Chapter 1 - Basic Concepts Flashcards by amanda kastel

if there is 100mg of drug administered and 80mg in circulation, what is the bioavailability

0.8

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symbol for bioavailability

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3 examples of how an API/drug can be simply chemically modified

forming esters
forming salts
forming complexes

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true or false

it is not possible for different dosage forms of the same drug to have different bioavailability in systemic circulation

FALSE - it is very possible

ie - bioavailability of IV is always 100%. oral is usually much lower

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briefly explain what biopharmaceutics is

the study of the relationship between the intensity of biological effects observed in living things and the characteristics of the drug and dosage form (ie - how does adjuvant affect bioavailbility and the subsequent clinical result?)

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true or false

intravenous injections have a rapid absorption mechanism

FALSE - NO ABSORPTION AT ALL

always 100% bioavailable. goes directly into circulation

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define absorption

process of the drug going from the GI tract (or other site - like through the skin) and into the blood

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the “plasma profile” we aim to control describes the amount of drug located where?

in CIRCULATION

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true or false

for every route of administration besides IV, absorption occurs

TRUE

even if it’s only a little bit - still absorbed somehwat

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true or false

IV infusion is an example of zero order kinetics

true

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can drug go from the circulation and into the GI tract?

YES, but very small amount

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what is the term for drug going from the circulation and into the tissues

distribution

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fick’s law

as concentration decreases, the rate decreases as well

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true or false

if 2 manufacturers make the same product (same drug, same dosage form), it is not possible for them to have different plasma concentrations

what if it’s the SAME manufacturer, same dosage form, same drug?

FALSE - it is - bc of different manufacturing processes

could STILL BE DIFFERENT - even if the manufacturer is the same

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2 general factors influencing drug availability

-physiochemical properties of the drug substance (API itself)

-Formulation factors that affect the drug releasing from the DOSAGE FORM

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as drug concentration gets lower at the absorption site, where is it going

into the body

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as drug concentration decreases in the body (systemic circulation), where is it going

either metabolized in the liver or getting excreted by the kidneys

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what helps us determine if the dose of a drug should be increased or decreased

the plasma profile

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prior to being absorbed, what must happen to the drug

MUST dissolve in the fluid at the absorption site - must be water soluble!

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true or false

reducing the particle size of a drug always increases its bioavailability

FALSE - doesn’t always work and may have to play around with other things

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for which does reducing particle size have a greater effect on increasing the bioavailability:

-drug that is poorly water soluble
-drug that is water soluble

drug that is poorly water soluble - can be expected to have greater effect on increased bioavailability

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explain why reducing the particle size can help to improve bioavailability

reducing the particle size INCREASES THE SURFACE AREA, thus increasing the dissolution RATE (NOT the solubility of the drug itself)

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true or false

reducing the particle size of a drug increases it solubility in water

FALSE - does not increase solubility. increases DISSOLUTION RATE

solubility is a constant value for each drug

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true or false

reducing the particle size increases the surface area

true

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true or false let's say a drug is being administered as 500mg capsule it is found that the micronized form has a higher dissolution rate is it possible to reduce this 500mg to a lower value and still get the same effect? (if we use the micronized version)

YES

true or false small particle size can actually be bad for some drugs

TRUE for drugs that already dissolve quickly, this could be bad bc the drug will be there in very large quantities OR reducing the particle size for drugs unstable in gastric fluid may enhance their inactivation

true or false small particle dissolve at a faster rate than larger particles

true

for a drug unstable in gastric fluids, what particle size do you want

COARSE - not super tiny. a super tiny particle size will make it all get degraded very quickly rate of inactivation is slower with a coarser particle size

a high particle size can slow down the gastric inactivation of some drugs what else may be beneficial about a large particle size

may reduce side effects

true or false polymorphism is very uncommon for drugs

false - common - around 70% of drugs

true or false compared to the crystalline form of a drug, the polymorphic form contains less energy

FALSE - contains more internal energy, so LESS external energy is needed for it to dissolve

true or false polymorphic forms are less stable than crystalline forms

true

true or false polymorphic forms have greater solubility than crystalline forms

true

true or false crystalline forms have a faster dissolution rate than polymorphic forms

FALSE - slower dissolution rate

true or false weak organic bases/acids are very water soluble

FALSE - poorly water soluble and need to be turned into their salt form

what is the term for the dissociation constant of acidic/basic drugs

acidic - Ka basic - Kb

explain how the dissociation constant of drugs is useful in determining its absorption

drugs in unionized forms are easily absorbed, but NOT easily soluble in the GI fluid dissociation constant indicates the extent to which a drug will dissociate into its IONIZED FORM if lot is ionized - won't be well absorbed through GI membrane but will dissolve

formula for partition coefficient

concentration in oil/conc in water

the rate of permeation of a drug through the membrane is based on what

FICK'S FIRST LAW

explain what Fick's first law is

the rate of diffusion of a substance through the membrane is DIRECTLY PROPORTIONAL to the concentration gradient

the drug diffusing through the membrane must be in ____ form

solution (dissolved)

true or false according to Fick's first law, the lower the concentration gradient, the higher the rate of diffusion

FALSE - the higher the concentration gradient, the higher (faster) the rate of diffusion

*class I solubility and permeability

high solubility, high permeability

*class II solubility and permeability

low solubility, high permeability

*class III solubility and permeability

high solubility, low permeability

*class IV solubility and permeability

low solubility, low permeability

a drug is considered highly soluble when.....

the HIGHEST DOSE STRENGTH is soluble in 250mL or less of aqueous media over pH range 1-8

as mentioned, a drug is considered highly soluble when the highest dose strength is able to dissolve in 250mL or less in the aqueous media, over a pH range 1-8 when is a drug considered to have LOW SOLUBILITY

if the volume of aqueous media needed to dissolve the drug over pH 1-8 is OVER 250mL

when is a drug considered to be highly permeable

when the extent of absorption is over 90% of the administered dose

how to improve the bioavailability of a class II drug

class II has low solubility and high permeability. to improve solubility profile, reduce the particle size to increase the dissolution rate! bioavailbility will increase

true or false class III has lower solubility than class II

FALSE - class II has lower solubility class III solubility is high

can tetracycline be dissolved in ringer injection solution

NO - contains calcim, will form a complex

do excipients affect the bioavailability of the drug

YES

Na CMC + amphetamine

decreased bioavailbility of amphetamine bc of interaction

what does phenobarbital react with and what is the result

PEG 4000. absorption of phenobarbital is reduced

component of some dosage forms that is hydrophobic

magnesium stearate (lubricant) in tabs and caps

3 tablet characteristics that influence bioavailability

-tablet hardness -tablet disintigration -coating (enteric, film)

what is the modified Noyed-Whitney equation based on

DISSOLUTION RATE controls the amount of drug in solution

name an oral dosage form that is immediately available in solution to be absorbed

solutions

true or false emulsions have the same absorption rate as solutions

FALSE emulsions depend on the drug partitioning between the aqueous and oil phases of the emulsion

the time for a tablet to DISINTEGRATE depends on what

on the compression used higher compressional force used = harder tablet -- disintegrate SLOWLY

rate limiting step for drug absorption from tablets for drugs that are: -poorly water soluble -poorly lipid soluble

poorly water soluble - dissolution rate is the rate limiting step for poorly lipid soluble - rate at which drug crosses cell membrane

the application of kinetics is the study of....

KADME "Kinetics of ADME"

what is Cp

plasma profile

2 different types of plasma profile

IV plasma profile (zero order) oral plasma profile (typically 1st order)

true or false pharmacokinetics can help to predict the concentration of the drug in various tissues and fluids of the body

true

the steady state plasma concentration of a drug is more relevant for which type of drug?

steady state concentration is more relevant for a drug that is administered chronically rather than for a short period of time

as mentioned, the steady state plasma concentration is more relevant for a chronic drug than one that is only administered for a short amount of time. what about half life?

half life is important for ALL drugs

AUC is a measure of...

the extent of drug absorption into the systemic circulation (extent that was absorbed from the administered dose)