PHARMACOLOGY Flashcards
what are the 4 drug targets ?
receptors, ion channels, enzymes, transport proteins
what is a drug
a chemical that affects physiological function in a specific way
what is affinity
the tendency of a ligand to bind to its receptor
what is an agonist
A ligand that binds to a receptor results in a biological response- evokes activation
what is an antagonist
A drug that reduces the action of another drug ( usually the agonist)
what is a partial agonist
An agonist that cannot produce as large an effect as can another agonist even with 100% receptor occupancy acting through the same receptors
what is efficacy
tendency for the agonist to activate the receptor to evoke a response
what is drug potency
conc . / amt of drug needed to produce a response
eg: EC50
explains drug activity, depends on receptor and tissue
what is dose
a specified quantity of drug administered
what causes adverse drug reactions?
High doses (leading to higher blood-plasma concentrations) can lead to the drug binding to ‘off targets’ and/or the appearance of adverse drug reactions.
This is because no drug is completely specific to a particular recpetor
disassociation equilibrium constan KA is
concentration of ligand required to occupy 50% of the receptors
Lower the Ka ___ the affinity for the receptor
Greater
when [A] = KA, pAR = ?
0.5
what is the Hill-Langmuir equation?
pAR = [A]/ KA + [A]
relationship between ligand concentration and receptor occupancy
what is chemical antagonism?
Chemical antagonism – the antagonist combines in solution directly with the chemical being antagonised
(e.g., chelating agents, used to treat lead poisoning, bind to heavy metals and form a less toxic chelate).
what is pharmacokinetic antagonism?
Pharmacokinetic antagonism – one drug reduces the effect of another drug by accelerating its metabolism or elimination
e.g., phenobarbitone increases hepatic metabolism of the anticoagulant drug warfarin)
what is physiological antagonism?
Physiological antagonism – Two agonists that produce opposing physiological actions and cancel each other out.
Each drug acts through its own receptors
(e.g., adrenaline relaxes bronchial smooth muscle reducing the bronchoconstriction of histamine)
what does Pindolol do?
drug
it is a partial agonist at beta1 and beta2 adrenoreceptors
what is Amitriptyline+ action, side effects
Tricyclic antidepressant
antagonist at : NET and SERT
side effects: sedation( H1 receptor blockade) ,dry mouth, constipation (ACh receptor blockade M1-M5)
nor-adrenaline transporter and serotonin transporter
Histamine H1 receptor and ACh M1-M5 receptor
what is Salbutamol and what does it do? + what is it used for
agonist at β2 adrenoceptors (activates it)
bronchodilation,
used for asthma
what is Propranolol
beta-blocker
reversible competivite antagonist at beta adreno receptors
how long do ligand gated ion channels take to produce a cellular effect?
milliseconds
how long do G-protein coupled receptors take to produce a cellular effect?
seconds
how long do kinase-linked receptors take to produce a cellular effect?
hours
how long do nuclear receptors take to produce a cellular effect?
hours
drugs that act as agonists at nicotinic acetylcholine receptors
acetylcholine
nicotine
varenicline- partial agonist
adrenoreceptors are what type of receptors?
G-protein coupled
at alpha1 adrenoreceptor which Gprotein does what?
Gq protein
activates phospholipase C
increases IP3 and DAG, which increases CA+2 and stimulates MLCK activity
causes vasoconstriction
in alpha2 adrenoreceptor which G-protein does what?
Gi protein
Inhibits adenylyl cylase
reduces cAMP, increases K+ channels, reduces Ca+2 channels
relaxation of GI tract
in beta1 adrenoreceptor which G-protein does what?
Gs
stimulates adenylyl cylase (converts ATP to cAMP)
increases cAMP
Increased heart rate and cardiac muscle contraction
in beta2 adrenoreceptor which G-protein does what?
Gs
stimulates adenylyl cylase (converts ATP to cAMP)
increases cAMP
bronchodilation
in beta3 adrenoreceptor which G-protein does what?
Gs
stimulates adenylyl cylase (converts ATP to cAMP)
increases cAMP
thermogenesis in skeletal muscle, lipolysis
what is theophylline?
Theophylline is a phosphodiesterase inhibitor
-Indicated for COPD
what does Phosphodiesterase do to cAMP?
Phosphodiesterase terminates action of cAMP - makes it into AMP- which cant activate PKA to phosphorylate
Steroid hormones are hydro____ (phillic/phobic)
hydrophobic/lipophilic
what do thiazides do?
Thiazides are used to lower arterial blood pressure by blocking sodium
what is hyponatremia? what hormone is released because of this?
hyponatremia- low levels of sodium
aldosterone is released in response to it- increases Na+ reabsorption
the hormone aldosterone binds to what type of receptor?
nuclear receptors
what type of drug is Ibuprofen
NSAID: non steroidal anti-inflammatory drug
cox-1,2 inhibitor
on what enzyme does Ibuprofen act?
cyclo-oxygenase: cox-1,2
how does Ibuprofen work?
it inhibits cox-1,2 enzymes, inhibits prostaglandins which decreases blood flow and causes vasodilation:
reduces pain and fever (pyrexia)
t1/2 of Ibuprofen
1.2-2 hours in normal paitemt
3-3.4 hours of paitent with liver dysfunction
side effects of Ibuprofen
irritation of GI tract, impairment of renal function
what ion channel does amlodipine block?
calcium
what is amlodipine used for?
angina, hypertension, reduces cardiac contractility
what the t1/2 of amlodipine
40 hours, more than 50 in paitents with renal dysfunction
what are the side effects of amlodipine?
not suitable for emergency, redces arterial blood pressure
