Part 1 Flashcards by amanda kastel

if a drug bottle has the expiration:

3/1/24

when can you use it until

the last day of march (3/31)

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name 3 drug stability issues and 3 mechanisms of degradation

stability issues:

-loss of Active ingredient from dosage form

-a toxic product can be produced with undesirable effects

-decreased bioavailability

3 mechanisms of degradation:

oxidation, hydrolysis, photolysis

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the mechanisms of degradation in regards to drug stability are _____ factors

environmental –
oxidation (atmospheric oxygen)

photolysis (by sunlight OR room light)

hydrolysis

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what is the most frequent type/mechanism of degradation of drugs?

hydrolysis

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name a drug that has a big issue with hydrolysis and what this means for the dosage forms which it is available

aspirin is very prone to hydrolysis

therefore, when it’s formulated as a suppository, water is not included

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name 3 medicinal compounds that are very susceptible to hydrolysis

esters
lactams
amides

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the OXIDATION mechanism of degradation is usually mediated through reaction with ____ under _____ conditions

reaction with molecular oxygen under ambient conditions (AUTO-OXIDATION)

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what is added to drugs to prevent oxidation

antioxidants

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true or false

photolysis is the degradation of drug molecules by normal sunlight

FALSE

normal sunlight OR room light

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give a method of shelf life estimation

Q10 method

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give the definition of stability

the extent to which a product retains, within specified limits and throughout its period of storage and use, the SAME PROPERTIES AND CHARACTERISTICS THAT IT POSSESSED AT THE TIME OF ITS MANUFACTURE

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name the 5 types of stability

chemical
physical
microbiological
therapeutic
toxicologic

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odor is an example of what kind of stability?

physical

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name 3 factors that must be considered because they can affect the chemical stability of the product

storage conditions
the dispensing container
anticipating interactions that may occur

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explain how storage conditions can affect chemical stability

temperature
light
humidity

(environmental factors)

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explain how different containers can affect chemical stability

glass vs plastic: plastic is preferred because it wont break but sometimes it has chemical stability issues with the product

clear vs amber – amber protects against photolysis if sensitive to light

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explain why it is important to anticipate interactions when trying to preserve chemical stability

anticipate the interactions that can occur when mixing drugs or when selecting certain DOSAGE FORMS

IE: ASPIRIN SUPPOSITORY DOES NOT HAVE WATER

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give an example of therapeutic instability

the insulin is there but has no therapeutic effect when injected

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define kinetics

motion or movement
rate of change over time

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give the rate equation and explain the variables

dC/dt -(C) ^n

dC = change in concentration
dt= change in time

dC/dt = change of concentration with change in time (rate of reaction)

C = concentration
n= the ORDER of the reaction

it’s a minus sign because the concentration is decreasing over time when considering stability

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what is zero order kinetics

the rate of the reaction is INDEPENDENT of the concentration of the reactants

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give the formula for the rate constant and the slope in a graph of a zero order reaction

ko = -dC/dt

slope = -ko

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give the full formula for ko in a zero order reaction

Ko = (C1-C2)/(t2-t1)

what does Ct mean in zero order reaction

concentration at “t” time

give the formula for Ct in a zero order reaction

Ct = C0-K0t

what is the formula and units for Ko?

KO = (C1-C2)/(T2-T1) units = concentration/time

give the formula for t1/2 of a zero order reaction

t1/2 = C0/2K0

true or false every drug has a constant Ko. the value only changes for different drugs

TRUE

the higher the Co value, the ____ the half life

higher (longer)

true or false in zero order kinetics, the t1/2 does not depend on concentration

FALSE it does. formula is t1/2 = Co/2ko higher the concentration, higher the half life

true or false the rate constant for a zero order reaction can be negative

FALSE -- IT CANT must be positive. we can't have a negative drug value in the body

in ZERO ORDER kinetics, the graph is ____ vs _____. what is on the y axis? what is on the x axis?

y axis = concentration x axis = time

in first order kinetics, the rate depends on.....

the first power of the concentration of a single reactant

in first order kinetics, what happens to concentration with time?

concentration decreases exponentially with time

what is the rate constant for 1st order kinetics? what is the rate constant for zero order kinetics?

rate constant for 1st order kinetics = k(c) for 0 order = Ko

first order kinetics: __________ = kc

-dc/dt

what is the slope formula for 1st order kinetics

-k/2.303

true or false for 1st order kinetics, K will be constant for the same drug but different for every drug (like Ko for zero order)

TRUE

Give the formula to calculating the rate constant in first order kinetics

K = (ln C1 - ln C2) / (t2-t1)

give the formula to calculate Ct for 1st order kinetics

ln Ct = ln Co - Kt

most drugs follow ______ order elimination rate constant

1ST second is ZERO order

give the formula to calculate half life in first order kinetics

t1/2 = 0.693/k

true or false for zero order kinetics, the half life does not depend on concentration but for first order it does

FALSE half life depends on concentration for zero order (t1/2 = Co/2Kt) half life does NOT depend on concentration for first order (t1/2 = 0.693/k)

ln ____ = 0.693

ln2

what are the units of the rate constant for zero order? what about first order?

zero order: Ko units = concentration/time first order: K units = 1/time (NOT CONC DEPENDENT)

for first order kinetics, dc/dt depends on......

drug concentration

define shelf life

the time required for 10% of drug to degrade (WITH 90% OF INTACT DRUG REMAINING)

Give the arrhenius equation. what is it used to calculate?

used in finding the energy of activation log K2/K1 = Ea (T2-T1) / 2.3 * R*T1 *T2 K = reaction rate constant T = absolute temp R = gas constant Ea= energy of activation

When using the arrhenius equation, Ea was calculated to be 25,651kcal/mol what does this mean?

if energy is not higher than 25,651 kcal/mol, degradation DOES NOT TAKE PLACE

in the arrhenius equation, what is the value of the gas constant (R)?

1.987 cal K ^-1 mol ^-1

what is the method of estimating shelf life

Q10 method

true or false for a 1st order reaction, as the concentration increases the shelf life also increases

FALSE -- the shelf life remains the same regardless of concentration RATE of degradation is dependent on concentration but not the shelf life

true or false for a zero order reaction, the shelf life IS dependent on concentration but not the rate of the reaction

true

give the formula for the Q10 method of estimating shelf life

t90 (T2) = t90(T1) / Q10 ^(diff in temp1 and 2/10) t90(T2) = estimated shelf life t90(T1) = given shelf life at given temp

what is the normal Q10 value for most drugs?