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Pharmacy Practice Lab II > Lab 5 > Flashcards

Lab 5 Flashcards

1
Q

many formulation issues can be solved by what 2 things?

A

the careful selection of excipients and the use of good techniques

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2
Q

name 3 suspending agents.
are they hydrophobic or hydrophilic?

A

methylcellulose (MC)
carboxymethylcellulose (CMC)
natural gums (tragacanth)

EXTREMELY HYDROPHOBIC COMPOUNDS

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3
Q

methylcellulose, carboxymethlcellulose, and natural gums (tragacanth) are suspending agents.
what is another term for them?

A

hydrocolloids

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4
Q

since MC, CMC, and tragacanth are extremely hydrophobic compounds, what is an important consideration when working with them?

A

they form lumps when added directly to water (fish eyes)

they are difficult to break up and slow to dissolve because the water does not penetrate beyond the hydrated surface

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5
Q

explain the structure of the lumps/fish eyes formed from the addition of extremely hydrophobic suspending agents directly to water

A

they consist of a swollen hydrated gel at the surface and a dry core at the center

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6
Q

___ and ____ are amphiphilic molecules containing polar and nonpolar moeities in their structure

A

glycerin and ethanol

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7
Q

true or false

glycerin and ethanol, because they are amphiphilic, can interact favorably with hydrophilic and hydrophobic drugs

A

true

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8
Q

glycerin and ethanol have ______ capacity

A

wetting

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9
Q

besides their wetting capacity, glycerin and ethanol can act as ______ for hydrocolloids

A

dispersants

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10
Q

name a common technique to prepare suspension vehicles when using hydrocolloids

name 2 other techniques

A

make a slurry of the hydrocolloid with glycerin or ethanol and then carefully add water to the slurry with stirring

the glycerin/ethanol forms a coat around the dry particles, delays the surface swelling, and even permits hydration

another method is to have the hydrocolloidal suspending agent mixed with water and kept standing for several hours before dissolving with the aid of heat

another is to vigorously agitate the water and the suspending agent is sprinkled carefully in the vortex (formed with the water) to ensure the quick dispersion of the particles

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11
Q

explain the vigorous agitation method of preparing suspensions with hydrocolloids further

A

vigorous agitation may result in foaming.
once dissolved, the colloidal suspension is allowed to stand for at least 24 hours to complete hydration and reach maximum viscosity

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12
Q

hydrocolloids

A

extremely hydrophobic
cellulose derivatives and gum

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13
Q

_____ are directly added to water as they do not form the same lumps as the cellulose polymers or gums (tragacanth)

A

clays (bentonite)

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14
Q

as mentioned, clays (bentonite) are added directly to water because they do not form the same lumps as the cellulose polymers and gums.

however….

A

a period of standing is still required for hydration

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15
Q

what is a simple method of preparing suspensions

A

to dissolve or suspend the drug in simple syrup

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16
Q

as mentioned, a simple method of preparing suspensions is to dissolve or suspend the drug in simple syrup.

what is the issue with this?

A

several drugs have serious stability and compatability issues and the physical, chemical, and microbial stability of the drug must be considered

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17
Q

define stability

A

the extent to which a product retains its labeled content and original properties through its shelf life (period of storage and usage)

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18
Q

where are the stability limits specified?
must be at least ______% of the labeled content

A

in the USP
at least 90%

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19
Q

not only must the drug be at least 90% of its labeled content, but also……

A

the suspension must also retain its desired characteristics such as sedimentation rate, dispersability, flavor, color, etc

20
Q

name 8 factors that alter stability

A

-pH
-temperature
-light
-humidity
-air (oxygen)
-particle size
-solvents
-other chemicals and contaminants/microbial contamination

21
Q

____ is one of the most important factors affecting the stability of a product

A

pH

22
Q

drug degradation often occurs via…

A

pH dependent hydrolysis

23
Q

how is stability determined?

A

degradation rate constants are calculated for a range of pH values

the degradation rate constants are plotted vs pH to plot a log K-pH profile

24
Q

on the log K-pH profile, the minimum points on the graph are the areas of ____ stability

A

BEST

25
Q

the pH of the least degradation is used.
how is this accomplished?

A

through use of buffers

26
Q

when adjusting pH with buffers, what is an important consideration

A

the pH must also be compatible with other excipients and other aesthetic properties of the formulation

27
Q

hydrochlorothiazide is what kind of drug?

A

a diuretic used to treat hypertension

28
Q

explain how HCTZ (hydrochlorothiazide) accomplishes its function as an antihypertensive agent

A

it reduces blood volume by increasing the excretion of sodium, water, and potassium. it is also used to treat heart failure and edema in newborns

29
Q

what is the recommended dose of hydrochlorothiazide

A

1-2mg/kg/dose every 12 hours

30
Q

should HCTZ be taken with meals? any allergy considerations?

A

should be taken with meals to enhance absorption
cross sensitivity may occur in patients allergic to sulfonamide derived drugs

31
Q

explain the physical properties of HCTZ

A

white (or nearly white) almost odorless, crystalline powder and has a slightly bitter taste
aqueous solubility of 722mg/L

32
Q

hydrochlorothiazide oral suspensions prepared using suspending agents (MC, CMC) are shown to produce…..

A

a flocculated suspension, forming a loosely linked polymer network system that is easily redispersed with mild agitation

33
Q

____ vehicles such as ___ and ___ have been used for extemporaneous HCTZ suspensions from commercial tablets

A

commercial vehicles such as ora plus and ora sweet

34
Q

what foods should be avoided and/or taken when taking HCTZ?

A

AVOID:
-alcohol
-natural licorice
-no calcium, aluminum, magnesium, or iron supplements within 2 hours of taking this medication

TAKE:
-With food
-increase potassium intake – add a banana or orange juice

35
Q

the suspension vehicle when preparing HCTZ suspension should be prepared as required for…

A

stability and aesthetic characteristics (flavor, color, etc)

36
Q

why should the drug be pulverized when preparing HCTZ suspension?

A

to achieve the desired particle size

37
Q

pulverization may ____ surface energy and ___ wetting

A

increase the surface energy and hinder wetting

38
Q

add suitable _____ to form a homogeneous paste

A

wetting agent

39
Q

in HCTZ suspension preparation, the drug is added to the vehicle with ____ intensity mixing

A

LOW

40
Q

why is the drug (HCTZ) added to the vehicle with low intensity mixing?

A

any high energy process will incorporate air into the suspension and promote foaming

41
Q

the _____ of the suspension makes it difficult to remove air bubbles

A

viscosity

42
Q

frequently, entrapped air from bubbles will affect the accuracy of the ______

A

volume

43
Q

knowing the _______ will ensure accuracy

A

specific gravity (density of the final product and adjustment of WEIGHT rather than volume)

44
Q

what pH range is HCTZ stable?

A

2-4

45
Q
A

Pharmacy Practice Lab II (12 decks)

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