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30 Cards in this Set

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1. Membrane structure
lipid bilayer with proteins
pores
complexes
2. Drug passage through membrane proper influenced by lipid solubility
3. Drug passage through pores is influenced by: shape and size of the molecule and degree of ionization (charge)
How do drugs pass membranes to reach their targets?
lipid bilayer with proteins
Chiefly lipids pass through this way to their targets.
pores
chiefly for small water soluble substances
complexes
chiefly for carrier mediated transport
lipid
Drug passage through membrane proper influenced by _______ solubility.
size and shape of the molecule

degree of ionization
Drug passage through pores is influenced by WHAT?
degree of ionization
charge

ions are less able to move passively

influenced by pH (less ionized in like environment, more ionized in opposite pH.
acidic drugs
LESS ionized at low environment pH, more ionized at high environment pH (ex. aspirin and barbiturates)
alkaline drugs
less ionized at HIGH environmental pH, more ionized at low environment pH (ex. morphine or quinine -- endings -ine or -amine indicate alkaline drugs)
The concentration at the active site might differ

The active site response differs

The patient might have other conditions or issues affecting drug responses
For a given dosage of a drug, patients do not always respond the same: Why not?
pharmacokinetics

bioavailability
Concentration of drug at active site - depends upon _____________, i.e. absorption, distribution, metabolism (biotransformation), and excretion of a drug - ____________.
Absorption
Transfer of drug molecules from place deposited to circulating fluids.
Absorption
1. route of drug administration
2. local conditions at site of administration
3. chemical properties of drug
4. form of medication given alters absorption
injections are usually more rapidly absorbed than oral route
What is the route of drug administration for faster absorption?
absorbed
oral
injections are usually more rapidly ________ than the _____ route.

(contrast plot of drug plasma concentration vs. time for oral route and IV administration)
amount of circulation to area
patient in shock
tourniquet or cooling
What are the local conditions at the site of administration, if injected?
pH
presense of food
What are the local conditions at the site of administration, if oral?
lipid solubility vs. water solubility

size and shape of molecule

degree of ionization (if water soluble)
For absorption of a drug to occur, what are the chemical properties of that a drug needs?
absorption

dosage
Form of medication given alters _________.
This is in addition to change in concentration that results from different ________ or frequency of administration.
enteric coating
time release
For an ORAL drug, what type or form of medication should be given to alter the absorption?
suspensions and gels can delay absorption of a given drug.
For an INJECTION drug, what type or form of medication should be given to alter the absorption?
Distribution
Manner in which a drug is transported by the bloodstream to various areas of the body and the drugs ability to accumulate in some tissues or its failure to enter other regions in significant amounts.
bloodstream
tissues

(def of distribution)
Manner in which a drug is transported by the ___________ to various areas of the body and the drugs ability to accumulate in some ________ or its failure to enter other regions in significant amounts.
Distribution
a. relative perfusion and permeability of area

b. binding to non-receptor sites like plasma proteins (albumin)

c. other storage sites (body fat, muscle, liver, kidneys, bone)

d. body weight (dose given per Kg body weight)

e. sex (female smaller, but more fat)
perfusion

permeability
Relative __________ and _________ of area.

blood brain barrier
placental barrier
blood brain barrier
capillaries less permeable
-glial cells close to caps
- pores are smaller
less interstitial space-packed with glial cells
*lipid soluble drugs penetrate
lipid soluble drugs penetrate
What type of drug can penetrate the B.B.B.?
placental barrier
many things do pentrate.

-rate of blood flow limits drug passage (anesthetic - 10 to 15 mins)
-particles as large as RBC's can cross
-lipid soluble drugs cross most readily
ex. narcotics, barbiturates, alcohol, tetracycline (retard bone growth)
non-receptor sites

def. of distribution
Distribution of drug binds to ___________ ____ like plasma proteins (albumin).
binding to non-receptor sites
What part of distribution is this?

can affect onset, intensity, and duration (due to decreased excretion rate)

usually weak binding so effect not severe

sometimes use PRIMING dose then smaller maintenance dose.