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DEN303 - IHD > Pharmacology 1+2 - Drug Kinetics and Toxicity > Flashcards

Pharmacology 1+2 - Drug Kinetics and Toxicity Flashcards

1
Q

Pharmacology

A

Effects of drugs on living systems

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2
Q

Pharmacodynamics

A

Study of biochemical and psychological effects of drugs and their mechanism of action on body

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3
Q

Pharmacokinetics

A

Absorption, distribution, biotransformation and excretion of drugs - effect of the body on the drug

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4
Q

Toxicology

A

Adverse effects of drugs and chemicals

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5
Q

Pharmacotherapeutics

A

Use of drugs in the prevention and treatment of disease

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6
Q

Fx of drugs

Effects

A

Modify physiological processes not create new ones

  • prevent, diagnose/treat disease
  • modify actions of other drugs
  • analyse mechanisms or functions of an organism

Expressed in terms of altering a known fx or process

  • returns a fx to normal operation
  • changes fx away from normal condition
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7
Q

Drug definition

A

Chemical substance of a known structure, which when given, produces a biological effect in a living organism

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8
Q

3 aspects of drugs

Describe terms

Goal of therapeutics is

A
  1. Specificity - only produces one effect
  2. Selectivity - one effect predominates over a particular dose conc –> THERAPEUTIC WINDOW
  3. Toxicity - usually occurs beyond therapeutic dose conc. Some show toxicity at higher end of therapeutic dose –> adverse effects

To achieve specificity

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9
Q

General mechanisms

Deficiency

Excess action

Antagonists also

Physiochemical environment

A
  1. Replacement therapy for conditions such as iron or hormone deficiency
  2. Chemical antagonists can block or reduce the effects of XS activity of normal processes
  3. block excess effects of exogenous substances e.g reversal of overdose
  4. Drugs can alter the environment or characteristics of a cell or tissue, changing its activity
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10
Q

Dose/concentration

A

Drug quantity in weight / volume

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11
Q

Response/effect

Different effects

A

Change occurring after administration

  1. Therapeutic - intended effect
  2. Side - effect other than therapeutic
  3. Toxic/adverse - harmful unexpected effects usually occurring at higher dose
  4. Lethal - death caused by very high drug dose
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12
Q

Acceptor

A

Substances drugs bind to without effect e.g plasma proteins

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13
Q

Receptor

A

Cell component directly involved in reaction

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14
Q

Receptors

Mechanisms on binding

A

Component of cell/organism which interacts with a drug and initiates chain reaction of events –> effect

Ligand binds to receptor

  • agonist - initiates response e.g NTS and hormones
  • antagonist - prevents agonist binding therefore no response
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15
Q

Drug receptors as molecular targets

Types of receptors

Mechanism and name of it

A

Molecules on or in the cell that the drug molecule first interacts with and activates/blocks?

Membrane receptors, enzymes, ion channels, DNA, cytosolic proteins

Receptors convert drug molecule signal to a biochemical signal via effectors = TRANSDUCTION

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16
Q

Receptor location

3 possible locations and examples

A

Cell membrane - transmitters/peptides

Nucleus - thyroxin and insulin sensitivity

Cytoplasm - steroids

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17
Q

Classes of cell surface receptors

A
  1. Ion channel linked
  2. G protein linked
  3. Enzyme protein linked
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18
Q

Receptor subtypes

Action

A

Adrenoreceptors

β1, 2 and 3

Found in heart, lungs and bladder

Beta-agonists = bronchodilation due to muscle relaxation

β agonist will down regulate β -adrenoreceptor during tolerance

β antagonist will up regulate β adrenoreceptor during withdrawal

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19
Q

Drug/receptor interaction terms

EC50

POTENCY

EFFICACY

AFFINITY

A

EC50 - drug concentration which produces 50% of the maximal effect

Potency - conc required to produce a particular effect - depends on E AND A

Efficacy - relationship between receptor occupancy and ability to initiate a response at molecular, tissue or cellular level

Affinity - ability to bind a receptor

drugs can have same affinity but different efficacy

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20
Q

Receptor activation

full agonist or partial

antagonist

A

based on maximal pharmacological response that occurs when all the receptors are occupied

binds but doesn’t activate and are used to prevent agonist from binding

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21
Q

Intracellular receptors

Binding sites for…

A

Steroids e.g hydrocortisone, betamethason, beclomethasone

22
Q

Steroid - anti-inflammatory action

A

Inhibit prostaglandin production

23
Q

glucocorticoids

Role in events

  • vascular
  • as inflammatory and immune mediators
  • as cellular population control
A

Reduce vasodilaton and reduce fluid exudation

Reduces production and action of cytokines

Reduces clonal expansion of T and B cells
Decreases action of cytokine-secreting T cells

24
Q

NSAIDs

Function and mechanism

A

Inhibit enzyme activity (COX1 COX2)
Inhibit prostaglandin release

Diclofenac
Aspirin
Ibuprofen
Paracetamol

25
Q

Benzodiazepines/barbiturates

A

Mimic GABA

Stimulate GABA receptors at allosteric sites therefore constant hyperpolarisation –> CNS depression

26
Q

Transport ion channel

A

Ion channels can be blocked by substances such as LA

Nervous impulse transmission is blocked

27
Q

Proton pump inhibitors

A

Irreversibly block the H+/K+ATPase gastric pump
Fr prolonged inhibition of gastric acid
Omeprazole
Lansoprazole

28
Q

Early therapeutic monoclonal antibodies

Depends on

A

host defence mechanisms
location of infection
pharmacokinetics and dynamic properties of the antibacterial agent

29
Q

Anti-infective agents

Mechanism

A

Protein synthesis inhibitor in bacteria

30
Q

B-lactam antibiotics

Function

A

Disrupt synthesis of peptidoglycan layer of bacterial cell walls
Destroy bacterium

31
Q

Anti fungal

Anti viral

A

e.g metronidazole inhibits DNA synthesis

Inhibit DNA polymerase

32
Q

Drug absorption mainly via MEMBRANE PENETRATION

A

G.I mucosa

Capillary endothelium

Blood-brain barrier

Cell membrane

Passes through via passive diffusion

IV drugs will actt quicker

33
Q

Gastric emptying

A

Essential for drug absorption

Most drugs absorbed from intestine due to greater SA

34
Q

Bioavailability
Definition

Depends on

A

Fraction of unchanged drug reaching the system circulation following any route of admin

Absorption
First pass metabolism
Food

Differs between drugs

35
Q

Distribution

Physiochemical properties

Physiological factors

A

molecular size
oil/water miscibility
protein binding
degree of ionisation

organ/tissue size
blood flow rate 
physiological barriers 
- blood cap membrane 
- cell membrane 
- specialised barriers
36
Q

Plasma proteins… are involved in …

A

Drug binding in blood
Acid drugs –> albumin
Basic drugs –> α1-acid glycoprotein
Displacement of one acid drug by another ==> free drug concentration increase

Free drugs will be eliminated faster

37
Q

Guidelines for rate of drug distribution

perfusion limited tissue distribution

permeability rate limitations or membrane barriers

A
  1. immediate equilibrium of drug in blood and in tissue
  2. only limited by blood
    flow i.e PERFUSION
  3. poor perfusion - skin, fat, bone, muscle
  4. high perfusion - lungs, liver, kidneys, brain

blood-brain barrier - extra layer
blood-testis barrier
placenta

38
Q

Placenta barrier

A

Mother’s blood –> foetus

  • sugars, fats and oxygen
  • passive immunity antibodies

Foetus –> mother
- Urea and CO2

Viruses can pass
Toxins e.g drugs and alcohol can pass

Lipid soluble toxic substances can pass to foetus

39
Q

Drug metabolism

De-activation

Activation

Excretion

A

Decrease of pharmacological effect
Decrease of toxicity

Increase pharmacological effect
Increase toxicity

Drug undergoes phase I –> primary metabolite –> excretion

Phase II –> conjugate –> excretion

40
Q

Phase I reactions

A

Drug –> primary metabolite

Exposure of a polar group
Metabolites may be excreted if sufficiently polar

41
Q

Phase II reactions

A

Primary metabolite –> conjugation

Drug –> conjugation

Attachment of an endogenous molecule to a drug

Produces less active compounds than phase I

42
Q

Drug metabolism enzymes
Phase 1

Phase II

A

Oxydation

  • cytochrome P450
  • found in liver
  • varying substrate specificity

Conjugation
- transferases

43
Q

Polymorphism

A

Occurrence of variant form of an enzyme/receptor through inheritance of drug metabolising enzymes

e. g lack CYP2D6
- poor metaboliser for CV, psychiatric and opiate drugs

44
Q

Biliary excretion

  • secreted by
  • important in
  • fate
  • composition of bile

factors influencing secretion of drugs in bile

where else can products end up

A

Hepatic cells of liver

Digestion and absorption of fats

90% reabsorbed from intestine and transported back into liver
Metabolites more excreted than parent drugs –> increased polarity

  • m.w
  • polarity
  • nature of biochange
  • gender, diseases, drug interactions

Some pass into intestine
Reabsorption from gut during process of enterohepatic recycling may prolong pharmacological effect of a drug

45
Q

Drug elimination

Two types

A

Renal

  • water soluble
  • ionised

Hepatic

  • lipid soluble
  • unionised e.g propanolol, cyclosporin

Drugs high in water/ionised excreted renally

Drugs lipid soluble or unionised will be hepatic ally processed

46
Q

role of nephron

A
  1. glomerular filtration - not much for protein bound drugs
  2. active secretion - adds to tubular fluid - free and bound drug
  3. passive reabsorption - only unionised drugs transfers back to blood
47
Q

renal clearance

formula

what may affect it

A

excretion = (filtration + secretion) - reabsorption

if > GFR = net secretion
efficiency of renal excretion

renal diseases

48
Q

Therapeutic index

A

Greater = greater safety of drug

Minimum toxic concentration is margin between therapeutic effects and toxic effects

49
Q

Factors affecting metabolism when

HIGH blood level - XS dose - decreased clearance

A 
Normal variation 
Saturable metabolism 
genetic enzyme deficiency 
Renal/liver failure
Age
Enzyme inhibition
50
Q

Factors affecting metabolism when

LOW blood level - too low a dose - no effect - increased clearance

A 
Normal variation 
Poor absorption 
High first pass metabolism 
Non-compliance 
Enzyme induction
51
Q

Factors affecting drug metabolism

A

Environmental

Disease

Genetic

Age

Drug interaction

52
Q

Saturable metabolism

A

Increase in the dose would result in a decrease in hepatic clearance and a more proportionate increase in the drug levels

DEN303 - IHD (58 decks)

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