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Pharmaceutics > Drug Properties, Physiochemical Incompatibilities and Stability > Flashcards

Drug Properties, Physiochemical Incompatibilities and Stability Flashcards

1
Q

drug properties are physical characteristics that can alter ___

A

bioavailability

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2
Q

define solubility

A

the max amount of substance that can dissolve in a given amount of solvent @ a specified temp and pressure

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3
Q

what is the word used when two liquid dissolve in each other

A

miscible

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4
Q

what is the word used when two liquids do not dissolve in each other?

A

immiscible

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5
Q

give an example of 2 liquids that are miscible

A

water and ethanol

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6
Q

give an example of 2 liquids that are not miscible

A

water and oil

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7
Q

explain why aqueous solubility is important for drugs

A

b/c drugs can only be absorbed into the bloodstream in the aq (dissolved) form

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8
Q

could a drug still have the desired effect if it didn’t dissolve in aq?

A

no

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9
Q

what are the 2 main ways to measure solubility?

A

quantitative and qualitative

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10
Q

what are the 6 factors that affect solubility?

A
  1. temperature
  2. solvent pH and solute Pka
  3. presence of other solutes
  4. chemical structure
  5. surface area
  6. melting/boiling point
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11
Q

the solubility of inorganic electrolytes depends on their __ properties and their interactions between their
ions with __ through a process called __

A

crystal; water; hydration

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12
Q

what needs tone overcome during hydration for ions to break free of their lattice structure and dissolve?

A

the heat of hydration needs to be high enough

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13
Q

salts that increase the solubility of a drug are called

A

salt-in

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14
Q

salts that decrease the solubility of a drug are called

A

salt-out

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15
Q

the effects of additives on drug solubility depend on its interactions with what 3 things?

A

water, the solute (drug) and the solvent

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16
Q

how can different functional groups influence solubility?

A

by affecting the molecular cohesion/interaction with water

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17
Q

polar FG groups ___ (raise/lower) solubility of solute. How?

A

raise; by forming H bonds with the water

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18
Q

non-polar groups ___ (raise/lower) solubility of solute

A

lower

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19
Q

ionization of a FG ___ (raises/lowers) solubility

A

raises

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20
Q

why does ionization of a FG raise solubility?

A

charged groups are more polar and therefor more hydrophilic and soluble in water

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21
Q

list the FG position of otrtho, meta, para in order from least to most soluble in water

A

para; ortho; meta

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22
Q

effect of pH is crucial to drugs with __ groups

A

ionizable

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23
Q

acidic drugs are more soluble in __ solutions and less soluble in __ solutions

A

basic; acidic

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24
Q

give an example of an acidic drug

A

NSAIDs

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25
Q

basic drugs are more soluble in __ solutions and less soluble in __ solutions

A

acidic; basic

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26
Q

why does surface area affect solubility?

A

b/c placing a solute molecule in the solvent requires solute-solvent contact points

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27
Q

a larger surface area means a ___ (higher/lower) solubility

A

higher

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28
Q

why does larger surface area result in greater solubility?

A

larger cavity required, more contact points made, making it easier for the solvent to dissolve the solute

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29
Q

the melting point of solids and the boiling point of liquids reflects what?

A

the strength of the interactions between the molecules in the compound

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30
Q

As melting and boiling points increase, what happens to solubility?

A

decreases

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31
Q

drug partition between 2 immiscible solvents is based on __ solubility

A

affinity

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32
Q

the partition coefficient (logP) measures what?

A

the spreading of solute between the aq and organs phases of an immiscible mixture

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33
Q

the P in the partition coefficient is represented by the rate of ___ over __

A

solubility in organic over solubility on aqueous

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34
Q

drug incompatibilities arise when __

A

a drug is mixed with other drugs/products and the result is unsuitable products

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35
Q

drug incompatibilities can result in the alteration of physical and chemical __ and the ___ of the active drug

A

structures; therapeutic effect

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36
Q

what are 2 potential concerns if a drug incompatibility causes a change in the chemical/physical structure of the drug?

A

reduced solubility and/or stability

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37
Q

during which steps of the drug making process can incompatibilities occur?

A

preparation, storage, Administration

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38
Q

what are the types of interactions that can happen in drug incompatibilities? (3)

A
  1. pharmacological / pharmacodynamics
  2. pharmacokinetic
  3. physiochemical
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39
Q

physiochemical interactions could involve an interactions with one/more of what 4 factors?

A
  1. other drugs
  2. solvents
  3. inactive materials (excipients)
  4. devices and packaging
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40
Q

what is poly pharmacy?

A

the concurrent use of multiple medications (all to treat one disease)

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41
Q

what are the 3 types of drug incompatibilities?

A
  1. physical (pharmaceutical)
  2. chemical
  3. therapeutic
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42
Q

what types of products are made by physical drug incompatibilities?

A

non-uniform, unacceptable, or unpalatable products

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43
Q

what is a dosing issue relative to physical incompatibilities?

A

the non-uniformity makes it difficult to accurately measure

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44
Q

what type of drug incompatibility can result in insolubility, immiscibility, precipitation, liquefaction, adsorption, and complexation of materials?

A

physical (pharmaceutical)

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45
Q

physical drug incompatibilities are preventable using __

A

pharmaceutical skills

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46
Q

chemical drug incompatibilities are due to chemical interactions involving the __

A

active ingredient

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47
Q

If an active ingredient is involved in one of the following reactions: hydrolysis, polymerization, effervescence, oxidation, decomposition, precipitation, what sort of drug incompatibility can arise?

A

chemical

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48
Q

a drug incompatibility that occurs immediately after compounding is called __

A

immediate

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49
Q

a drug incompatibility that occurs later on after compounding is called __

A

delayed

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50
Q

a therapeutic drug incompatibility occurs when

A

the prescribers intended purpose does not math the therapeutic outcome

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51
Q

what are the 2 classes of drug incompatibility prevention?

A

chemical and physical

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52
Q

what are the six methods of prevention against physical incompatibilities?

A
  1. sequence of mxing
  2. change solvents
  3. change AI type/form
  4. change volume
  5. emulsification and addition of suspension agents
  6. addition, replacement, or removal of unnecessary ingredients
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53
Q

low solubility can result in crystallization. The mechanism of drug crystallization is often involves what factor?

A

pH

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54
Q

some IV drugs are unable to be safely mixed due to __

A

drug crystallization

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55
Q

pH of commercially available infusion fluids can vary between __ to ___ pH units. What is the issue with this?

A

1-2; pH is measured on a log scale, so 1-2 units is actually a big difference, so the drug. may be compatible with 1 batch, but not another

56
Q

what is a common solubility issue associated with pH

A

crystallization

57
Q

how can the mixing of drugs be done more safely with respect to concerns of pH affecting solubility?

A

using equations that relate pka to solubility to predict the solubility

58
Q

what are the 7 causes of drug incompatibilities?

A
  1. pH change
  2. alteration of solvent characteristics
  3. cation–anion interactions
  4. effect of salts
  5. chelation
  6. ion-pair formation
  7. adsorption
59
Q

a change in pH often leads to what physical/ chemical change of the drug?

A

precipitation

60
Q

provide an example of in vitro (in drug) effects of pH change

A

change in solubility/stability of the active ingredients or excipients

61
Q

solubility of Ca and phosphate in TNP is __ dependent

A

pH

62
Q

is a low or high pH more suitable for solubility?

A

low (acidic)

63
Q

what are some (3) in vivo (in patient) effects of pH change?

A

can neutralize H ions in the stomach, increasing the pH; change rate of gastric emptying; change pH of urine

64
Q

in vivo pH can be altered with ingestion of __, __ and __

A

antacids, food, weak electrolytes

65
Q

what is the effect of antacids containing Ca on gastric emptying?

A

slows

66
Q

what is the effect of antacids containing Mg on gastric emptying?

A

speeds up

67
Q

explain the incompatibility cause of : alteration of solvent characteristics

A

the solvent can be altered by become diluted (if involved in co-solution with water) and can also be altered by becoming supersaturated if the drug (solute) concentration is too high

68
Q

cation–anion interactions result in the formation of _ through the methods of __, __, or __

A

insoluble complexes; complexation, precipitation, phase separation

69
Q

explaiin how salting out decreases solubility

A

highly hydrated non-organic ions deprive organic ions/molecules from getting enough water to dissolve

70
Q

the release of CO2 from carbonated beverages when NaCl is added is an example of the effects of ___ on solubility

A

salts

71
Q

what is chelation?

A

complex between a metal atom/ion and an organ anion

72
Q

in chelation, what is the e- acceptor and donor?

A

acceptor is the metal and donor is the organic

73
Q

chelation results changes in __ and __

A

solubility and absorption

74
Q

T/F chelation can result in either increased or decrease absorption

A

true

75
Q

deferiprone is used for treatment of __ by forming a chelate with

A

iron toxicity; iron

76
Q

EDTA is used for treatment of __ and __ poisoning

A

lead; mercury

77
Q

tetracycline forms chelates with which metal ions?

A

Ca, Fe, Mg, Al

78
Q

how does tetracycline use its ability to chelate with Mg ?

A

uses to target the ribosomes of the bacteria which are rich in Mg

79
Q

what is an adverse effect of tetracycline forming a chelate with ca?

A

discolouration of teeth

80
Q

explain ion-pair formation

A

production of neutral species when opposing charges on atoms interact through electrostatics

81
Q

ion-pair formation results in the charges being __

A

“buried”

82
Q

the products of ion-pair formation are ___ enough to dissolve in non-aqueous solvents

A

lipophilic

83
Q

provide an example of ion-pair formation

A

absorption of highly charged drugs

84
Q

what is adsorption?

A

sticking of dissolved drugs onto surface of adsorbents

85
Q

medical adsorbents are used for __

A

removing toxic substances form the gut

86
Q

what elements of a drug can act as adsorbents?

A

the excipients and the packaging

87
Q

proteins/peptides are adsorbed on what type of surfaces?

A

glass

88
Q

define stability

A

the extent to which a product retains its same properties throughout its storage and use as it had when it was first mad e

89
Q

what are the 5 types of stability?

A
  1. chemical
  2. physical
  3. microbial
  4. therapeutic
  5. topological
90
Q

describe what is meant by “chemical stability”

A

the active ingredient of the drug maintains its chemical integrity and labeled potency within specified limits

91
Q

describe what is meant by “physical stability”

A

the original physical properties are maintained (appearance, palatability, uniformity, dissolution, and suspend ability)

92
Q

describe what is meant by “microbial stability”

A

preservatives maintain effectiveness and microbial growth is resisted

93
Q

describe what is meant by “therapeutic stability”

A

the therapeutic effect is unchanged

94
Q

describe what is meant by “topological stability”

A

no significant increase in toxicity

95
Q

what is the temp range for “freezer”?

A

-25 to -10

96
Q

what is the temp range for “cold”

A

less than 8

97
Q

what is the temp range for “controlled cold temp?”

A

2 to 8

98
Q

what is the temp range for “cool”

A

8 to 15

99
Q

what is the temp range for “room temperature”?

A

basic temperature of the workspace

100
Q

what is the temp range for “ controlled room temp”

A

20-25

101
Q

what is the temp range for “warm”

A

30-40

102
Q

what is the temp range for “excessive heat”?

A

greater than 40

103
Q

a drug that must be stored is a “dry place” must not be stored in a spot with greater than ___ % relative humidity

A

40

104
Q

what are 2 consequences of drug degradation?

A

potency loss and change in physical appearance

105
Q

what 5 FG are prone to degradation?

A

amides, amides, lactones, esters, lactams

106
Q

what are the 5 ways in which drugs can degrade?

A
  1. hydrolysis
  2. oxidation
  3. isomerization
  4. photo-chemical
  5. polymerization
107
Q

what 5 FG are susceptible to hydrolysis?

A

ester, amide, imide, lactam, carbamate

108
Q

Hydrolysis can be catalyzed by 2 different atoms, leading to 2 different kinds of catalysis; what are they?

A 
H = acid catalyzed 
OH = basic catalyses
109
Q

give an example of hydrolysis that happens in penicillin

A

breaking of the beta lactic ring

110
Q

what are 2 ways you can prevent degradation by hydrolysis?

A
  1. make the drug @ the pH of most stability

2. alter the dielectric constant of the solo by adding non-aq solvents

111
Q

oxidation is caused by the addition/removal of a ___

A

electronegative atom

112
Q

oxidation is catalyses by which atoms?

A

oxygen and heavy metals

113
Q

oxidation can be automatic, with one step (____), or can happen in a chain rxn of ___, ___, ___

A

autooxidation; initiation,propogation, termination

114
Q

give 4 examples of compounds suseptible to degradation by oxidation

A

steroids & sterols, polyunsaturated fats and phenothiazines

115
Q

what are 4 ways we can prevent degradation by oxidation?

A
  1. replace oxygen with CO2 or N2 in drug containers
  2. avoid heavy metals
  3. store at reduced temp
  4. add in antioxidants when making the drug
116
Q

describe the effect of degradation by isomerization

A

conversion to different optical/geometric isomers, which lowers the therapeutic effect

117
Q

what is the effect of isomerization on epinephrine?

A

racemisation in acidic soln

118
Q

what is the effect of isomerization on tetracycline?

A

epimerization in acidic solo

119
Q

cephalosporins undergo isomerization that is catalyses by __

A

base

120
Q

vitamin A undergoes what type of isomerization?

A

cis-trans

121
Q

describe photosensitivity in drug degradation

A

sunlight penetrates the skin and degrades the drug circulating in the surface capillaries

122
Q

phenothiazines, hydrocortisone, prednisolone, riboflavin, ascorbic and folic acid are sensitive to what type of drug degradation?

A

photochemical

123
Q

what are 2 ways we can prevent degradation by the photochemical route?

A
  1. using amber vials that block wavelengths bellow 470nm

2. coating tablets with a polymer film that contains ultraviolet absorbers

124
Q

describe the process of degradation by polymerization

A

2/more identical drug molecules combine to make a complex compound

125
Q

amino-penicillins are sensitive to what type of degradation?

A

polymerization

126
Q

how can degradation by polymerization be prevented?

A

monitor polarity of the aq solvent

127
Q

what are 5 factors that affect the drug stability of liquids?

A
  1. pH
  2. temp/light
  3. ionic and solvent effect
  4. oxidizing agents
  5. surfactants
128
Q

what are 3 factors that affect drug stability of solids?

A
  1. temp/light
  2. moisture
  3. oxidizing compounds
129
Q

what is the relationship of zero order rate of degradation to concentration?

A

no relationship (independent of each other)

130
Q

what is the relationship of first order rate of degradation to concentration>

A

rate is dependent on 1 concentration

131
Q

what is the relationship of second order rate of degradation to concentration?

A

rate is dependant on 2 concentrations

132
Q

drug suspension with poorly water soluble drugs are __ order of degradation

A

zero

133
Q

zero order drug degradation have __ rate of depletion of drug

A

constant

134
Q

the half-life of second order degradation is dependent on the ___ of reactants

A

initial concentrations

135
Q

what can be used to calculate shelf-life?

A

degradation kinetics (accelerated stability testing0

136
Q

what theory / set of equations are used to calculate stability and shelf-life?

A

Arrhenius

Pharmaceutics (2 decks)

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