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PHRM 1300 - Midterm > Lecture 3: Solution Dosage Form > Flashcards

Lecture 3: Solution Dosage Form Flashcards

1
Q

What is a solution?

A

A thermodynamically stable, one-phase system composed of two or more components, one of which is completely dissolved in the other

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2
Q

Why is a solution homogeneous?

A

Because the solute is dispersed throughout the solvent in molecular or ionic sized particles

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3
Q

What is the most common solvent for pharmaceutical solutions?

A

Water

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4
Q

What are 4 common solvents for pharmaceutical solutions?

A

1) Ethanol
2) Glycerin
3) Propylene glycol
4) Isopropyl alcohol

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5
Q

What must be considered when choosing a solvent for a solution?

A

1) Must completely dissolve the drug and other solid ingredients at the desired concentration
2) Be non-toxic and safe for ingestion or topical application
3) Be aesthetically acceptable to the patient

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6
Q

What are 5 advantages to solutions as a dose form?

A

1) Completely homogeneous
2) Immediately available for absorption into the body
3) Flexible in terms of dose adjustment
4) Can be used by any route of administration
5) Can be administered to patients who cannot swallow tablets or capsules

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7
Q

What are 5 disadvantages to solutions as a dose form?

A

1) Drugs less stable when in solution
2) Some drugs not soluble in solvents that are acceptable for pharmaceutical use
3) Drugs with objectionable taste require taste masking
4) Heavier and bulkier than solids
5) Require measurement by patient or caregiver

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8
Q

How can rate of dissolution be increased?

A

1) Heating – but the solvent must be non-volatile and the solute stable to heat
2) Stirring
3) Reduction of particle size

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9
Q

What are 2 characteristics that a solution must have for it to be considered “pharmaceutically elegant”?

A

1) Should be very clear

2) Small particulates should be removed by filtration

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10
Q

What does solubility of an agent indicate?

A

The maximum concentration to which a solution can be prepared using that agent, solvent, and temperature

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11
Q

What is involved in the process of dissolution?

A

The breaking of solvent-solvent and solute-solute forces and establishment of solvent-solute forces

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12
Q

What is a factor in solubility?

A

Temperature

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13
Q

What are factors of rate of dissolution?

A

Particle size and agitation

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14
Q

When is pH a significant factor in solubility?

A

When the drug is ionizable

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15
Q

For dissolution, when is heat required?

A

To break the bonds holding the solute together and the solvent together

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16
Q

For dissolution, when is heat released?

A

When the new solute-solvent bonds form

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17
Q

When will a dissolution be endothermic?

A

When the heat given off is less than the heat required

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18
Q

When will a dissolution be exothermic?

A

When the heat given off is more than the heat required

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19
Q

True or false: the volumes of the components of a solution are additive

A

False, they are not additive

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20
Q

What happens when a salt is added to a fixed volume of water?

A

The volume will likely change

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21
Q

What is the proper procedure when making 100 mL of a 20% solution of NaCl?

A
  • Weigh proper amount of NaCl
  • Dissolve in about 80 mL of water
  • Transfer to a measuring cylinder and add enough water to make 100 mL
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22
Q

What is a displacement volume?

A

The volume occupied by the powder when a suitable diluent is added during reconstitution

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23
Q

When is a displacement volume particularly important?

A

When dose is needed only for a proportion of the vial content

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24
Q

When does displacement volume vary?

A

For each drug, for each strength of drug, and for different brands/manufacturers formulas

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25
Q

Why does pH matter to many drugs?

A

Because they are weak acids or bases and pH will affect their solubility

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26
Q

What are 4 solubility generalizations?

A

1) Like dissolves like
2) Organic molecules with polar functional groups can H-bond with water to effect solution
3) The more polar functional groups present, the more likely the molecule will be water soluble
4) Introduction of a halogen atom into a molecule will reduce solubility – increases MW without increasing polarity

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27
Q

What effect does decreasing the diffusion coefficient of a drug have on dissolution rate?

A

Decreases it (takes longer to dissolve)

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28
Q

What effect does increasing the area exposed to solvent have on dissolution rate?

A

Increases it (dissolves faster)

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29
Q

What effect does decreasing the thickness of the diffusion layer have on dissolution rate?

A

Increases it

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30
Q

How can the diffusion coefficient of a drug be decreased?

A

By being in the presence of substances that increase the viscosity of the medium

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31
Q

How can the area exposed to a solvent be increased?

A

By microionization

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32
Q

How can the thickness of the diffusion layer be decreased?

A

Agitation

33
Q

What effect does the solubility in the diffusion layer have on dissolution rate?

A

Can increase and decrease it

34
Q

How can solubility in diffusion layer be changed?

A

Changing temperature or pH (through the use of a buffer) for ionizable drugs

35
Q

What effect does decreasing the concentration in bulk solution have on dissolution rate?

A

Increases it

36
Q

How can the concentration in bulk solution be decreased?

A

By adding fluid or removing drug by adsorption or absorption

37
Q

How can purified water be obtained?

A

Using distillation, ion-exchange, or reverse-osmosis

38
Q

What makes purified water be considered purified?

A
  • No added substances

- Cannot contain more than 0.001% of solids

39
Q

In pharmaceutical usage, what does “alcohol” refer to?

A

Ethanol or ethyl alcohol

40
Q

What is the recommended alcohol content for different age groups?

A
  • Under 0.5% for children under 6 y
  • 5% for 6-12 y
  • 10% for over 12 y
41
Q

What is alcohol useful for?

A

Preparing solutions of drugs with limited solubility

42
Q

What kind of alcohol is never used pharmaceutically and why?

A

Methanol due to its toxicity

43
Q

When could isopropanol be used?

A

In some topical preparations

44
Q

What is propylene glycol miscible with and when is it used?

A
  • Miscible with alcohol and water

- Used in combination with them or as a substitute for alcohol

45
Q

What polymeric glycol is used and what is never used and why?

A
  • Polyethylene glycol may be used

- Ethylene glycol is never used due to toxicity

46
Q

What is glycerin used for?

A

As a solvent

47
Q

What are 2 properties of glycerin?

A
  • Very viscous

- Some preservative activity

48
Q

What are 3 common solution types?

A

1) Oral
2) Ophthalmic, otic, and perenteral
3) Topical

49
Q

What can be found in oral solutions?

A

Sweeteners and preservatives

50
Q

What are common volumes per dose of oral solutions?

A

Drop, teaspoonful, or tablespoonful

51
Q

What are ophthalmic solutions used for?

A

Eye

52
Q

What are otic solutions used for?

A

Ear

53
Q

What are parenteral solutions used for?

A

Injection

54
Q

What type of auxiliary label is required for topical solutions?

A

“For external use only”

55
Q

What are elixirs?

A

Clear, hydro-alcoholic oral solutions

56
Q

What is the common alcohol content of elixirs?

A

About 30%

57
Q

What can be used as a substitute for alcohol in elixirs?

A

Propylene glycol

58
Q

What are elixirs effective for?

A

Water and alcohol soluble components

59
Q

What type of containers should elixirs be stored in and why?

A

Tight, light-resistant containers away from excessive heat because of alcohol and volatile oil (flavourings)

60
Q

What are tinctures?

A

Hydro-alcoholic solutions containing 15-80% alcohol

61
Q

What happens if a tincture is diluted with water?

A

Precipitation of the ingredients

62
Q

What can tinctures be used for?

A

Topical or oral use

63
Q

What are aromatic waters and what are they used for?

A
  • Clear, aqueous solutions saturated with volatile oils

- Used for flavor or odor

64
Q

What are spirits?

A

Similar to aromatic waters but contain varying amounts of alcohol and higher content of volatile oil

65
Q

What are collodions?

A

Liquid preparations containing pyroxylin

66
Q

What are common solvents in collodions?

A

Alcohol or diethyl ether

67
Q

What are collodions used for?

A

Delivery of keratolytic medications

68
Q

What are syrups?

A

Concentrated aqueous preparations of a sugar or sugar-substitute

69
Q

What do syrups contain and what are they used for?

A
  • Contain flavouring, but not medication

- Used as vehicles into which medications may be added

70
Q

Why must syrups be preserved?

A

To prevent microbial growth

71
Q

What must be considered when preserving syrups?

A
  • Amount of free water

- Concentration of free water must be effective but low enough to avoid toxicity

72
Q

What are 4 common preservatives for syrups?

A

1) Alcohol
2) Benzoic acid or sodium benzoate
3) Potassium sorbate
4) Parabens

73
Q

What is special about simple syrup?

A
  • 85% sucrose

- Contains no free water and is therefore self-preserving

74
Q

What kinds of syrups require preservation?

A

Syrups with concentration below 85%

75
Q

What is needed to estimate the amount of free water when preserving diluted syrup with alcohol?

A
  • 18% alcohol preserves free water
  • 1 g of sucrose occupies 0.632 mL
  • 1 g sucrose preserves 0.545 mL water
76
Q

How must syrups be prepared?

A

Using heat if no volatile or heat-liable components are present

77
Q

Why must you be careful with heat when preparing syrups?

A

Don’t want to caramelize sucrose

78
Q

True or false: syrup has higher solvent power than water

A

False, syrup has LOWER solvent power

PHRM 1300 - Midterm (4 decks)

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