block A - intro Flashcards
learn the intro to pharmacology
what is pharmacology?
it deals with the mechanisms of action, uses and unwanted effects if drugs on living tissues
what is a drug?
its a substance that modifies the activity of living tissue
what is physiology?
its the science of how living tissues function
they interfere with either normal or abnormal phisiology
can drugs modify activity positively or negatively?
both
what is abnormal physiology also referred to as?
pathophysiology
what is therapeutics?
its the study of the use of pharmacological agents in disease states
its also the attempted remediation of a health problem, usually following a medical diagnosis
therapies usually have inidcations and contradictions
there are many different types of therapies and many can produce unwanted adverse effects
what is pathology?
its the study of how the body goes wrong in disease
it also refers to the study of disease in general
this incorperates a huge breadth of biology research areas and medical practices
whats an agonist?
it activates the receptor i.e. it elicits a response
its affinity is to the binding of the agonist (or any drugs) to its receptor
how do you quantify the response of an agonist
you create a measurable response to be quantified, as you increase the concentrations, you can see that the response gets greater
a sigmoidal-response curve can be generated on a semi-log scale
what is the Ec50 value?
its the concentration of the drug on a semi-log scale
the Ec50 value is the concentration of the drug at 50% max effective concentration
what does an agonist’s efficacy mean?
its the ability of the agonist (or any drug) to activate the receptor i.e. elicit a response
what is the affinity of a drug? [agonist]
its the binding of the drug to its receptor
what type of graph can be created when a measurable response is created and the response is quantified?
a sigmoidal dose-response curve can be generatef on a semi-log scale
the name of the graph is a concentration-response curve
what agonist concentration do you always try and get Ec50 under?
10*-9 / under micromolar
what does the lower the Ec50 value mean?
the lower the value, the more potent the drug
what is the affinity of an antagonist?
its the binding of the antagonist (or any drug) to its receptor
what is the efficacy of the antagonist?
there is none
what is pharmacological antagonism?
its when drugs counteract each other by acting on the same receptor type
what id chemical antagonism?
its when one drug antagonises the action of another by chemically combining with it
what is physiological antagonism?
its when two drugs counteract each other by producing opposing effects on different receptors
what often has a higher affinity for the receptor, the agonist or antagonist?
the antagonist
what will increasing agonist concentration do?
it will restore the response
what does a rightward parallel shift do on a response curve?
it shows competitive antagonism as the agoinst and antagonist are competing for the same site on the recpetor
if the sigmoidal curves aren’t parallel on the response curve, what does that show?
its not a competitive antagonist
what does a control curve parallel shifted to the rigt by increasing concentrations of the antagonist show?
competitive antagonism
what is irreversible-competitive antagonism?
this is when the bond between the antagonist and the receptor is so strong that even increasing concentrations of agonists cant displace the antagonist
its often due to covalent bonding
what is non-competitive antagonism?
antagonists that act as sites other than the agonist binding site are classified as non-competitive antagonists
the antagonist binds to a different receptor from the agonist so theres no competition
antagonists and agonists can have the same physiological effect, but what does it depend on?
receptor location
what is toxicology?
its the toxic effects of drugs and environmental hazards
ideally, how big do you want the theraputic window to be?
as big as possible so that if theres a slight error in dosing, theres no adverse effects
give an example of something that is very toxic but is still used as a theraputic compound?
botulinum toxin
its caused by clostridium botulinum and is one of the most deadly poisons in the world, just a tsp could kill millions of people
DOSE MATTERS
what is the therapeutic use of botulinum toxin?
Temporary removal of facial wrinkles
Severe underarm sweating
Cervical dystonia - a neurological disorder that causes severe neck and shoulder muscle contractions
Blepharospasm - uncontrollable blinking
Strabismus - misaligned eyes
what does iatrogenicity mean?
its the capacity to produce disease from the side effects or innapropriate prescribing of drugs i.e. anti-malairial drugs mefloquine (lariam) associtaed with neuropsychiatric side effects
it could cause suicidal thoughts
what does teratogenicity mean?
its the capacity to produce abnormalities of the unbirn child or foetus e.g. thalidomide
what does thalidomide being a racemic mixture mean?
it means its got an R form (sedative) and S form (teratogenic)
the r form helps with nausea but the s form can bind to enzymes involved in the development of limbs in the unborn foetus
why cant just the R form of thalidomide be created?
becuase it can just be converted to the S-form in the liver
what is high-throughput screening?
this is the method of choice for most drug companies
thousands of compounds are screened every day (first pass)
cell lines can be used (sometimes theyre genetically modified) to screen drugs and characterise pharmacological properties
then ex-vivo tissues are used , if the properties are good, the drug could be taken to in vivo testing in animals
testing on tissue is much more reliable than testing on just cells or on just enzymes
what are types of drug targets?
ion channels - either open or closed (Ca2+ channel blocker= verapamil)
enzymes - inhibitors (ibeprofern = cyclo-oxegenase inhibitor)
transporters/ carriers - (prosac = 5-HT uptake inhibitor)
receptors - agonists (salbutamol for asthma)
antagoniusts (cimetidine - for peptic acid)
receptors as drug targets
they’re chemical structures made up of protein
they have recognition molecules to receive and transduce signals that might be integrated into biological systems
the concept of receptors are central to pharmacology to recognise and respond
soluble physiological mediators can produce their effects (hormones, neurotransmitters and inflammatory mediators)
why do we need receptors in physiology?
they act as a central switchboard of chemical communication in the body
they coordinate the activities of their cells and organs
ligands- agonist, soluble mediator - released
what condition would an agonist be useful in treating?
asthma- it would be useful in opening the airways- the drug is called salbutamol
what natural hormone is salbutamol similar to?
adrenaline