Pharmacology Flashcards
Pharmacodynamics is…
What a drug does to the body
Pharmacokinectics is…
What a body does to the drug (absorption, distribution, eliminations etc.)
Efficacy is…
They ability of an agonist to evoke a response
Higher efficacy = larger response
Affinity is…
The strength of association between agonist and its receptor
Greater affinity = greater duration of binding
EC50 is…
The concn of agonist that results in a half maximal response (i.e. 50% of receptors are occupied)
Agonist A requires 0.01 concn to elicit a response.
Agonist B requires 0.05 concn to elicit a response.
Agonist A is more ____ than agonist B.
Potent
In the presence of a competitive antagonist, EC50 is unchanged. True/False?
False EC50 increases (need to increase concn of agonist to get response)
Both the ionised and unionised form of a drug readily diffuse across the lipid bilayer. True/False?
False
Only the unionised form does
pKa is…
The pH at which 50% of a drug is ionised and 50% is unionised
Henderson Hasselbach Equation
pH = pKa + log[A-]/[HA]
pKa - pH = log[HA]/[A-]
FOR WEAK ACIDS ONLY
Increasing the pH of an acidic drug causes it to become less ionised. True/False?
False
It becomes more ionised (acid drugs are less ionised in an acid environment)
Administration routes that by-pass first pass metabolism are…
Sublingual, rectal
Vd = volume of distribution = ?
Volume in which a drug is dissolved
Dose given/Plasma Concn
Vd less than 5L suggests…
Drug is contained in vascular compartment
Vd less than 15L suggests…
Drug is restricted to extracellular water
Vd greater than 15L suggests…
Drug is in total body water
Efferent signals travel ___ from the CNS
Away
Sympathetic preganglionic NT is?
Acetylcholine (cholinergic)
Sympathetic postganglionic NT is?
Noradrenline (adrenergic)
Parasympathetic pre and post ganglionic NT is acetylcholine. True/False?
True
Sympathetic outflow is craniosacral. True/False?
False
Thoracolumbar (T1-L2)
Preganglionic neurone of sympathetic chain is long. True/False?
False
Short - preganglionic neurone of parasympathetic chain is long as ganglions are usually embedded in the target organ
Location of cranial parasympathetic ganglia in the head and neck
C3, C7, C9, C10
Parasympathetic stimulation decreases force of heart contraction. True/False?
False
Has no effect on force of contraction, but does decrease heart rate
Components of a G-protein
α (contains guanine nucleotide binding site)
β + γ complex
GP couples with receptor to increase affinity for GDP. True/False?
False
Affinity for GDP decreases and it eventually dissociates, increasing affinity for GTP to bind on α subunit
M1 G-protein coupled receptor is G_
Causes ___ acid secretion in stomach
q
Increased
M2 G-protein coupled receptor is G_
Causes ___ heart rate
i
Decreased
M3 G-protein coupled receptor is G_
Causes ___ of airways; ___ of vasculature
q
Contraction, relaxation
ACh and NA can be broken down in the synaptic cleft if not taken up by the effector cell. True/False?
False
NA is not broken down in the cleft - U1 and U2 are involved
Uptake 1 is located on the?
Post-ganglionic neurone
Uptake 2 is located on the?
Effector cell
NA can be taken up by U1 and broken down by which enzyme?
MAO, a target of anti-depressant drugs
NA can be taken up by U2 and broken down by which enzyme?
COMT
B1 G-protein coupled receptor is G_
Causes ____ heart rate and force
s
Increased
B2 G-protein coupled receptor is G_
Causes ___ of airways and vasculature
s
Relaxation
α1 G-protein coupled receptor is G_
Causes ____ of vasculature
q
Contraction
α2 G-protein coupled receptor is G_
Causes ____ NA release
i
Decreased
ACh binding to post-ganglionic M2 receptor causes ____ Ca2+ entry, which results in ___ NT release
Reduced, less
NA binding to post-ganglionic α2 receptor causes increased Ca2+ entry, resulting in more NT release. True/False?
False
Decreased Ca2+ entry, resulting in less NT release
Cocaine blocks U_, causing an ___ in NA concn in the synaptic cleft
α1 and B1 stimulation causes ____ and ____
Cocaine blocks U1, causing an increase in NA concn in the synaptic cleft
α1 and B1 stimulation causes vasoconstriction and increased heart rate
Amphetamine inhibits the enzyme ___, resulting in ___ in NA in the cytoplasm
Amphetamine inhibits the enzyme MAO, resulting in increase in NA in the cytoplasm
Ganglionic nicotinic ACh receptors, a type of ligand-gated ion channels, consist of which α and B subunits?
3 x B4
2 x α3
The concn a drug must reach in the plasma to achieve an effect is termed the…
Minimum effective concn
The maximum tolerated concn is defined as…
The drug concn in the plasma which must not be exceeded to prevent toxic effects
Therapeutic ratio/index is given by…
MTC/MEC
Co (initial concn) is given by…
D/Vd
Rule of first order kinetics is…
Rate of elimination (Kel) is proportional to drug concn
t1/2 (half life) =
0.69/Kel
For drugs exhibiting 1st order kinetics, the dose administered changes __ directly, but has no effect upon __ or __
Cp, t1/2, Kel
Plasma clearance, Clp, is given by…
Vd x Kel
Rate of 1st order kinetic drug elimination is given by…
Cp x Clp
Css = steady state concn and is normally achieved after _ half lives
5
The time to reach Css is determined by the infusion rate but not the half life. True/False?
False
Css is determined by the half life, not infusion rate
Depolarisation is when the membrane potential becomes more negative. True/False?
False
Less negative
Resting membrane potential, Vm, is normally approx…
-70mV
Activation of Na+ channels and subsequent Na+ channels is an example of ____ feedback
Positive
Refractory period of the AP describes…
The inactivated state of sodium channels, ultimately causing repolarisation to closed state
In the relative refractory period, a strong enough stimulus can elicit the generation of a new AP. True/False?
True
What is the function of Schwann cells?
Wrap around axons in a “myelin sheath” to provide insulation and speed up chemical conduction
Saltatory conduction describes…
APs jumping between gaps between adjacent Schwann cells
