Chemistry - Pharmacodynamics Flashcards
What are the Physiological responses produced through drug-receptor interactions?
- Change in contractility of a tissue
- change in neuron excitability
- change in gene transcription
What dictates the extent of the change produced through drug-receptor interactions?
Depends on the drugs affinity and efficacy
What is an agonist?
Drug binds and activates receptor
What is a partial agonist?
Binds and activates a receptor, but not as well as the agonist
What is an antagonist?
Binds to a receptor, but doesn’t activate so prevents the agonist
What is a competitive antagonist?
Binds to the same site as the agonist
What is a non-competitive antagonist?
Binds to an allosteric site on the receptor to prevent activation
Do competitive antagonists bind reversibly or irreversibly?
Reversibly
Do non-competitive antagonists bind reversibly or irreversibly?
irreversibly
What are inverse agonists?
Produce a net decrease in the receptors activity
What are allosteric interactions?
Secondary binding sites that change the affinity of the primary binding site, by changing its conformation
What is affinity?
What is potency?
The amount of a drug required to produce an effect of given intensity
What is efficacy?
The ability of a drug to elicit a physiologic response when it interacts with a receptor
What is Specifity?
How specific a drug is to a receptor
What are examples of membrane targets?
Cellular receptors
ion channels, pumps and transporters
What are examples of large protein targets?
Enzymes
Carrier proteins
What is autocrine?
A cell secretes a hormone or chemical messenger that binds to autocrine receptors on that same cell, leading to changes
What is paracrine?
A cell produces a signal that induces change in nearby cells, altering the behaviour of those cells
What is the chief neurotransmitter of the parasympathetic nervous system?
Acetylcholine (ACh)
What are cell surface receptors?
Receptors embedded in the plasma membrane of cells that allow communication between the cell and the extracellular space
What prevents a substance from passing through the cell membrane?
Ions or Polar and Large molecules
What are the two main types of surface receptor?
G protein coupled and kinase receptors
What are G protein receptors?
Receptors that release a alpha sub unit when the G protein is activated. The sub unit will then activate/deactivate an enzyme or ion channel within the cell
What is atropine?
A antagonist drug which binds to muscarinic receptors
What does atropine do in the heart?
removes vagal inhibition. Modest tachycardia.
What does atropine do in the gastro-intestinal tract?
removes parasympathetic stimulation: motility is reduced. Secretions reduced
What does atropine do in Smooth muscle?
blocks constriction: dilatation
What does atropine do in the eye?
unbalanced sympathetic causes mydriasis
What does atropine do in the neural?
many effects including vagal stimulation! (paradoxical bradycardia at low dose)
What are catecholamines?
Hormones made by your adrenal glands which help with the ‘‘fight or flight response’’
What are the 3 main catecholamines?
Dopamine
Adrenaline
Noradrenaline
Where are a1 receptors mainly found?
Vascular smooth muscle
What happens when adrenaline activates an a1 receptor?
Causes constriction
Where are b1 receptors mainly found?
Found mainly on heart muscle cells
What happens when adrenaline activates b1 receptors?
Increases rate and force of contraction
some effect on skeletal muscle
Where are b2 receptors mainly found?
Mainly smooth muscle (including respiratory)
What happens when adrenaline binds to b2 receptors?
Relaxation
glycogenolysis
What are the side effects when adrenaline binds to a1?
Vasoconstriction increases blood pressure for given cardiac output
What are the side effects when adrenaline binds to b1?
Increased rate and force of heart contraction
tachycardia and anxiety
What are the side effects when adrenaline binds to b2?
Bronchodilatation
Increased blood sugar
skeletal muscle-tremor
What are nuclear receptors?
located in the cytosol, they cause changes in gene expression and therefore protein synthesis over hours or days
What are kinase linked receptors?
A transmembrane receptor, which causes phosphorylation of amino acids - mainly tyrosine - within the cell, when the drug binds to the receptor-binding site.
How do insulin receptors enable glucose to enter the cell?|
2 insulin molecules bind to the receptor causing the phosphorylation of amino acids within the cell, this leads to a channel being created in the membrane to allow glucose to enter the cell
What is GTN?
A powerful venodilator which widens blood vessels increasing the blood supply to your heart, reducing chest pain
What are side effects of GTN?
Reduced BP causes dizziness and a reflex increase in heart rate
tachycardia
Headache
