Introduction Flashcards
Describe the 2 phases in the plasma concentration curve
Distribution-immediately after administration of the drug
-drug moves from central to peripheral compartments
Elimination phase-more gradual as drug is removed from circulation
how does the degree of protein binding relate to volume of distribution?
Inversely proportional
Drugs bound to proteins have low volume of distribution
Which drugs bind to albumin?
Acidic
Which drugs tend to bind to alpha-1-acid glycoproteins?
basic drugs–local
How does binding to protein affect ability to cross cell membrane and elimination
Only unbound drug may cross cell membrane.
Free drug will be more available for elimination
Are protein bound drugs inert?
No,law of mass action shows that since reactions are occuring, protein bound drugs will be released as free drug is metabolized to keep equilibrium
What are the two factors that determine the ionization of a drug?
pKa of substrate
pH of surrounding fluid
If a drug has a pKa of 4.4 and is placed into a solution with a pH of 4.4 how does it ionize?
50% ionized, 50% non-ionized
What is ion trapping?
Occurs when a membrane separates 2 areas of differing pHs (stomach, renal tubules, placenta)
Nonionized portion of the drug will diffuse and equilibrate, but the ionized form cannot
Thus a large concentration differrence exist between the membrane
What is clearance?
Removal of drug from plasma
What is metabolism
enzymatic alteration of a drug’s chemical structure
WHat are the 4 major types of metabolic reactions for drugs?
oxidation
reduction
conjugation
hydrolysis
What is the difference between pharmacodynamics and pharmacokinetics?
Pharmacodynamics–what the drug does to the body
This included intrinsic sensitivity/responsiveness of the body’s receptors to a drug
Pharmacokinetics–what the body does to the drug
This includes absorption, distribution, metabolism, and excretion of drugs
What are enantiomers?
2 molecules having the same chemical composition but different orientations around a central atom–mirror images
What is the term used to describe a mixture containing both enanitiomers in equal proportions?
Racemic
What is the difference in a agonist and antagonist
Agonist–a drug that produces its clinical effect by binding to a receptor and activating it (mimetic)
Antogonist–a drug that produces its clinical effect by binding to a receptor WITHOUT activating it and simultaneously provents an agonist from stimulating it (blocking)
A(n) ___________-acting receptor agonist combines directly with its receptor to trigger its physiologic response, while a ___________-acting receptor agonistproduces its physiologic response by increasing the concentration of ENDOGENOUS substrate at receptor site
direct
indirect
What is the difference between competitive and noncompetitive antagonism?
In competitive antagonism the receptor inhibition can be overcome by increasing the concentration of the agonist at the receptor
In noncompetitive antagonism inhibition CANNOT be overcome by increasing the concentration of the agonist
A small dose gives an exaggerated effect
hyperactive
An allergic reaction
hypersensitive
Situation where an exceptionally large dose is required to produced the desired/expected pharamcologic effect
hypo reactive
tolerance develops within a few doses of a drug. Having to increase the dose to get the same effect
tachyphylaxis
the effect of two chemicals taken together is greater than the sum of their separate effect
Synergistic effect
the effect of two chemicals taken together is less than the separate effect of either alone
antagonistic effect
the effect of two chemicals taken together is equal to the sum of their separate effects
Additive effect
What is a prodrug
A biologically inactive compound that can be metabolized in the body to produce a drug
Of the 3 routes of enteral administration, which is subject to first pass effect
The three routes are oral, rectal and sublinqual. Oral subject to first pass
What is the central compartment and at what speed does it uptake drug
Rapid uptake
Includes IV fluid, and highly vascularized tissues such as heart, brain, kidneys and liver.
Drugs will equilibrate between compartments and eventually be eliminated from the central compartment
what is the peripheral compartment? how quickly does it take up drug?
Slow uptake
Includes les vasuclar tissus like fat, bone, and inactive skeletal muscle
What is the volume of distribution?
Total approximation of all the compartments to which a drug goes.
Relates the amount of drug in the body to the concentration of drug in the blood or plasma
