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68 Cards in this Set

  • Front
  • Back
What is pharmacokinetics?
What the BODY does to the DRUG
What is pharmacodynamics?
What the DRUG does to the BODY
What are the 4 pharmacokinetic processes of a drug?
A bsorption
D istribution
M etabolism
E xcretion
What type of diffusion requires energy?
Active transport
What type of diffusion is limited to movement down a concentration gradient (i.e. from higher to lower)
Passive transport
What factors affect drug distribution?
1. lipid solubility
2. degree of ionization
3. molecular size
What type of drug penetrates the cell membrane better, ionized or unionized?
Unionized (nonionized)
What does the pKa of a drug mean?
50% is unionized & 50% unionized in a specific pH
Give examples of weak base drugs
1. Ketamine
2. Opioids
3. Benzodiazepines
4. Etomidate
Give an example of a weak acid
1. barbituates
If a weak acid drug is placed in an acidic pH, what is the dominant form (ionized/unionized)?
Unionized
(Remember: Acid + Acid = more unionized)
If a weak base drug is placed in an acidic pH, what is dominant form (ionized/unionized)?
Ionized
(Remember: Base + Acid = ionized)
If a weak acid drug is placed in an alkalotic pH, what is dominant form (ionized/unionized)?
Ionized
(Remember: Base + Acid = ionized)
If a weak base drug is placed in an alkalotic pH, what is dominant form (ionized/unionized)?
Unionized
(Remember: Base + Base = more unionized)
Does the pKa determine if a drug is a weak base or a weak acid?
No; pKa only tells the degree of ionization/unionization from the pH of the solvent (depending if acid/base drug in acid/base solution)
Lidocaine is injected IV into a pregnant woman, it crosses the placenta and is unable to come back out. This is an example of:
Ion Trapping
What factors affect absorption of a drug?
1. Lipid Solubility
2. Concentration
3. Blood flow
4. Surface area for absorption
5. Route of administration
Which routes are considered to result in 100% bioavailablity?
1. IV (parenterally)
2. inhalation
What affects bioavailability in an orally administered medication?
"First pass effect" (liver metabolism)
What factors affect drug distribution?
1. Lipid solubility
2. Blood flow
3. Tissue binding
4. Protein binding
What protein prefers to bind to weak acid drugs?
Albumin
What proteins prefer to bind to weak base drugs?
1. alpha-acid glycoprotein (AAG)
2. beta-globulin
If drugs are protein bound, what CANNOT occur to the drug?
1. Diffusion
2. Metabolization
3. Excretion
4. Cause effects
Binding of drug molecules to proteins is usually _____________
competitive
What is the Blood-Brain barrier?
cerebral capillaries held tightly together by astrocytes that limits passage of molecules
What is the formula for volume of distribution (Vd)?
flow (Q)
Vd = ---------------
plasma conc.(Cp)
Does volume of distribution refer to any anatomical or physiological compartment?
No; only infers how quickly the uptake of the drug occurs outside of the central compartment
What 2 processes comprise elimination?
1. metabolism (biotransformation)
2. excretion
What is a metabolite?
The result of metabolism of the parent drug
What is a prodrug?
An inactive form that becomes active after metabolization in the body
What are basic Phase I reactions in metabolism?
1. Oxidation
2. Reduction
3. Hydrolysis
What is a basic Phase II reaction in metabolism?
1. Conjugation (synthetic rxn)
Besides the liver, where else does biotransformation take place?
1. Plasma
2. Kidneys
3. Lungs
4. GI tract
The liver uses what enzyme pathway?
CYP-450 (Cytochrome P-450)
What drugs induce (speed up) the CYP-450 pathway?
1. Alchohol
2. Phenobarbital (anti-sz)
3. Phenytoin (anti-sz)
4. Rifampin (TB drug)
5. Carbamazepine (anti-sz)
What is stereochemistry?
Study of 3-D isomers
What is a chiral center?
The center of a 3-D molecule that is assymetric when the mirror image is superimposed
What is a racemic mixture?
A 50/50 mix of drug enantiomers
What is the drug receptor response formula?
D + R <---> DRC <---> TR
D = drug
R = receptor
C = complement
T = tissue
What is efficacy?
The amount of cellular response in relation to receptor binding
True or False:
Receptors on cells are static
False; they are dynamic (constantly changing)
What condition prompts cell receptor up-regulation?
An UNDER stimulation results in a quantitative INCREASE of surface receptors
What condition prompts cell receptor down-regulation
An OVER stimulation results in a quantitative REDUCTION in surface receptors
What is affinity?
The degree of attraction between two things (e.g. drug & receptor)
What determines affinity and efficacy?
The closer a drug's molecular structure is to the receptor shape, the higher the affinity and the higher the efficacy
What are the 2 different types of receptors?
1. Receptors that open gates/channels
2. Receptors that prompts internal enzymatic activity (2nd messengers)
Name an example of a 2nd messenger that functions outside of the cell membrane
ACh-esterase projects outward into the synaptic cleft to metabolize ACh
Which portion of the G-protein sub-unit relays the message: alpha, beta, or gamma?
Alpha
Name examples of second messengers
1. cAMP
2. cGMP
3. Calcium
4. Inositol triphosphate (IP3)
5. Calcium-calmodulin
If a synthetic drug can bind to the same site as an endogenous substance, the drug is called a(n) ______________
Agonist I
A synthetic drug that has no effect on a receptor unless the endogenous substance accompanies it is called a(n) ______________
Agonist II
A synthetic drug that binds to the same receptor as an endogenous substance but causes no effect is called a(n) ______________
Pure antagonist
A synthetic drug that can bind to both inhibitory and excitatory receptors is called a(n) ______________
Agonist-Antagonist
A synthetic drug that binds to a different receptor as an endogenous substance and causes an opposite effect is called a(n) ______________
Physiologic antagonism
Chemicals can act as: agonist, antagonists, or both?
Both
What is an ED-50?
Dose that causes a specified effect in 50% of the population
What is a LD-50
Dose required to produce a specific toxic effect in 50% of animals
What organs/tissues represent the central compartment in volume of distribution?
1. Brain
2. Heart
3. Lungs
4. Liver
5. Kidneys
6. Endocrine glands
What organs/tissues represent the peripheral compartment in volume of distribution?
1. muscle
2. skin
3. fat
What percent of the central compartment is body mass?
How much of the cardiac output does it receive?
1. 10% mass
2. 75% C.O.
What percent of the peripheral compartment is body mass?
How much of the cardiac output does it receive?
1. 90% mass
2. 25 % C.O.
What is zero order kinetics?
A CONSTANT amt of drug is eliminated per unit of time
What is first order kinetics?
A constant FRACTION of drug is eliminated per unit of time
What does the alpha phase of first order kinetics represent?
Initial distribution of drug
What does the beta phase of first order kinetics represent?
The fractional elimination of the drug
According to kinetics, what is responsible for rapid recovery from induction drugs such as propofol, barbituates & non-barbituates?
The rapid distribution in the alpha phase
How much drug is left after 18 hours in the following scenario:
T1/2: 6 h
Dose: 10 mg
1.25 mg
How much drug is removed after 50 hours in the following scenario:
T1/2: ???
Dose: 160 mg
After 30H: 20 mg
How much is lost after 50H: ???
35 mg