Drug Induced Diseases+Geriatric Considerations

Agonist vs Partial Agonist vs Antagonist

agonist:
binds to receptor→activates it
has intrinsic activity

partial agonist: doesn’t give maximum possible response

antagonist:
binds to receptor→doesn’t activate it
blocks off agonist
-competitive vs non-competitive

Competitive vs Non-Competitive Antagonist

competitive antagonist:
competes with agonist for receptor site

highest concentration gets receptor site

reversible: increased concentration of agonist→reverses antagonism

non-competitive:
antagonist binds to receptor→stays bound

blocked from exerting effect

not reversible

Mx Pharmacokinetics (ADME)

absorption:
acidity
adsorption
GI

distribution

metabolism:
inhibition
induction

excretion

p-glycoprotein interactions

Pharmacokinetics: Absorption (General)

movement of mx from site of administration into central compartment/target

mainly PO mx

Bioavailability

measurement of the effective dose which reaches systemic circulation (bloodstream) from site of administration

contributing factors:
route of administration
ionization
protein binding
metabolism
ability of mx to pass through membranes

Pharmacokinetics: Absorption→Acidity (pH)

acidity/pH of the GI tract affects absorption

works in both directions on pH scales

mx: omeprazole
antiacids
etc.

Adsorption

one element binds to another on its surface (interaction between two molecules)
-cations+binding resins (cholestyramine)→don’t want to bind

ex: fluoroquinolones need to be given 2 hours prior/6 hours after antacids

Absorption Considerations

GI motility+absorption:
motility affects rate of absorption
not necessarily amount of mx absorbed
ex: metoclopramide (Reglan) speeds rate of gastric emptying
opiates decrease rate of gastric emptying

GI flora:
bacterial in stomach responsible for metabolism
-abx
-ethinyl estradiol (birth control)

first pass effect:
some PO mx metabolized by liver before going into circulation

Pharmacokinetics: Distribution (General)