ILA: Drug Absorption and Distribution Flashcards
the area b/t minimal effective concentration (MEC) and minimal toxic concentration (MTC)
therapeutic window
what kind of administration of drug immediately gets to the max effective dose
IV adminitration
drug concentration in plasma
Cp
achieve efficacy w/out toxicity is what
first goal of drug therapy
get Cp w/in therapeutic window in the shortest possible time is what
second goal of drug therapy
maintain Cp w/in therapeutic window during pharmacotherapy
third goal of drug therapy
what the body does to the drug is called
pharmacokinetics
what the drug does to the body is called
pharmacodynamics
plasma concentration correlates with drug concentration at the receptor (increase Cp= increase effect)
central dogma of pharmacokinetics
these 4 things affect plasma concentration of drug
ADME (absorption, distribution, metabolism, and elimination)
2 main types of drug delivery we will discuss
Oral (P.O. swallowing)
Parenteral (I.V.)
size of drug molecule, hydrophobicity, charge, pH trapping, and area of absorption are all what
obstacles to drug absorption
what junction prevents paracellular transport
tight junctions
flux=
(concentration difference x area)/thickness
a _____ drug is a neutral molecule that can reversibly dissociate into anion and proton (H+)
weak acid
a ______ drug forms a cation by combining with a proton (H+)
weak base
protonated form of a weak acid is ______
neutral (lipid soluble)
unprotonated form of a weak base is ______
neutral (lipid soluble)
in acidic environment (high proton), a weak acid will exist as what
neutral form (higher uptake)
in acidic environment (high proton), a weak base will exist as what
cation form (less uptake)
henderson-hasselbach eq. for weak acids
pH= pKa + log [charged/deprotonated/trapped]/[uncharged/protonated/membrane permeable]
_____ is the pH at which 50% of molecules dissociate
pKa
henderson-hasselbach eq. for weak bases
pH=pKa - log [charged/deprotonated/trapped]/[uncharged/protonated/membrane permeable]
when pH of environment (like stomach) is super low, uncharged/permeable form prevails, favoring ________
absorption
when pH of environment (like blood) is 7.4, charged form prevails, favoring _____
trapping
example of very fast absorption, having therapeutic effect before drug is even metabolized
sublingual administration
ex of drug that is administered sublingually
nitroglycerine
first pass of absorption when the drug is administered P.O. enteral (into GI tract)
hepatic (portal vein)
produce a local effect
prolong systemic action
methods for delayed absorption
once absorption happens, what 3 things come next
- binding to plasma proteins
- distribution
- elimination
binds mainly acidic drugs
plasma albumin
_______ do not saturate the plasma protein binding sites
therapeutic doses
drug that binds to fat and cannot achieve rapid induction; it’s a general anesthetic
thiopental
drug that binds to calcium and leads to bone and teeth toxicity
tetracycline
apparent volume of distribution
Vd
volume of distribution (Vd) (in vitro)=
Vd= D/Cb
D- dose
Cb- solvent in beaker
volume of distribution (Vd) (in vivo)=
Vd=D/Cp
D-dose
Cp- concentration of drug in plasma
where does most of the drug go when it is being distributed
most to tissues, some is eliminated
LD50 or TD50/ED50
therapeutic index
