Ointments, Creams, Pastes
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Purpose of topical preparations
- Protection of injured area and rejuvenation of the skin
- Hydration, lubrication or emollient effect
- Convey medication(s) to the skin or mucosa (specific effect, topically or systemically)
- Application to skin, eye, nose, vagina, and rectum
Topical dermatological products
Deliver drug into the skin (the target) to treat dermal disorders (topical absorption)
Deliver drugs through the skin (percutaneous absorption) to the general circulation for systemic effects (skin is not the target)
What are the five factors that affect drug penetration?
- Surface area
- Condition of the skin
- Base/Delivery system used
- Occlusive dressings
Another name for ointment?
Semisolid preparations for external application to the skin or mucous membranes?
- Soften or melt at body temperature
- Spread easily
- Not gritty
Where are oinments applied?
dry, scaly lesions: skin, mucosa and eye
Ointment base + drug (s)
What do stiffeners do?
What is the purpose of humectants?
Escape of moisture
help penetration into the skin
Manual prepartion of ointments?
- Pill tile (ointment pad or parchment paper + spatula
- Mortar and pestle
- Zip Bag
Mechanical methods of ointment preparation?
- Large quantity: kitchen mixers with paddles/blades
- Electronic mortar and pestle (the Unguator) mixing and dispensing in the same container
How do you choose an ointment base?
- Drug release rate
- Enhancement of percutaneous absorption
- Occlusion of moisture (if skin is dry, wet it; if it is wet, dry it)
- Stability of drug
- Influence of drug on the other components of formulation (consistency)
- Patient factors (dry skin, intact or broken skin)
Two methods of preparing ointments
Two ways of incorporating
- By Trituration (mortar and pestle)
- Spatulation (ointment tile and spatulas)
Incorporation of liquids
- Base capacity to accept liquids (40-50% for absorption bases)
- Final consistency desired
- pre-incorporation into a minimum amount of another miscible base
- Alchooic solutions (only small volumes into oleaginous and emulsion bases)
What is fusion?
- Melting of ingredients together and cooling with constant stirring until congealing
- Trituration or spatulation after cooling
- Melting of materials that are too thick or chucky
- Use of "solvent action" prevent high temperatures
- Heat-sensitive and volatile ingredients: cooling needed
Steps in fusion
- 1. Oleaginous phase: oils and waxes are melted together
- 2. Aqueous phase: solutions of heat-stable and water-solube ingredients are heated to similar temperatures of oily phase
- 3. POUR AQUEOUS INTO OILY WITH STIRRING
- 4. Cooling with frequent stirring until congealing
What ointments are required to be sterile?
What are rectal, urethral and vaginal ointments tested for?
yeasts and molds
Compendial requirements (USP) for Ointments
- Microbial content
- Minimum fill
- Packaging, Storage, and Labeling
what can ointments be stored in?
What temperatures should ointments be stored in?
Room temperature, away from excessive heat to prevent softening and separation of phases
Labels must include?
Appropriate route and mode of admistration
Change in consistency
Need levigating agent if?
bleeding of liquid ingredients and phase separation
If grittiness occurs
Chemical stabilty of active ingredient compromised
Need humectant if?
Drying out of ointment base
Examples of humectant
Glycerin, Propylene glycol
Which are more stable Oleaginous and anhydrous bases or Emulsion bases?
Oleaginous and anhydrose bases
Beyond use date of extempraneous preparations with wat?
2 weeks supply max
Beyond use date of extemporaneous non-aqueous liquids or anhydrous preparations that use a manufactured product
25% of the time remaining on the product's expiration date or 6 months, whichever is earlier
What are creams?
- Opaue soft solids or very thick liquids for external application
- Semisolid dosage forms containing one or more drug substances dissolved or dispersed i a suitable base. Traditionally, they possess a relatively fluid consistency and are formulated as o/w or w/o emulsions. Recently the term is used for products consisting of o/w emulsions or aqueous microcrystalline dispersions of long chain fatty acids or alcholos that are water washable and more cosmetically and aesthetically acceptable
Benefits of creams
easier to spread and remove than ointments
Uses for creams
Topical, rectal, vaginal
What are vanishing creams?
Creams of the o/w emulsion-type with large percentage of water and stearate soap type emulsifiers (water evaporates leaving a thin film on skin
Applications of creams?
- weeping or oozing lesions
- Drying effects: body fluids miscible with cream aqueous external phase
Stablilty concerns with creams
- Emulsion breakage
- Crystal growth
- gross microbial contamination
Thick, stiff ointments that ordinarily do not flow body temperature and have reduced absorption
Pastes coat the affected area to provide
How much solid material is in a paste?
At least 25% of solid materials
Application of Pastes
- Areas that require protection
- Remains in place longer than ointments (sticky)
- Absorption of serous discharge from skin lesions
- Less greasy feeling than some oleaginous ointments
- Not suited for hairy parts of the body
Pastes can be prepared by?
- Incorporation by spaturlation
- Fusion- heat improves workability of base prior to incorporation of solids
Can portion of the base be used as a levigating agent?
If baste is too stiff and difficult to apply what must be done?
Reduction of waxy component concentration
What are gels?
- Semisolid systems consiting of dispersions of small inorganic particles or large organic molecules interpenetrated by a liquid
- Gels are semirigid systems in which the movement of the dispersing medium is restricted by an interlacing three-dimensional network of particles or solvated macromolecules of the dispersed phase
Taking up of liquid with no measureable increase in volume
Taking up of liquid with increase in volume (solvation)
Intense interaction between particles of the dispersed phase so that, on standing, the dispersion medium is squeezed out in droplets and the gell shrinks (instability)
Reversible gel-sol formation with no change in volume or temperature (sol=liquid form of a gel upon agitation)
Removal of the liquid from a gel, leaving only the framwork (gelatin sheets, acacia tears, tragacanth ribbons)
Preservatives recommended for gels
- Sodium benzoate
- Benzalkonium Chloride
Gels and Magmas are
Semisynthetci Cellulose derivatives
Single-phase gels made from synthetic or nautral macromolecule
Systems with large particle size of floccules of small distinct paticles
Common gelling agents
- Acacia, pectin, starch, tragacanth, xanthan gum, etc
- Alginic acid (seaweed)
- Animal/vegtable fars: lard, cocoa butter
- Bentonite, Veegum
- Carbomer resins
- Carbowax bases
- Colloidal silicon dioxide
- Polyvinyl alcohol
- Petrolatum, mineral oil/polyethylene gel, plastibase
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