pharmocology Flashcards
what is pharmacodynamics
interaction of drugs with cells - including the binding of drugs to cells, their uptake and intracellular metabolism
what is pharmacokinetics?
how drugs are handled within the body - absorption, distribution, metabolism and excretion
what are the 5 ways drugs can transfer across the membrane
passive diffusion transporters membrane pores vesicle mediated transport active transport
what are 4 things that affect drug absorption?
particle size and formulation
GIT enzyme/acid
GIT mobility
physiochemical factors
how does pH affect drug diffusion?
drugs can only pass cell membrane if they are uncharged due to the membranes lipophillic nature
pH alters the charge on drugs
what does subcataneous administration involve?
injecting into fat layer
what does intravenous administration involve?
injecting into blood
when is intramuslcular administration suitable?
when it is a suspension or oily vehicle
what is buccal administration?
under the tongue/ cheek
what is transdermal administration
delivered across the skin for systemic distribution- transdermal patches etc
what is intrathecal administration?
injected into cerebrospinal fluid
what is epidural administration?
injected into epidural sac - around the spinal cord
what is topical administration?
application to body surfaces - skin or mucous membrane
how is protein binding used in drugs?
binding of drugs to albumin or glycoprotein for transport- this is a reversible mechanism. can changed amount of unbound drug, so changes biological activity
what are 4 roles of processing drugs?
activation of inactive drugs
inactivation of active drugs
production of active drug with increased activity
change in the nature of the activity
6 factors affecting drug metabolism
first pass effect hepatic blood flow liver disease genetic factors age other drugs
how is the liver involved in the elimination of drugs?
chemically alters drugs to make inactive or more active
depends on blood flow to the liver and activity of the enzymes
how is kidney function used to assess drug clearance?
creatine (which is excreted through the kidneys) clearance is used to estimate drug clearance
what is clearance?
the volume of blood/plasma cleared of drug per unit of time
what are the 4 major metabollic barriers that have to be passed before drugs reach the general circulation?
intestinal lumen
intestinal wall
liver
lung
what is the cockcroft gault equation
estimated creatine clearance in ml/min
what is efficacy?
the extent of functional change imparted to a receptor upon binding of a drug
what is potency?
dose of the drug needed to produce a biological effect
what is affinity?
the chemical forces that cause the drug to bind to the receptor site
what is an agonist?
drug that binds to receptors and inniates a cellular response that mimics what naturally happens in the body - it has a high affinity and efficacy
what is a partial agonist?
a drug that acts on the same receptor but does not produce the same maximal response
what is an inverse agonist?
drug that acts on a receptor but produces an opposite
what is an antagonist?
a drug that binds to receptors but does not initiate a cellular response - it has affinity but no efficacy
what is the difference between competitive and non-competitive antagonist?
compeitive binds to the same site as the agonist but does not activate it, where as non compeitive binds to an allosteric site to prevent activation of the receptor
what are 4 general mechanisms of drug action?
action on receptors
action on synapses
enzyme action
inhibit cell transport
what are 2 different types of drug enyzme interaction?
competitibe and non-competitive inhibition
what are 5 types of drug receptor?
cell-surface receptors
ligand gated ion channels
G-protein coupled receptors
enzyme-linked transmembrane receptors
intracellular receptors
what is receptor occupancy?
quanitfy thr binding of therpeutics to their targets on the cell surface used to generate pharmacodynamic biomarker data
what is dissociation equilibrium constant?
type of equilibrium that measures the propensity of a larger object to separate reversibly into smaller components
what is EC50?
the concentration of a drug that gives a half maximal response
what is the therapeutic index?
a quantitative measurement of the relative safety of a drug. a comparison of therpeutic agent that causes the therapeutic effect to the amount that causes toxicity
what is the certain safety factor?
an aspect of the dose-response relationship
ratio of the lethal dose to 1% of the population to the effective dose to 99% of the population
what receptors do salbutamol act on?
beta 2 adrenergic receptors found on smooth muscle lining the airways of the lungs
what is the clinical use of salbutamol?
marketed as ventilin
opens up medium and large airways in the lungs
used to treat asthma , induced bronchoconstriction and chronic obstructive disease
what receptors do propanadol act on?
it is a competitive antagonist of beta adrenergic receptors
propanadol exerts its effects primarily by blocking the action of endogenous catecholamine, epiephrine and norepinephrine at beta anergic recptors
what are the clinical uses of propanadol?
tremors angina hypertension heart rhythm disorder prevent heart attack reduce severity and frequecny of heart attacks
what receptors do antenolol work on?
beta-1-adrenergic receptors in the heart
what are the clinical uses of antenolol?
to reduce heart rate and workload
type of beta blocker, used to treat hypertension
prevents strokes, heart attacks and kidney problems, chest pain adn improves survival after a heart attack
what is volume of distribution?
the volume of plasma that accounts for the total amount of drug
what is the volume of distribution used for?
it allows you to calculate the loading dose neccessary for the desired blood concentration of a drug
estimating blood concentration in treatment of an overdose
what is the bioavailability of a drug?
the proportion of a dose that reaches the systemic circulation
what is the half life of adrug?
time taken for the concentration of a drug to reduce by 50%
what are NSAIDs?
non steroidal antiinflammatory drugs
how do NSAIDs work?
prevent prostoglandin production so act as pain releif as prostoglandins increase the sensitivity of pain receptors
how do ACE inhibitors work?
ACE inhibitors lower blood pressure by reducing angiotensin II in the body so blood vessel widen
how do local anaesthetics work?
block sodium channels in nerve cells, so prevent action potential generation
what characteristic of a drug preducts that it will be easil absorbed across a cell membrane?
lipophillic, unionised
what is chloramphenicol?
antibiotic
how does chloramphenicol act?
antibiotic that targets bacterial ribosome
