Pharmacology Flashcards
what is the medical definition of a drug?
a chemical substance intentionally administered that alters body function, used for the prevention or treatment of disease
what is the definition of a ligand?
a chemical or compound that binds to a receptor
what is the definition of an agonist?
a compound that binds to and activates a receptor
what is the definition of an antagonist?
a compound that reduces the effect of an agonist at a receptor
what is the definition of a partial agonist?
a low efficacy agonist that is unable to elicit the maximal response from a receptor, irrespective of the concentration applied
what is the definition of affinity?
a measure of the equilibrium constant of the reversible reaction between a drug (agonist/antagonist) and a receptor
what is the definition of efficacy?
a measure of the magnitude of the cellular response produced when an agonist binds to a receptor
what is the definition of potency?
a measure of the concentration of a drug at which it produces an effect of a given magnitude
what is the definition of specificity?
a measure of the number of receptor sites that a drug may bind to or the range of effects it may produce
what is the definition of selectivity?
the degree to which a drug binds to a given receptor site relative to the other receptor sites (related to affinity)
what is a competitive antagonist?
an antagonist that binds to the same site as the agonist (endrogenous ligand) and competes for binding
how can the effect of a competing antagonist be overcome?
increasing agonist concentration
what is a non-competitive antagonist?
an antagonist that binds to a different site to the agonist binding site, causing a conformational change in the receptor restricting agonist binding
what does thr ADME pneumonic stand for?
A - absorption
D - distribution
M - metabolism
E - excretion
pharmacokinetics refers to the ___ of a drug ___, ___ and ___ of the body, the 4 aspects of pharmacokinetics are ___, ___, ___ and ___ (___)
pharmacokinetics refers to the movement of a drug into, through and out of the body, the 4 aspects of pharmacokinetics are absorption, distribution, metabolism and excretion (ADME)
absorption is the process where drugs ___ the body and move from the ___ ___ into the ___ ___
the ability of drugs to pass through ___ is determined by their ___ ___, ___ and ___ ___
absorption is the process where drugs enter the body and move from the administration site to the blood plasma
the ability of drugs to pass through barriers is determined by their chemical properties, formulation and administration route
distribution is how the drug ___ around the body and its ability to ___ in ___ ___ and ___
it is determined by ___ ___, ___ ___, ___ ___ and ___ ___ ___
distribution is how the drug moves around the body and its ability to accumulate in certain tissues and organs
it is determined by blood perfusion, tissue binding, regional pH and cell membrane permeability
metabolism is how the body ___ ___ the drug
the princliple metabolic site is the ___ and it occurs in ? ___
metabolism is how the body breaks down the drug
the princliple metabolic site is the liver and it occurs in 2 phases
excretion is the ___ and ___ through which the ___ exits the body
excretion is the rate and process through which the compound exits the body
most drugs are administered ___, an alternate administration is needed when a drug is ___ ___ (small amount reaches ___ ___), ___ ___of action is needed or a drug ___ ___ ___
most drugs are administered orally, an alternate administration is needed when a drug is poorly digested (small amount reaches blood circulation), rapid onset of action is needed or a drug irritates stomach lining
a subcutaneous administration is an ___ ___ ___
a percutaneous administration is an ___ ___ ___ ___
an intrathecal adminstration is an ___ into ___ ___ ___
a subcutaneous administration is an injection beneath skin
a percutaneous administration is an injection passing through skin
an intrathecal adminstration is an injection into spinal cord space
drug molecules can move around the body by ___ ___ ___ in the ___, ___ ___ and ___, ___ within ___ ___ such as ___ or ___ ___, and they can travel across ___ such as ___, ___ and ___ membranes
drug molecules can move around the body by bulk flow transfer in the bloodstream, lymphatic system and CSF, diffusion within body fluids such as cytoplasm or interstitial fluid, and they can travel across barriers such as epithelial, endothelial and cytoplasmic membranes
drugs can move across cells by ___ ___, ___ ___, ___ ___ and ___ (drug binds to ___ on ___ ___ and is ___ into a ___ and then ___ into ___)
drugs can move across cells by passive diffusion, facilitated diffusion, active transport and pinocytosis (drug binds to receptor on cell membrane and is engulfed into a vesicle and then exocytosed into bloodstream)
drug factors affecting ___ and ___ of drug absorption include ___ ___ (___ favoured), ___ ___ (___ ___ ___) and ___/___
drug factors affecting rate and extent of drug absorption include molecular size (small favoured), lipid solubility (non-polar preferred) and pKa/pH
when a drug is administered orally it passes through the ___, ___ and ___ and must avoid ___ or ___ by ___ ___ and ___ ___ in order to reach ___ ___
this is known as ___ ___ ___
when a drug is administered orally it passes through the stomach, intestines and lives and must avoid inavtivation or degredation by stomach acid and digestion enzymes in order to reach systemic circulation
this is known as first pass metabolism
___ is the term used to quantify the amount of drug reaching the systemic circulation
bioavailability is the term used to quantify the amount of drug reaching the systemic circulation
drug distribution is when a drugs leaves ___ (___) entering ___ ___ (___) to reach its ___ ___
factors increasing drug distribution include ___ ___ ___, ___ ___ ___ and ___ ___ ___
drug distribution is when a drugs leaves bloodstream (intravascular) entering extracellular fluid (extravascular) to reach its action site
factors increasing drug distribution include increased blood flow, decreased protein binding and increased lipid solubility
the bodys water (?l) is distributed into 4 categories: ___ (?l), ___ (?l), ___ (?l) and ___ (water in ___ ___ ___ such as ___ or ___)
the bodys water (42l) is distributed into 4 categories: plasma (3l), interstitial (11l), intracellular (28l) and transcellular (water in epithelial lined spaces such as synovial or CSF)
cell membranes form a ___ between each ___ where a drug exists in ___ between a ___ ___ or ___ form, only the ___ drug can move across the cell membrane between ___ to elicit an effect
cell membranes form a barrier between each compartment where a drug exists in equilibrium between a protein bound or unbound form, only the unbound drug can move across the cell membrane between compartments to elicit an effect
distribution volume is an estimation of ___ ___ and can be defined as the volume of ___ necessary to account for ___ ___ ___ in the patients ___
it is calculated from ___ ___ relative to ___ ___ ___ ___
distribution volume is an estimation of drug distribution and can be defined as the volume of plasma necessary to account for total drug amount in the patients body
it is calculated from administered dose relative to blood plasma drug concentration
estimation of volume distribution is used clinically to determine ___ ___ necessary for a ___ ___ ___ of ___
its then divided by ___ ___ ___ and expressed in ?/??
a low Vd occupies ? ___, a medium occupies ? ___ and a high occupies ___ ___
estimation of volume distribution is used clinically to determine loading dose necessary for a desired blood concentration of drug
its then divided by patients body weight and expressed in l/kg
a low Vd occupies 1 compartment, a medium occupies 2 compartments and a high occupies all compartments
drug metabolism takes place in the ___, where a drug will undergo 2 reactions: ___ ? and ___ ?
these reactions ___ eachother and involve an ___ reaction and a ___ reaction of the drug
the goal is to make the drug ___ ___ ___ so it will be ___ and not ___
drug metabolism takes place in the liver, where a drug will undergo 2 reactions: phase 1and phase 2
these reactions proceed eachother and involve an anabolic reaction and a catabolic reaction of the drug
the goal is to make the drug less lipid soluble so it will be excreted and not reabsorbed
drug excretion is mainly done through the ___, ___ ___ and ___, where most drugs leave through ___
drugs can also be excreted through ___ or ___ ___ or in ___ (___ or ___)
drug excretion is mainly done through the kidneys, hepatobiliary system and lungs, where most drugs leave through urine
drugs can also be excreted through faeces or exhaled air or in secretions (milk or sweat)
the liver plays 3 roles in drug metabolism which are:
___ ___ and ___ by converting them into a __-___ ___
___ ___ by converting ___ ___ to an ___ ___
___ ___ by converting ___ ___ to an ___ ___
the liver plays 3 roles in drug metabolism which are:
detoxify toxins and carcinogens by converting them into a non-toxic metabolite
activate prodrugs by converting inactive precursor to an active drug
inactivate drugs by converting active form to an inactive form
phase 1 reactions (___/___) involve creating a functional ___ ___ by ___, ___ or ___ (___)
this requires ___ ___ enzymes such as ___ ___ ___ embedded in the ___ ___ and ___
to reach these enzymes the drug must cross the ___ ___
phase 1 reactions (non-synthetic/catabolic) involve creating a functional reactive group by oxidation, reduction or hydrolysis (functionalisation)
this requires drug metabolising enzymes such as cytochrome P450 system embedded in the smooth ER and mitochondria
to reach these enzymes the drug must cross the plasma membrane
in phase 2 reactions (___/___), ___ occurs (___) of a ___, ___, ___ or ___ group that usually results in an ___ ___
the 2 phases combined yield a drug with lower ___ than the parent drug preventing ___
in phase 2 reactions (synthetic/anabolic), conjugation occurs (attachment) of a methyl, acetyl, glucuonyl or sulphate group that usually results in an inactive product
the 2 phases combined yield a drug with lower lipophilicity than the parent drug preventing reabsorption
patient polymorphism is when there are ___ forms of a ___ that occurs among different ___ or ___ leading to ___ ___ ___ in individuals
patient polymorphism is when there are multiple forms of a gene that occurs among different individuals or populations leading to variable enzyme activity in individuals
increases in patient metabolism will ___ the ___ ___ amount so the ___ ___ may not be met
decreases in patient metabolism ___ the ___ ___ therefore ___ ___ of ___ ___ will accumulate leading to ___ ___ ___
increases in patient metabolism will increase the inactive drug amount so the therapeutic dose may not be met
decreases in patient metabolism reduces the inactive drug therefore high concentrations of active drug will accumulate leading to toxic side effects
patients may be taking ___ ___ simultaneously (___) interfering with the ___ ___
they can either be ___ which ___ the ___ enzyme activity increasing ___ ___ and shortening ___ ___
or ___ which ___ the ___ enzymes decreasing ___ ___ and lengthening ___ ___
patients may be taking multiple drugs simultaneously (polypharmacy) interfering with the drug metabolism
they can either be inducers which upregulate the CYP450 enzyme activity increasing drug metabolism and shortening half life
or inhbitors which downregulate the CYP450 enzymes decreasing drug metabolism and lengthening half life
drugs can be excreted through the ___ in ___, the ___ ___ in ___, the ___ in ___ ___ and the ___ ___ in ___
the ___ are the principle organ for excreting hydrophilic drugs
drugs can be excreted through the kidneys in urine, the hepatobiliary system in bile, the lungs in exhaled gases and the GI tract in faeces
the kidneys are the principle organ for excreting hydrophilic drugs
blood filtration begins at the ___ where all drugs except ___ ___ drugs diffuse into ___ ___. the filtrate then passes into the ___ ___ ___ which has ___ ___ to actively transport drugs from the blood into the ___, as the filtrate passes the ___ ___ ___, and drugs left ___-___ can be ___ into the bloodstream
blood filtration begins at the glomerulus where all drugs except protein bound drugs diffuse into bowmans capsule. the filtrate then passes into the proximal convoluted tubule which has secretory pumps to actively transport drugs from the blood into the tubule, as the filtrate passes the loop of henle, and drugs left non-ionised can be reabsorbed into the bloodstream
factors reducing drug excretion include reduction in ___ ___ ___ (___), increased ___ ___ ___, high levels of ___ ___ ___ in the ___, high levels of ___ ___ ___, ___ or ___ drugs, ___/___/___ drugs and low ___ ___
factors reducing drug excretion include reduction in glomerulus filtration rate (GFR), increased protein bound drug, high levels of transporter saturating drugs in the plasma, high levels of transport inhibiting drugs, small or hydrophobic drugs, ionised/acidic/basic drugs and low urine volume
drug clearance is the volume of ___ cleared of the total ___ ___ per unit of time (??/???)
drug clearance relates the ___ ___ ___ to the ___ ___ ___
it is dependant on ___ and ___ primarily controlled by the ___ and ___
drug clearance is the volume of plasma cleared of the total drug amount per unit of time (ml/min)
drug clearance relates the drug elimination rate to the drug plasma concentration
it is dependant on metabolism and excretion primarily controlled by the liver and kidneys
first-order enzymatic kinetics means as the ___ ___ ___ increases then the ___ ___ also increases due to the number of ___ involved increases ___
once all ___ are occupied the reaction follows ___-___ ___ ___
first-order enzymatic kinetics means as the drug plasma concentration increases then the drug metabolism also increases due to the number of enzymes involved increases proportionally
once all enzymes are occupied the reaction follows zero-order enzymatic kinetics
zero-order enzymatic kinetics is when all available ___ are actively ___ ___ and they are ___
as ___ ___ increases there are no additional ___ to process the drug to its ___ ___ meaning the rate of ___ ___ is ___ leading to the ___ of ___ in the ___ causing ___ ___ ___
zero-order enzymatic kinetics is when all available enzymes are actively drug processing and they are saturated
as drug concentration increases there are no additional enzymes to process the drug to its inactive metabolite meaning the rate of drug metabolism is constant leading to the accumulation of drug in the plasma causing toxic side effects
steady-state concentration is the time during where the ___ ___ is ___ when administered ___ or ___
the time to reach steady-state is a function of ___ ___-___ and is achieved when the rate of ___ entering ___ ___ equals ___ ___
steady-state concentration is the time during where the drug concentration is stable when administered repeatedly or continuously
the time to reach steady-state is a function of drug half-life and is achieved when the rate of drug entering systemic circulation equals elimination rate
