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PHRM 513 > Semisolid dosage forms and rheology > Flashcards

Semisolid dosage forms and rheology Flashcards

1
Q

Overview of semi solid dosage forms

A

Ointments, creams and gels are semisolid dosage forms intended
for topical application
• May be applied to skin, placed on the surface of the eye, used
nasally, vaginally or rectally
• Most used for the effects of the therapeutic agents they contain;
unmedicated ones are used as protectants or lubricants
• Topical applications can be used for local or systemic effects

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2
Q

Ointments

A

Semisolid preparation intended for external application to skin or
mucous membranes
• May be medicated or not
• Ointment bases may be used for their physical effects or as vehicles
for medicated ointments

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3
Q

Ointment bases

A
  1. Oleaginous
  2. Absorption
  3. Water-removable
  4. Water-soluble
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4
Q

Oleaginous (or hydrocarbon) bases

A

On application to skin, have an emollient effect, protect against
escape of moisture, effective as occlusive dressings, can remain on
the skin for long periods without drying out, and are difficult to wash
off due to their immiscibility with water

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5
Q

Levigation

A

commonly used to reduce particle size and grittiness of added powders

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6
Q

Oleaginous bases, when powder substances are to be incorporated

A

mineral oil may be

used as the levigating agent

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7
Q

Oleaginous bases examples

A

Petrolatum, USP - yellow petroleum and petroleum jelly ( vaseline)
White petrolatum- petroleum jelly ( white vaseline)
Yellow ointment- simple ointment
White ointment

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8
Q

Petrolatum, USP – Also known as (AKA), yellow petrolatum and petroleum jelly

A

Purified mixture of semisolid hydrocarbons obtained from petroleum
– Unctuous mass, varying in color from yellowish to light amber
– Melts at 38-60 C
– Can be used alone or in combination with other agents as an ointment base
– Example: Vaseline

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9
Q

White petrolatum, USP – AKA, petroleum jelly

A

Purified mixture of semisolid hydrocarbons from petroleum
– Wholly or nearly decolorized
– Considered more esthetically pleasing by some
– Example: White Vaseline

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10
Q

Yellow ointment, USP – AKA, simple ointment

A

1000 g contains: 50 g yellow wax and 950 g petrolatum

– Has a slightly greater viscosity than plain petrolatum

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11
Q

White ointment, USP

A

1000 g contains: 50 g white wax (bleached yellow wax) and 950 g white petrolatum

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12
Q

Yellow and white ointments are prepared by

A

melting the wax component, adding the

petrolatum until mixture is uniform, then cooling and stirring until congealed

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13
Q

Absorption bases

A

May be used as emollients
- are not easily removed from the skin because external phase is oleaginous, and are useful as pharmaceutical adjuncts to incorporate small volumes of aqueous
solutions into hydrocarbon bases

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14
Q

Two types of absorption bases

A

A. Those that permit incorporation of aqueous solutions resulting in water-in-oil emulsions (W/O)* (called Anhydrous)
B. Those that are water-in-oil (W/O) emulsions that permit incorporation of additional quantities of aqueous solutions

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15
Q

*Emulsions are

A

disperse systems where a liquid is dispersed in an external liquid phase

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16
Q

Absorption bases examples

A
  • Hydrophilic petrolatum, USP

- Lanolin, USP – AKA, anhydrous lanolin

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17
Q
  • Hydrophilic petrolatum, USP
A

Type A absorption base
- Stearyl alcohol and white wax are melted, cholesterol added with stirring until
dissolved, white petrolatum added, then cooled while stirring until congealed
– Aquaphor is a variation of hydrophilic petrolatum

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18
Q

Lanolin, USP – AKA, anhydrous lanolin

A

Type B absorption base
– Obtained from wool of sheep
– Wax-like substance that has been cleaned, deodorized and decolorized
– Contains no more than 0.25% water; additional water may be incorporated by
mixing

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19
Q

Water-removable bases

A

Oil-in-water (O/W) emulsions resembling creams
– External phase is aqueous
-More easily washed from skin, may be diluted with water or aqueous
solutions, and can absorb serous discharges

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20
Q

Water-removable bases example

A

Hydrophilic ointment, USP
-Stearyl alcohol and white petrolatum are melted together at ~75 C; the
other agents, dissolved in the purified water, are added with stirring until
mixture congeals

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21
Q

Water-soluble bases

A

Do NOT contain oleaginous components
- are completely water
washable and often referred to as greaseless
- Soften greatly with water, large amounts of aqueous solutions not
effectively incorporated
• Mostly used for incorporation of solid substances

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22
Q

Water-soluble base example

A

Polyethylene glycol ointment, NF

Numeric designations associated with PEGs refer to average molecular
weight of the polymer
• Viscosity increases with molecular weight
• <600 – Clear, colorless liquids
• 600-1000 – Semisolids
• >1000 – White, wax-like

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23
Q

Selection of the appropriate
base
• Depends on number of factors, including

A
  1. Desired release rate of drug substance from base
  2. Desirability of topical or percutaneous drug absorption
  3. Desirability of occlusion of moisture from skin
  4. Stability of drug in the base
  5. Effect, if any, of the drug on consistency or other features of the
    base
  6. Desire for a base easily removed by washing with water
  7. Characteristics of the surface to which it is applied
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24
Q

Effect of ointment bases on drug release

A

The partition of a water-insoluble (lipophilic) drug into the skin may decrease in an oleaginous phase due to the drug’s affinity toward the formulation

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25
Q

Lipophilic drug release can be significantly increased when

A

the ointment base shows

an increased water affinity

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26
Q

When would you recommend water-soluble and water-removable bases

A
  • rapid release of lipophilic drugs
    -also useful for drugs that undergo hydrolytic degradations,
    as formulations can be made that contain no water
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27
Q

For hydrophilic drugs, absorption bases

(anhydrous and W/O emulsion systems) can

A

provide greater drug release rates, as the base has low affinity for the drug and also
absorbs water, allowing easier passage of the drug through the ointment matrix

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28
Q

Preparation of ointments methods

A
  1. Incorporation

2. Fusion

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29
Q

Incorporation

A

Components mixed until uniform preparation is attained

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30
Q

Incorporation of solids

A

Ointment base placed on one side of working surface and powdered components, their particle size previously reduced*, on the other side, add powder with a portion of the base and continue with geometric dilution until all is combined and uniformly blended

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31
Q

Incorporation of liquids

A

Add only after due consideration of an ointment base’s

capacity to accept the volume required

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32
Q

*Levigating ointments

A

agent in which it is insoluble in

- reduces particle size of a powder before incorporation into the ointment base

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33
Q

When necessary to add an aqueous preparation to a hydrophobic base

A

the solution first may be incorporated into a minimum amount of hydrophilic
base, and then this added to the hydrophobic base

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34
Q

Fusion

A

All or some of the components of an ointment are combined by
being melted together and cooled with constant stirring until
congealed
- Components not melted are added as it is being cooled and stirred

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35
Q

Examples of ointments prepared by fusion

A
  • beeswax
  • paraffin
  • stearyl alcohol
  • high molecular weight PEGs
36
Q

The method of manufacture for ointments having an emulsion base,
involves

A

both melting and emulsification

37
Q

Microbial content

A

With the exception of ophthalmic preparations, topical applications are not required to be sterile; however, must meet microbial limits stated
by USP
– Antimicrobial preservatives used: Methylparaben, propylparaben and others

38
Q

Minimum fill

A

Determination of net weigh or volume of contents of filled containers to
ensure proper contents compared with the labeled amount

39
Q

Packaging, storage and labeling

A

Packaged in large-mouth ointment jars or in metal
or plastic tubes, must be stored in well-closed containers and in a cool place, light sensitive preparation are packaged in opaque or light-resistant containers, USP
directs labeling for certain ointments include the type of base used

40
Q

Additional standards

A

Examine for viscosity and in vitro drug release to ensure within-lot and lot-to-lot uniformity

41
Q

Cream

A

Semisolid preparation containing one or more medicinal agents
dissolved or dispersed in either a water-in-oil (W/O) or oil-in-water
(O/W) emulsion, or in another type of water-washable base
- Creams find primary application in topical skin products and
products used rectally and vaginally

42
Q

creams vs. ointments patient wise?

A

Many patients and physicians prefer creams to ointments because
they are easier to spread and remove

43
Q

How to prep of creams

A

May be formulated from a variety of oils and from fatty alcohols, fatty acids and fatty esters
- Solid excipients are melted at the time of preparation

44
Q

Prep of creams steps:

A

Preparation usually involves separating the formula components into lipid and aqueous
➢ The lipid portion contains all water-insoluble components and the aqueous, the water-soluble
➢ Both phases are heated to a temperature above the melting point of the highest melting
component
➢ Phases are then mixed, and stirred until reaching ambient temperature
➢ Mixing generally is continued during the cooling process to promote uniformity
-Active ingredients can be added to the appropriate phase at the beginning of the process or after
cream is prepared by a suitable dispersion process, such as levigation

45
Q

Creams: Emulsifying agents include

A

nonionic surfactants, detergents and soaps

46
Q

Gels

A

Semisolid systems consisting of dispersions of small inorganic particles or large organic molecules in an aqueous liquid vehicle rendered jellylike by the addition of gelling agents

  • May be formulated to contain a drug
  • May be prepared for administration via skin, eye, nose, vagina and rectum
47
Q

Gelling agents

A

Synthetic macromolecules (Ex. Carbomer 934)

  • cellulose derivatives
    (Ex. Carboxymethylcellulose)
  • natural gums (Ex. tragacanth)
48
Q

Single-phase gel

A

Macromolecules uniformly distributed throughout liquid with no apparent boundaries between the dispersed macromolecules and the liquid

49
Q

Two-phase system (or magma)

A

Gel mass consisting of floccules* of small distinct
particles
Example: Milk of magnesia
- *A loose aggregation of particles held together by weak bonds

50
Q

Pastes

A

Semisolid preparations intended for skin
– Generally contain a larger proportion of solid material than ointments and are
stiffer

51
Q

Pastes example

A

Zinc oxide paste to protect and soothe skin

52
Q

Plasters

A

Solid or semisolid adhesive masses spread on a backing of paper, fabric, moleskin or
plastic
– Applied to skin to provide prolonged contact
– Example: Salicylic acid plaster for removal of corns

53
Q

Plasters example

A

Salicylic acid plaster for removal of corns

54
Q

Glycerogelatins

A

Plastic masses containing gelatin (15%), glycerin (40%), water (35%) and a medicinal
substance (10%)
– Applied to skin for long-term contact

55
Q

Glycerogelatins example

A

Zinc gelatin for treatment of varicose ulcers

56
Q

Topical dermatologic products are packaged

A

in jars, tubes or
syringes, whereas ophthalmic, nasal, vaginal and rectal semisolid
products are almost always packaged in tubes and syringes

57
Q

Ointments and creams are susceptible to contamination by

A

Pseudomonas aeruginosa and Staphylococcus aureus, so preservatives added

58
Q

Preservatives examples

A
  • Parabens
  • phenols
  • benzoic acid
  • quaternary ammonium
    salts or sorbic acid
59
Q

Dermatological preparations: In treating skin diseases, the drug should penetrate and be retained in the
skin for a period of time

A

•Substances with both aqueous and lipid solubility characteristics are good
candidates for passive diffusion through the stratum corneum (outer layer of the skin)
•Once through, drug molecules may pass through the deeper epidermal
tissues and into the dermis
• If drug reaches the vascularized dermal layer, it becomes available for
absorption into general circulation

60
Q

Transdermal dermatological

preparations: Ointments, creams and gels designed to

A

deliver a drug through the
skin to the general circulation for systemic effects
-Accomplished by addition of penetration enhancers to the topical
vehicle

61
Q

Transdermal dermatological

preparations: Some penetration enhancers:

A

Dimethyl sulfoxide

  • ethanol
  • PEG
  • urea
  • Spans
  • Tweens
  • lecithin
62
Q

Oleaginous bases provide

A

greater occlusion (blockage) and emollient effects than do hydrophilic or water-washable bases

63
Q

Pastes offer even

A

greater occlusion and are more effective than ointments

at absorbing serous discharge

64
Q

Creams, usually oil-in-water emulsions,

A

spread more easily than ointments

and are easier to remove

65
Q

Water-soluble bases are

A

non-greasy and are easily removed

66
Q

For ophthalmic preparations: Semisolids used in the topical treatment of conditions and diseases of the eye

A

Ointments and gels

67
Q

Major route by which drugs enter the eye is

A

simple diffusion via the cornea

68
Q

Compared to ophthalmic solutions

A

ointments and gels provide extended
residence time on the surface of the eye, increasing the duration of their surface effects and bioavailability for absorption into the ocular tissues

69
Q

Ophthalmic preparations

A

Ointment bases must not be irritating to the eye and must permit diffusion of medicinal substances throughout the secretions bathing the eye

  • Ointment bases should have a softening point close to body temperature, for comfort and drug release
  • Medicinal agents are added to an ointment base either as a solution or as a finely micronized powder, and the ointment made uniform and smooth by fine milling
70
Q

Which are used as bases in ophthalmic ointments

A

mixtures of white petrolatum and mineral oil

71
Q

A gel base of PEG and mineral oil is also used which

A

permit water and water insoluble drugs to be retained within the base

72
Q

Ophthalmic ointments MUST meet the

A

USP sterility test and test for metal particles in ophthalmic ointments

73
Q

USP directs that ophthalmic ointments must be packaged in

A

in collapsible ointment tubes, which have elongated narrow tips that facilitate application of a narrow band of ointment to the eye

74
Q

Drugs introduced into the nasal passage are primarily

A

for local effects on
the mucous membranes and underlying tissues, i.e., nasal decongestants;
however, drug absorption to general circulation does occur through the
blood supply feeding the nasal lining

75
Q

Nasal route is used

A

for the systemic absorption of a number of drugs

76
Q

Nasal Preparations: semisolids used

A

Ointments and gels

77
Q

The unit of viscosity is

A

the poise (p)

78
Q

Lipophilic drugs are more capable

A

of penetration than hydrophilic compounds

79
Q

Rectal preparations: Semisolids used

A

Ointments, gels, creams and cream-like aerosol foams

80
Q

Rectal:Ointments, creams and gels are used

A

for topical application to the perianal area and insertion within the anal canal

81
Q

What are rectal semisolids used for

A

Largely used to treat local conditions or anorectal pruritus inflammation and
the pain and discomfort associated with hemorrhoids
-used for systemic absorption of some drugs, when the oral
route is unsatisfactory

82
Q

Rectal semisolids examples

A

Anusol and Tronolane

83
Q

Rectal semisolids are

A

Substances may be absorbed by diffusion into the general circulation

84
Q

Rectal semisolids bases

A

used include combination of PEG300 and 3350, emulsion cream bases using cetyl alcohol and cetyl esters wax, and white petrolatum and mineral oil

85
Q

Vaginal preparations Semisolids used

A

Ointments, creams, creamlike foams and gels

Packaged in tubes and aerosol canisters

86
Q

Vaginal Topical products used to treat

A

vulvovaginal infections, vaginitis, conditions of

endometrial atrophy and for contraception with spermatocidal agents

PHRM 513 (13 decks)

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