Pharmacodynamics & Pharmacokinetics Flashcards
Bonding can occur through…
In, hydrogen, or van der waals
Acidic drugs bind to…
albumin
Alkalotic drugs bind to..
a-1 acid glycoprotein
Free drugs can
-cross cell membranes
-determine concentration available to receptor (potency)
What decreases plasma proteins
-age
-hepatic disease
-renal failure
-pregnancy
If normal free fraction of drug is 2% and 50% of plasma proteins are lost then free fraction of drug is?
4%
If poor protein binding and lipophilic will have…
-Big volume of distribution
i.e. thiophental, diazepa,
If highly protein bound then…
-low volume of distribution
ex: warfarin
Examples of active metabolites
-diazepam
-propranolol
-morphine
-codeine
How are drugs MAINLY metabolized?
Hepatic microsomal enzymes
Most common CYP 450 enzyme?
CYP3A4
Rate of drug metabolism equation
R= Q(C inflow - C outflow)
Q= cardiac output
C= concentration
Flow limited clearance
CO limits metabolic rate
Capacity limited clearance
liver’s ability to metabolize is limiting factor
Elimination 1/2 time
Time necessary to eliminate 50% of drug from plasma after bolus dose
Elimination 1/2 life
Time necessary to eliminate 50% of drug from body after bolus dose
Context-sensitive half time
Time to a 50% decrease after infusion d/c
increases the longer infusion increases
Ionization
When PK and pH are identical
Weak acid drugs
barbituates
Weak base drugs
local anesthetics and opioids
Which ionization form is active and can cross lipid bilayers
non-ionized
Weak acids you put PK…
AFTER pH
Weak bases you put PK…
BEFORE pH
Which number is nonionized
negative
