can be cut into dozens of pieces, with each regenerating a new animal
• Planaria's ability to regenerate is related to its abundance of stem cells called neoblasts

Salamander Regeneration

• Salamanders can regenerate limbs, tail, jaw, and parts of the eye
• An amputated limb can regrow, but cannot regenerate a new body
• Salamander regeneration is credited to the formation of a blastema of dedifferentiated cells

Japanese Fire-bellied Newts Lens Regeneration

• Lens regeneration remains robust even after 18 rounds over 16 years in Japanese Fire-bellied Newts
• The regenerate lenses produces are structurally normal with normal gene expression
• Repetition and age do not affect the regenerative capabilities of these Newts

Crab Limb Regeneration

• Crabs can sacrifice claws during attacks by predators
• Regeneration occurs through the molting process
• New claws start smaller and expand with subsequent molts
• Regrowth is faster in young crabs, who can rebuild an appendage in months
• Crabs can regenerate up to 95% of a lost claw after three molts

Zebrafish Heart and Fin Regeneration

• Zebrafish can regenerate part of heart tissue
• Surviving heart muscle cells can divide and produce more cells
• Fibroblasts, or connective tissue cells, play a key role by producing repair signal proteins
• Zebrafish can fully restore cardiac function within 90 days after damage
• They can also regenerate tails

Deer Antler Regeneration

• Deer are the only mammalian appendages capable of repeated regeneration
• Deer shed and regrow annually from a blastema
• Antler growth in deer can exceed 2 cm per day, the fastest organ growth in the animal kingdom
• Important molecules include parathyroid hormone-related peptide and retinoic acid
• Antler regrowth varies in time of weeks or months
• Other cervids, like elk, moose, and caribou; also shed and regrow antlers yearly

Human Regeneration

• Humans can regenerate certain tissues (liver, gut lining, fingertips)
• The regeneration process in humans is similar to development
• Studies of species with regenerative abilities aim to develop methods for human limb regeneration
• Similar molecules appear across different regenerating species, suggesting underlying molecular machinery
• Despite molecular similarities, regenerative abilities differ greatly between species

Regenerative Medicine

• Birth defects, trauma, aging, disease, and cancer involve cells that are not knowing or being able to build the right thing
• Bioelectricity refers to how embryonic bodies build themselves without a brain
• Cells function like hardware while electrical patterns function as software
• Michael Levin proposes that using bioelectricity to shape cellular "software" may be key to future regenerative medicine

Key Concepts and Definitions

• Blastema refers to a blob of dedifferentiated cells that can develop into new limbs or structures
• Multipotent progenitor cells are the cells that can differentiate into multiple cell types
• Fibroblast cells are connective tissue cells that produce proteins that act as repair signals
• Xenobots are not explicitly defined in the lecture notes

What Constitutes a Drug?

• A typical drug is an organic small molecule that activates or inhibits biomolecules, like proteins, to provide therapeutic benefits
• Small molecules have low molecular weight, allowing them to penetrate cells easily
• Drugs can be developed through rational design or isolated from natural resources

Drug Design Approaches

• Drug design involves creating molecules complementary in shape and charge to their target biomolecule

Approaches to Drug Discovery

• Identifying new targets for existing drugs, which is a process called drug repurposing
• Rational drug design, also known as reverse pharmacology
• De novo design, where scientists create entirely new molecules from scratch
• Modifying known molecules
• Developing synergistic or additive drug combinations
• Screening existing chemical entities
• Genetic approaches

Drug Repurposing

• Applying existing drugs to new diseases outside their original approved indication
• Drug repurposing is also called drug repositioning or reprofiling
• Drug repositioning involves identifying, developing, and commercializing new uses for existing or abandoned drugs
• Benefits of Drug Repurposing are minimizing risk of attrition, reducing development time, saving money in development costs and giving new life to expired patents
• Phase 3 clinical trials for efficacy are still needed, which cost the same as for new drugs

Examples of Repurposed Drugs

• Aspirin was originally for pain and fever, but is now also used as an antiplatelet medication
• Minoxidil was originally for hypertension treatment, but is now used for hair loss treatment
• Naltrexone was originally for opioid addiction, but is now used to treat alcohol withdrawal
• Fenfluramine was originally for obesity treatment, but is now used to treat epilepsy
• Sildenafil (Viagra) was originally for angina and hypertension, but is now used to treat erectile dysfunction
• Thalidomide was originally for morning sickness, it is now also used to treat leprosy and multiple myeloma

Case Study: Sildenafil (Viagra)

• Sildenafil was originally developed by Pfizer as an antihypertensive drug
• Sildenafil's side effect was recognized and commercially exploited
• Sildenafil is marketed as Viagra for erectile dysfunction (ED)

Case Study: Thalidomide

History

• Thalidomide was first synthesized in 1953 by Swiss Pharmaceuticals, but development was discontinued
• It was developed by Chemie Grünenthal in 1954 and marketed in 1957 as an anticonvulsant for epilepsy, as well as for its sedative drowsiness side effect
• By the late 1950s, 14 pharmaceutical companies marketed thalidomide worldwide
• Thalidomide's molecule is chiral and exists in two different spatial arrangements, which are called enantiomers
• These enantiomers are (R)-enantiomer, which has sedative effects and (S)-isomer, which is teratogenic and causes birth defects
  • Under biological conditions, the isomers interconvert, making separation ineffective

Dr. Frances Oldham Kelsey

• Dr. Kelsey was a FDA scientist who refused to approve thalidomide in the USA
• She was born in Cobble Hill, Vancouver Island, B.C.
• She has a B.Sc. from McGill University and has a Master's in pharmacology, a PhD, and an M.D. from the University of Chicago
• She did editorial work for the American Medical Association, reviewing therapeutic papers
• Dr. Kelsey taught pharmacology and practiced medicine
• She received highest recognition for a USA civil servant for saving thousands from death or incapacitation

Thalidomide Revival

• Despite being recalled for teratogenicity and causing embryonic limb deformities, thalidomide was later approved for treating leprosy in 1998 and multiple myeloma in 2006
• Thalidomide works by inhibiting tumor necrosis factor

Fenfluramine

• Fenfluramine was initially used for obesity treatment by reducing appetite and food intake
• It was withdrawn, but it is now used in several countries for treating forms of epilepsy like Dravet syndrome and Lennox-Gastaut syndrome
• Fenfluramine works by regulating serotonin levels in the brain to reduce seizure frequency and severity

Future of Drug Repurposing

• Drug repurposing is a promising alternative pathway for drug development, especially in academic environments
• It is still in early stages with legal and patenting challenges
• Some molecules may serve as starting scaffolds for derivative compounds
• Method-of-use patents may provide protection for repurposed drugs

Key Terms in the context of drug repurposing

• Drug attrition refers to the high failure rate of drug candidates during clinical development due to safety concerns, lack of efficacy, or toxicity
• Teratogens are substances that harm the fetus during pregnancy, causing congenital disorders or increasing risk of pregnancy complications
• Target discovery is the identification of molecular vulnerabilities of a specific disease
• A therapeutic target is a macromolecule, typically protein, associated with disease that can be modulated by therapeutic agents
• A therapeutic agent is a molecule that modifies the function of a perturbed target to restore health or alleviate symptoms
• Chirality is a term for the property where an object is non-superimposable on its mirror image, important in drug development

Drug Discovery and Development Process Overview

• Stage 1 includes drug design and development that involves target identification, target validation, lead identification, and lead optimization
• Stage 2 includes pre-clinical development that involves in vitro and in vivo experiments following Good Laboratory Practice, it also includes key evaluations
• Stage 3 is clinical development that involves human testing to prove safety and efficacy and human testing, and is also time-consuming, at 6-7 years and expensive
• Stage 4 involves government review and regulatory approval and its evaluation by local regulatory authorities, and it is also required before market introduction
• Stage 5 involves post-market safety monitoring (Phase IV), which includes systemic monitoring after market release

Important aspects in the drug discovery and development process

In Stage 1 included are:

Target Identification - Identifying molecular vulnerabilities of a specific disease - Utilizing Modern computational tools - Targeting a biological target that can bind with high affinity to a drug Target Validation Establishing a disease-causative effect and therapeutic potential

• This is the most important step in innovation value chain
• Poor validation is a major reason for drug attrition A target is fully validated only when the drug proves effective in human

Lead Identification

• Finding chemical molecules with desired biological activity

• Some methods include: identifying a drug by chance, chemical modification of active molecules, rational drug discovery, and screening

• Lead Optimization

  • Refining lead compounds to improve properties

Stage 2 Pre-clinical Development includes:

• Following Good Laboratory Practice (GLP) in both in vitro and in vivo experiments.
• Key evaluations of:
  • Pharmacokinetic Studies, called ADME or ADME-Tox/ADMET, to determine;
    • How the drug is Absorbed into the body
    • How the drug is Distributed throughout the body
  • How the drug is Metabolized and broken down
    • How the drug is Excreted and leaves the body
    • and its Potential for harmful effects (Toxicity)
  • Pharmacodynamic Studies to determine dose-response relationships while monitoring biochemical and physiological changes
  • Toxicity Studies testing for potential cell, organ damage, or cancer risk in both rodent and non-rodent species
  • Acute, sub-chronic, and chronic exposure testing used to look at reproductive issues

Key components of drug discovery and development

In Stage 3, Clinical Development, parts include: Efficacy Evaluation - Testing on cancer cell lines - Xenograft experiments (transplanting cells between species) - Use of Genetically engineered mice models - Pharmaceutics Evaluation looking at the drug's ability to dissolve in the body Pharmaceutics Evaluation - Is made up by understanding its solubility with the drug's ability to dissolve in the body - How Bioavailable: Fraction of drug that reaches systemic circulation drug's bioavailability - Understanding these factors with administration via routs, the drug's physical properties and patient factors (age, gender, disease. In doing so food interactions must be taken into account as well Synthetic Viability -Scaling up production from lab to manufacturing - Conducting stability studies - Having quality control that is regulated

Phases of Clinical Development Phase I - This is conducted on small group around 20-80 participants usually healthy people - This process takes several months to assess how well treatment goes - This allows the highest safe dose and the accurate dosage to be measured This typically lets ~70% move on to the next phase

Phase II - In this phase involves monitors candidates of the target being studied - Effectiveness levels are tested with monitor for side affects as some candidates continue the process This typically lets ~33% move on to the next phase

Phase III

• The final largest phase of testing where medication is tested with 3,000 of participants with target being studied;
• The lasts phases may last year compared to existing treatments testing effectiveness using - randomization and double-blind methodology This typically lets ~25% move on to the next phase

Stage 4: Government Review and Regulatory Approvall, which means drugs must be accessed with - Evaluation by local regulatory authorities before it gets approved before market introduction Stage 5: Post-Market Safety Monitoring (Phase IV), where if it goes to launch then Systematic monitoring after market must take place

18 The stages in the drug discovery process include:

critical component of pharmacovigilance because there are benefits that result: there is usually an Early detection of safety signals, Improvement of drug labeling, which leads the development that results a high management that can improve the patients stay and keep them safe that involves a lot testing and safety measurements with drugs and a lot of testing and lab testing for safety measures

approaches to drug design that must be followed.

Drug design where one searches for new targets or drugs or existing approaches where one rational drug design the molecules, with other aspects with testing on the genetic approaches.

Terminogy to understanding of the drug:

where there is certain aspects to the the drug the terminology that there is Target, Target, how its able to bind within a body, pharmacokinetics.

Pharma Industry terms

LD50 and LC50 in relation to drug

• LD50 can be the dose, where it can can used with units of weight Typically is typically taken a lower score with lower measurements and is with toxicity

There are also concepts that work with: - DNEL that are risk assessments that are monitored for important Doses : ED50 TD50 are the measurements to maintain

Important key dose in realtionships:

• DNEL is the first
• And and LD50 being the last which is lethal to the most

With that the therapeutic and toxicity are meant for equal balance.

• Other Terminology:*

• Druggability: A biological target's ability to bind with high affinity to a drug

• Target: Molecular vulnerability in a disease

• Lead compound: Chemical molecule showing desired biological activity

• Pharmacokinetics: How the body affects the drug

• Pharmacodynamics: How the drug affects the body - In vitro: Testing in lab environment (test tubes, culture dishes)

• In vivo: Testing in living organisms.

• In situ: Testing in original place/position - De novo: Creating something from scratch/beginning