Dose, Potency and Efficacy Flashcards
what is potency
concentration or dose of a drugs maximal effect
EC50 or ED50
nearest to 0 in x-axis
what is efficacy
maximum response or effect
checked before potency
farthest from 0 in y-axis
discuss the dose-response curve
x: dose of drug; 0-30 mg basta highest dose
y: different effects of drug
discuss subtherapeutic dose
low doses that will not provide the drug effect
below min effective dose
discuss therapeutic dose
there is clinically significant effect
has plateau - peak effect/efficacy
once drug plateaus inc dose will not inc relief only side effects
discuss median effective dose
ED50: dose that produces therapeutic effect in 50% of popu
seen in quantal dose curve
- x: concentration of drug in plasma
- y: percent of indiv responding
discuss median toxic dose
TD50: dose that produce toxic effect on 50% of popu
discuss therapeutic index
ratio of TD50/ED50
OTC: wide therapeutic index = safe
chemo and antiarrhytmic: narrow = side effects
discuss therapeutic window
dose where you get good effect
varies from pt to pt and drug - pedia vs adult doses
index is wider than window
discuss median lethal dose
dose that kills far from TD and ED
what are the 2 primary routes of administration
alimentary - passes GI tract
non-alimentary - outside GI tract
discuss oral route
convenient, cheap and self-administered
limited - not all can be tablet, capsule or syrup
has first pass effect = less bioavailability
can cause gastric irritation
may or may not be take c meals
cannot give to unconscious pt
discuss sublingual
under tongue - venous plexuses straight to systemic
fairly rapid for emergency - 10 to 15 mins
avoids first pass but limited
ask pt to not swallow saliva until dissolved
examples of sublingual drugs
anti-HTN
analgesics
nitroglycerine - MCI
discuss rectal route
non-cooperative pt - geria, pedia, unconscious
limited and unpredictable - since has feces and causes irritation
direct to venous plexuses in rectum
suppositories
discuss inhalational route
rapid onset - goes direct to lungs
bronchodilators or GA
direct but limited
need tot each pt how to use inhalers
discuss topical route
local effect on outer skin - lesions, infection, eczema, insect bites
eye drops, ear drops
discuss transdermal
on skin but to systemic
nicotine patches or nitroglycerine buccal mucosa spray
discuss injection
quickest onset but hard to self-administer
needs aqueous solution
discuss IV injection
most direct - vein
bypasses first pass
needs catheter
most hazardous since cannot be removed
discuss IA injection
high local concentration to tissue - direct to organ
chemo on kidneys
discuss SQ injections
fat is poorly vascularized = slow absorption
can be depository - releases p 24 hrs
large volumes not feasible
insulin
discuss IM injections
effect in 15 mins - vaccines
if drug is diff via IV
painful since longer needle and can cause tissue damage
discuss subarachnoid injections
on arachnoid matter - drugs mixed in CSF
spinal anesthesia and chemo drugs for pedia
discuss epidural injections
above epidural space - via epidural catheter
used in labor or big surgeries - local anesthesia
discuss tendon sheath or bursa injections
for ligaments tears, muscle tears and OA
PRP
steroids
local anesthetics
dry needling
hydrodissection
what is bioavailability
amount of unchanged drug reaching systemic circulation
what affects bioavailability
GI absorption - first pass
plasma protein binding - albumin, globulin
adipose tissue storage
biotransformation - inc or dec
elimination
discuss fluid mosaic model
cell membrane has bi-lipid later c proteins
drugs need to be lipophilic to pass
discuss selective barrier
BBB
limits amount of drugs that can pass since any drug can cause neuro effects
discuss passive diffusion
from high to low concentration
permeability coefficient - substance needs to be permeable
rate of diffusion depends on
permeability coefficient
concentration gradient
area - inc area = inc diffusion
thicker = less diffusion
discuss active transport
uses ATP to pass from low to high
discuss facilitated diffusion
uses carrier protein to faci or speed up diffusion
discuss endocytosis and exocytosis
cell membrane can engulf drugs
endo - embrace drug then breaks of membrane and brings insed cell
exo - drug inside cell the engulf it will break membrane then release out
