Pharmacology Flashcards
what causes a parallel right shift in the response curve with no depression?
reversible competitive antagomism
what do nuclear receptors do?
regulate gene transcription
which drugs can act as agonists at the acetylcholine receptors (nAchRs) ?
acetylcholine
nicotine
varenicline
which kind of receptor is involved in signal amplification?
G protein coupled receptor
what is occupying alpha binding site when there is no signalling?
GDP
what hydrolyses GTP to GDP + Pi when turning signal off?
alpha subunit
what does alpha 1 do?
blood vessel vasoconstriction
what does alpha 2 do?
presynaptic inhibition of noradrenaline in CNS
GI tract relaxation
Decrease in persistalsis
what does beta 3 do?
thermogenesis in skeletal muscle
lipolysis
what does beta 1 do?
inc. heart rate & cardiac muscle contraction
tachycardic response
what does beta 2 do?
bronchodilation
inc. heart rate & cardiac muscle contraction (lesser extent than Beta 1)
what can activate cyclic AMP (cAMP) second messenger pathway?
G-protein coupled receptors
state the selectivity & extent of agonist of nicotine, varenicline & acetylcholine
nicotine: full agonist, selective
varenicline: partial agonist, selective
acetylcholine: full agonist, non-selective
greater pKi means greater or lesser affinity for receptor?
greater
lower KA means greater or lesser affinity for receptor?
greater
what does the Hill-Langmuir equation model?
relationship between ligand concentration and receptor occupancy
what is EC50?
concentration of agonist that elicits half maximal effect
what does non-competitive agonism do to the sigmoidal curve?
depresses the slope & maximum response curve
no right shift
what is pKa?
pH at which 50% of the drug is ionised and 50% is unionised
what is bioavailability (F)?
how available to exert effect, the amount of drug that eventually reaches systemic circulation
what is the bioavailability calculation?
quantity of drug reaching systemic circulation (AUC) / Quantity of drug administered (dose)
what can clearance be broken down into?
renal (CLR)
hepatic (CLH)
other elimination routes (CLO)
total clearance (CLT)
how do you calculate clearance? (CL)
rate of drug elimination/ [drug] plasma
what is first order kinetics?
initially, the rate of drug elimination increases as drug plasma increases (follows Michaelis-Menten kinetics)
what is zero order kinetics?
when elimination rate (RE) reaches Vmax
when elimination mechanisms become more saturated and reach Vmax
e.g. with ethanol
what is clearance?
the volume of blood removed of a drug per unit of time
what is the dosage rate calculation?
[drug]plasma x CL
what is steady state?
when rate of drug administration (R0) = Rate of elimination (RE)
what is the drug half-life calculation?
t1/2 = 0.693 x Vd / CL
what is antagonism?
when the antagonist forms a covalent bond with the receptor, permanently preventing the
agonist from binding and activating the receptor
which bonds are susceptible to hydrolysis?
ester
amide
what are two drugs that can go directly into Phase II metabolism?
codeine
morphine
what is phase I oxidation accomplished by?
cytochrome P450 enzymes
(family of microsomal haem proteins)
what happens in nuclear receptors once hormone is bound to receptor?
-activated hormone-receptor complex forms within cell
-the complex binds to DNA & activated specific genes
-gene activation leads to production of key proteins
