7 – Pharmacodynamics Flashcards

1
Q

Pharmacodynamics

A
  • What the drug does to the body
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2
Q

Receptors

A
  • Strictly defined as proteins that normally serves as receptors of ENDOGENOUS LIGANDS
  • For this course: any cellular constituent (ex. enzymes, cell membranes, DNA)
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3
Q

Agonists

A
  • Drugs that bind to receptors and mimic the effect of ENDOGENOUS LIGAND
  • High affinity and highly lipophilic (to only have to take once a day)
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4
Q

Antagonists

A
  • Drugs that bind to receptors and produce NO response
  • Competitive or non-competitive
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5
Q

Partial agonists

A
  • Drugs that bind receptors and produce LESSER effect than endogenous ligand
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6
Q

Classical receptor theory

A
  • Reversible interaction between drug and receptor follows the law of mass action
  • [D]+[R] <-> [DR] -> EFFECT
  • DR=activated drug-receptor effect
  • *amount of drug and amount of receptor determine DR which determines the effect
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7
Q

Dose-response relationships: 2 main types

A
  • Graded
  • Quantal
  • *all plots of dose (x-axis, independent) vs response (y-axis, dependent)
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8
Q

Graded dose-response relationships

A
  • Show responses of INDIVIDUALS
  • Continuous responses
  • Y-axis: ‘percent response’ (0-100%)
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9
Q

Graded dose-response provides info about

A
  • Intensity of response over a dose range
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10
Q

Quantal dose-response relationship

A
  • Show POPULATION responses
  • ‘all or none’ responses
  • Y-axis: ‘percent of individuals responding’ (0-100%)
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11
Q

Quantal dose-response provides info about

A
  • Number of patients exhibiting a specified effect over a dose range
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12
Q

Graded response curve

A
  • Used mainly to compare potency and efficacy
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13
Q

Quantal response curve

A
  • Used mainly to determine drug safety
  • Important to see where the dose is on an average distribution curve
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14
Q

Relative potency

A
  • More potent if it takes LESS of a dose to get a desired response
    *further left=more potent (horizontal)
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15
Q

Relative efficacy

A
  • More efficacious if at its max it can get 90% maximal effect
    *further up=more efficacious (vertical)
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16
Q

EC50 or ED50

A
  • Concentration or dose causing 50% maximal response
  • Used to characterize drugs and compare potencies
17
Q

Dose response curves can be used to

A
  • Determine any effective dose (ED) (Ex. ED1, ED10)
  • Determine toxic doses (TD) or lethal doses (LD)
18
Q

What are the 2 main measures to measure drug safety?

A
  • Therapeutic index
  • Margin of safety
19
Q

Therapeutic index

A
  • Difference in dose need to get a response and dose that is toxic/kills the animal
  • Want it to be very big
20
Q

Therapeutic index equation

A
  • =TD50/ED50
21
Q

Margin of safety

A
  • Conservative measure of drug safety
  • Ratio of drug dose that causes toxicity/death in 1% of population to the drug dose that causes desired therapeutic effect in 99% of the population
22
Q

Margin of safety equation

A
  • =TD1/ED99
23
Q

Dynamic nature of receptors: desensitized

A
  • Can happen upon continuous exposure to drug
  • One reason for drug tolerance and need for ‘drug holidays’
  • Ex. desensitization of beta-adrenergic receptors due to DOWNREGULATION
24
Q

Dynamic nature of receptors: sensitization

A
  • UPREGULATION
  • Due to increased receptor concentration
  • Ex. some auto-immune diseases
  • Rare
25
Q

Significance of receptor subtypes

A
  • Tissue specificity and selectivity
  • Allows same endogenous signaling agent to act in different tissues
26
Q

Orphan receptors

A
  • Receptor with no know endogenous ligand
  • Classic example: opioid receptors IDed using morphine as agonist
  • New example: cannabinoid receptors IDed using THC as agonist
27
Q

Signal transduction pathways: 2 main things they do

A
  1. Involved in phosphorylation of proteins
  2. Influence gene expression
28
Q

Main signals/molecules in the brain

A
  • Glutamate: excitatory
  • GABA: inhibitory