Phamacology Flashcards
Define pharmacology
Study of the actions and effects of chemicals on body and body on chemicals
What are the main 2 components of pharmacology
Pharmacokinetics
Pharmacodynamics
Define pharmacodynamics
Drugs effect on body
Define pharmacokinetics
Bodys effect on drugs
3 considerations of drugs in terms of pharmacodynamics
interaction with …, what about drug, modifies?
Interaction with cells
Effect of drug concentration on body
Drug modifying disease
3 properties of drugs
Affinity
Efficacy
Potency
Define affinity
Ability of drug to bind to receptor
Define efficacy
Ability of drug to induce an response
Define potency
Amount of drug required to illicit desired response
What is the equation for potency
Affinity + efficacy
List 4 families of receptors for drugs
Ligand gated ion channels
G coupled protein receptors
Enzyme linked receptors
Intracellular receptors
List 4 drug action sites
Enzymes
Receptors
Carriers
Ion channels
What are 2 ways things a drug can act as?
As an agonist or an antagonist
List 3 types of agonists
Full agonist
Partial agonist
Inverse agonist
List 3 types of antagonists
Antagonists
Competitive antagonists
Non-competitive antagonists
Define a full agonist drug
Drug that binds to receptor to initiate a response
What do agonist drugs mimic?
Body’s function
What are 2 features of a full agonist
High affinity and efficacy
Define a partial agonist drug
Drug that binds to a receptor to initiate a response but without the efficacy of a full agonist
Partial agonists can act as what when given with a full agonist?
Competitive agonist
Define a inverse agonist drug
Drug that binds to a receptor to initiate the opposite response e.g. naloxone on opioid receptors
Define a antagonist drug
Drug that binds to a receptor to initiate no response/prevent response from occurring
Define a competitive antagonist drug
Drug that binds to same receptor as another drug/ligand thus competes for receptor site
Define a non-competitive antagonist
Drug that binds to a different site on receptor leaving the receptor ineffective
What do dose response curves show?
Body’s response to drug against logarithmic dose
On a dose response curve graph what does the X axis demonstrate about which feature of a drug (i.e. efficacy, potency, affinity)?
(which direction is highest to lowest)
X axis demonstrates a drugs potency from highest to lowest (left to right)
On a dose response curve graph what does the Y axis demonstrate about which feature of a drug (i.e. efficacy, potency, affinity)
(which direction is highest to lowest)
Y axis demonstrates a drugs efficacy and affinity from lowest to highest (bottom to top)
True or false, modified forms/doses of drugs should never be crushed or chewed?
True
3 considerations of drugs in regards to pharmacokinetics
route, time, exit
Process of absorption from administered route
Period between administration and effect
Process of elimination from body
What are the 4 stages of pharmacokinetics?
ADME Absorption Distribution Metabolism Excretion
Define absorption
from where to where
Transfer of drug from administered site into systemic circulation
What % of drug is absorbed in how many hours given via oral route?
75%
1-3 hours
What 3 cause the loss of 25% of a drug administered orally?
GIT acid
Enzymes
1st pass metabolism
First pass metabolism only occurs when drugs are taken orally?
True
List 6 factors that effect oral absorption of a drug
Particle size Formulation Enzymes and pH of GIT GIT motility Physiochemical factors e.g. salt form Food eaten
What would inactivate a drug to mean that it couldn’t be given orally?
Drugs left inactive due to first pass metabolism
Define a depot and what does it mean for speed of absorption?
Drug given in a suspension
Allows for slow sustained absorption
What type of substance does a specialised depot come in and what does does this mean for absorption?
Oily substance
Slow absorption
Drugs given IM in an aqueous solution have fast or slow absorption?
Fast
Which 2 routes can suspensions be given into?
IM or subcut
What is the bioavailability of a drug given IV?
100%
Define distribution
Process where drug is reversibly transferred
Name 2 methods of distribution
clue: transfer, distance
Bulk flow transfer - in blood
Diffusion transfer - molecule by molecule through phospholipid bilayer
How are drugs reversibly transferred?
By binding to plasma proteins
Name 2 proteins that help transfer drugs
Albumin
Glycoproteins
True or false, drugs are chemically inert when bound to plasma proteins
True
List 4 methods by which drugs cross cell membrane
Passive diffusion
Facilitated diffusion
Active transport
Pinocytosis
During passive diffusion what concentration do drugs move from to?
High to low concentration
What drug action site facilitates passive diffusion?
Ion channels
What drug action site facilitates facilitated diffusion
Protein carriers
Which is quicker facilitated or passive diffusion?
Facilitated
What does active transport allow for in terms of drug concentration?
Movement of drug against concentration gradient
What does a drug need to be soluble in to be able to cross the blood brain barrier?
Lipid soluble
List 5 factors that effect drug distribution
Plasma protein binding Location of receptor site Regional blood flow Lipid solubility Disease
How do pregnancy and liver conditions effect distribution of drugs?
Reduce albumin concentration
What would you do to the dose of a drug if a patient had low albumin levels and why?
Reduce dose
As drug is bioactive when unbound increasing likelihood of ADRs and toxicity occurring
What does the % of protein binding of a drug have to be for displacement of another protein bound drug to be clinically significant?
90%
Define narrow therapeutic index
Drug with a small difference between therapeutic and toxic concentrations
What do you need to do when a pt is prescribed a drug with a narrow therapeutic index
Monitor blood plasma concentrations of drug
What tissue is responsible for the difference in drug distribution in children and the elderly?
Adipose tissue
List 6 factors effecting metabolism
1st pass effect Perfusion of liver Liver disease Generic factors Other drugs Age
Define bioavailability
% of drug that makes it into systemic circulation
Define bioequivalence
Drug that has no difference in its rate of uptake/action at receptor site when given at same dose via same route
List 4 outcomes of metabolism
Activation of inactive drug
Increased activity of already activated drug
Inactivation of active drug
Change in activity of drug
List 4 metabolic barriers
GIT mucosa
Lung
Liver
GIT wall
What is the main site of local hormone metabolism?
Lungs
Define clearance
Measure of the time it takes for a volume of blood plasma to be completely clear of a drug
Clearance a measure of the time it takes for a drug to be removed from blood plasma OR a measure of the amount of drug removed from blood plasma?
Measure of TIME of drug removal not amount
Define half life
Time taken for plasma concentration of a drug to halve
True or false, half life is effected by the dose of drug taken?
False
What does an enzyme inducing drug do to the bioavailability of another?
Reduces bioavailability
When given an enzyme inducing drug, what might you have to do to the dose of the original drug?
Increase dose
What does an enzyme inhibiting drug do to the bioavailability of another?
Increases bioavailability
When giving an enzyme inhibiting drug, what might you have to do to the dose of the original drug?
Decrease dose
What does the liver do to help with the elimination of drugs from the kidneys?
Metabolises/breaks down drugs so that they are more water soluble to help with excretion from the kidneys.
List 4 stages of excretion of drugs from the kidneys
Filtration
Re-absorption
Secretion
Excretion
What 2 types of drugs are reabsorbed by the kidneys during excretion?
Lipid soluble
Unionised
What type of membrane transport occurs during secretion in excretion of drugs from the kidneys?
Active transport by membrane carriers
Where in the kidneys does secretion of drugs during excretion occur?
Transporters in the PCT membrane
Define rate of absorption
Speed at which drug is transferred from administered route into systemic circulation
Define extent of absorption
Amount of total drug transferred from administered route into systemic circulation
What does increased GIT motility do to the rate of absorption?
Increases rate of absorption
What does hyper GIT motility do to the extent of absorption?
Decreases the extent of absorption
Name 4 routes that require absorption into systemic circulation first before they are able to take effect
Inhalation
Oral
Vaginal
Ocular
What 2 factors determine receptor effect?
Rate and extent of absorption
What about a drug determines it’s rate and extent of absorption?
Size of drug particles
During decreased GIT motility is there a change in the extent of absorption?
No
List 5 barriers between oral route and drug receptor site
GIT mucosa
Vascular endothelium
Renal tubule cells
Blood brain barrier
Lipid soluble drugs cross the cell membrane by what form of transport?
Passive diffusion
What happens to the blood brain barrier during inflammation and what does this allow in terms of drug solubility?
Becomes leaky
Allows for water soluble drugs to cross from blood plasma into CSF
What type macromolecule is present in a drug meaning that it is unsuitable to be given via the oral route?
Proteins e.g. insulin
What route should protein containing drugs be given via?
Injection
What is the name given to drugs that are inactive until activated by being metabolised?
Prodrugs
Which 2 groups of drugs are important to substitute for one that is bioequivalent?
Mood enhancing drugs
Anti-epileptics
What 3 compartments is water and thus drugs distributed into?
Intracellular
Extracellular
Adipose tissue
What is volume of distribution used to work out?
Dose of drug needed to reach certain plasma concentration
Does a highly protein bound drug have a high or low volume of distribution?
Low
Does a highly lipid soluble drug have a high or low volume of distribution?
High
Do water soluble drugs need to be metabolised to be excreted into the urine?
No
What does a phase I reaction do to a drug?
Makes it more chemically reactive
What does a phase II reaction do to a drug?
Adds water via a process called conjugation to make drug inactive and able to be renally excreted
Drugs excreted into the bile end up being excreted via what?
The faeces
What stage of renal excretion removes large protein bound drugs?
Secretion
What % of small water soluble drugs are removed by filtration?
20%
Define teratogenic
Drugs able to cross the placenta during 1st trimester leading to congenital malformations
List 7 factors that effect transfer of drug from mother to foetus via placenta
Concentration of drug Blood flow via placenta Anion or cation pH of maternal blood Protein affinity Lipophilicity Molecular weight
What does pharmacodynamics allow for the prediction of?
A drugs effect and ADRs
Name 3 target molecules for drugs
Enzymes
Transport mechanisms
Receptors
What is a ligand?
Molecule that binds to receptors initiating a response/preventing a response thus regulating bodily functions.
Name 2 locations of receptors
Intracellular
Plasma membrane bound
List 5 classes of plasma membrane receptor
Adrenoreceptors Dopamine Opioid 5HT Acetylcholine
What ligand binds to a 5HT receptor?
Seritonin
What ligand binds to adrenoreceptors?
Adrenaline and noradrenaline
How many types of andrenoreceptors are there?
4
What are the 4 types of andrenoreceptors called?
alpha 1
alpha 2
beta 1
beta 2
Name the 4 locations of beta 1 andrenoreceptors?
Heart
GIT smooth muscle
Glandular tissue
Nerve terminals
Stimulation of beta 1 andrenoreceptors in the heart causes what?
Increase in heart rate and force of contraction
Stimulation of beta 1 andrenoreceptors on smooth muscle stimulates what?
Relaxation
Stimulation of beta 1 andrenoreceptors on glandular tissue stimulates what?
Increased secretion
Stimulation of beta 1 andrenoreceptors on nerve terminals stimulates what?
Increased neurotransmitter release
Name the 4 locations of beta 2 andrenoreceptors
Liver
Vascular, uterine, bronchial, bladder smooth muscle
Skeletal muscles
Mast cells
Stimulation of beta 2 andrenoreceptors in the liver stimulates what?
Glycogenolysis
Stimulation of beta 2 andrenoreceptors on skeletal muscle causes what?
Tremour
Stimulation of beta 2 andrenoreceptors on mast cells stimulates what?
Decreased histamine release
Stimulation of beta 2 andrenoreceptors on smooth muscle stimulates what?
Relaxation
Where are beta 2 smooth muscle receptors located?
Uterine, bladder, bronchial and vascular
Where are beta 1 smooth muscle receptors located?
GIT
How many types of 5HT receptors are there?
3
How many types of acetylcholine receptors are there and what are their names?
2
Muscanic
Nicotinic
How many types of dopamine receptors are there?
4
What endogenous ligand to intracellular receptors usually bind to?
Steroids
Explain the mechanism of drugs that bind to intracellular receptors
(which part of the cell do they go to to change what, causing what change to cell metabolism)
Drug receptor complex moves to nucleus where it changes gene transcription
Change in gene transcription changes protein synthesis.
Steroids bind to which type of receptor?
located where
Intracellular
