Pharmacology Flashcards
What is an agonist?
a drug or molecule that binds to its receptor AND causes a downstream biological effect
What is an antagonist?
a drug or molecule that binds to its receptor physically preventing another substance bind therefore preventing downstream effects indirectly
What are ligand-gated ion channels?
transport that requires a ligand to bind thus allowing the transfer of ions through the membrane
Give an example of g-protein coupled receptors?
adrenoreceptors
what hormone binds to adrenoreceptors?
adrenaline
adrenoreceptors are involved in the parasympathetic response, true or false
false, they are involved in the sympathetic response as they respond to adrenaline
Give an example of a drug that uses kinase linked receptors?
insulin
What is the role of alpha 1 and 2 adrenoreceptors upon stimulus by adrenaline?
1 - g protein couples with phospholipase C causing vasoconstriction
2 g protein blocks the activity of adenyl cyclase preventing ATP-generated cAMP and increasing potassium channels thereby relaxing the GI tract
adrenoreceptor beta 1 causes dilation of the bronchi, true or false?
false, this is the role of adrenoreceptor 2
How do beta adrenoreceptors illicit downstream effects?
upon binding of adrenaline to the receptor the g protein is activated and then binds to adenyl cyclase, this allows ATP to produce cAMP
What are the physiological effects of beta 1 2 and 3 adrenoreceptor stimulation?
1 - increased heart rate and cardaic muscle contraction
2 - bronchial-dilation
3 - thermogenesis of skeltal muscle
what is an example of a drug that is a beta 2 adrenoreceptor agonist?
salbutamol
What partial agonists reduce heart rate and bind to beta-adrenoreceptors?
propanolol and pindolol
What is a partial agonist?
a drug or molecule that exerts sub-maximal responses
What is the EC50
the minimum plasma concentration required for the drug to be effective
What is efficacy?
tendency of the drug to activate the receptor and result in a biological response
What is affinity?
tendency of the drug to bind to its receptor successfully
What drug compensates for the adrenoreceptor downregulation?
theophylline
also inhibits phosphodiesterase
What are nuclear receptors?
protein monomers located in the nucleus of target cells and contain DNA binding domains
What is Ka
dissociation equilibrium constant
what is the dissociation equilibrium constant (Ka)?
the concentration at which the ligand occupies 50% of the receptors
Give an example of an antidepressant that is a antagonist?
amitryptiline
What drug is a calcium channel blocker and important for hypertension?
amlodipine
What enzymes does ibuprofen block
Cox1 and Cox2
What is the mechanism of amlodipine?
calcium channel blockers used for hypertension
Which beta receptor does propranolol primarily target and which is the secondary target?
primary - beta 1 adrenoreceptor
secondary - beta 2 adrenoreceptor
propranolol is an agonist, true or false?
false it is an antagonist
Are SSRIs antagonists or agonists?
they are antagonists that bind to SERT which usually reuptakes excess serotonin leaving more freely available in the synapse
If EC50 of Drug A is 0.5 and Drug B is 1.4, which has the higher potency?
Drug A
ionised molecules readily diffuse over membranes, true or false
false, unionised diffuse more readily because they are non-polar
What is Pka?
the pH at which 50% of the drug is ionised and 50% is unionised
Which two types of transport can be involved in saturation kinetics
facilitated diffusion and active transport
active transport requires ATP and occurs along the concentration gradient, true or false?
false, it does require ATP but occurs against the concentration gradient
What does the Henderson hasslebach equation tell us?
how drugs ionise each other at different pH levels
Why will a weak base be absorbed in the gut more readily?
because it has a higher pH - more basic conditions which is favourable to a weak base
weak acids are ore readily absorbed by the stomach, true or false?
true because it has a lower pH
how much body water does the intracellular fluid/water comprise?
2/3
what is the equation for the apparent volume of distribution (Vd)?
dose/drug plasma concentration
what does a low Vd suggest about the drug distribution in the body?
it is retained in the vascular compartment
what does a high Vd suggest about the drug distribution in the body?
the drug can be found in non-vascular compartments such as the muscle and adipose tissue
can also find plasma protein binding
What is the most abundant plasma-binding protein
albumin
What is the bioavailability?
The amount of drug that reaches circulation
lipophilic drugs tend to have a high Vd, true or false
true, as they are uptaken by fatty tissue
What is the equation for bioavailability (f)?
F = quantity of drug that reached circulation/dose
What is the responsibility of cytochrome P450 (CYP450)
It is an enzyme family that can modify the drug making it more excretable and activating drugs in some cases influencing drug interactions
What happens during phase II reactions
the drugs are modified to become more polar (different molecular groups added on) and more readily excreted from the kidneys
CYP450 is used in which phase reaction?
Phase 1
What is clearance
the volume of blood that is completely cleared of drug per unit of time (usually L/hr)
What does clearance aid in?
helps determine dosage rate needed to maintain a desired plasma concentration
What is the equation for clearance?
CL = rate of drug elimination/drug plasma concentration
What is first-order kinetics?
where the rate of elimination increases and the plasma concentration of the drug increases also
What is zero-order kinetics?
where elimination reaches a maximum as the elimination mechanisms have become saturated
What is the elimination half-life
determines how much time is required for the drug to be eliminated from the body
What is the equation for the elimination half-life
0.693 x Vd/CL
What do Cox 1 and Cox 2 enzymes produce?
prostaglandins
Name a few factors that affect the Vd?
ageing and obesity
How do ageing and obesity influence the elimination half-life?
ageing causes a decrease in muscle mass thereby recreated the half-life and obesity causes an increase in adipose disse thereby increasing the half-life
