SEMISOLIDS Flashcards
Emollient
softens the skin
soothes irritation in skin or mucous membrane
Protective
protects injured skin
protects exposed skin surfaces from harmful or annoying stimuli
Occlusive
promotes retention of water in the skin by forming a hydrophobic barrier that prevents moisture in the skin from evaporating
Humectant
a substance that causes water to be retained because of its hygroscopic properties
Uses of Dermatologicals
To protect skin or mucous membranes from chemical or physical irritants in the environment
To permit rejuvenation of the skin
To provide hydration of the skin or an emollient effect
To provide a vehicle for applying a medication either for local or systemic effects
Ointments features
1) Semisolid preparations intended for the external application to the skin or mucous membranes
2) Soften or melt at body temperature
3) Should spread easily and be non-gritty
4) Semisolid plastic flow characteristics
5) Definite yield value
6) Resistance to flow drops as application continues
Desirable Properties of Bases
1) Chemically and physically stable under normal conditions of use and storage
2) Nonreactive and compatible with a wide variety of drugs and auxiliary agents (such as emulsifier, preservatives)
3) Free from objectionable odor
4) Nontoxic, nonsensitizing and nonirritating
5) Aesthetically appealing
6) easy to apply and nongreasy
7) Remains in contact with the skin until removal is desired, then is easily removed
Ointment Bases types
Oleaginous
Absorption
Water-removable
Water-soluble
Oleaginous Bases properties
1) Also called hydrocarbon bases; water insoluble
2) Emollient effect; prevent escape of moisture
3) Can remain on skin for prolonged periods without drying out; difficult to wash off
4) Not water washable
5) Can only incorporate small amounts of water
5) Oily, occlusive, lack cosmetic appeal
Advantages of Oleaginous Bases
Inexpensive, Nonreactive, Nonirritating,
Good emollient, protective and occlusive properties,
Not water-washable, so they stay on the skin and keep incorporated medications in contact with the skin
Disadvantages of Oleaginous Bases
1) Poor patient acceptance because of their greasy nature
2) Not removed easily with washing
3) Can only incorporate limited amounts of water and aqueous preparations and then with great difficulty
Oleaginous Bases types
Petrolatum, USP
White Petrolatum, USP
Yellow Ointment, USP
White Ointment, USP
Petrolatum, USP
1) Yellow petrolatum and petroleum jelly
2) Purified mixture of semisolid hydrocarbons obtained from petroleum
3) Unctuous mass, varying in color from yellowish to light amber
4) Melts at 38° to 60°C
5) May be used alone or in combination with other agents as an ointment base
White Petrolatum, USP
1) Purified mixture of semisolid hydrocarbons that has been decolorized
2) More esthetically appealing than petrolatum, but used for same purposes
Yellow Ointment, USP
1) Simple ointment
2) Slightly more viscous than plain petrolatum
3) Petrolatum 95% w/w and Yellow wax 5% w/w
Yellow wax is obtained from honeycomb
White Ointment, USP
Same as yellow ointment, but is made with white wax (bleached and purified yellow wax) instead of yellow wax
Absorption Bases properties
1) May be used as emollients, but don’t provide the degree of occlusion of oleaginous bases
2) Not easily removed from the skin with water washing
3) Useful as adjuncts to incorporate small volumes of aqueous solutions into hydrocarbon bases
4) Oily, occlusive, lacks cosmetic appeal
Absorption Bases: Two basic types:
1) Those that permit the incorporation of aqueous solutions resulting in the formation of water-in-oil emulsions (e.g., hydrophilic petrolatum)
2) Those that are water-in-oil emulsions that permit the incorporation of additional quantities of aqueous solutions (e.g., lanolin)
Advantages of Absorption Bases
1) Moderately good protective, occlusive and emollient properties
2) Do not wash off easily, so they hold incorporated medications in contact with the skin
3) Can absorb liquids
Disadvantages of Absorption Bases
1 Some bases in this class have poor patient acceptance
2) Not easily removed with washing
3) May be sensitizing
4) Can have compatibility issues related to the emulsifying agent
5) May be chemical stability issues with bases that contain water and ingredients sensitive to hydrolysis
6) Those that contain water may be subject to microbial growth ( adding preservative can reduce microbial growth but sensitive to skin)
Absorption Bases
Examples
Hydrophilic Petrolatum, USP
Aquaphor and Aquabase
Lanolin, USP
Modified Lanolin, USP
Lanolin, USP
1) Obtained from the wool of sheep
2) Purified wax-like substance that has been cleaned, deodorized and decolorized
3) Contains not more than 0.25% water
4) Modified Lanolin, USP has been processed to reduce the contents of free lanolin alcohols and any detergent and pesticide residues
Water-Removable Bases
1) Water-washable bases
2) Oil-in-water emulsions also called creams
3) Easily washed from the skin
4) May be diluted with water or aqueous solutions
5) Can absorb serous discharges
Advantages of Water-Removable Bases
1) Nongreasy
2) Can be removed from the skin by washing
3) Can absorb some water or alcohol
4) Will allow dissipation of fluids from injured skin
Disadvantages of Water-Removable Bases
1) Less protective, less emollient, a less occlusive than hydrocarbon or absorption bases
2) Can have compatibility issues with certain emulsifying agents
3) May be chemical stability issues with bases that contain water and ingredients sensitive to hydrolysis
4) Those that contain water may be subject to microbial growth
5) May dry out due to evaporation of water
Water-Removable Bases
Examples
Hydrophilic ointment
Vanishing cream
Dermabase®
Water-Soluble Bases
1) Contain no oleaginous components
2) Completely water washable, greaseless
3) Soften greatly with addition of water so not able to incorporate large amount of aqueous solutions effectively
4) Mostly used to incorporate solids
Advantages of Water-Soluble Bases
1) Soluble in water, so easily removed by washing
2) Leaves no oil residue
3) Can absorb limited amounts of water or aqueous solutions
Disadvantages of Water-Soluble Bases
1) Irritating
2) Little to no emollient properties
3) PEG-type bases may have compatibility problems with drugs that are sensitive to oxidation
4) Those that contain water may have the compatibility and stability problems associated with water and require a preservative
Selection of the Appropriate Base
1) Desired release rate of the drug substance from the ointment base
2) Desirability of topical or percutaneous drug absorption
3) Desirability of occlusion of moisture from the skin
4) Stability of the drug in the ointment base
5) Effect of the drug on the consistency of the ointment base
6) Desire for a base that is easily removed from the skin
7) Characteristics of the surface to which it is applied
Preparation of Ointments
Incorporation
Fusion
Preparation of Ointments: Compounding:
Equipments:
1) Ointment Slabs or Pads
2) Spatulas
3) Small-scale ointment mills
Preparation of Ointments: Compounding
Allow excess to compensate for loss during compounding
Either % (e.g., 10%) or stated amount (e.g., 3 g)
Preparation of Ointments: Compounding:
Incorporation of Solids
1) Should be solubilized or the particle size should be reduced as far as possible
2) Auxiliary agents, levigating agents and solvents, can be added to facilitate making a smooth, elegant product
Preparation of Ointments: Compounding:
Choice of drug form
If possible, select fine powder
Preparation of Ointments: Compounding:
Levigation
Levigating agents are usually chosen to be similar to the ointment base
Melted ointment base may be used
Common levigating agents
1) Mineral oil – oleaginous, absorption, W/O emulsion bases
2) Glycerin/propylene glycol/water - O/W Emulsion bases, water-soluble bases
Preparation of Ointments: Compounding
Fusion
1) Heat highest melting point material first
2) Water phase a few degrees higher
3) W/O: add water slowly
4) O/W: add oil slowly
Beyond-Use Dates – Compounded Preparations
For Nonaqueous Formulations
The BUD is not later than the time remaining until the earliest expiration date of any API or 6 months, whichever is earlier.
Beyond-Use Dates – Compounded Preparations
For Water-Containing Topical/Dermal and Mucosal Liquid and Semisolid Formulations—
The BUD is not later than 30 days
Creams
Semisolid preparations containing one or more medicinal agents dissolved or dispersed in either a water-in-oil emulsion or an oil-in-water emulsion base or in another type of water-washable base
Creams:
Preparation usually involves
separating and heating lipid and aqueous components separately and then combining the phases
Creams primarily used in
topical skin products and rectally and vaginally and Often preferred to ointments because they are easier to spread and remove
Gels
1) Semisolid systems consisting of dispersions of small or large molecules in a liquid vehicle rendered jellylike by the addition of a gelling agent
2) May also contain drug substances, solvents, preservatives and/or stabilizers
Gels route of administration
skin, the eye, the nose, the vagina and the rectum
Gelling Agents:
Synthetic Macromolecules
Carbomer 934
Gelling Agents: Cellulose Derivatives
Carboxymethylcellulose
Hydroxypropyl methylcellulose
Gels: gelling agents: Natural gums
Tragacanth
Types of Gels
Single-phase gels
gels in which the macromolecules are uniformly distributed throughout a liquid with no apparent boundaries between the dispersed macromolecules and the liquid
Two-phase gels
magmas; gel mass consisting of floccules of small distinct particles
Hydrogels
include ingredients that are dispersible as colloidals or soluble in water
Organogels
include ingredients such as hydrocarbons, animal and vegetable fats, etc
Syneresis
When the interaction between particles of the dispersed phase becomes so great that on standing, the dispersing medium is squeezed out in droplets and the gel shrinks
Swelling
The taking up of liquid by a gel with an increase in volume
Imbibition
The taking up of a certain amount of liquid without a measurable increase in volume
Thixotropy
A reversible gel-sol transition with no change in volume or temperature
Xerogel
Formed when the liquid is removed from a gel and only the framework remains
Transdermal Preparations
Topical ointments, creams and gels can be designed to deliver a drug systemically by the addition of penetration enhancers to the vehicle
transdermal preparations: Penetration enhancers
dimethyl sulfoxide (DMSO), ethanol, propylene glycol, glycerin, polyethylene glycol, urea, dimethyl acaetamide, sodium lauryl sulfate , the poloxamers, Spans, Tweens, lecithin, terpenes and others
Pluronic Lecithin Organogel (PLO)
Commonly compounded transdermal preparation which aids in the rapid penetration of many active drugs through the skin
Pluronic Lecithin Organogel (PLO) consists of
Pluronic (Poloxamer) F127 gel (usually 20% or 30% concentration) mixed at a ratio of approximately 1:5 with a mixture of equal parts of isopropyl palmitate and lecithin
