1 Flashcards
(102 cards)
1
Q
1) What are the types of new drugs?
A
- New drug for novel use: New discovery about a disease state that may have no treatment before or this drug represents a new approach in treatment 2. A new drug that represents a new generation of another group of drugs already in use. 3. A new drug that is just another variation of a known drug (me-too)
2
Q
2) What are the different approaches to target selection?
A
- Hypothesis driven (traditional approach): identify disease -> understand disease ->devise approach -> identify drugs that fit approach 2. Genomic approach: - Analysing the entire genetic information of an organism in the context of healthy vs disease state - Understanding genotype-phenotype correlation to identify disease target genes - Eg. Molecular basis of CML: Philadelphia chromosome encodes constitutively active tyrosine kinase, BCR-ABL. Imatinib blocks ATP binding and thus inhibits BCR-ABL kinase activity. 3. Post genomics approach-proteomics: Separation and characterization of proteins in an organism. Compare protein expression in normal vs disease state to identify novel target proteins.
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Q
3) How do you know that a gene/protein is targetable?
A
RNAi screens can be done. This is carried out by ‘knocking down’ individual genes to find genes that regulate key disease processes. This allows identification of targets by function. There are in vitro and in vivo approaches to this.
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Q
4) How is target validation carried out?
A
- In vitro: cell based assays to verify that the target gene/protein is involved in disease progression at the cellular level. Cell lines can be engineered to display loss of function (using siRNA/shRNA) or gain of function (overexpression). This allows analysis of specific roles of the target. 2. In vivo assays: Animal disease models that can be used to verify that your target gene/protein contributes to disease progression in a more complex environment. To study loss of function: inject mice with tumor cells, use shRNA to knock down a potential oncogene and observe tumor progression. To study gain of function, overexpress normal mice with potential oncogene and observe if tumors form.
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Q
5) Define a 1) HIT 2) LEAD 3) preclinical development candidate.
A
• HIT A compound that interacts with the chosen target at a given concentration (usually in the micromolar range) • LEAD A compound with drug-like properties, initial SAR and a promising IP position • Preclinical Development Candidate NCE with optimized pharmacological and pharmacokinetic properties and a secure IP position
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Q
6) What are the methods of lead identification? What are their benefits/drawbacks?
A
(full answer on p2) 1. Rational drug design: Understanding structure activity relationship. This requires coordination of structural biology and organic chemistry, and drug design is based on the pharmacophore of endogenous ligand/substrate. Designed to bind active site and block receptor activation or enzyme activity. Eg. BCR-ABL inhibition: Identification of c-ABL autoinhibitory mechanism. Myristoylation of N-Term of c-ABL causes binding of myristate moiety into deep hydrophobic pocket of kinase domain. This results in a 90 degree bending of the a-1 helix of the C-term and autoinhibition. BCR-ABL lacks N-term myristoylation site, but it can be replaced with allosteric inhibitors. 2. High throughput screening: Often relies on cell free/cell based assays– Target-specific effects are measured quantitatively by a reporter assay Ex: fluorescence, luminescence, cell shape, cell metabolism, color formation. Drug candidates are evaluated for ability to block activity. Formats: 96-well and 384-well plates (high-throughput), 1,536-well plates (ultra high-throughput (UHTS)). SAR is difficult to do without knowing the exact molecular target and mode of drug interaction.
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Q
7) What are the cell based/cell free approach to HTS? What is a robust screening assay?
A
Cell free: based on isolated target molecule (can be whole or active fragment). Examples are binding and enzymatic activity assays. Cell based: Cell based reporter gene assay. Disadvantage is that the drug hit may be acting either directly on target or indirectly be interfering pathway (up or downstream of target) Z’=1–(3s +3B)/(μs-μB) Z’>0.8 (very good) Z’>0.6 (good) Z’<0.5 (not robust for screening)
8
Q
8) How does fragment based screening work?
A
Run diverse set of structures and identify those that bind to the target (does not have to be a perfect fit. Custom building the drug based on fragments that bind.
9
Q
9) How are compound libraries created? What are the requirements for a good library?
A
– Acquisition from external vendors – Generation from chemical library synthesis • Random libraries • Focused libraries – Generation from medicinal chemistry efforts • Targeted synthesis • Combinatorial synthesis • A good library should be – Large – Diverse – Examples of libraries: FDA-approved drugs, Natural product libraries – Containing only “lead-like” or “drug-like”compounds • Non-reactive • No known toxic moieties • Following Lipinski’s Rule-of-5 • Aqueous soluble
10
Q
1) What is Lipinski’s rule of 5?
A
- Fewer than 5 hydrogen bond donors 2. Fewer than 10 hydrogen-bond acceptors 3. A molecular weight of less than 500 daltons 4. A partitioning coefficient (logP) of less than 5
11
Q
2) What is lipophilicity and how is it calculated?
A
Lipophilicity is the ability of a compound to partition between lipophilic organic phase (octanal) and polar aqueous phase (water) LogP =[Conc]octonal/[Conc]water LogP <1: poor permeability 1-3: moderate permeability 3-5: high permeability >5: high permeability
12
Q
1) What are the key issues to be addressed in lead optimization?
A
- Efficacy 2. Potency (target affinity and PK parameters) 3. Adverse effects/toxicity profile 4. Route of administration (stability, absorption, distribution) 5. Onset and duration of action
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Q
2) What are the key criteria for a lead series?
A
• Binding/functional potency in primary assay (IC50 < 100nM) • Potency in secondary assay (cell proliferation GI50 <500nM) • Meets Lipinski rules (of 5) (MW<500, cLogP<5) • In vitro ADME liabilities (tó >60min) • Synthesis in less than 10 steps • Multiple points of modification • Patentable
14
Q
3) Explain chemical modification.
A
The goal of chemical modifications is to determine which functional groups are important for biological activity. The procedure is to alter or remove functional groups using chemical synthesis and test the activity of the altered molecule. Bioisosteric replacement involves substitution of atoms or groups of atoms in a the parent molecule to produce compounds with broadly similar biological properties to the parent with structural diversity.
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Q
4) What are the factors that affect absorption and permeability?
A
- Route of administration: Oral administration is the most convenient and cost-effective. Absorption takes place mostly from the small intestine. 2. Rate of dissolution (tablet, capsule, suspension or solution): 3. Speed of uptake by GI tract: Dependent on the lipophilicity and extent of ionization of the drug. 4. Drug complex with dissolved food.
16
Q
5) What happens after the drug is absorbed?
A
It passes through the portal vein and enters the liver, where is may be metabolized.
17
Q
6) What factors affect solubility and stability?
A
Solubility requires adherence to Lipinski rule of 5. Stability is measured at different pH and temperatures. Eg. Orally available gemcitabine: prodrug mediates oral-mediated absorption of gemcitabine with less toxicity. Minimal hydrolysis of prodrug to gemcitabine at low pH.
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Q
7) What is bioavailabilty and why is it important? How is it calculated?
A
Bioavailabilty is the fraction of unchanged drug that enters systemic circulation. It should be studied as early as possible because a lack of desired response may be due to lack of bioavailability (not reaching the required drug concentration). Compounds can be suitably modified to maximize bioavailability. F=[AUC(test) x D(iv)]/[AUC(iv) x D(test)] X 100%
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Q
8) How does drug distribution affect drug response?
A
A drug can be distributed to tissues/organs from the bloodstream. Different drug concentrations are attained in different tissues/organs. A drug may be preferentially distributed to its target tissue/organ or not at all.
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Q
9) Explain clearance and metabolism.
A
• Drugs may be eliminated either unchanged (as the parent drug) or as metabolites depending on the lipophilicity • Most drugs are eliminated through the kidneys which can excrete only relatively polar substances • Thus lipophilic drugs must be metabolized into more polar metabolites for elimination • Drugs are metabolized to different extent mostly in the liver • Metabolism mostly lead to inactivation of a drug but many drugs have active metabolites • Therefore important to study the metabolism of a drug under development in order to know the impact it may have • First studied in liver microsomes • CYP enzymes inhibition – Drug-drug interactions
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Q
10) What is the process of liver metabolism?
A
Phase I (Functionalization): Functional groups are altered through monooxygenase reaction via CYP enzymes, leading to a loss of activity. Eg. Paclitaxel undergoes metabolic modifications before it can be renally excreted. Phase II (Conjugation): Addition of highly polar conjugates to drugs to increase their hydrophilicity. Eg. Irinotecan is metabolized to SN38, an active metabolite. SN-38 is inactivated by UGTs via the addition of glucuronic acid. UGT1A1*38 polymorphism inactivates UGT, making SN-38 difficult to be inactivated, leading to increased toxicity.
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Q
11) What are the in vitro ADME assays?
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- In vitro: -Microsome metabolism. Incubate animal/human microsome with lead drug candidate, incubate over a timecourse and analyse by LC/MS. Higher percentage of parent compound remaining indicates higher metabolic stability. -PAMPA assay: A well within a larger well, lipid membrane in the inner well. Lead molecules in the inner well, identify those that pass through lipid membrane.
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Q
12) What are the in vivo ADME assays?
A
- Animal based models: -validate in vivo biomarkers for drug efficacy -required for efficacy and toxicity drug evaluation -in vivo evaluation of PK/PD in normal/disease animal models -Dynamic evaluation of drug efficacy: Histological analysis, tissue sample analysis (RNA,DNA,Protein), in vivo imaging of disease progression. 2. Human chimera mice: These are mice that contain transplanted human hepatocytes. It is a more accurate preclinical model than regular mice in terms of ADME properties. It allows evaluation of disease in human liver model (eg. Hepatitis viral infection) and evaluate new drug efficacy (ie. Antiviral drugs)
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Q
14) What other evaluations can be done before selection of a preclinical candidate?
A
Gross pathology, Histopathy, immunohistochemistry, molecular pathology hematology, immunology.
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1) What are the non-GLP CMC studies?
1. Chemical development: Improvement of the synthesis to reduce cost, increase output, safety and quality (purity and consistency). 2. Salt and formulation: - Finding best salt to balance solubility and lipophilicity of the drug (eg. Co-solvents, emulsions, pH adjustment, salt formation etc) - Finding best formulation for the chosen route of administration (eg. Tablet, capsule, solution, controlled release etc)
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2) What are the GLP CMC studies?
1. ICH stability 2. ICH impurity analysis 3. Develop prototype clinical formulation (pill, liquid etc)
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3) What are the non-GLP animal studies?
Benchmark in vivo models, validate disease models, models in other disease areas. Finalize animal used for GLP/GMP studies.
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4) What are the non-GLP ADME studies?
1. Optimized analytical method development: - Determine exposure levels in toxicology studies: • For small molecules: use HPLC/MS. Identify molecular structure. • For biologics: use ELISA. It does not show structure and does not demonstrate activity because it uses binding as an endpoint. - Validation of assays: Extraction technique recovery, linearity of standard curve, intra and inter assay precision, bench top and freeze thaw stability, sensitivity (lower limit of quantification), establish QC standards 2. Pk profile 3. Oral bioavailability 4. Determine metabolism of drug
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5) What are the GLP ADME studies?
1. Comprehensive ADME 2. Bioavailability and Pk: -using optimized bioanalytical method, quantify drug or metabolites usually in plasma -determine bioavailability via Single dose, iv and intended route -determine blood brain barrier bioavailability – measure drug accumulation in brain, brain vs plasma levels 3. GLP Pk profile -rodent and non-rodent, drug availability by intended route, mean residence time, half-life 4. GLP toxicokinetics profile 5. Comprehensive determination of metabolites 6. Multi animal Pk studies: Comparative metabolism: To account for interspecies differences between animals. Done via comparing hepatic microsomes and cytosolic fractions from different species: human, mouse, rat , rabbit, dog, non-human primate, guinea pig etc. Study parameters such as half life and identify metabolites produced. Interspecies scaling improves Pk predictions and allows identification of toxic metabolites that are specific to each species. 7. Metabolic inhibition: to identify certain drugs may inhibit Cyp enzymes or be affected by drugs that inhibit Cyp enzymes
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8) What are the requirements in toxicology evaluation?
1. Appropriate species: 1 rodent, one second species (dog, pig or monkey generally). These animals should have good exposure and metabolism similar to humans, they must cover all human metabolites. Also, they should have the same pharmacologic effect as humans (same target binding, effect in disease models, pharmacologic effects). The exposures achieved in the test subjects should be sufficient to cover multiples of the intended human dose/exposure in order to establish a safety margin. 2. Higher doses to evaluate possible toxicities: FDA guidance to dose up to 1g/KG 3. Administer compound long enough to support intended clinical study 4. Endpoints: body weight, clinical observations, serum chemistry, hematology, organ weights, histology, drug exposure (toxicokinetics)
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9) What are the non-GLP toxicology studies?
(goal: define upper bounds of safe drug administration) 1. Single dose (acute) toxicity: Determination of adverse effects within short time frame of single dose administration. Animals are observed for 14 days after dosing. Not many endpoints with focus on clinical observation and may be non terminal. Identifies single dose MTD. 2. Repeated dose toxicity: Involves a longer schedule of repeated dosing and establishes dosage levels for subsequent toxicity studies. Duration of dosing should ideally match duration of clinical study. Exception (for non-rodent species: if clinical study is \>6 months, minimum duration of repeated dose tox study is 6 months in the EU. 3. Preliminary cardiovascular safety
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10) What are the GLP toxicology studies?
(full ans in p8) 1. Acute and repeated dose toxicity: • Acute and repeated dose toxicity studies in 2 species (rodent and non-rodent) selected from non-GLP range-finding studies. • More comprehensive: (greater number/gender/species) • More complete toxicology study o Standard toxicology design: o 1) Plasma: drug analysis, 2) tissue: histopathology, 3) blood: clinical pathology, 4) clinical endpoints: survival, body weight, clinical signs, behaviour • Determination of adverse effects resulting from daily dosing to identify MTD and NOAEL (No Observed Adverse Effect Level) 2. Genotoxicity/mutagenicity testing: • in vitro non-mammalian cell system – e.g. Ames Test – Salmonella typhimurium - Determine if cells treated with drug can survive without histidine, indicating mutagenicity • in vitro mammalian cell system – e.g. CHO (Chinese Hamster Ovarian) cells - Determine % chromosomal aberration across a range of drug concentrations • in vivo mammalian system –e.g. mouse micronucleus assay - Immature mice treated with mutagen for period of 2-4 weeks, RBC’s observed under microscope for increased % of micronuclei 3. Carcinogenicity testing: • Long term toxicity testing - ~lifetime exposure • Usually in rats – 24 – 30 months • Mouse or hamster may also be used • 50 / gender / dose level and 100 / gender /control group • Determine potential tumorigenic effects of drug 4. Reproductive toxicology: • Fertility and general reproductive performance – Rats – Dosing of males for 60-80 days prior to mating – Dosing of females for 14 days prior to mating and during gestation and lactation • Potential drug-induced embryotoxicity and teratogenicity -Rat/mouse and Rabbit -Escalating dosages -1 month of treatment in pregnant females during embryonic and fetal development. • Late fetal development, labour, delivery, lactation and newborn viability (Rat or Mouse) – pregnant females using escalating dose levels – Dosing from last gestation day (day 16-17) to end of weaning – If reproductive capacity of offspring is evaluated, study duration is 5-6 months 5. Safety pharmacological core battery: 1. CNS: Irwins test, global nervous system assessment (autonomic, sensorimotor, neuromuscular, behavioural) 2. Respiratory system (in vivo): Whole body plethysmograph chambers (put rodents in chamber before and after drug, as the rats breathe in and out the chamber measures the change in volume). Measures tidal volume and respiratory rate before and after drug. 3. Cardiovascular: measure QT interval prolongation that is mediated by inhibition of hERG ion channel. (hERG channel involved in pumping of K+ out) - In vitro: Recording of K+ current from hERG expressing CHO cell line, generate full concentration effect curve to identify dosage of drugs that changes action potential - In vivo: Telemetry receiver inserted into dogs, measure QT interval change after drug administration and varying dosage. 6. Irritation and sensitisation testing (may or may not be required), dependent on route of administration 1. Rabbits eye test 2. Skin tests – rabbit, guinea pig
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11) How are dosages translated from animals to humans?
• Maximum Recommended Starting Dose (MRSD) is converted from NOAEL in animal studies converted to HED divided by a safety factor of at least 10. • Human equivalent dose (HED) can be converted from animal dosage as a ratio of body weight, normalized by body surface area (BSA). (Allometric scaling)
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12) Why is allometric scaling better than isometric scaling:
• Isometric scaling (straight conversion based on body weight) may lead to overestimation of human dosage and/or underestimation of toxicity of a given dose. • Allometric scaling takes into account lower metabolism of larger animals (humans) compared to smaller animals (rodents, dogs, etc.). • Max Rubner (1883) demonstrated that while the ratio of blood volume to body weight decreases in larger animals, blood volume is constant to body surface area.
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13) How is combination index calculated?
• Km = body weight (kg) divided by BSA (m2) • HED (mg/kg) = animal dose (mg/kg) × (animal Km/human Km)
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1) What is the definition of a biomarker?
- A defined characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or responses to an exposure or intervention, including therapeutic interventions. - Molecular, histologic, radiographic, or physiologic characteristics are types of biomarkers.
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2) What is the definition of a clinical endpoint?
A characteristic or variable that reflects how a patient feels, functions or how long a patient survives.
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3) What is the definition of a surrogate endpoint?
A biomarker intended to substitute a clinical endpoint. A clinical investigator uses epidemiological, therapeutic, pathophysiological or other scientific evidence to select a surrogate endpoint that is expected to predict clinical benefit, harm, or lack of harm.
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4) What is a diagnostic biomarker?
- A biomarker used to identify individuals with the disease or condition of interest or to define a subset of the disease. - Examples: • Sweat chloride levels in cystic fibrosis (CF) • Galactomannan in invasive aspergillosis • Blood sugar or HbA1c in DM • Blood pressure in hypertension • Serum creatinine or GFR (glomerular filtration rate) in kidney failure • Ejection fraction in heart failure
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5) What is a monitoring biomarker?
- A biomarker measured serially and used to detect a change in the degree or extent of disease. - Monitoring biomarkers may also be used to indicate toxicity or assess safety, or to provide evidence of exposure, including exposures to medical products. - Examples: • HCV-RNA in chronic hepatitis C • INR or PT in warfarin • PSA in prostate cancer • CA-125 in ovarian cancer • BNP or NT-proBNP in pediatric pulmonary hypertension
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6) What is a pharmacodynamic (response) biomarker?
- A biomarker used to show that a biological response has occurred in an individual who has received an intervention or exposure. - Examples: • Circulating CD20-positive B lymphocytes in SLE treated with B lymphocyte stimulator inhibitor • Blood pressure in HTN treated with anti-hypertensives or sodium restriction • Cholesterol in hyperlipidemia treated with lipid-lowering agents or dietary changes • HbA1c in DM treated with anti-hyperglycemic or lifestyle changes • Sweat chloride in cystic fibrosis treated with anti-hyperglycemic • INR in patients treated with warfarin • Viral load in anti-retroviral treatment
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7) What is a predictive biomarker?
- A biomarker used to identify individuals who are more likely than similar patients without the biomarker to experience a favourable or unfavorable effect from a specific intervention or exposure. - Examples: • EGFR mutations in NSCLC for anti-EGFR drug therapy • BRCA1/2 mutations in OC for PARP inhibitors (give) • KCNJ11 mutations in pediatric diabetes for sulfonylurea treatment • HLA-B\*5701 genotype in HIV pre-abacavir treatment for severe skin reactions (don’t give) • CFTR mutations in CF for ivacaftor • TPMT genotype in 6-mercaptopurine or azathioprine treatment for severe toxicity
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8) What is a prognostic biomarker?
- A biomarker used to identify likelihood of a clinical event, disease recurrence or progression. - Examples: • BRCA1/2 mutations in BC patients for the likelihood of a second BC • Ch17p deletions in CLL for the likelihood of death • PSA in prostate cancer for the likelihood of cancer progression • Plasma fibrinogen in COPD for high risk for exacerbation • CRP levels in adults for the likelihood of coronary artery disease • Gleason score in prostate cancer for cancer progression • Total kidney volume in PCKD for high risk renal function decline • Peak VO2 \<15 ml/kg/min, PVR/SVR \> 1.0 in pediatric pulmonary hypertension
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9) What is a safety biomarker?
- A biomarker used to indicate the presence or extent of toxicity related to an intervention or exposure. - Examples: • Hepatic aminotransferases in hepatotoxicity o Released in the bloodstream during liver damage o ALT/AST measured o Acetaminophen induced hepatotoxicity • Serum creatinine in nephrotoxicity • Urinary kidney biomarkers (Kim-1, Albumin, Total Protein, b2 Microglobulin, Urinary Clusterin, Urinary TFF3, Urinary Cystatin C) in acute drug-induced nephrotoxicity • Corrected QT interval in Torsades de Pointes
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10) What is a susceptibility (risk) biomarker?
- A biomarker that indicates the potential for developing a disease or medical condition or sensitivity to an exposure in an individual without clinically apparent disease or medial condition. - Examples: • BRCA1/2 mutations in the predisposition for breast cancer • Factor V leiden in the predisposition for DVT • APOE gene variations in the predisposition of earlier onset of Alzheimer’s disease • Infection of HPV subtypes in the likelihood for cervical cancer
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11) What is an example of a biomarker with multiple purposes?
1) pre hypertensive ppl with high BP undergoing lifestyle changes experiences a drop in BP (in this case, BP is a monitoring and response biomarker) 2) if the person who undergoes lifestyle changes does not experience a drop in BP, BP becomes a diagnostic biomarker
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12) What is the paradigm shift in biomarkers?
In the past: All subjects are randomly assigned to drug and placebo, then responders/non-responders are stratified. Now: subjects are genotyped to identify levels of certain biomarkers before stratified to drug and placebo group based on whether they are tested positive/negative on certain biomarkers.
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13) What are the strategies of biomarker driven trial design?
Take tumor samples from patients, do tumor genomic analysis. Identify predictive/prognostic/pharmacogenomic biomarkers and design trial based on these results. One type of clinical trial design in the umbrella trial design. This involves testing all patients with the same disease for certain biomarkers. Stratify patients based on biomarkers, then assign a specific intervention to each group. Another type is the basket design, where patients with different diseases but have the same biomarker are assigned the same intervention. Essentially, this allows for design of more customized treatment for each patient.
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1) What is the purpose of preclinical development?
•To determine: Safety - if the compound can be safely entered into human trials, and Efficacy - if the compound exhibits anticipated pharmacological activity •Considerations (for human use): –Target organ/disease –Dosage form – Oral/Intravenous/Subcutaneous/Topical –Expected therapeutic dose –Anticipated/Unanticipated toxicities
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2) What is the definition of a clinical trial?
A clinical trial is any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcomes. (prospective not retrospective)
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3) What happens during a phase 1 Trial (predicates, goals, characteristics, subjects)?
Predicates: Biological Validity, Drug Discovery, Chemistry, Safety First studies of compound in humans: Establishes tolerability and initial indication of safety; Establishes Pharmacokinetics (Exposure, Dose Linearity, Interactions); Some initial indication of Pharmacodynamics (Glucose, Tumor Size, Viral Load, Biomarkers) Next Steps •Inform Phase 2 with regards to –Doses, Safety issues, Population, PD, Biomarkers Characteristics •Number of subjects/patients: 20-80 •Duration: 3-12 months •Highly intensive monitoring •Conducted in specialised units –Specialized laboratory tests –Monitoring –Explore biomarkers •Can be divided into Ph 1a and Ph 1b Can involve healthy volunteers or patients: -Healthy patients: homogenous population; limited confounding factors; easily studied under controlled conditions; able to comply with complex procedures/restrictions; paid for participation Patients: they have the disease; pharmacology may be disease dependent; AE may be population dependent; closer to real life
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4) What is the purpose of a control group?
-To allow discrimination of patient outcomes caused by test treatment from those caused by other factors 1. Natural progression of disease 2. Observer/patient expectations 3. Other treatment -fair comparisons for study to be informative
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5) How does placebo controls work and why is it necessary?
The placebo effect is well documented. Usually use 1) no treatment + placebo or 2) standard of care + placebo. Matched placebos are necessary so patients and investigators cannot decode the treatment assignment.
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6) How does randomization and blinding work? Why is this necessary?
-Principle: Groups must be alike in all important aspects and only differ in the treatment each group receives. In practical terms, “comparable treatment groups” means “alike on the average”. -Randomization: Each patient has the same chance of receiving any of the treatments under study. Allocation of treatments to participation is carried out using a chance mechanism so that neither the patient or physician know in advance which therapy will be assigned. -Blinding: The process used in clinical trials in which the participants, investigators and/or assessors do not know which treatments the participants are receiving. The aim is to minimise observer bias, in which the assessor, the person making a measurement, have a prior interest or belief that one treatment is better than another, and therefore scores one better than another just because of that. - In a single blind study it is may be the participants who are blind to their allocations, or those who are making measurements of interest, the assessors. - - In a double blind study, at a minimum both participants and assessors are blind to their allocations.
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7) How are subjects dosed?
Single ascending dose: A small group of subjects/healthy volunteers receive a single dose of study drug while being observed and tested for a period of time to confirm safety and characterize the PK of the study drug, where safety and PK assessments are done for a predefined time. Multiple ascending dose: Multiple ascending dose studies investigate the pharmacokinetics and pharmacodynamics (PK and PD) of multiple doses of the drug, looking at safety and tolerability. (in nutshell Mad studies check for safety/tolerability and PK/PD)
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8) What is the purpose of a phase II trial?
Phase II trials are also referred to as therapeutic exploratory studies: •Determine safety in target population •Identifying the patient population that can benefit from the drug •To estimate and verify dosing regimen •Patient volunteers with the disease to be treated: -Otherwise free of hematologic, hepatic, renal, cardiac or other serious diseases\* -Not receiving concomitant therapy, if feasible
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9) What are the characteristics of a phase II trial?
•Number of patients: 100-300 •Duration: 6 months - 3 years •At the end of Phase 2 –Defined patient group/disease state –Established safe and efficacious dose, dosing regimen, dose response –Established likely toxicities and side effects –Further validation of biomarkers and end points
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10) What is the purpose of a phase III trial?
May be referred as Therapeutic Confirmatory studies. 1. Pivotal Studies –Intended to provide adequate basis for marketing approval –Primary objective is to demonstrate or confirm therapeutic benefit shown in previous phase II studies 2. Purpose –Confirming safety –Confirming efficacy –Confirming drug dosage and formulation 3. Population –A well-defined population of patients with the disease to be treated
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11) What are the characteristics of a phase III trial?
•Randomised, blinded, controlled (standard/placebo) studies •Number of patients: 1000-3000 •Duration: 2-5 years •Can include other studies to support registration, such as bioavailability/bioequivalence and PK in special populations.
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12) What are the characteristics of phase IV trials?
•Conducted after the drug is marketed •May be required by regulatory authorities as a condition of market approval •Focused on two key issues: –Keeping track on how safe the drug is in a large population and especially in the groups not involved in the pre-marketing trials –Long-term morbidity and mortality profile of the drug •To find new indications for the drug
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1) What is the definition of good clinical practice?
Good Clinical Practice (GCP) is defined as International ethical and scientific quality standard for designing, conducting and reporting clinical trials that involve human subjects. Compliance of GCP assures the public that the rights, safety and well-being of trial subjects are protected, and that the clinical data are credible
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2) What is the history of Good clinical practices?
• 460BC Oath of Hippocrates: “first, do no harm” “never do harm” • 1938 US Food Drugs and Cosmetic Act • 1947 Nuremberg Code: - Required is the voluntary, well-informed, understanding consent of the human subject in a full legal capacity. - The experiment should aim at positive results for society that cannot be procured in some other way. - It should be based on previous knowledge (like, an expectation derived from animal experiments) that justifies the experiment. - The experiment should be set up in a way that avoids unnecessary physical and mental suffering and injuries. - It should not be conducted when there is any reason to believe that it implies a risk of death or disabling injury. - The risks of the experiment should be in proportion to (that is, not exceed) the expected humanitarian benefits. - Preparations and facilities must be provided that adequately protect the subjects against the experiment’s risks. - The staff who conduct or take part in the experiment must be fully trained and scientifically qualified. - The human subjects must be free to immediately quit the experiment at any point when they feel physically or mentally unable to go on. - Likewise, the medical staff must stop the experiment at any point when they observe that continuation would be dangerous. • 1964 Declaration of Helsinki: Ethical principles to guide physicians and participants in medical research involving human subjects • 1979 Belmont Report: - Respect for persons –person’s dignity and freedom (autonomy); consent needed - Beneficence–researchers maximise benefits and minimise harm, reasonable risks vs expected benefits. Do no harm(Non-maleficence) - Justice–equitable selection and recruitment and fair treatment of subjects • 1982 International guidelines for biomedical research involving human research - To help developing countries apply the Nuremberg code and declaration of Helsinki. • 1996 International Conference on Harmonisation’s “Guideline for Good Clinical Practice” (ICH GCP): - To overcome inconsistencies in GCP internationally 1. Clinical trials should be conducted in accordance with the ethical principles that have their origin in the Declaration of Helsinki, and that are consistent with GCP and the applicable regulatory requirements 2. Before a trial is initiated, forseeable risks and inconveniences should be weighed against the anticipated benefit for the individual trial subject and society. A trial should be initiated and continued only if the anticipated benefits justify the risks 4. The rights, safety, and well-being of the trial subjects are the most important considerations and should prevail over interests of science and society 3. The available non-clinical and clinical information on an investigational product should be adequate to support the proposed clinical trial 4. Clinical trails should be scientifically sound, and described in a clear, detailed protocol 5. A trial should be conducted in compliance with the protocol that has received prior MCRC and hospital EC approval 6. The medical care given to, and medical decisions made on behalf of, subjects should always be the responsibility of a qualified physician or, when appropriate, a qualified dentist 7. Each individual involved in conducting a trial should be qualified by education, training, and experience to perform his or her respective tasks 8. Freely given informed consent should be obtained from every subject prior to clinical trial participation 9. All clinical trial information should be recorded, handled, and stored in a way that allows its accurate reporting, interpretation and verification 10. The confidentiality of records that could identify subjects should be protected, respecting the privacy and confidentiality rules in accordance with the applicable regulatory requirements 11. Investigational products should be manufactured, handled, and stored in accordance with applicable good manufacturing practice(GMP). They should be used in accordance with the approved protocol 12. Systems with procedures that assure the quality of every aspect of the trial should be implemented
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3) What are the key players in GCP?
1. Investigational product (lead, GMP, pre clinical testing) 2. Regulator (ethical reviews and approval) 3. Investigator (ability to conduct clinical trial) 4. Participants (informed consent) 5. Sponsor (trial protocol)
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4) What should a trial protocol include?
1. General information 2. Background information 3. Trial objective and purpose 4. Trial design (eg. Whether giving tablet x 2 tablets 3 times a day for 2 weeks gives adverse effects/efficacy for a specific form of cancer (tumor size, biomarkers etc) 5. Selection and withdrawal of subjects 6. Treatment of subjects 7. Assessment of efficacy 8. Assessment of safety 9. Statistics
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5) What are the basic principles of ethics? How can these principles be applied in clinical trials?
1. Respect: Autonomy, free to decide 2. Beneficence: Do good, do no harm 3. Justice: uphold rights of subjects Ethics and clinical trials: -Protect the right and welfare of the subjects -Maintain compliance with regulation, ethical codes and guideline -Facilitate valuable research for the benefit of society -Adherence to proper process
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6) What are the 2 key protections in clinical trials?
1. Ethical review by an independent committee 2. Informed consent by voluntary participants
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7) What are the key features of informed consent?
1. One of the primary ethical considerations (respect and autonomy) underlying research with human subjects 2. More than a piece of paper to be signed, informed consent is an ongoing communication between researchers and subjects (supersedes the importance of any other part of the research) 3. Subjects should feel that participation is voluntary, and that their refusal to cooperate is free of consequence to them.
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8) Why is informed consent necessary?
All clinical trial involves obtaining informed consent (Nuremberg code, declaration of Helsinki, Belmont report, ich gcp, local law and regulations). The process of obtaining informed consent as a fundamental prerequisite for conducting research.
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9) What are the principles of medical ethics?
1. Respect: Acknowledge a person’s right to make choices, hold views and take actions based on personal values and beliefs 2. Non-maleficence: obligation not to harm intentionally; in medical ethics, a physicians guiding maxim is “do no harm” 3. Justice: Treat others equitably, distribute benefits/burden fairly 4. Beneficence: Provide benefits to persons and contribute to their welfare. Refers to an action done for the benefit of others.
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10) What is the rules of obtaining consent?
1. It is a process that involves the IRB, clinical investigators and research sponsors. All share responsibility for ensuring the IC process is adequate 2. The investigator is responsible for ensuring the IC is obtained from each research subject before that subject participates in the research study. While the investigator is not required to personally conduct the consent interview, the investigator remains ultimately responsible, even when delegating the task. 3. Date 4. A copy of the consent document must be provided to the subject and the original signed copy should be retained in the study 5. IRB should be aware of who will conduct the consent interview. Those conducting consent procedures should be adequately trained.
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11) What are the 3 components of informed consent?
1. Capacity: -a person is unable to make a decision for himself if he is unable to do all or any one of the following: o Understand the information relevant to the decision o Retain that information o Use or weigh that information as part of the process of making the decision o Communicate his decision (whether by talking, using sign language or any other means) 2. Voluntary (coercion or legal rights) - Neither the investigator, nor the trial staff, should coerce or unduly influence a subject to participate or to continue to participate in a trial. - None of the oral and written information concerning the trial, including the written informed consent form, should contain any language that waive or to appear to waive any legal rights, or that releases or appears to release the investigator, the institution, the sponsor, or their agents from liability for negligence. 3. Information - A person is not to be regarded as unable to understand the information relevant to a decision o if he is able to understand an explanation of it given to him in a way that is appropriate to his circumstances (using simple language, visual aids or any other means); o is able to retain the information relevant to a decision for only a short period does not prevent him;
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12) Who should obtain informed consent?
The investigator or an adequately trained individual delegated by the investigator. The person obtaining consent should pass CT certification that is verified by the IRB + CV.
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13) What should the language and choice of words be used?
Non-technical, practical and should be understandable to the subject or the subject’s impartial witness, where applicable
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14) To what extent are subjects/subjects LAR allowed for inquiry about the trial?
Before informed consent may be obtained, the investigator, or a person designated by the investigator, should provide the subject or the subject’s LAR ample time and opportunity to inquire about details of the trial and to decide whether or not to participate in the trial. All questions about the trial should be answered to the satisfaction of the subject or the subject’s LAR. (Legally Authorized Representative)
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15) What signature is required in the informed consent?
Prior to a subject’s participation in the trial, the written informed consent form should be signed and personally dated by the subject or by the subject’s LAR, and by the person who conducted the informed consent discussion.
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16) What is required in the event a subject/subject’s LAR is unable to read?
An impartial witness should be present during the entire informed consent discussion. After the written informed consent form and any other written information to be provided to subjects, is read and explained to the subject or the subject’s LAR, and after the subject or the subject’s LAR has orally consented to the subject’s participation in the trial and, if capable of doing so, has signed and personally dated the informed consent form, the witness should sign and personally date the consent form. By signing the consent form, the witness attests that the information in the consent form and any other written information was accurately explained to, and apparently understood by, the subject or the subject’s LAR, and that informed consent was freely given by the subject or the subject’s LAR.
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17) What should the contents of informed consent cover?
1.An explanation that the trial involves research, the purposes and the expected duration of the subject's participation, a description of the procedures. 2.The trial treatment(s) and the probability for random assignment to each treatment or placebo 3.The subject’s responsibilities. 4.A description of any reasonably foreseeable risks or discomforts to the subject. 5.A description of any benefits to the subject or to others which may reasonably be expected from the research. 6.A disclosure of appropriate alternative procedures or courses of treatment, if any, that might be advantageous to the subject. 7.A statement describing the confidentiality of records identifying the subject will be maintained. 8.An explanation of any compensation and an explanation as to whether any medical treatments are available if injury occurs and, if so, what they consist of, or where further information may be obtained. 9.An explanation of whom to contact for answers to pertinent questions and the subjects' rights, and whom to contact in the event of a research-related injury to the subject. 10.A statement that participation is voluntary, that refusal to participate will involve no penalty or loss of benefits, and that the subject may discontinue participation at any time without penalty or loss of benefits to which the subject is otherwise entitled.
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18) When is a waiver of informed consent required?
1.The research involves no more than minimal risk to the subjects. 2.The waiver or alteration will not adversely affect the rights and welfare of the subjects. 3.Whenever appropriate, the subjects will be provided with additional pertinent information after participation. 4.The research could not practicably be carried out without the waiver or alteration. (Waiver of Documentation of Informed Consent (Only Verbal Consent obtained))
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19) What happens if a subject can understand and comprehend spoken English, but is physically unable to speak or write?
If (1) the person retains the ability to understand the concepts of the study and evaluate the risk and benefit of being in the study when it is explained verbally (still competent) and (2) is able to indicate approval or disapproval to study entry, they may be entered into the study. An impartial third party should witness the entire consent process and sign the consent document.
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20) What happens if the subject is a non-english speaking participant?
IRB requires a translated consent document to be submitted. A copy of the consent document must be given to each subject. Translation is needed to facilitate conversation with a non-english speaking subject, but should not be substituted for a written translation.
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1) What is the main purpose of post marketing surveillance?
o (most important) To monitor safety and identify real, rare adverse effects (special indication for patient subgroups) o To evaluate long term efficacy/tolerance
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2) How is post marketing surveillance done?
1. Hospital/HSA websites have reporting systems for adverse effects 2. Prolonged multicentre trials (generally not feasible, require reapplication of new trial)
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3) Why are adverse effects not detected in earlier clinical trials?
Rare ADR at the rate of 1 in 5000 to 10000, require 15000 to 30000 trial subjects to be reasonably sure even one ADR occurs.
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4) What happens if rare ADR occurs during post marketing surveillance?
•the ADR/risks are added to the drug's labeling, black box warning •doctors are informed of the new information through letters and other education. •rarely that the drug needs to be reassessed
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5) What is a black box warning?
•The strictest warning put in the labelling of prescription drugs or drug products by the FDA when there is reasonable evidence of an association of a serious hazard with the drug •A means of communication from the FDA to highlight the potential risk in taking the drug so these risks may be taken into consideration •Indicates a need to closely evaluate and monitor the potential risks of the medication, or an adverse reaction to the drug that may lead to death or serious injury
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6) What are the considerations when deciding whether a drug gets withdrawn?
1. The nature and frequency of ADR 2. How the drug compares with the ADR of treatment alternatives
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7) Why does a drug get withdrawn?
1. Rare, unpredictable problems 2. More toxic than expected 3. When safer options are available 4. Dangerous combinations 5. Improper use (that lead to severe ADRs)
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8) What are examples of drugs that got withdrawn and what is the cause?
•Rofecoxib: In the treatment for pain, voluntary withdrawal by MSD following reports of increased MIs following chronic use. COX2 inhibitors being reviewed as a class. •Thioridazine: Old phenothiazine antipsychotic, associated with sudden CV collapse and death. Voluntary withdrawal worldwide. •Nefazodone: possible liver dysfunction, poor sales
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1) What is HSA and its role?
Key regulatory functions: 1. To regulate health products: Quality, safety and efficacy 2. To serve the administration of justice: Forensic medicines, forensic science and analytical chemistry testing 3. To secure the nation’s blood supply: Safe and adequate blood supply for Singapore public
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2) What are the laws regulating pharmaceuticals in Singapore?
1. Health products act: Health products (therapeutic products) regulation 2. Misuse of drugs regulation
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3) What is the product lifecycle approach?
(emerging areas) 0. Product begins from scientific and technological developments -eg. 3D printing (pre-market) 1. New drug undergoes pre market benefit-risk assessment (quality, efficacy, safety) -drug registration -GMP/GDP standards -special access scheme 2. Drug undergoes marketing approval (post-market) 3. Increasing knowledge 4. Post market variation -eg. New indication, change in manufacturing site, reclassification 5. On-going benefit risk assessment (pharmacovigilance) -safety monitoring and risk benefit assessments of marketed health products -risk communication with healthcare professionals and consumers -product quality surveillance -routine audits of dealers for GDP and GMP compliance 6. If there are safety issues, lack of efficacy, poor quality, removal of product
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4) What are the requirements for drug registration in Singapore?
For foreign source: 1. Undergo drug registration and obtain importer’s licence for importing drug 2. Obtain wholesaler’s licence 3. Obtain retail pharmacy licence For local source: 1. Obtain manufacturer’s licence and undergo drug registration 2. Obtain wholesaler’s licence 3. Obtain retail pharmacy licence
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5) What are the different approaches to drug evaluation?
Abridged (1987): -approved by 1 drug regulatory agency -full quality and abridged clinical; internal and external evaluation -180 days Full (1988): -no prior approval by any drug regulatory agency -full quality, non-clinical and clinical; internal and external evaluation -270 days Verification (2003): -approved by 2 reference agencies -reference agency assessment report; internal evaluation only -60 days
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6) What is the current approach to drug evaluation?
Risk based approach: •Depth of evaluation calibrated according to prior approvals •Multiple evaluation routes with different turnaround times allowing flexibility •In-house capabilities complemented by external experts and advisory committee (Medicines Advisory Committee) •Reference agencies: FDA, EMA, MHRA, TGA, Health Canada
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7) What are the factors involved in quality control?
Manufacturing process and process controls; control of material, intermediates; process validation; manufacturing process development; specifications; container closure system; stability (manufacturing process and controls ensure good quality product manufactured consistently)
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8) What needs to be established before clinical trials?
Pharmacology, pharmacokinetics, toxicology (single and repeat dose toxicity, genotoxicity, carcinogenicity, reproductive and developmental toxicity, local tolerance) (establish safety and toxicity before proceeding to human studies. Provides information on potential safety signals)
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9) How is clinical efficacy and safety carried out? What needs to be included in the study?
1. Biopharmaceutic studies, PK/PD studies 2. Clinical efficacy and safety studies: -study design; inclusion/exclusion criteria; treatment; efficacy endpoints; statistical method; study population, demographics and baseline characteristics; efficacy analysis; safety analysis (provides confirmatory effect and safety data for benefit vs risk assessment of the drug)
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10) How is risk-benefit assessment carried out for new drugs?
1. Study the efficacy vs safety profile via: -magnitude of clinical benefit -disease profile and prognosis -adverse event profile -local factors eg. Disease epidemiology, patient population 2. Decide if risks can be mitigated
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11) What are the studies required for generics and biosimilars?
Generics (conceptually exact copy of the innovator chemical drug): Bridging of safety and efficacy using pharmacokinetics parameter (bioequivalence studies) Biosimilars (follow-on copies of the innovator biologic drug): Structural and functional comparability using phase III clinical studies
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12) How is post marketing monitoring carried out?
On-going re-assessment of emerging safety & efficacy data to optimize benefit-risk of the drug and modify/update the product label as necessary. 1. Risk management plan –Measures to mitigate any potential risk associated with the use of a drug –Physician education materials, patient medication guide –Active surveillance programmes (incl. targeted safety signal detection), restricted access scheme, registries, post-authorization clinical studies etc 2. Other post-market surveillance activities –ADR reporting –Dissemination of safety information to healthcare professionals (e.g. Dear Healthcare Professional Letter) –Product recall
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13) How is transparency and predictability ensured?
1. Publishing information on website: -regulatory documents: submission requirements, guidance documents, checklists -legislation -processing timelines for drug applications -approvals of new drug and new indications -product labels 2. Communication with applicants: -clarification of data during evaluation -basis of regulatory decision 3. Stakeholders engagement: -industry dialogue and consultation prior to implementation of new regulations or regulatory requirments
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12) How can lead optimization be optimized in terms of drug efficacy?
-isolate cells from disease tissue, grow in monoculture, conduct secondary assays (proliferation, cell rounding, proliferation, motility, metastasis) with lead series -secondary assays with organoid spheroids
