Block 1 Bolded Terms Flashcards

1
Q

Receptor

A

Any macromolecular component in an organism that binds a drug/ligand

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2
Q

Affinity

A

The substance’s ability to form a complex with a receptor. In other words, how strong the ligand and receptor bind

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3
Q

Ligand

A

A molecule that binds to a receptor (a drug)

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4
Q

KD

A

The dissociation equilibrium constant

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5
Q

Rt

A

The total number of receptors bound (bound [LR] + free [R])

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6
Q

Agonist

A

A substance that mimics the regulatory effects of the endogenous signaling compound

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7
Q

Antagonist

A

A substance that binds to the receptor without regulatory effect

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8
Q

Partial agonist

A

Partial agonists may act as agonists when no full agonist is around or they may act as antagonists if a full agonist is present - A partial agonist may have higher affinity for a receptor than a full agonist, but it can never produce Emax

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9
Q

Intrinsic Activity

A

The ability of a ligand to produce a cellular effect after it has bound to a receptor

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10
Q

Spare Receptors

A

The relationships between the amount of ligand bound and the effect on the cell is not linear but rather a rectangular hyperbola in most systems because very small amounts of receptor occupancy produce large effects because there are spare receptors available

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11
Q

EC50

A

The ligand concentration at which the effect is 50% Emax

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12
Q

Potency

A

The relationship between the amount of drug administered and its effect, the less drug needed to produce an effect, the more potent the drug

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13
Q

Maximal efficacy

A

The maximum effect of a particular drug on the patient

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14
Q

ED50

A

The dose of drug that is effective in 50% of the population - ED50 tells how potent a drug. A lower ED50 indicates that the drug is more potent and less is necessary to produce the desired effect

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15
Q

TD50

A

Toxic dose in 50% of people

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16
Q

LD50

A

Lethal dose in 50% of people

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17
Q

Therapeutic Index

A

TD50:ED50 ratio. Ideally this is a large number to ensure if the patient takes too much drug it will be less likely that they will suffer toxic consequences

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18
Q

Log-normal distribution

A

Represents most drug effects. The curve shows the number of people in the population that respond to a given dose of the drug

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19
Q

Hyporeactive

A

Patients who did not respond until the dosage of the drug was very high

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20
Q

Hyperreactive

A

Patients who responded with very little drug dosage

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21
Q

Hypersensitivity

A

People that have an allergic or inflammatory response to the drug

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22
Q

Bioavailability

A

Fraction of a drug administered that reaches the systemic circulation

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23
Q

First pass effect

A

The amount of drug metabolized or excreted on its first pass through the liver before it reaches the systemic circulation - Reduces bioavailability

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24
Q

Bioequivalence

A

Two preparations that have:

  • Same drug (active ingredients)
  • Same route of administration
  • Same amount of drug
  • Same rate of entry into the circulation
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25
Q

Redistribution

A

Drug action is terminated because the drug redistributes from its site of action into other tissues

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26
Q

Therapeutic window

A

The concentration of a drug in the body that is high enough to produce the desired effect with a minimum of toxicity

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27
Q

Volume of distribution (Vd)

A

A measure of the apparent space in the body available to contain the drug

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28
Q

Clearance

A

Rate of elimination/concentration

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29
Q

Rate of elimination

A

Directly proportional to drug concentration. As the concentration increases, the elimination increases proportionally so the clearance stays the same

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30
Q

Half life

A

The time required to decrease the concentration of the drug by one half

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31
Q

Loading dose

A

A larger dose of the drug that allows for therapeutic levels to be achieved immediately

32
Q

Maintenance dose

A

Dose of the drug needed to maintain the drug concentration within the therapeutic window; balance clearance

33
Q

Pro-drug

A

Drugs that are inactive as given and subsequently metabolized into their active forms

34
Q

Phase I Metabolism

A

Small change in the makeup of a drug including: oxidation, reduction, dealkylation, or hydrolysis reactions. They often introduce or reveal a functional group

35
Q

Phase II metabolism

A

A large change in the makeup of the drug; conjugation of the drug or drug metabolite to an endogenous substrate molecule

36
Q

Cytochrome P450

A

Hemeproteins that are major catalysts of Phase I biotransformation reactions

37
Q

Monooxygenase

A

Enzyme that catalyzes the addition of oxygen to substrate (Part of P450 catalytic cycle

38
Q

P450 Reductase

A

Single isoform of P450 reductase in all cell types but many different isoforms of cytochrome p450

39
Q

CYP3A

A

Handles 50% of drugs - Inhibited by grapefruit juice

40
Q

CYP2D6

A

Handles 25% of drugs

41
Q

CYP2C9

A

15% of drugs

42
Q

CYP2C19

A

≦5%

43
Q

CYP1A2

A

≦5%

44
Q

CYP2E1

A

≦5%

45
Q

Flavin-containing monooxygenase

A

Flavoprotein localized in smooth endoplasmic reticulum that catalyze monooxygenation reactions, primarily of soft nucleophiles (Requires NADPH, O2 and Substrate)

46
Q

UDP-Glucuronosyl Transferase

A

Located on endoplasmic reticulum - Adds glucuronic acid to substrate in Phase II metabolism

47
Q

Glucuronidation

A

Process of adding UDP-glucoronic acid to substrate - Conjugation Capacity: High
- Abundance of raw materials for conjugation: High

48
Q

N-Acetyltransferase (NAT)

A

Replaces -OH or -NH2 with an acetyl group on substrate

49
Q

Acetylation

A

Process of adding Acetyl-CoA to substrate -

  • Conjugation Capacity: Variable
  • Abundance of Raw Materials for Conjugation: Variable
50
Q

Sulfotransferase (SULT)

A

Replaces -OH or -NH2 with 3’-phophoadenosine-5’-phosphosulfate group (PAPS)

51
Q

Sulfation

A

Processing of adding PAPS to substrate

  • Conjugation Capacity: Low
  • Abundance of Raw Materials for Conjugation: Low
52
Q

Glutathione S-Transferase (GST)

A

Detoxify xenobiotics by catalyzing the nucleophilic attack by GSH on electrophilic carbon, sulfur, or nitrogen atoms of said nonpolar xenobiotic substrates

53
Q

Glutathione Conjugation

A

High energy intermediate is the drug itself: arene oxides, epoxides, etc…

  • Conjugation Capacity: Low
  • Abundance of Raw Materials for Conjugation: Low
54
Q

Enzyme Induction

A

Exposure to some drugs and environmental chemicals can markedly upregulate enzyme amount and/or activity - usually transcriptional increases (increase or decrease drug effects)

55
Q

Enzyme Inhibition

A

Drug or environmental chemical may inhibit the metabolism of several drugs (Competitive vs. Non-competitive)

56
Q

Acetaminophen

A

Has interplay of multiple phase II reactions (SULT, UGT, GST), phase I reaction, CYP2E1 induction

57
Q

Pharmacogenetics

A

Genetic factors that alter an individual’s response to a drug

58
Q

Genotype

A

An individual’s composition at the gene level; the specific genes they have

59
Q

Phenotype

A

An individual’s expression of their genotype

60
Q

Genetic Polymorphism

A

Mendelian trait that exists in the population in at least two phenotypes neither of which is rare

61
Q

Single nucleotide polymorphism

A

A change in one single base pair in the DNA sequence that differs form the “wild type” or predominant sequence

62
Q

Halotype

A

A cluster of SNPs that occur together in an individual

63
Q

Haplotype

A

Refers to closely linked genetic markers on a chromosome that tend to be inherited together

64
Q

Autosomal co-Dominance

A

Each allele contributes to phenotype

65
Q

Autosomal Recessive

A

Wild-type allele has predominant effect; it takes two recessive alleles to see the effect

66
Q

Autosomal Dominant

A

A single allele predominates over the presence of other possible alleles

67
Q

X-linked inheritance

A

Genes inherited on X chromosome; all males will express these traits

68
Q

Homozygous

A

Have two identical alleles

69
Q

Heterozygous

A

Have 2 different alleles

70
Q

N-Acetyltransferase-2 polymorphism

A

Responsible for metabolism of anti-tuberculosis drug izoniazid - Genetic differences in NAT-2 explain “fast” versus “slow” acetylators (autosomal recessive)

71
Q

CYP2D6 polymorphism

A

First identified from those that suffered severe hypotension following administration of the anti-hypertensive debrisoquiine - poor metabolizer variants - also handles antidepressants

72
Q

CYP2C19

A
Poor metabolizer phenotype
Affects several important classes of drugs
- Anti-convulsants
- Proton pump inhibitors
- Anti-platelet drugs
- Anti-depressants
- Anti-cancer
- Hormones
73
Q

CYP2C9

A

Poor metabolizer phenotype ( *2 and *3 variants)

Several substrates including some drugs with a narrow therapeutic window (warfarin cleared almost entirely by CYP2C9)

74
Q

Vitamin K receptor (VKORC1) polymorphism

A

Subunit of the vitamin K epoxide reductase complex - inhibited by warfarin
A clade - Haplotypes H1 and H2 require lower warfarin doses and associated with lower expressoin of VKORC1
B clade - Haplotypes H7, H8, H9 require higher warfarin doses and associated with higher expression of VKORC1

75
Q

Pseudocholinesterase polymorphism

A

Variant response to succinylcholine, a depolarizing muscle relaxant - due to reduced activity variants of pseudocholinesterase (30-90% decrease in cholinesterase activity)

76
Q

TPMT polymorphism

A

Presents as increased risk for life threatening bone marrow suppression in patients treated with thiopurine drugs due to variants with decreased activity of thiopurine methyltransferase

77
Q

P-Glycoprotein (Pgp) polymorphism

A

ATP binding protein that effluxes drugs from the gastrointestinal mucosa - polymorphisms result in increased net uptake of the cardiac glycoside, digoxin