Pharmacokinetic part 2 Flashcards
What is the Cmax and Tmax and how does it affect what drug you choose?
T max- time from administration to reach Cmax
Cmax- max drug concentration in circulation
you would want the drug that reaches Cmax soonest for acute pain
absorption is defined as the movement of drug molecules from the site of administration to the __________
systemic circulation
How does the route of administration impact drug absorption?
SC and IM route bypasses epithelial barrier so absorption is better. Oral administration has more barriers to absorb than parenteral
Through what process do most drugs pass across epithelial membranes?
passive diffusion
describe the perfect drug for maximal absorption regarding ionization, polarity, lipid solubility, and molecule size
non-ionized, low polarity, highly lipid soluble, small molecular size.
T or F: intramuscularly administered drug will always exhibit a faster onset of action than the same dose of drug administered orally
It depends on the formulation of the IM drug. Aqueous solutions absorb faster than oily solutions; salts formulations; absorb slower than non-salt forms etc.
Which part of the bilayer is hydrophobic?
the middle lipid layer is hydrophobic
instantaneous distribution to most body tissues and fluids is assumed in which compartment model?
one-compartment model
the amount of drug per unit of volume is defined as the:
concentration
Factors that cause variability in plasma drug concentrations after the same drug dose is given to different patients include variations in what parameters
bioavailability: route, dissolution of drug first pass effect, degree of ionization and polarity, intestinal motility, age, gender, genetics, physical activity, drug interactions
why do tablets take longer to be absorbed than parental drugs?
It must first be disintegrated (dissolution) before it can be absorbed and parenteral is already an absorbable form
what is the first step in absorption of oral drugs?
dissolution
what are the parts of the cell membrane?
outer- hydrophilic, middle- hydrophobic
what are the four ways drugs could pass cell membranes?
passive diffusion, facilitated passive diffusion, active transport, or pinocytosis
How are most drugs absorbed across the cell membrane?
passive diffusion
what is Ficks law?
the calculation rate of absorption through the tendency for molecules to move in the direction from higher to lower concentration
what is aqueous diffusion and what drugs can be absorbed this way?
passage through aqueous pores in cell membranes. Only small molecule drugs with low molecular weights can be absorbed this way.
which type of membrane transport requires an ATP molecule and why?
active transport- the ATP is a carrier molecule form of energy
what size should molecules be to diffuse across the intestinal wall?
at least less than 1000 daltons but most that are easily diffused are 250-600 daltons
why is the molecular size important?
some drugs cannot be given orally like heparin due to their large molecular size in Dalton’s.
what is an acid?
a substance that releases positively charged hydrogen ions when it is in a solution.
what is a base?
a substance that can bind H+ ions by accepting the protons attaching them to a compound and then removing them from a solution
is you add a base to an acid will it make it more or less acidic?
less acidic
how does ionization affect the absorption of drugs?
non ionized drugs cross cell membranes easier and are less acidic, ionized drugs are more acidic and do not cross cell membranes easier
What are factors that affect transport?
size of molecule, lipid solubility, polarity, degree of ionization, pH of the environment
which compartment model is distributed faster, one or two parts?
one part
does perfused organs make drug distribution faster or slower?
faster
what plasma protein are most drugs bound to?
albumin
what is the difference in free drug and bound drug?
bound drugs are not active and free drugs are
what type of molecules are restricted from the blood brain barrier?
polar and ionized molecules
what are factors that attribute to low bioavailability?
oral drugs that are poorly water soluble and slowly absorbed.
what is the most common cause of low bioavailability?
insufficient time for absorption in the GI tract
