Pharmaceutical Semi-solids

Cream
Viscous semi-solid emulsions which contain excess emulsifier. There are other components at the droplet surface which produce a semi-solid multiphase. This ensures the disperse phase is at a distance, not interfacial films
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Water in oil cream
Produced by emulsifying agents of natural origins, like beeswax, wood alcohols/fat. Provide an oily barrier that reduces water loss from the stratum corneum. Good emollient properties.
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Oil in water cream
Produced by synthetic waxes, like macrogol. Best for achieving rapid drug absorption and penetration. Suitable for application to oozing wounds
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Oil in water cream
Composed of: dispersed oil phase, crystalline gel phase (intermellar fixed water), crystalline hydrate phase and bulk aqueous phase (dilute solution of surfactant). It is the interaction between surfactant and fatty alcohol that form these structures
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Trituration
The incorporation of finely divided insoluble powders or liquids into the base using the doubling up technique. Liquids are incorporated by adding a "well" in the centre of the powder. Volatile and non-volatile liquids can be added
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Levigation
The incorporation of insoluble coarse powders into the base. A considerable sheering force is applied to avoid a gritty product - also known as "wet grinding"
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Ointments
Preparations that are immiscible, miscible or emulsifiable with the skin secretion. They use greasy bases
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Water-soluble ointment
A mixture of solid and liquid versions of polyethylene glycol. Easily washed off and non-occlusive. Used in burns dressings as lubricants and as vehicles that allow passage of drugs into the skin
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Emulsifying ointment
Made from emulsifying wax and paraffin oils. It is a greasy moisturiser that provides a layer of oil on the surface of the skin to prevent water evaporation from the surface
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Ointment bases
Oleaginous, absorption, water in oil emulsion, oil in water emulsion, water miscible
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Oleaginous base
Made of oleaginous compounds, is anhydrous and hydrophobic, difficult to spread, non-washable, occlusive, incorporates solid, hydrolyzable and oil-soluble drugs
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Absorption base
Made of oleaginous base and w/o surfactant, is anhydrous but hydrophilic, is difficult to spread, non-washable, occlusive, incorporates solid, oily, non-hydrolyzable drugs as well as small amounts of aqueous solutions
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Water in oil base
Made of oleaginous base + water + w/o surfactant, is hydrous and hydrophilic, moderately easy to spread, poorly washable, unstable, sometimes occlusive, incorporates solid, liquid and non-hydrolyzable drugs
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Oil in water base
Made of oleaginous base + water + o/w surfactant, is hydrous and hydrophilic, easy to spread, washable, unstable, not occlusive, incorporates solid, liquid, and non-hydrolyzable drugs
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Water-miscible base
Made of polyethylene glycols, is anhydrous/hydrous and hydrophilic, easy to spread, stable, not occlusive, incorporates solid drugs and aqueous solutions
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Pastes
A semi-solid preparation that contains a high percentage (up to 50% w/w) of insoluble powders in a fatty base. The high amount of particulate matter makes it stiff.
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Levigation
Preparation method of pastes
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Plastic
Rheology of pastes
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Zinc oxide
An example of a fatty paste
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Tragacanth jelly
An example of a non-greasy paste
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Gels
A semi-solid preparation in which a liquid phase is constrained within a 3D polymeric matrix having a high degree of physical or chemical crosslinking. They have a high water content and the drugs can be suspended in the matrix or dissolved in liquid
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Pectin agar
Examples of natural gums that are found within the liquid phase of gels
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Methylcellulose
Example of a semi-synthetic material found within the liquid phase of gels
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Carbomers
Example of a synthetic material found within the liquid phase of gels
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Anaesthetic
Example of a use of gels
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Spermicide
Example of a use of gels
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Jellies
Transparent or translucent non-greasy semi-solid gels. Some are as transparent as water, others are turbid because the colloidal aggregates disperse light
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Type one
Irreversible gel system made of covalent bonds
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Type two
Heat reversible gels held together by weak hydrogen bonds
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Gel point
A point that defines the state at which sufficient polymer bonding has occurred to create a coextensive polymer phase - these can be temperature values
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Gelling agent
This undergoes high degrees of cross linking when hydrated/dispersed or dissolved in dispersing medium. This means movement is restricted, leading to a more viscous product
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Single phase
A gel system where linear or branched polymer macromolecules dissolve in water. There are no apparent boundaries with dispersing medium
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Humectant
A substance that absorbs or helps to retain moisture, e.g. glycerol, sorbitol or propylene glycol
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Wetting agent
Air trapped in solid particles make them float on top of the vehicle so these agents help to disperse/suspend them by adsorbing at the liquid/air interface
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Suppositories
Solid, single dose preparations. The shape, volume and consistency make them suitable for rectal administration. They consist of a vehicle in which the drug is incorporated - either a oleaginous fatty base or a water-miscible base
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Theobroma oil
An example of an oleaginous fatty base of suppositories, alongside synthetic triglyceride mixtures. Fatty bases are preferred for rectal administration due to emollient properties
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PEG polymers
An example of a water-miscible base of suppositories, alongside glycerinated gelatin. PEG is irritating to rectal tissues (stinging and burning sensation) and can cause defecating reflex
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Viscosity enhancers
Colloidal silicon dioxide, aluminium monostearate, phosphatidylcholine
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Pessaries
Solid, single-dose preparations. They have various shapes, usually ovoid, with a volume and consistency suitable for insertion into the vagina. They contain drugs intended for a local effect only
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Other cards in this set

Card 2

Front

Produced by emulsifying agents of natural origins, like beeswax, wood alcohols/fat. Provide an oily barrier that reduces water loss from the stratum corneum. Good emollient properties.

Back

Water in oil cream

Card 3

Front

Produced by synthetic waxes, like macrogol. Best for achieving rapid drug absorption and penetration. Suitable for application to oozing wounds

Back

Preview of the back of card 3

Card 4

Front

Composed of: dispersed oil phase, crystalline gel phase (intermellar fixed water), crystalline hydrate phase and bulk aqueous phase (dilute solution of surfactant). It is the interaction between surfactant and fatty alcohol that form these structures

Back

Preview of the back of card 4

Card 5

Front

The incorporation of finely divided insoluble powders or liquids into the base using the doubling up technique. Liquids are incorporated by adding a "well" in the centre of the powder. Volatile and non-volatile liquids can be added

Back

Preview of the back of card 5
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