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Pharmaceutics II FINAL > Part 1 > Flashcards

Part 1 Flashcards

1
Q

if a drug bottle has the expiration:

3/1/24

when can you use it until

A

the last day of march (3/31)

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2
Q

name 3 drug stability issues and 3 mechanisms of degradation

A

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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3
Q

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

A

environmental –
oxidation (atmospheric oxygen)

photolysis (by sunlight OR room light)

hydrolysis

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4
Q

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

A

hydrolysis

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5
Q

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

A

aspirin is very prone to hydrolysis

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

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6
Q

name 3 medicinal compounds that are very susceptible to hydrolysis

A

esters
lactams
amides

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7
Q

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

A

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

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8
Q

what is added to drugs to prevent oxidation

A

antioxidants

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9
Q

true or false

photolysis is the degradation of drug molecules by normal sunlight

A

FALSE

normal sunlight OR room light

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10
Q

give a method of shelf life estimation

A

Q10 method

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11
Q

give the definition of stability

A

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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12
Q

name the 5 types of stability

A

chemical
physical
microbiological
therapeutic
toxicologic

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13
Q

odor is an example of what kind of stability?

A

physical

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14
Q

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

A

storage conditions
the dispensing container
anticipating interactions that may occur

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15
Q

explain how storage conditions can affect chemical stability

A

temperature
light
humidity

(environmental factors)

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16
Q

explain how different containers can affect chemical stability

A

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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17
Q

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

A

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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18
Q

give an example of therapeutic instability

A

the insulin is there but has no therapeutic effect when injected

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19
Q

define kinetics

A

motion or movement
rate of change over time

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20
Q

give the rate equation and explain the variables

A

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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21
Q

what is zero order kinetics

A

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

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22
Q

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

A

ko = -dC/dt

slope = -ko

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23
Q

give the full formula for ko in a zero order reaction

A

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

24
Q

what does Ct mean in zero order reaction

A

concentration at “t” time

25
Q

give the formula for Ct in a zero order reaction

A

Ct = C0-K0t

26
Q

what is the formula and units for Ko?

A

KO = (C1-C2)/(T2-T1)

units = concentration/time

27
Q

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

A

t1/2 = C0/2K0

28
Q

true or false

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

A

TRUE

29
Q

the higher the Co value, the ____ the half life

A

higher (longer)

30
Q

true or false

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

A

FALSE
it does.

formula is
t1/2 = Co/2ko

higher the concentration, higher the half life

31
Q

true or false

the rate constant for a zero order reaction can be negative

A

FALSE – IT CANT

must be positive. we can’t have a negative drug value in the body

32
Q

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

A

y axis = concentration
x axis = time

33
Q

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

A

the first power of the concentration of a single reactant

34
Q

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

A

concentration decreases exponentially with time

35
Q

what is the rate constant for 1st order kinetics?

what is the rate constant for zero order kinetics?

A

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

for 0 order = Ko

36
Q

first order kinetics:

__________ = kc

A

-dc/dt

37
Q

what is the slope formula for 1st order kinetics

A

-k/2.303

38
Q

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)

A

TRUE

39
Q

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

A

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

40
Q

give the formula to calculate Ct for 1st order kinetics

A

ln Ct = ln Co - Kt

41
Q

most drugs follow ______ order elimination rate constant

A

1ST

second is ZERO order

42
Q

give the formula to calculate half life in first order kinetics

A

t1/2 = 0.693/k

43
Q

true or false

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

A

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)

44
Q

ln ____ = 0.693

A

ln2

45
Q

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

A

zero order:

Ko units = concentration/time

first order:

K units = 1/time (NOT CONC DEPENDENT)

46
Q

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

A

drug concentration

47
Q

define shelf life

A

the time required for 10% of drug to degrade

(WITH 90% OF INTACT DRUG REMAINING)

48
Q

Give the arrhenius equation.

what is it used to calculate?

A

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

49
Q

When using the arrhenius equation, Ea was calculated to be 25,651kcal/mol

what does this mean?

A

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

50
Q

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

A

1.987 cal K ^-1 mol ^-1

51
Q

what is the method of estimating shelf life

A

Q10 method

52
Q

true or false

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

A

FALSE – the shelf life remains the same regardless of concentration

RATE of degradation is dependent on concentration but not the shelf life

53
Q

true or false

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

A

true

54
Q

give the formula for the Q10 method of estimating shelf life

A

t90 (T2) = t90(T1) / Q10 ^(diff in temp1 and 2/10)

t90(T2) = estimated shelf life
t90(T1) = given shelf life at given temp

55
Q

what is the normal Q10 value for most drugs?

A

3

56
Q
A

Pharmaceutics II FINAL (11 decks)

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