Class Flashcards
Receptor
Regulatory role-interact with drug and initiates drug effects
Inert binding site
Drug binds without changing any function of receptor
Ligand
Binds to receptor
Covalent bond of ligand and receptor
Irreversible
Need to resynthesize
Non covalent ligand receptor binding
Reversible
Most
List types of bonds strongest to weakest (non covalent)
Ionic, hydrogen, hydrophobic interaction, van der waals
What are van der walls
Weak electrostatic interactions involving dipole moments within functional groups
Dose response curve
Drug and its effects
Linear?
Log of dose response curve
Drug dose log x
Y drug effect
Hyperbolic
Concentration effect curve log vs response
Sigmoidal curve
Emax
Max effect
ED50
Dose that produces 50% of its maximal effect
Graded response
How much
Magnitude of response varies continuously
Mean value within a population or subject
Quintal response
Yes or no
Binary response
Is there a response, if so how many
Need predefined response
Examine frequency of a large population
Quantal non cumulative dose response curve
Number or % of individuals responding at a certain dose of a drug and only at that dose
Cumulative quantal dose response curve
Number or % of individuals responding at a certain dose of a drug and at all doses lower than that dose
what kind of graph do you get TI from
Cumulative dose response curve
TI
TD50/ED50
Therapeutic window
Range at which safe and effective
What determines the binding and nteraction of drugs with their receptors
Size shape charge
High affinity
Less drug needed to produce a response
Low affinity
More drug needed to produce a responses
Kd
Parameter describing affinity
Equilibrium dissociation constant
What is the Kd
Drug concentration at which 50% of the drug receptor binding sites are occupied by the drug
Unit of Kd
Molar concentration (micromoles, nanomoles
Low Kd
Higher affinity of a drug for receptor
Higher Kd
Lower affinity of a drug for a receptor
Formula for Kd
L+R LR
Kd=(L)(R)/(LR)
What are L R and LR
Molar concentrations of ligand, receptor, and their complex
__ determine the quantitative relationship between a drug and its effects
Receptors
The magnitude of a drugs effects will be proportional to the degree of its interactions with a __
Receptor
Ec50=Kd or Ec50=Kd
Depending on the outlying of receptor occupancy and a response to a drug
Two graphs
Ok
Agonist have __ activity
Intrinsic
Antagonist do not have __ activity
Intrinsic
Competitive antagonist
Compete with endogenous chemicals or agonist drugs for binding to the receptor
Non competitive antagonists
Receptor inactivation is not surmountable
Irreversible or allow=steric antagonist
Irreversible antagonist
Irreversibly bind to and occlude the agonist site on the receptor by forming covalent bonds
Allosteric antagonists
Bind to a site other than the agonist site to prevent or reduce agonist binding or activation of the receptor
Competitive antagonist
Agonist EC50 increases, Emax does not change
Non competitive antagonism
Agonist Emax decreases
EC50 does not change
Potency
Amount of a drug required to produce a specific pharmacological effect
What drugs tend to be more potent
Higher affinity (lower Kd)
What represents potency
ED50
Lower ED50
More potent
How determine dose
Potency
Efficacy
Maximal pharmacological effect that a drug can produce
What represented efficacy
Emax
The greater the Emax, the more ___ the drug
Efficacious
What is efficacy related to
Total receptors available to bind a drug
What does efficacy determine clinically
Effectiveness
Potency determines __ and efficacy determines ___
Dose
Effectiveness
Potency is related to __ and efficacy is related to ___
Affinity
Total number of receptors available to abind a drug
What is a drug target
Important regulatory proteins in the existing cell signaling pathways
What are the classes of drug targets
Membrane receptors, nuclear receptors, ion channels, transport proteins, enzymes
Protein kinases
Covalently attach phosphate group to an aa residue
-serine threonine kinases
Tyrosine kinases
Phosphorylation
500 in human genome
Response element
Specific DNA region that transcription factors bind to
What do transcription factors have
DNA binding domain
What do transcription factors bind to
Enhancer or promoter regions that are usually adjacent to the coding sequence of the regulated gene
GPCR makes up _% of genome
4
About _% of marketed drugs act on GPCR
30
Ligand for GPCR
Bio genie amines, peptides/proteins, amino acids, lipids, nucleotides
The N terminal (__) domain of GPCR is often __
Glycosylated
The C terminal (__) contains multiple phosphorylation sites (__/__)
Cytosolic
Serine/threonine residues
What do cytoplasmic loops of GPCR contain
G protein binding sites
The 7 transmembranes is ___
Hydrophobic
Phosphorylation of C terminal
Diminished G protein coupling and can promote receptor endocytosis
G protein cycl
- G protein receive ligand to activate
- Promotes release of GDP from G protein
- allowing entry of GTP into nucleotide binding site
- GTP bound state the G protein regulates activity of an effector enzyme or ion channel
- Signal terminated by hydrolysis of GTP
- Return to the basal unstimulated state
Rec
Hormone receptors
PDE
Phosphodiesterase that hydrolyze cAMP
Pase
Phosphatase
S
Protein substrates
So…AC turns ATP to Camp. What happens to Camp
Phosphodiesterase turns it to 5-AMP
Or cAMP+R2C2–> R2cAMP4+2C
What happens to 2C
With ATP turns S to SP to make ADP with Pase
What does SP do
Response
What happens to IP3
Ca enzyme and CaM—>CaM-E which causes response
What does DAG do
Activate PKC
Which with ATP turns S to SP which causes a response and releases ADP
What receptors have intrinsic enzyme activity
RTK
What growth factors bind to RTK
IGF-1, insulin, VEGF, EGF, NGF, PDGF
Most RTK
Single polypeptide chain
Insulin and IGF receptor RTK
2 chains a and b linked by disulfide bond
___ domain shows very little similarity between the members of the family
Ligand-binding
___ __ domain is similar between the members of the family
Tyrosine kinase
How is the EGF receptor activates
- EGF bind and conformation change (monomeric inactive, dimeric active—bound noncovalently)
- Cytoplasmic domains become phosphorylated on specific tyrosin residues
- anzymatic activities are activated , catalyzing phosphorylation of substrate proteins
Turning S into SP with ATP and releasing ADP
JAK
Receptor coupled to cytosolic protein kinases
Transmit the effect of a number of hormones and cytokines (Growth hormones, erythropoietin, leptin, interferons, interleukins 2,20,15)
Describe JAK STAT pathway (family of cytosolic tyrosine kinases (JAK1 to 5, TYK2) that bind to an activated receptor to start signaling cascade
- Activate and JAK(intracellular) are activated (dimerize), resulting in phosphorylation of signal transducers and activation of transcription STAT molecules
- STAT diners then travel to the nucleus where they regulate transcription
Ligand for nuclear receptors
Steroid hormones, thyroid hormones, vit D, vit A, FFA and their products
Steroid receptor families
Androgen receptor Estrogen receptor Progesterone receptors Glucocorticoid receptors Mineralocorticoid receptors
When do we see effects of nuclear receptors
Lag period
And the effects can persist after the agonist concentration has bee reduced to zero
Mechanism of a steroid hormone action
Nuclear receptor polypeptide is depicted as a protein with three distinct domains.
Heat shock protein, hsp90, binds to the receptor in the absence of hormone and prevents folding into he active conformation of the receptor. Binding of a hormone ligand causes dissociation of the hsp90 stabilizer and permits conversion to the active configuration
What do ion channels do
Change the cell membranepotential
Change concentration of ions in cytosolic
Voltage gated channels
About 300 genes code for subunits of coltage gated channels
Conductance is induced by membrane potential changes
Na Ca K channels are targets of drug action
Ligand gated channels
Multimeric channels span the cell membrane and have a binding site for a neurotransmitter inducing the current, and an ion conducting pore
How are voltage gated ion channels controlled
Not by binding a ligand
Controlled by membrane potential
Voltage gated Na channels
A and b subunits
What drugs inhibit voltage gated Na channels
Local anesthetics
Antiarrhythmic drugs
Drugs used for the treatment of epilepsy
Voltage gated ca channel
L type channels are located on cardiac and smooth muscle cells
Blockers and antagonists
Direct gated ion channels
Receptors for neurotransmitters that have an ion conducting pore
Excitatory neurotransmitters
Open cation channels, depolarize the cella nd induce generation of action potential in excitable cells
Examples of excitatory NT
Acetylcholine and glutamate
Inhibitory neurotransmitters
Open anion channel causing inward anion flux and hyperpolarization, prevent generation of action potentials
Examples of inhibitory neurotransmitters
GABA and glycine
Activation of nicotonic acetylcholine receptors
Induces inward Na fluxes and membrane depolarization
What and where are nicotonic acetylcholine receptors
Pentameric receptors with two major locations
- skeletal muscle, responsible for depolarization of skeletal muscle fibers
- neuronal cells
What is a nicotonic acetylcholine receptor
Ligand gated ion channel
The nicotonic acetylcholine receptor is in the ___
Membrane
The extracellular part of the nicotonic acetylcholine receptor has _ subunits. What are they
Five
2a, b, y, and delta
What does the nicotonic acetylcholine receptor do
Opens a central transmembrane ion channel when ACH binds to sites on the extracellular domains of its a subunits
GABA receptors
Anionic channels causing inward Cl influx and hyperpolarization
What does GABA mediate
Synaptic inhibition in CNS via these channels
Structure of GABA receptos
Pentameric structure
What is the GABA receptor a target for
Inhalation general anesthesia drugs
Intravenous general anesthesia drugs
Ethanol
Hypnotic and anti anxiety benzodiazepine drugs
Binding sites on GABA receptor
Binding site and allosteric
Biotransformation
Enzymatically driven process whereby a substance is changed from one chemical to another in an organism
Usually xenobiotics
What compounds are not readily excreted
Lipophilic, unionized, large compounds
What it’s he body’s main method of elimating substances
Biotransformation of xenobiotics into more polar (and sometimes larger ) derivatives
Consequences of Biotransformation
May lead to products still biologically active or more active
L dopa biotransformation
Dopamine
Prodrug into active compound
What is l dopa
Pro drug
Example of active compound becoming an active compound
Diazempam—>oxazepam
Example of inactivation
Acetylsalicylic acid(asprin)-> acetic acid+ salicylate
What is a prodrug
Inactive drug that undergoes biotransformation to become an active drug
*sum drugs designed as inactive so not active until absorption
Where does biotransformation happen
Liver (main), GI, lung, skin, kidneyER mitochondria cytosolic lysosomes nuclear envelope or plasma membrane
First pass
Oral drugs are absorbed in the small intestine and transported to the liver via the hepatic portal system, where they undergo extensive metabolism (drugs given via parent earl routes of administration do not undergo first pass)
First pass limits drugs?
Yea look at other routes of administration
Digestive enzymes and intestinal bacteria
May metabolically activate or inactivate drugs
How can normal GI flora increase bioavailability of certain drugs, ugh as estrogen in contraception
By increasing enterohepatic cycling of metabolites (antimicrobial drugs may reduce estrogen efficacy)
Morphine
Extensive first pass
Clinical significance of morphine undergoing extensive first pass biosynthesis
Oral 35% absorbed
So need to give IV
Phase I
Oxidation, reduction, or hydrolysis reactions
Biological inactivation
Phase II reactions
Conjugate the substrate
Make more water soluble and increased molecular weight which facilitates elimination
Phase I
Catabolic
Enzymes that convert the parent drug to a more polar metabolite by introducing or unmasking a functional group (OH, NH2, SH, COOH, O)
Mainly oxidation
Common reactions phase I
Oxidation, reduction, and hydrolysis
Less common reactions phase I
Hydroxylation, epoxidation, dealkylation, deamination, desulfurization, decholrination
Phase I enzymes
MFO (mixed function oxidase) MFO or monooxygenases
- CYP P450
- flavin containing monoxygenases (FMO
- epoxied hydrolysis (mEH, sEH)
Phase II
Anabolic,
Enzymes that form a conjugate of the substrate
Make more polar, higher molecular weight, and often inactive
Conjugation in phase II
Conjugation dependent upon endogenous substrates such as glucoronic acid, sulfuric acid, acetic acid, or an aa
Phase I or phase II faster
Phase II conjugation
Where does most conjugation take place
Liver
Are some drugs not metabolized phase I or II
Yup
Many phase I reactions occur ___
Concurrently
Before phase I
Phenytoin highly liophilic
After phase I
4-hydroxy phentoin
Slightl soluble in water
After phase II
4-hydroxy-penytoin-glucuronide
Very soluble in water
Cytochrome p450
Superfamily of enzymes that carry out phase I biotransformation
Most common p450s
CYP1A2, CYP2A6, CYP2D6, CYP2E1, and CYP3A4
What is the most abundantly expressed p450 and involved in the metabolism of about 50% of clinically used drugs
CYP3A4
All p450 contain a molecule of __ that is __ bound to the polypeptide chain
Heme
Noncovalently
P450 use molecular _ and _ derived from the cofactor-reduced NADPH to carry out the oxidation of substrates
O2 H
P450 cycle
One molecule of oxygen is reduced per drug molecule with one oxygen atom added to the drug (the drug is oxidized) and the other oxygen in the byproduct water RH, parent drug; ROH, oxidized metabolite; e_ electron.
What does NADPH do
Turns flavinprotein(oxidized) to flavinprotein reduced with P450 reductase
What does a reduced flavinprotein do
Give 2 electrons to p450-RH
Succinylcholine
Depolarizing neuromuscular blocking drug
Genetic defect in ___ can metabolize can metabolize succinylcholine at 50% the rate as normal individuals
Pseudocholinesterase
What is slow acetylator phenotype
Autosomal recessive trait have a decrease in N-acetyltransferase levels, rather than a mutated form of the enzyme , in the liver
Result of slow acetylator phenotype
Isoniazid (used to treat TB), hydralazine(used to treat hypertension), caffeine, and other similar amines are metabolized at slower rates, which can lead to hepatotoxicity (hepatitis)
How many people are slow acetylator phenotype
This phenotype occurs in roughly 50% of the US population, 83% French, and is less common in Asian populations
Page 43 katzung
Ok
CYP2E1
Is endured by chronic ethanol
Tobacco smoke(benzo a pyrene
Inducer
Rifampin
For TB
Inducer
Rats pretreated with phenobarbital
Significantly faster half life of chloramphenicol in comparison to control rats
Grapefruit juice effect
Irreversibly inhibit CYP3A4
Alters oral bioavailability of drugs, including antihypertensive, immunosuppressant, antidepressants, antihistamines, and statins
Allopurinol and mercaptopurine
Allopurinol used to treat excess uric acid (gout) and acts by inhibiting xanthine oxidase
Xanthine oxidase is a key enzyme in the biotransformation pathway of the immunosuppressive agent mercaptopurine (used during cancer)
Coadministration of allopurinol with mercaptopurine prolongs the duration of mercaptopurine action and enhances its chemotherapeutic and toxic effects
Doses of mercaptopurine must be reduced in patients receiving allopurinol
Neonate biotransformation
Low hepatic enzymes actively involved in drug biotransformation
Biotransformation in postnatal period and elderly
Hepatic enzymes increase rapidly in postnatal period and are heterogenous in elderly population
Premature infants
Decreased conjugating activity
Hyperbilirubinemia in new born
During metabolism of fetal hemoglobin , bilirubin levels accumulate int he blood
Due to the immature hepatic metabolic pathways, newborns are unable to conjugate bilirubin with UDP glucuronic acid (UDP glucuronosyl-transferase levels are low) and bilirubin is unable to be excreted
Bilirubin induced encephalopathy is a concern when levels become dangerously high
Why are fetus and neonate highly susceptible to drug toxicity
A poorly developed bbb, weak biotransforming activity, and immature excretion mechanisms
Does metabolism for drugs decrease with age
Sometimes not really
Bc drug half-life is more dependent on the drug itself
Liver and kidney disease
In elderly
Important factor accounting for decreased drug metabolism
Age related variables that affect pharmacokinetics
Body water, lean body mass, body fat, serum albumin, kidney weight, hepatic blood flow
Young or old people have more body water
Young
Young or old people have more lean body mass
Young
Young or old people have more body fate
Old
Young or old people have more serum albumin
Young
Young or old people have more kidney weight
Young
Young or old people have more hepatic blood flow
Young
Liver disease
Hepatic drug metabolizing enzymes (p450) may be compromised and drug elimination rates could be reduced
Disease states that could decrease metabolism
Alcoholic hepatitis, cirrhosis, acute viral or drug induced hepatitis, biliary cirrhosis, hemochromatosis, chronic active hepatitis
Flow limited biotransformation drugs
Rate of elimination is dependent upon the rate of blood flow supplying the drug to the liver
Cardiac disease may cause specific drug levels to rise
Atenolol, propranolol, isoniazid, lidocaine, morphine, verapamil (calcium channel blocker)
What happens when endogenous detoxifying cosubstrates are limited
The toxic pathways may prevail resulting in organ toxicity or carinogenesis
What may cause cosubstrate limitation
Dietary insuffiency or an alternative underlying defiency
Example of biotransformation to more toxic product
Acetaminophen-induced hepatotxicity
For a normal adult 1.2 g/day, how is acetaminophen metabolized
95% undergoes glucuronidation and sulfation with 5% biotransformed via P450 pathways
What happens when acetaminophen intake exceeds therapeutic dose
Hepatic GSH is depleted faster than it is regenerated and toxic metabolites accumulate resulting in hepatotoxicity
Glucuronidation of acetaminophen
to nontoxic glucuronide
Sulfation of acetaminophen
Nontoxic sulfate
CYP2E1 and CYP3A4 of acetaminophen
To reactive toxic intermediate
What happens to reactive toxic intermediate of aceteminophen
GSH conjugation
To mercapturic acid conjugate
Or
Nucleophillic cell macromolecules to cause liver cell death
Pharmacogenomics/pharmacogenetics
Study of genetic factors that underlie variation ind rug response
Genome wide association studies
Hundreds of thousands of genetic variants across the genome are tested for association with drug response led to discovery of many other important polymorphism in genes that encode transporters , HLA, cytokines, and other proteins
Precision/stratified personal medicine
Genetic information is used to guide drug and dosing
Clinical pharmacogenetics implementation consortium (CPIC)
Series of guidelines for using genetic information in selecting medications and in dosing
Allele
One of two or more alternative forms of a gene that arise by mutation and are found at the same genetic locus.
CYP2D6 is a variant allele for a drug metabolizing variant of CYP2D6
CSNP
Snp in coding region
HaplotypE
Series of alleles found in a linked locus on a chromosome
Hardy Weinberg
Allele frequencies will remain constant from generation to generation in absence of evolution
Linkage disequilibrium
Nonrandom association of alleles at two or more loci that descend from a single ancestral chromosome
Nonsynonymous snp (nsSNP)
Single base pair substitution in the coding regions hat results in an aa change
PM, IM, EM, UM
Poor, intermediate, extensive, or ultra rapid metabolized phenotype
Synonymous SNP
Base pair substitutions int he coding regions hat do not result in an aa change
Extensive metabolized
Individuals metabolic rate of a particular drug that is a known substrate of a specific enzyme, were used to describe genetic effects on drug etabolism
*
Specific sequence variant
*1xN
N number of copies
Enzyme activity is ___ or _-
Co dominant
Additive
If an individual has one normal and one functional allele
Have intermediate
0, .5, 1-2, >2
PM, IM, EM, UM
CYP2D6
1/4 of all rugs
B blockers, antidepressants, antipsychotics, opoid analgesics
CYP2D6*4
20% of Europeans and absent in Asians
CYP@D^ alleles
*1, *2 functional
10, 17, 41 reduced function
3, 4, 5, 6 nonfunctional
LPM CYP2D6
3, 4, 5, 6 more in Europe’s
*5 deletion CPY 2D6
Similar frequencies European and Asian
Hardy Weinberg
Ethnicity specific@
Look at ethnicity of patient you are treating
Codeine active metabolite
Morphine
What do codeine and morphine bind to
Mu-opoid receptor in CND
Why is conversion of codeine to morphine essential for it to work
Morphine 200 times more potent
What enzyme converts codeine to nomrphine
O-demethylation -a CYP2D6
EM CYP2D6
Convert sufficient (5-10% of codein0 to get analgesic
PM IM CYP2D6
Insufficient pain relief
UM CYP2D6
Side effects of codeine
Drowsy, respiratory depression, due to high morphine
CYP 2C19
Metabolizes acidic drugs including proton pump inhibitors, antidepressants, antiepileptics, and antiplatelet drugs
CYP2C19 alleles
2 3 are nonfunctional
1 fully functional
17 increased function
CYP2C19*17
Increased function allele is unable to fully compensate for nonfunctional alleles and in combination with a nonfunctional allele could be considered IM
PM CYP2C19
Asians
CYP2C19*2
Asians
CYP2C19*17
Not Asians
In Europeans and Africans
Clopidogrel
Thienopyridine antiplatelet prodrug indicated for prevention fo atherothrombic events
How does clopidogrel work
Active metabolites selectively and irreversibly inhibit adenosine diphosphate induced platelet aggregation
How is clopidogrel metabolized
85% rapidly hydrolyzed by hepatic esterases to its inactive carboxylic acid derivative,
15% converted cia two sequential CYP mediated oxidation reactions (CYP2C19) to the active thiol metabolite responsible for antiplatelet activity
CYP2C19*2 and clopidogrel
Increased risk for serious adverse CV events, coronary syndrome and stent thrombosis, and percutaneous coronary intervention
CPIC recommendations clopidogrel
Standard starting dose for EM, UM
Give antiplatelet agent to PM and IM
FDA says alternative antiplatelet for poor metabolizes
Recommendation CPIC for CYP2D6 and codeine
Standard starting dose for EM, IM (close monitoring IM
Don’t use in PM and UM
Dihydropyrmiidine dehydrogenase (DPD)
First rate limiting step in pyramiding catabolism and major elimation route for fluoropyridime chemotherapy agents
Three nonfunctional alleles of DPD
DPYD*2A, *13, and rs67376798
DPYD*2A
Common in Swedish populations
Lower in European, African and Asian
Fluoropyridime 5-FU
Treat solid tumours (colorectal cancer, breast cancer, must be given IV
DPYD*2A and fluoropyridime
If treat with 50% of normal dose the adverse effects decreases
What do phase 2 enzymes do
Biotransformation reactions typically conjugate endogenous molecules into things to eliminate
Polymorphic phase 2 enzymes
Diminish drug elimation and increase toxicities
Uridine 5-diphosphoglucuronosyl transferase 1 (UGT1A1)
Enzymes conjugate glucuronic acid into small lipophilic molecules so readily excreted in bile
UGT1A1 *28
Common all ethnic groups
Gilbert syndrome
UGT1A1 *28/28
28 allele Gilbert’s
Extra TA in proximal promoter
Gilberts syndrome
Increased unconjugated bilirubin and increased risk for adverse drug reactions due t recused biliary elimination
Irinotecan
Topoisomerase inhibitor prodrug for chemo
Irinotecan metabolized to ___
An-38, toxic and inhibits topoisomerase leading to DNA termination or rep and cell death
How in SN-38 inactivated
UGT1A1
Irinotecan SN38 and UGT1A1*38
Severe life threatening toxicities (neutropenia, diarrhea, due to decrease SN38 clearance)
Thiopurine S-methyltransferase (TPMT)
Covalently attaches a methyl group into aromatic and heterocyclic sulfhydryl compounds and is responsible for the pharmacological deactivation fo thiopurine drugs
Phenotypes of TPMT
High intermediate and low activity
Who has most high one nonfunctional TPMT
Europeans and Africans
What percent of Europeans have two defective TPMT
.3
TMPT*2, 3A, 3B, 3C
Non functional alleles
Thiopurine drugs and TPMT
Treat immunologic disorders
TPMT is major determinant of thiopurine metabolism and exposure to cytokines dosing strategies
G6PD
Rate limiting step in PPP and supplies NADPH and reduced glutathione which prevent oxidative damage
G6PD normally in RBC to detoxify unstable oxygen species while working at 2% of its capacity
Exposed to ROS
G^PD activity in RBS increases proportionately to meet NADPH demands
G6DP defiency
Risk for abnormal RBC destruction hemolysis due to antioxidant capacity under oxidative pressures
What chromosome is G6PD on
X chromosome
How many people have G6PD decent
400 million
G6PD defiency associated with
High malaria prevelance AFRICA Mediterranean Asia East Asia
Rasburicase
Recombinant rate oxidase enzyme for initial management of high uric acid levels in cancer patients receiving chemo
Rasburicase
Alleviates the uric aid burden that often accompanies tumor losing treatments by converting uric acid into allantoin, a more soluble and easily excreted molecule
During the conversion fo uric acid to allantoin, __ is formed
H2O2
Rasburicase and G6PD
Can’t reduce H2O2
Risk for hemolytic anemia and methemoglobinemia
Recommendation
Rasburicase no use in people with G6PD defiency
Organic anion transporter (OAT1B1) from SLOC)1B1
Sinusoidal membrane of hepatocytes and is responsible for the hepatic uptake of mainly weakly acidic drugs and endogenous compounds like statins, methotrexate and bilirubin
Reduced function OAT1B1
Rs4149056
- 5
- 15 17-reduced function
Statins
HMG-coenzyme A reductase inhibitors
Statin and SLCO1B1 5, 17
Myopathy
Recommend alternative
Breast cancer resistance protein (BCRP, ABCG2)
An effluvia transporter in the ATP binding cassette superfamily on epithelial cells of the kidney, liver, and intestine and on endothelial cells of BBB
BCRP issue
East Asians (Chinese Japanese)
Allopurinol and BCRP, statin,
Problem
Drug induced hypersensitivity reactions
Stevens Johnson, necrosis, liver injury,
Drug classes associated with hypersensitivity
Antibiotics, NSAIDS< aanti-epileptic, methotrexate
Carbamazepine induced skin toxicities
East Asian
HLA B, , DQ, DR
Drug induced hypersensitivity reactions to allopurinol, carbamazepine, abacavir, and flucloxallin
HLA-B and abacavir
Nucleoside reverse transcriptase inhibitor used in HIC associated with hypersensitivity reactions in the skin , SJS, TEN
Ethnic group for abacavir and HLAB57:)1
Ligand bound peptide onthe cell surface in a structurally different configuration which is recognized by CD8 cells
Increase testing genetic variants of HLAB5701
For chemo
Flucloxacillin
Hypersensitivity reaction HLAB5701 liver toxicity
HLAB5701 and flucloxallin
Liver injury
Interferon lambda-3 (IFN-gamma3)
IFNL3 (IL-28B)
Encdedn by IFNL3
Directly induced by viruses and act through JAK STAT final transduction pathways to produce antiviral activity inc Ellis
HepC
Genetic variants IFNL3 and HCV treatment
Ribavirin-greater cure in patients with favorable
IFNL3 is considered what
Strongest baseline predictor variant, is inherited most frequently in Asians
Peggy lasted interferon with ribavirin
Chronic HCV want a sustained virologist response (SVR)
Europeans homozygous favorable
More likely to achieve SVR
Unfavorably IFNLE
Lesss SVR with ribavirin
Warfarin
CYP2C9 and VKORC1
CYP2C9
Phase I drug metabolizing enzyme that acts primarily on acidic drugs including warfarin, phenytoin, and NSADIS
CYP2CP *2, 3,
Reduced metabolism of warfarin common European
Why warfarin variability in Africans
High CYP2C9, *5, 6, 8, 11
VKORC1
Vitamin K epoxied reductase complex subunit 1
VKORC1
Target of warfarin and key enzyme in VK recycling
VK dependent cofactors
II, VII, IX, X, C, S
Variation in VKORC1
Bleeding , like multicoagulation factor defiency type 2A or warfarin resistance
VKORC1-1639>A
Reduced expression of VKORC1 in the liver
Increased sensitivity to warfarin
Asians
Warfarin
VK antagonist, widely prescribed oral anticoagulatnt
Why do dose variation cause problems with warfarin
Narrow therapeutic range
What polymorphism are important for warfarin
CPY2C9 and VKORC1
S- R- warfarin entantimer
How its administered. Increased risk for bleeding if CYP92C9 and VKORC1
Epigenomics
Epigenomics
Can regulate genes involved in pharmacokinetics or drug targets include DNA methylation and histone modification
Ok