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Pharmaceutics 2 > Quiz 2 > Flashcards

Quiz 2 Flashcards

1
Q

Orally disintegrating tablets

A

dosage form placed on surface of the tongue, disintegrates with minimal saliva
highly soluble diluents and more disintegrates that conventional tablets
contain flavorants and sweeteners

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2
Q

Advantages of ODTs

A

packaged in moisture resistant blisters
mimic immediate release tablet formulations
good for dysphasia patients or patients at risk with non-compliance

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3
Q

Chewable tablets

A

pleasant tasting
disintegrate in mouth with chewing
good for patients with difficulty with swallowing whole tabs
good if prepared as an IR tablet/capsule is too large to swallow
mainly API and diluent
do not usually have disintegrants

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4
Q

Nanoparticles

A

type of drug delivery system
range from 10-100nm
consist of drug entity and polymers/lipids

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5
Q

What allows for better and favorable interactions of nanoparticles with cellular membranes?

A

large surface area to volume ratio

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6
Q

What are examples of drug entities that may form nanoparticles?

A

small molecule drug
peptides/proteins
nucleic acid (mRNA)

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7
Q

Liposomes

A

bilayered lipid assemblies
can be located with high amounts of hydrophilic drugs
most studied colloidal system for drug delivery

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8
Q

Micelles

A

nanosized assemblies of surfactants (amphiphilic molecules)
used to load and carry hydrophobic drugs

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9
Q

Polymers can be used to make?

A

drug conjugates

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10
Q

What is a key advantage of micelles and liposomes as applied to drug solubility?

A

both increase drug solubility

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11
Q

mRNA is highly x and y charged

A

hydrophilic
negatively

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12
Q

How do nanoparticles enter a cell?

A

endocytosis

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13
Q

Are nanoparticles rapidly cleared from the kidneys?

A

no, their size is the problem
renal filtration cut off is 10nm

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14
Q

Where do nanoparticles circulate and accumulate longer?

A

in tumors

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15
Q

Less than 10nm means what for the kidneys?

A

rapid filtration

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16
Q

What characteristics make nanoparticles useful for anti cancer drug delivery?

A
  1. greater drug loading capacity
  2. loading of multiple drug molecules, drug-drug combos
  3. allow to modify/tune drug release rate
  4. circulate longer, lesser elimination by the kidneys
  5. can be modified with PEG to decrease non-specific uptake into liver and spleen; increase circulation times
  6. multivalency/drug targeting
  7. enhanced permeability and retention effect
  8. can overcome drug resistance and still delivery drug to cells
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17
Q

PEGylation

A

masks the surfaces of nanoparticles
decreases non-specific binding of proteins -> decreases uptake by the liver
increases nanoparticle circulation
causes nanoparticles to have a positive surface charge

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18
Q

Serum albumin is known as opsonin. How does PEG change opsonin’s effect on nanoparticles?

A

it reduces opsonin association with nanoparticles; increases circulation

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19
Q

PEG is what kind of polymer?

A

nonionic

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20
Q

Multivalency

A

concept of nanoparticles being modified/decorated with many ligand copies

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21
Q

Multivalent particles increase and promote what?

A

increase particle uptake into cancer cells
promote effective drug delivery

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22
Q

Can nanoparticles be internalized into cancer cells at higher amounts compared to the free drug?

A

yes

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23
Q

Enhanced permeability and retention in tumors allows for what?

A

greater drug delivery and effective cancer killing

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24
Q

Gaps in between endothelium are > 100nm which means nanoparticles can?

A

escape and accumulate/ extravasate/ permeate through leaky capillaries into tumor region

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25
Q

Tumors do not have functional lymphatic drainage which means nanoparticles are?

A

retained there longer

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26
Q

What do nanoparticles avoid getting recognized by? Why is it helpful?

A

efflux pumps
prevents them from getting sent out of the cell
helps overcome drug resistance

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27
Q

t 1/2

A

circulation half-life time
time taken for original dose/concentration to reduce to 50%

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28
Q

clearance

A

volume of blood/plasma cleared of the drug per unit time

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29
Q

Nanoparticles show longer t1/2 circulation times in comparison to ?

A

the free drug

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30
Q

Nanoparticles show a slower rate of clearance in comparison to ?

A

the free drug

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31
Q

How do PEG chains impact the half life of liposomes?

A

increase the circulation half life; reduces clearance
modification with targeting ligands increases tumor cell uptake

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32
Q

In stealth liposomes the lipid bilateral contains polymer lipids which could have what attached to them?

A

Peptides

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33
Q

Doxil

A

anti cancer drug
dramatically decreases cardiotoxicity of the free drug doxirubicin

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34
Q

What does Daunorubicin treat?

A

leukemias

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35
Q

What is AmBisome?

A

amphotericin B- hydrophobic drug localized in lipid bilayers
treats fungal infections

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36
Q

What is paclitaxel?

A

hydrophobic cancer drug

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37
Q

Micelles can circulate longer and have a slower clearance compared to what?

A

the free drug

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38
Q

Micelles have improved therapeutic efficacy compared to what?

A

the free drug

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39
Q

What does GRAS stand for?

A

Generally recognized as safe

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40
Q

Where do pharmaceutical polymers come from?

A

natural sources
made synthetically

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41
Q

General uses of polymers

A

packaging, containers, devices, septa, tubing, contact lenses, stents/inserts, films

liquid dosage forms: flocculating agents, viscosifiers, surfactants, cosolvents

suppository bases

transdermal patches: backing, membranes, adhesives

semisolids/topicals: thickeners/ointment bases

oral: binders, disintegrants, films, controlled drug delivery

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42
Q

What does the degree of polymerization indicate?

A

how many monomers have combined to form a polymer

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43
Q

What are polymers commonly referred to as?

A

Large molecules or macromolecules

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44
Q

How does polymerization impact molecular weight?

A

distribution of polymer chain lengths means no singular molecular weight

average molecular weight is what is usually presented on commercially available polymers

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45
Q

As molecular weight of polymers increases what happens to the melting temperature?

A

it increases

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46
Q

Oligomers are made of how many monomers?

A

30-100

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47
Q

Room temperature in celsius

A

25

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48
Q

Body temperature in celsius

A

37

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49
Q

Macromolecules have difficulty organizing themselves into ?

A

lattices

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50
Q

How do polymer molecules organize themselves?

A

periodically organized (crystalline)
randomly (amorphous)

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51
Q

What are spherulites?

A

folded polymer chains separated by entangled connecting links with no discernible order

semi-crystalline

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52
Q

What affects how a polymer could be used in pharmacy?

A

the degree of crystallinity or absence of it

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53
Q

What dissolves faster: amorphous API or crystalline API?

A

amorphous because there are fewer interactions to break

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54
Q

What is more likely to recrystallize rapidly: amorphous or crystalline?

A

amorphous

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55
Q

If API molecules are dissolved in amorphous regions of a water soluble polymer what can be prevented?

A

recrystallization

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56
Q

Molecules cannot be absorbed by the body until?

A

they have been dissolved in the GI fluid

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57
Q

How can properties of a homopolymer be modified?

A

chemically reacting polymers together or physically mixing/blending polymers together

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58
Q

co-polymerization

A

chemical reaction involving in more than one type of monomer
results in different types of copolymers based on individual monomers

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59
Q

What are some types of copolymers?

A

random - used as binders/viscosifiers
alternate - used for DR or XR
block - used for surfactants
graft - used for specialized XR, not common

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60
Q

Viscosifiers/ Thickening Agents

A

polymeric excipients, usually cellulosic, used in liquid and semisolid dosage forms

polymers dissolved/dispersed in vehicle of formulation and have long chains

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61
Q

Viscosity

A

resistance to flow of a system under an applied stress

62
Q

Water molecule H bonded to polymer functional groups makes the solution more x to flow?

A

difficult

63
Q

D = (RT)/ (6pi x viscosity x N)

A

Stokes-Einstein equation
compares how diffusivity and viscosity affects the movement of molecules

64
Q

As viscosity of the medium increases, diffusivity x. The amount of time it takes a molecule to diffuse with the concentration gradient by random motion will also y.

A

decreases
increases

65
Q

t= (x^2)/ (2D)

A

Brown’s equation
relates distance and diffusivity to time

66
Q

The more viscous a liquid, the greater ?

A

the applied force required to make it flow at a particular rate

67
Q

Why would we use a viscosifier be used in topical preparations?

A

desirable texture and consistency
slow separation of components
shear-thinning base = easy application and retention against gravity following application

68
Q

Why would a viscosifier be used in oral liquid preparations?

A

acceptable palatability
improve flavor
may help coat throat and soothe inflammation
shear-thinning vehicle allows easier pouring following shaking and slower settling of particles/solutes on storage

69
Q

Why would we use a viscosifier be used in ophthalmic and intranasal products?

A

prolonged residence time following administration; allows more time for drug absorption

70
Q

Why would we use a viscosifier be used in parenteral formulations?

A

slower diffusion of the drug away from the injection site
prolonged therapies

71
Q

Semi synthetic cellulose derivates

A

based on cellulose- a structural polymer of fibrous stalks and branches in plants

modify cellulose-> functional groups easily hydrated by water

viscosifer

methylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, sodium carboxymethylcellulose

72
Q

Natural polymer

A

gums
derived from high molecular weight polysaccharides from seaweeds, plants, or bacteria
hydrophilic, good for gel forming and viscosifiers

acacia, tragacanth, xanthan gum, carrageenan, sodium latinate

73
Q

Synthetic Polymers

A

viscosifiers made from precisely designed chemical reactions

controlled growth and chemical cross linking from these is good for hydrogels

carbomer, poloxamer

74
Q

Pharmaceutical gels form when lyophilic colloidal particles interact with?

A

liquid vehicles to form a 3D continuous network

75
Q

Gelling agents

A

excipients that activate to form a gel on contact with fluid or are in manufactured gels

76
Q

Type 1 gels

A

chemical gels
covalently cross-linked at junctions between homopolymer chains
highly hydrophilic but not soluble in water
sometimes termed hydrogels
mechanically rigid

77
Q

Type 2 gels

A

physical gels
physically interact at junction zones via non covalent interactions
hydrophilic homopolymer
disperse with mixing; form gels at rest- demonstrate shear-thinning rheology

78
Q

Gel Preparation

A
  1. other dry components are pre-mixed with the powdered gelling agent
  2. mixture is pre-wetted using propylene glycol, glycerol, or ethanol
  3. mixture is slowly and deliberately added to a vortexed medium to avoid clumping
  4. gelatin is triggered using prescribed stimulus (pH and temperature)
79
Q

Examples of gelling agents

A

carbomers
carboxymethylcellulose
sodium carboymethylcellulose
sodium alvin ate
propylene glycol alginate
tragacanth
poloxamers
gelatin
methylcellulose
colloidal silicon dioxide

80
Q

Macroscopic hydrogels

A

sizing between mm and cm
typically implanted surgically/ used for transdermal delivery

81
Q

microgels

A

hydrogel particles typically sized less than 5um
delivered through oral or pulmonary routes

82
Q

nanogels

A

hydrogel particles typically sized 10-100nm
delivered parenterals

83
Q

What kind of bonds are drugs to mesh structures?

A

covalent

84
Q

(rmesh/rdrug) > 1

A

drug freely diffuses through the mesh
XR takes 1-24 hours

85
Q

(rmesh/rdrug) = 1

A

drug slowly diffuses through mesh
XR takes days

86
Q

(rmesh/rdrug) < 1

A

drug is immobilized, mesh must degrade or swell for drug to be released

XR takes months

87
Q

Thermoreversible Polymers

A

undergo a reversible sol-gel transformation, forming gels at high temperatures and solutions at low temperatures

88
Q

Why would hydrogels be good for injections?

A

Injected as a liquid, forms a solid, controlled release over time

89
Q

Passive diffusion

A

spontaneous movement of molecules through a membrane that does not actively participate in the process

driven by a concentration gradient

90
Q

Donor side of the membrane

A

where delivery occurs
typically GI lumen

91
Q

Receptor side of the membrane

A

typically blood

92
Q

Transcellular diffusion

A

passive diffusion
how most small molecule API are absorbed by the body
through the cell

93
Q

Paracellular diffusion

A

passive diffusion through leaky junctions

94
Q

Transcytosis/Receptive mediated

A

active process
receptors bind to ligand and cytoplasm around engulfs it
transports through the cell, then exocytosi

95
Q

Mass transport processes are important to

A

drug absorption, elimination, and delivery
osmosis
filtration and dialysis

96
Q

What do mass transport models help show?

A

how groups of molecules move spontaneously

97
Q

Diffusion

A

process where molecules move spontaneously from one location to another by a concentration gradient

[high] -> [low]

98
Q

Diffusion proceeds until the solution becomes ?

A

homogenous

no areas of [high] or [low]

99
Q

flux

A

diffusion rate per unit area [mass/(area x time)]
proportional to diffusivity
represented by the letter J

100
Q

Diffusivity

A

diffusion coefficient [area/time]
reflects amount of solute diffusing across an area in a fixed amount of time under the influence of a concentration gradient

101
Q

(dW/dt) = -DA(dC/dX)

A

Fick’s FIrst Law of Diffusion

102
Q

J = dW/ (Adt) = -D(dC/dt)

A

flux
is proportional to diffusivity

103
Q

(dC/dt) = D ((a^2)x C) / (ax^2)

A

Fick’s 2nd law of diffusion
how concentration with time also change with respect to position

104
Q

J = (D(C1-C2)) / h

A

given time and constant donor and receptor compartment concentrations, gradients reach a constant value

falls under Fick’s second law of diffusion

105
Q

What is the steady-state?

A

constant slope of the diffusion layer

106
Q

What are sink conditions?

A

time at which C1-C2 is a constant and no longer changing

107
Q

Partitioning

A

movement of molecules from one phase into another across an interface

concentrations at equilibrium are determined by the affinity of the molecules in each phase

108
Q

A diffusant will have a different affinity for the membrane than for ?

A

donor and receptor compartments

109
Q

Permeability

A

coefficient having units of cm/s or distance/time

constant for a molecule partitioning into a material/environment, reflective of its affinity for that environment

110
Q

P = (DK)/ h

A

permeability, how fast something moves

111
Q

In delivery from transdermal systems to API partitions from membrane into skin. How is the API removed from the delivery site?

A

blood

112
Q

Transdermal delivery systems overload the reservoir of API, why?

A

To keep C1 constant; constant delivery

113
Q

Sink conditions assume donor and receptor compartments will?

A

reach an equilibrium where C1> C2 and the difference between them remains constant

114
Q

Diffusion at a steady-state is what kind of process?

A

a constant rate process

115
Q

Does diffusion at a steady-state immediately establish a concentration gradient?

A

no

116
Q

W = PAC1 X t

A

equation for constant rate diffusion

117
Q

Lag effect: W= PAC1 (t-tL)

A

slow initial release; takes time to speed up to steady state
occurs when membrane is unsaturated at t=0
diffusion experiments
physiological experiments

118
Q

Burst Effect: W = PAC1 (t + tB)

A

rapid initial release; takes time to slow down to a steady state
occurs when membrane is pre saturated at t=0
devices
drug products

119
Q

tL = (h^2)/ 3D

A

lag time equation

120
Q

tB= (h^2)/3D

A

burst time equation

121
Q

A molecule diffusing through a series of consecutive layer will be rate limited by?

A

the least permeable layer

122
Q

In a multi-layer series diffusion the overall diffusion rate will be described by?

A

an apparent permeability

123
Q

Observed flux for diffusion through a series of consecutive layers is determined by?

A

the apparent permeability

124
Q

What is the general process of the Higuchi molecule?

A
  1. API partitions into and then diffuses through lipid layer
  2. API partitions into hydrous layer and then diffuses through it
  3. API transits away from region by blood- maintains sink conditions
125
Q

What does the Higuchi model consider rate limiting for pathways?

A

layer where diffusion encounters the greatest resistance

126
Q

To eliminate patient-to-patient physiologic variability, many drug products are designed to have what?

A

a rate-limiting boundary

127
Q

Resistance

A

reciprocal of permeability
has units of s/cm or time/distance
how much difficulty a molecule has diffusing through a layer

128
Q

The greater the resistance in a layer, the slower the?

A

diffusion

129
Q

Greater resistance in a layer means permeability is?

A

low

130
Q

If Ri is significantly larger than other layers (greater than 10), diffusion through the layer is rate determining and ?

A

Rtot is about the same as Rapp

131
Q

Which layer in the Franz Diffusion cell is subject to stirring? Which is not?

A

Bulk of solution is
Static diffusion layer is not

132
Q

Rtot = (2hw)/Dw + (hm)/(DmKm)

A

resistance at physiological conditions

133
Q

If Rm> Rx what kind of diffusion is it?

A

membrane limited

134
Q

The layer a molecule diffuses through the fastest in parallel pathways is?

A

rate determining

135
Q

What does partition coefficient K describe?

A

relative affinity of a molecule for water an lipid phases
magnitude is proportional to its permeability
assumes unionized molecules only

136
Q

K>1

A

lipophilic molecule

137
Q

K<1

A

hydrophilic molecule

138
Q

logP>0

A

lipophilic molecule

139
Q

logP<0

A

hydrophilic molecule

140
Q

Ionization makes molecules more?

A

polar

141
Q

pH-partition hypothesis

A

biological membranes are largely lipophilic, drug permeability will be higher in regions regions where the unionized form is predominant

142
Q

When pH<pKA for an acidic api?

A

the unionized form will be greater than the ionized form

143
Q

Molecules with a lower affinity causes molecules to diffuse

A

slower

144
Q

Increasing ionization reduces the affinity that API have for?

A

lipid membranes

145
Q

Distribution coefficient

A

K’
assumes only unionized molecules

146
Q

when logD=logP the pH favors ?

A

the unionized form of the molecule
ionization is insignificant

147
Q

What is significant for alphaionized?

A

greater than 0.50

148
Q

As alphaionized becomes significant, what happens to K’, P, and the absorption rate?

A

they all decrease

149
Q

When ionization is significant, K’>K, permeability of a mixture of ionized and unionized species will be xxx compared to completely unionized species?

A

smaller

150
Q

Mass transport from a solution containing a mixture of ionized and unionized species will be xxx compared to completely ionized species

A

slower

Pharmaceutics 2 (6 decks)

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