Pharmacology Flashcards
is the study/science of chemicals (drugs) that interact with the human body, is defined as what
pharmacology
what a drug does to the body (biological effects and mechanism of action) is defined as
pharmacodynamics
what the body does to a drug (absorption, distribution, metabolism and excretion of drugs and their metabolites), is defined as
pharmacokinetics
the science and technique of preparing, dispensing and reviewing of medical drugs) , is defined as
pharmacy
What is a drug:
any single synthetic, or natural, substance of known structure used in treatment, prevention or diagnosis of disease.
what is a medicine
a chemical preparation, containing one or more drugs used with the intention of causing a therapeutic effect
do drugs work by acting on target molecules
yes or no
yes
what s a ligand
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose.
drugs acting or receptors can either be what
agonist or antagonists
is a drug/chemical that activates a receptor and causes a response (acetylcholine), is an example of what
agonist
is a type of drug which combines with a receptor but does not activate it. Thus blocking the action of the agonist by binding to the same receptor.
is an example of what
antagonists
what must there be, for the binding between the receptor and agonist
affinity
define affinity
Affinity is the strength of association between ligand and receptor.
once the agonist has combined the receptor is activated, what is the next response
efficacy response
what is efficacy
Efficacy is the ability of an agonist to evoke a cellular response
Affinity is ‘strength of association’ between ligand and receptor
how would low affinity affect the dissociation rate
Low affinity = fast dissociation rate
Affinity is ‘strength of association’ between ligand and receptor
how would moderate affinity affect the dissociation rate
Medium affinity = moderate dissociation rate
Affinity is ‘strength of association’ between ligand and receptor
how would high affinity affect the dissociation rate
High affinity = slow dissociation rate
efficacy is the ability of an agonist to evoke a cellular response
if there is a low affinity, how will that affect the cellular response (efficacy)
If there is a low affinity, then there will be small cellular response
efficacy is the ability of an agonist to evoke a cellular response
if there is a high affinity, how will that affect the cellular response (efficacy)
If there is a high affinity, then there will be a greater cellular response
what do antagonists possess and lack
possess affinity and lack efficacy
the process by which a drug enters the body from its site of administration and enters the general circulation: is defined as what
Absorption
the transport of drug by the general circulation: is defined as what
distribution
the process by which tissue enzymes (principally in the liver – hepatic metabolism) catalyze the chemical conversion of a frequently lipid soluble drug to an often less active and more polar form that is more readily excreted from the body: is defined as what
metabolism
the processes that remove the drug, or its metabolites, from the body (principally the kidneys – renal excretion): is defined as what
excretion
the drug must dissolve (dissolution) in an aqueous environment order to be absorbed: is defined as what
solubility
some drugs are destroyed by acid in the stomach, or enzymes in the gastrointestinal tract. in a few instances, a compound is modified within the gut to release the active drug: is defined as
chemical stability
the ratio of the drug concentration in the membrane and concentration in water at equilibrium: is defined as what
partition coefficient
what does an acid donate
proton or electron
protons
what does a base do
accepts a proton (decreases pH)
Factors affecting gastrointestinal absorption
Gastrointestinal mobility:
the rate at which the stomach is emptying and movement through the intestines, this is modified by some drugs, disease states and the presence of food.
Factors affecting gastrointestinal absorption
pH:
at the absorption site (varies along the gastrointestinal tract).
Factors affecting gastrointestinal absorption
Blood flow:
blood flow to the stomach and intestines (increased by food intake). Certain drugs are manufactured so that they can release drugs at different rates and sites.
Factors affecting gastrointestinal absorption
Physicochemical interactions:
the rate of absorption of drugs is modified by calcium rich-rich foods
The presence of transporters in the membranes of epithelial cells of the g.i tract can facilitate drug absorption
what is oral availability of a drug
is the fraction of drug that reaches the systemic circulation after oral ingestion
what is the Systemic availability of a drug
is the fraction that reaches the systemic circulation after absorption
when would use the rectum to delive drugs
when oral route is compromised
what is the disadvantage of taking medication via the oral route
inactivation by some enzymes/acids
food binding
what are the advantages of taking medication via the sublingual/buccal route
rapid absorption
by-passes the portal system
what are the advantages of intravenous route for drugs
rapid onset
continuous infusion
complete availability of drugs that cause local tissue damage
what are the disadvantages of taking intravenous route
sterile preparation required
risk of sepsis
embolism
high drug levels at the heart
what is the advantage of taking intramuscular drugs
rapid onset of lipid soluble drugs
A symptom that suggests a certain medical treatment is necessary, is defined as
Indication:
A specific situation in which a drug, procedure or surgery should not be used because it may be harmful to the person, is defined as
Contraindication:
acceptable if benefits outweigh risk, is defined as
Relative contraindication:
life threatening – do not take, is defined as
Absolute contraindication:
normal dose interval (given) is based on what
1 half life
when is the next dose given (dosage sechdule/interval)
- Next dose is given as previous dose reaches half life
define half life:
- Half-life: the time taken for the total amount of drug in blood plasma to diminish by half once it reaches peak concentration.
define overdose
Overdose: an excessive and dangerous dose of drug (paracetamol more than 10g lethal dose, codeine more than 350mg leads to CNS and respiratory depression).
define,
Drug-drug interactions
where several drugs are prescribed simultaneously to patients where one drug modifies the response to the co-administrating drug
when effects or action of multiple drugs combine to produce adverse effect, is defined as
Pharmacodynamics
when one drug affects the delivery of another drug to its target. May involve absorption, metabolism or elimination, is defined as
Pharmacokinetic
is codeine safe to take during pregnancy
no
what are the 7 checklist, before prescribing drugs
1) Patient’s identity!
2) Patient’s age and gender
3) Medical History / other conditions
4) Any allergies
5) Any recent / current medication
6) Consider special conditions: Pregnancy, lactation, can they swallow tablets
7) Sugar free available?
the process by which a drug enters the body from its site of administration and enters the general circulation, is defined as
absorption
the transport of drug by the general circulation. Drugs most often leave the blood and enter perfused tissues, is defined as
distribution
the process by which tissue enzymes (principally in the liver – hepatic metabolism) catalyze the chemical conversion of a frequently lipid soluble drug to an often less active and more polar form that is more readily excreted from the body, is defined as
metabolism
the processes that remove the drug, or its metabolites, from the body (principally the kidneys – renal excretion), but other routes may be important for specific agents, is defined as
excretion
for a drug to achieve effect, a drug must reach critical concentration in the plasma, what must it reach?
Minimum effective concentration (MEC)
ideally a drug should be below the level of causing significant unwanted side effects. what must a drug not reach to avoid side effects
maximum tolerated concentration (MTC)
what is the therapeutic window
is the blood plasma concetration between MTC and MEC
what is the consequence of a small therapeutic window
there is a chance you can overdose
drugs with smaller therapeutic window are classified as unsafe true or false
true
when is steady state of a drug achieved
drug adminsitration is equal to drug elimination
what is a loading dose
A loading dose is an initial increase dose taken to get to the therapeutic window and then decrease to a lower dose to maintain a steady state.
which is the main organ for drug metabolism
liver (hepatic metabolism)
where does first pass metabolism occur
in the liver
how does making a drug more hydrophilic help with elimination
hastens its excretion by the kidneys
what is the name of the substances after metabolism
metabolites
are metabolites more or less active then their parent form
less active
the mechanism involved to increase affinity for water or solubility in water for a drug is called what
hydrophilicity
the enzyme in the liver metabolising the drug needs to act on a wide variety of substances, and therefore must have a low what
low substrate specificity
drug metabolism occurs in two phases.
what occurs during phase 1
addition of polar groups
drug metabolism occurs in two phases.
what occurs during phase 2
conjugation
oxidation reaction is catalysed by a family of enzymes known as
cytochrome P450 oxidases
what occurs during phase 2
Cytoplasmic enzymes conjugate the functional groups introduced in phase 1.
where are cytochrome P450 oxidases found
they are found in the endoplasmic reticulum
what factors affect drug metabolism
- Enzyme inhibition
- Naringin found in citrus fruits
- Ciprofloxacin
- Erythromycin
- Herbal remedies
the process by which a drug enters the body from its site of administration and enters the general circulation: is the definition of what
absorption
the transport of drug by the general circulation. Drugs most often leave the blood and enter perfused tissues. Once within a tissue further, reversible, distribution dictated by a concentration gradient, may occur by diffusion (or carrier-mediated transport): is teh definition of what
distribution
the process by which tissue enzymes (principally in the liver – hepatic metabolism) catalyze the chemical conversion of a frequently lipid soluble drug to an often less active and more polar form that is more readily excreted from the body: is the definition of what
metabolism
the processes that remove the drug, or its metabolites, from the body (principally the kidneys – renal excretion), but other routes may be important for specific agents: is the definition of what
excretion
is the mathematical analysis of all drug disposition factors (absorption, distribution, metabolism and excretion): is the definition of what
pharmacokinetics
when do drugs exhibit first-order kinetics
where the rate of elimination is directly proportional to drug concentration.
what determines the maintenane dose rate
clearance
Probably the single most important pharmacokinetic parameter – the volume of plasma cleared of drug in unit time,
what must occur for a drug to achieve steady state
rate of drug administration = rate of drug elimination
an initial higher dose is given during treatment at the beginning before stepping down. what is the name of this initial dose
loading dose
The time for the concentration of drug in plasma (or the amount of drug in the body) to halve’ - is referred to as what
half life
which organ is responsible for the elimination of most drugs
the renal system (kidneys)
drugs are metabolised to become more …………. compounds which are are more easily excreted
polar
if drugs are lipid soluble, they are easily reabsorbed in the ……………. by passive diffusion
renal tubules
Drugs or phase 1 metabolites that are not sufficiently polar to be excreted rapidly by the kidneys are made more hydrophilic by conjugation with endogenous compounds - by which organ
liver
which test is used to show how well the kidneys are working
Glomerular filtration rate (GFR)
what does a Glomerular filtration rate (GFR) estimate
- It estimates how much blood passes through the glomeruli every minute
what is a normal Glomerular filtration rate (GFR)
- Normal GFR is 90 mls / min or higher
a Glomerular filtration rate (GFR) of 60-89 mls/min = what stage
mild stage 2
a Glomerular filtration rate (GFR) of 30-59 mls/min = what stage
moderate stage 3
a Glomerular filtration rate (GFR) of 15-29 mls/min = what stage
severe stage 4
a Glomerular filtration rate (GFR) of 15-29 mls/min = what stage
established renal failure stage 5
drugs or its metabolites that have poor renal excretion cause what -
toxicity
if renal impairment is reduced, how does this affect the effectiveness of drugs
some drugs wont be as effective
