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Pharmacogenomics > Week 1 > Flashcards

Week 1 Flashcards

1
Q

Pharmacogenetics definition and use

A
  • Influence genes on the efficiency and side effects of drugs.
  • Variable response due to individual gene(s)
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2
Q

Phamacogenomics definition and use

A
  • describes the interaction between drugs and the whole genome
  • Variable response due to multiple loci across the genome
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3
Q

Five stages following drug administration

A
  1. Absorption into the body
  2. Distribution to the site of action
  3. Target integration e.g. binding to cellular receptors or ion channels
  4. Metabolic processing
  5. Excretion - From the body
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4
Q

What are the most influential genes when studying variation in drug responses?

A
  1. Those influencing Pharmacokinetic properties, the drug metabolising enzymes and transporters, effecting how the drug is handled in the body.
  2. Those influencing Pharmacodynamic properties, including drug targets; enzymes, receptors and ion channels, and associated pathways determining the drugs effect in the body.
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5
Q

Example of a gene which effects the Pharmacokinetic drug properties

A

The ABCB1 gene encoding for the MDR1 drug transporter, variants of the gene are associated with the resistance to the effects of drugs such as the anti-epileptic agent phenytoin.

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6
Q

Example of a gene which effects the Pharmacodynamic drug properties

A

The CYP2C19 gene encoding metabolic enzyme cytochrome p450. Variants of the gene are associated with decreased responsiveness to omeprazole used to treat peptic ulcers and other gastric complaints.

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7
Q

What is the most common genetic variant which affect drug action?

A

SNPs Single nucleotide polymorphisms which substitutes one base for another. when there are sets of closely linked SNPs are called haplotypes.

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8
Q

If there are two common variants C or T at a specific position in a multi drug transporter gene ABCB1. How could this effect how the drug effects people.

A

Different people would have different genotypes for example CC CT or TT, these genotypes could be link to resistance or enhancement of the administered drug.

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9
Q

Efficacy definition

A

Maximum beneficial or therapeutic response that a drug can produce and is a measure of clinical effectiveness. It can be expressed in percentage who show a therapeutic response at a given, standard dose.

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10
Q

Toxicity

A

The extent of a drug inducing unwanted or harmful side effects.
- Expressed as the percentage of patients who show adverse side effects at a given dose.

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11
Q

The optimal dose range

A
  • Is that at which the efficacy is greatest and toxicity is lowest.
  • Extreme drug responders such as:
    • Non-responders - drug ineffective
    • Adverse responders - causes major harmful side effects.
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12
Q

Cancer therapeutics

A

Means that we can look at the specific differences between healthy and cancerous cells, meaning the differences can be exploited to target therapeutics.

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13
Q

The issues with chemotherapy

A

To achieve reasonable efficacy, a substantial degree of toxicity is required.

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14
Q

What is Herceptin?

A
  • Which is an antibody-based therapeutic used for the treatment of HER2 positive breast cancers.
  • Normally HER2 is bound to by grown factors but Herceptin, competitively binds known as a blocking growth factor.
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15
Q

What are CPIC Guidelines used for?

A

To help clinicians understand how available genetics test results can be used to optimise drug therapy.

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16
Q

Absorption

A

The movement of a drug from its site of administration into the system circulation.

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17
Q

Active drug

A

The drug takes effect immediately. e.g. Morphine

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18
Q

Adverse drug reaction

A

An unintentional, harmful reaction to medicines.

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19
Q

ADME

A

Absorption, distribution, metabolism and elimination (the key components of pharmacokinetics)

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20
Q

Allele

A

One of two or more single forms of a gene.

21
Q

Base pair

A

Two nucleotides on complementary DNA strands.

22
Q

Candidate gene

A

A gene predicted to be associated with a particular trait e.g disease, adverse reaction to a drug.

23
Q

Cytochrome P450

A

A group of enzymes involved in drug metabolism and found in high levels in the liver. These enzymes change many drugs, including anti-cancer drugs, into less toxic forms that are easier for the body to excrete. Examples include CYP2D6, CYP2C19 and CYP2C9

24
Q

DNA

A

(Deoxyribonucleic acid) carries genetic instructions for all living things

25
Q

Enzyme

A

A biologists catalyst, usually a protein which speeds up the rate of a specific chemical reaction, each specific.

26
Q

Excretion

A

A pharmacokinetic term that refers to removal of a drug in the unchanged form. Excretion along with metabolism, account for the drug elimination.

27
Q

Exome

A

Part of the genome formed by DNA sequences that encodes genes (exons)

28
Q

Genes

A

The basic physical unit of inheritance

29
Q

Genotype

A

An individuals collection of genes

30
Q

GWAS

A
  • Study common genetic variations across the genome of a large population
  • To see if investigated variations are associated with a phenotype of interest
31
Q

Haplotype

A

Collection of genetic variants that travel together on the same allele. E.g. SNP

32
Q

Heterozygosity

A

When two different alleles are present on a chromosome pair

33
Q

Homozygosity

A

When two identical alleles are present on the chromosome pair

34
Q

Poor metaboliser

A

Have two non-functional alleles and therefore have little to enzyme activity.

35
Q

Intermediate metaboliser

A

Have one non-functional allele and one normally functioning allele and therefore have decreased enzymes activity.

36
Q

Extensive metaboliser

A

They have 2 normally functioning alleles, and therefore have normal enzyme activity.

37
Q

Ultra-Rapid metabolisers

A

Have one or more alleles which results in increased enzyme activity compared to extensive metabolisers.

38
Q

Nucleotides

A

The building blocks of DNA. Four nucleotides make up DNA: Adenine (A), Cytosine, (C), Guanine (G) and Thymine (T).

39
Q

Phase I metabolism

A

Chemical changes - compound more hydrophilic
- so it can be eliminated by the kidneys.
- Reactions usually involve either adding or unmasking a
hydroxyl group
- usually involve hydrolysis, oxidation or reduction mechanisms.

40
Q

Phase II metabolism

A

Takes place if phase I is insufficient or if it creased a reactive metabolite

  • Clear a compound from circulation
    • Reactions involve adding large polar group (conjugation reaction) increasing the compounds solubility.
  • Functional groups generated in phase I reactions are required for polar group attachment.
41
Q

Phase III

A
  • Involves drug transporters which moves drugs across cellular barriers, meaning accumulation at target site.
  • Influencing absorption, distribution and elimination of a drug.
    Location: epithelial and endothelial cells of the liver, gastrointestinal tract, kidneys, blood-brain barrier.
42
Q

Phenotype

A

Observable physical characteristics

43
Q

Polymorphism

A

A variant that has two or more alleles and is present at a frequency of at least 1% of the population.

44
Q

Prodrug

A

A precursor of a drug. A prodrug must undergo chemical conversion by metabolic processes before becoming an active pharmacological agent .

45
Q

SNPs

A

A single nucleotide locus with two or more naturally occurring alleles defined by a single base pair substitution.

46
Q

What converts codine into its active metabolite?

A

CYP2D6 converts Codine into morphine its active metabolite

47
Q

Whats an example of a polar group?

A

glucuronide

48
Q

What enzymes are responsible for phase I reactions?

A

Cytochrome P450 enzymes

49
Q

What enzymes are responsible for phase II reactions?

A

Transferase enzymes

Pharmacogenomics (11 decks)

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