exam 1 Flashcards
Transfer of drug from site of administration to systemic circulation
Absorption
Transfer of drug from systemic circulation
Distribution
Enzymatic alteration of a drug
Metabolism
Removal of a drug from the body
Excretion
metabolism + excretion
Elimination
Action of the drug on the body
The reason you take the drug
Pharmacodynamics
Action of the body on the drug
Fate of the drug in the body
“ADME”
Pharmacokinetics
The more _____________ the drug, the easier it is to cross the cell membrane
lipophilic
Hydrophilic
heads
lipophilic:
tails
The extent of drug absorption
bioavailability (F)
what is the primary area of absorption
duodenum
(dissolution + disintegration = stomach)
reflects loss of drug due to hepatic (and intestinal) metabolism on the way to the systemic circulation
first pass effect
what type of drug form diffuses across membrane
NON-ionized (lipid soluble)
where does the majority of metabolism occur
plasma or central compartment (where the kidneys and the liver reside)
true or false
IV (both infusion and single dose/bolus) are always 100% or 1
true
what are the 3 steps of distribution
1st disintegration: drug leaves the capsule; optional step (e.g., suspensions)
2nd dissolution: drug molecules dissolve in gastric fluid
3rd absorption
_____________ = metabolism + excretion
elimination
The more ____________ the drug, the easier it is to cross the barrier
lipophilic
the heads of the membrane are _______________
Hydrophilic
the tails of the membrane are ________________
Lipophilic
______hill Transport = Passive
DOWN
What is an example of passive diffusion
facilitated diffusion
particles that are transported by facilitated diffusion (passively) are (4):
o Small (monomers)
o Polar (water-soluble/hydrophilic)
o Charged ions (e.g., glucose, Ca, Cl, Na, K)
o Transport proteins (e.g., membrane transporters)
2 types of facilitated diffusion
pores/channels
carrier proteins
___hill Transport = Active
UP
factors that influence the GI tract
- GI motility
- Gastric emptying
- Intestinal motility
- Perfusion of the GI tract
- Presence of other drugs
- Presence or absence of food
second opportunity to be absorbed
enterohepatic recycling
which form is most easily absorbed
un-ionized form
Primary site for drug:
disintegration + dissolution
stomach
Primary site for oral drug:
absorption
duodenum
binding to tissue/protein components
ADsorption
water-soluble, high protein binding
small/low Vd
lipid-soluble, low protein binding
large/high Vd
> ____% protein bound = highly protein bound
this IS clinically relevant for protein binding issues
> 90%
what 3 things create DIFFICULT transport
tight junctions
astrocytes
pericytes
what 2 things create EASY transport
lipophilic/un-ionized
small molecular weight
If an efflux transporter is exposed to a drug inhibitor (preventing the efflux pump from working properly), it will ___________ the likelihood of absorption
ENHANCE
EFFLUX transporter example
ATP-Binding Cassette (ABC) Transporters
INFLUX transporter example
Solute Carrier Transporters (SCT)
Factors Impacting Drug Binding for HIGHLY Bound (>90%) Plasma Proteins
- Protein concentration
- Protein size (Da, kDa)
- Number of protein binding sites; bound (CB)
- Association binding constant
o Measure of the tightness of the binding (whether the drug can detach from a protein easily) - Concentration of unbound drug (Cu) or free drug (Cf)
hydrostatic balance; keeps the blood volume intact
medium MW
large concentration
albumin
medium MW
VARIABLE concentration (goes up in times of stress; non-detectable in healthy people)
a1-acid glycoprotein (AAG)
protein carrier of fat
large MW
small concentration
lipoprotein
Factors that Decrease Albumin Concentrations
decreased protein synthesis
liver dx
Factors that Decrease Albumin Concentrations
excess elimination of protein
kidney dx
Factors that Decrease Albumin Concentrations
increased protein catabolism
trauma, surgery
Factors that Decrease Albumin Concentrations
decreased protein synthesis and increased protein catabolism
malnutrition
Factors that Decrease Albumin Concentrations
distribution of albumin into extravascular space
burns
Metabolism =
Biotransformation
* Enzymatic (usually) or non-enzymatic
what 3 things impact the liver metabolism
blood flow
enzyme activity
protein binding
the liver makes the drug more ______________, _____________ the polarity (so that the kidneys can eliminate it)
HYDROphilic
INCREASED polarity
so that it can be eliminated
- Drugs are transported into hepatocytes by
o 1) Passive diffusion
o 2) Carrier-mediated transport
4 Major Consequence of Drug Biotransformation/Metabolism
- Increase in water solubility
- Increase in rate of elimination
- Termination of biologic activity
- Bioactivation (desired or undesired)
Something that is not pharmacologically activated until the body does something to activate it
Normally metabolized to their active form, and then can be metabolized further
prodrug/desired drug
codeine
Instead of being inactive, it is __________, and could be transformed into an active metabolite, same effect, or different effect from a drug
active drug
demerol (normeperidine)
superfamily of monooxygenases
Heme-containing enzymes, catalyze the oxidation of organic substances
CYP450
phase 1
of hepatic metabolism
o Conjugation reactions
o Glucuronide
phase 2
of hepatic metabolism
P-Glycoprotein (P-gp) or ABC-B1
ABC transporters
efflux
Proposed to predict the kinetics of drugs such as
digoxin,
cyclosporine
and fexofenadine
P-Glycoprotein (P-gp) or ABC-B1
transporters: influx
SLC transporters (solute carrier)
Located on both the basolateral/blood/plasma side and the apical/lumen/organ side
SLC (influx) + ABC (efflux)
plasma/blood
side
basolateral
lumen/organ
side
apical
most important factor for excretion
nephron
transporters actively making the drug more concentrated in the urine
secretion
(example: abx)
drug gets placed back into the plasma/blood from the urine; GIVE EXAMPLE
reabsorption
lithium is example
If clearance of a drug is LESS than < 120 ml/min, then we know the drug is filtered + net ___________________
reabsorption
If clearance of a drug is MORE than > 120 ml/min, then we know the drug is filtered + net ______________
secretion
taken back up through the portal vein into the liver
enterohepatic recycling
Excretes drug by emptying into the duodenum
bile
_______________ ____________ is why some drugs have a long half-life
enterohepatic recycling
Primary drug of
biliary extraction (intact or as metabolites)
diazepam
Primary drug of
enterohepatic circulation:
morphine
Determinants in the Selection of Drug Route
- Type of desired effect
- Physiochemical properties
- Rapidity of effect
- Quality of effect
- Condition of patient
Pharmacokinetic Parameters:
Assessment of ________________
Bioavailability
Max concentration
Cmax
Time to max concentration
Tmax
the % of the drug available to systemic circulation
fraction absorbed from gut
The rate and extent to which an active drug ingredient or therapeutic moiety is absorbed from a drug product and becomes available at the site of action
Bioavailability (F)
rate + extent of drug exposure in the body
Area Under the Curve (AUC)
RATE of ELIMINATION, per unit of time
K
hr-1, min-1, sec-1
Rate of elimination, per unit of time (K)
o Linear vs. non-linear (____________-________)
Michaelis-Menten
VOLUME of drug eliminated per unit of time
clearance (Cl)
ml/hr, L/min
only ml or L!
hour, min, seconds
t 1/2 life
5 x t1/2 =
steady state
ml or L only
Vd
The comparison of bioavailability of different formulations, drug products, doses, or batches of the SAME drug product
Example: tablet vs solution
bioequivalence
example of drug with narrow therapeutic index/range
phenytoin
most drugs have a _______ therapeutic index
WIDE
peak (tied to _________) and a trough (tied to _________)
efficacy
toxicity
AUC:MIC
AUC: minimum inhibitory concentration (MIC) needed to kill off bacteria
amount= changes
fraction= constant
first order