Ointments, creams, gels Flashcards
protectants
cover surface for barrier between atmosphere and skin
emollients
make skin more flexible/pliable
lubricants
reduce friction between two surfaces
what are unmedicated ointments
protectants, emollients, lubricants
what are application sites of dermatalogic applications?
skin, nose, surface of eye, vagina or rectum
How are the bases affected going down this list? oleaginous bases absorption bases water-removable bases water-soluble bases
water is easier to remove from the skin going from top to bottom
How do you decrease particle size of an oleaginous (hydrocarbon) base?
add a levigating agent
What type of effect do oleaginous bases have?
an emollient effect (soften and smooth) making the skin more flexible/ pliable to protect against moisture escape
Oleaginous bases are effective occlusive dressings what does that mean??
air and water tight trauma dressing used in first aid
Do oleaginous bases wash off easily?
no
What is petrolatum, USP?
- an oleaginous base
- purified mixture of semisolid hydrocarbons obtained from petrolatum
- color ranges from yellowish to amber
- used alone or in combination with other agents as an ointment base
What is the melting temp of petrolatum, USP?
melts at 38 degrees celsius to 60 degrees celsius
What are examples of petrolatum?
yellow petrolatum and petroleum jelly (vaseline)
What is white petrolatum, USP?
- decolorized purified mixture of semisolid hydrocarbons from petroleum
- lighter color compared to yellow petrolatum - pharmacists prefer this variety
- white vaseline or white petroleum jelly
Why do pharmacists prefer white petrolatum?
because it is more pharmaceutically elegant
Why is the minimum melting temperature of petrolatum 38 degrees celsius?
because physiological temperature is 37 degrees celsius
How is yellow ointment USP made?
50g yellow wax
950g petrolatum
How is yellow ointment prepared?
- it is purified wax from honeycomb of bee Apis mellifera
- prepared by melting yellow wax in a water bath and adding petrolatum until uniform mixture
- cool and stir
- viscosity of yellow ointment is greater than plain petrolatum
How is white ointment USP made?
50 g white wax
950g white petrolatum
What are the two types of absorption bases?
type I: permit the incorporation of water in oil (w/o) emulsions (e.g. hydrophilic petrolatum)
type II: water in oil (w/o) that permits additional aqueous solutions (lanolin)
What are absorption bases useful for?
incorporating small amounts of aqueous solutions into hydrocarbon bases
How do absorption bases incorporate small amounts of aqueous solutions into hydrocarbon bases?
by incorporating aqueous solution into the absorption base, and then incorporating the mixture into the hydrocarbon base
**only for small amounts of H2O
Why are absorption bases not easily washed from the skin sufrace?
because water in oil - the external phase of the emulsion is oleaginous (oily) - oil is in the continuous phase of water in oil emulsions which means it is harder to wash off
What are some examples of absorption bases?
hydrophilic petrolatum, USP
yellow ointment, USP
Lanolin, USP
How is hydrophilic petrolatum, USP made?
30g cholesterol
30g stearyl alcohol
80g white wax
860g white petrolatum
How is lanolin USP made?
- obtained from sheep wool
- cleaned, deodorized and colored
- no more than 0.25% water
- additional water may be added by mixing (type II)
- must be smooth, not dents - don’t want to see a finger in is, inside of cap shouldn’t have product
What is a water removable base?
- oil in water (o/w) emulsions that closely resemble creams
- may be diluted with water (aqueous phase)
- may absorb serous discharges
Why are water removable bases referred to as water washable bases?
water is in the continuous phase and hence easily washed from the skin
What is an example of a water removable base?
Hydrophilic ointment, USP
What are water soluble bases?
- water soluble bases do NOT contain oleaginous components (aka ~ greaseless)
- soften with the addition of water
- large amounts of aqueous solutions are not effectively incorporated in these bases
- normally used for the incorporation of solid substances
- *completely water washable
What is an example of a water soluble base?
polyethylene glycol ointment, NF
How is polyethylene glycol ointment, NF made?
PEG 3350 400g
PEG 400 600g
How can you prepare a firmer (less liquid like) water soluble base of polyethylene glycol ointment?
Use equal amounts of the two ingredients
- the greater the molecular weight, the greater the viscosity
What should be considered when selecting a base?
- desired release rate of drug from the ointment base?
- desirability of topical or percutaneous drug absorptioin
- stability of drug in the ointment base (how long it needs to be retained - preclinical study)
- characteristics of the surface to which the base is applied
- the base providing the best combination of most desired attributes should be used*
What are creams applied to?
weeping or oozing surfaces
What are lotions applied to?
usually applied to where friction may occur (under arm pits, thighs)
What are ointments applied to?
dry and scaly skin surfaces
How are ointments prepared?
mix component until uniform mixture
- mortar and pestle
- spatula and ointment slab or parchment paper
How are solids incorporated into ointments?
- levigating agents are used to reduce powder particle size to reduce grittiness prior to incorporation of the solid material into the base
How should you select levigating agents to incorporate solids into ointments?
levigating agents should be physically and chemically compatible with drug and base
When is mineral oil used as a levigating agent to incorporate solids into ointments?
When is glycerin used?
mineral oil is used for when oil is the external (continuous) phase
glycerin is used when water is the external (continuous) phase
What is the process of incorporating a solid into an ointment?
- use a stainless steel spatula except when ingredients react with the stainless steel (i.e. iodine). a rubber spatula can be used in this case
- thorough rubbing and working of the components together on solid surface until smooth and make preparation uniform (shouldn’t be gritty)
- now separate freshly prepared base from the fine powders prepared in the mixing step
- add a small amount of each together and mix until uniform
- continue until all of the powder and base are combined and uniformly blended
- levigation may be used to reduce powder particle size
How are liquids incorporated into ointments?
- consider the capacity of ointment base - note the difference between oleaginous vs hydrophilic ointment
How do you incorporate a liquid into a hydrophobic base?
- add solution to minimum amount of hydrophilic base, and then
- add this freshly prepared mixture to the hydrophobic base
How can you add small volumes of alcoholic solutions to oleaginous vehicles or emulsions with ease? think of peru balsam
natural balsams (i.e. peru balsam) is mixed with equal amounts of castor oil prior to incorporation into base. this results in an even distribution of the balsams throughout the base due to a reduced surface tension caused by the balsams
What is the fusion method of preparing ointments?
by this method “all or some of the components of an ointment are combined by being melted together and cooled with constant stirring until congealed”
What are the main methods of fusion (ointment preparation)
- heat sensitive or volatile components are added when the temperature of the mixture is low enough (last) not to cause decomposition or volatilization
- in general, components having the highest melting points are heated to the lowest required temperature to produce a melt
What are two alternative methods from the main method of fusion for ointment preparation?
- melt the component with the lowestmelting point first, followed by the addition of the remaining components in order of their melting points - as it cools
- melting all components simultaneously and increasing the temperature only as needed
Why would you use the fusion method of melting all components simultaneously and increasing the temperature only as needed ?
because they have the same melting points
What is required about topical applications and their microbial content?
Topical applications are not required to be sterile, but antimicrobial action is a must because:
- water content is an issue
- staphylococcus aureus often found in dermatologic preparations
What does the USP chapter “microbiological attributes of non sterile pharmaceutical products” deal with?
environmental control and application of good manufacturing practices to minimize both the type and number of microorganisms in unsterilized pharmaceutical products
usp states that certain products should be tested routinely
In the USP chapter “microbiological attributes of non sterile pharmaceutical products” , which products does it state should be routinely tested? Why?
Vaginal, urethral, and rectal due to the presence of yeast and molds at the site or application
How are ointments, creams, and gels packaged?
the package must have a large mouth container, or metal or plastic tubes
- in opaque or light sensitive containers when necessary
How are ointments, creams, and gels stored?
must be stored in a cool place in sealed containers
What are requirements for ointment and cream labels?
ointments and creams must include the type of base (water soluble or water insoluble)
What are creams?
semisolid preparations containing one or more drug agents dissolved or dispersed in w/o or o/w emulsion or another water-washable base
Where are creams used?
topically, rectally and vaginally
What happens when creams evaporate?
generally, when creams evaporate a thin residue film consisting of stearic acid (or other oleaginous components) is left behind
Are creams or ointments preferred? by who?
Creams are preferred by both patients and pharmacists because they are easily removed
What are gels?
semisolid systems consisting of dispersions of small or large molecules in an aqueous liquid rendered jellylike by the addition of a gelling agent
What are some gelling agents?
carbomers (high molecular weight, water soluble polymers)
How are gelling agents prepared?
they can be prepared to be used various routes including skin, eye, the nose, vagina and the rectum
What determines the viscosity of carbomers?
their polymeric composition
NF contains monographs of 6 they are 910, 934, 934P, 940, 941, and 1342 - used as gelling agents at 0.5% to 2% water
Which polymeric composition of carbomers has the highest viscosity?
940
What are pastes?
semisolid preparations intended for application to skin. they contain more solid material compared to ointments (~25%) this makes them stiffer
What are pastes used form?
to absorb serous secretions, remaining in place after application
How are pastes made?
- a portion of the base is softened prior to incorporating the solids
- a portion of the base is used rather than a liquid because the liquid will soften the base
What are examples of pastes
tender wrap - unna boot
zinc oxide paste bandage
What are plasters?
solid or semisolid adhesive masses spread on the backing of paper, fabric, moleskin or plastic
- provide long contact at the site
- adhesive tape- use adhesive plaster
What are plasters used for?
to treat corns on the feet
What is the medicated variety of plasters that provide prolonged contact at the site?
concentration of salicylic acid used in commercial plasters (range from 10% to 40%) to treat corns on the feet
What do glycerogelatins consist of?
15% gelatin
40% glycerin
35% water
10% medicinal substance (i.e. zinc oxide)
How are glycerogelatins used?
they are melted and cooled to just above body temperature before being applied to affected area
- a fine brush is used to apply the material, and is generally covered with bandage after hardening
- applied to skin for long-term *currently zinc gelatin is used to treat varicose ulcers)
What are opthalmic ointments?
- major route of drug transport in the eye by simple diffusion via the cornea
- if not efficient secondary routes are conjunctiva and sclera
What are the three barrier layers of interest for opthalmic ointments?
- lipophilic epithelial layer
- hydrophilic stromal layer
- less lipophilic endothelial layer on inside
What drugs penetrate the layers of interest for ophtalmic ointments better than hydrophilic compounds?
lipophilic drugs
What are nasal ointments?
- ointments and gel used for nasal delivery
- can be used to deliver insulin, vaccines, polypeptides and proteins
What assists with mucus movement of nasal ointments?
the ciliated epithelium
What are local effects of nasal ointments?
it is the primary treatment approach (i.e. nasal decongestants)
What is the vascular region of the nasal passage helpful for when using nasal ointments?
the vascular region of the nasal passage does enable general circulation, so systemic absorption does occur
Is sterilization of opthalmic ointments effective?
no
What are approved antimicrobial preservatives for opthalmic ointments?
- methylparaben (0.05%)
- propylparaben (0.01%)
- benzalkonium chloride (0.008%)
What are dermatologic preparations?
the drug should both penetrate and be retained in the skin for a specific period
What factors affect drug preparation of dermatologic preparations?
- physicochemical properties of the drug (molecular weight range 100-800)
- characteristics of the vehicle
- concentration of drug in the vehicle
- oil-water partition coefficient
- general condition of the skin
What does the skin do during dermatologic preparations?
it acts as a natural barrier as it does in TDDS controlling the rate and extent to which drugs can penetrate it, however with dermatologic preparations the therapeutic drug concentration delivered is unknown - so more qualitative measures are used
What must be done for general use of dermatologic preparations?
- patient must throughly wash affected area with soap and water
- dry the area with clean soft cloth
- thin layer of medication is applied to skin area, and spread evenly (***typically 1-3 mg of ointment or cream is applied per square centimeter of skin)
- area of application should remain uncovered unless otherwise stated
- clean hands immediately following use
When a patient is using a dermatologic preparation, what should the pharmacist tell the patient?
- instruct patient of proper method of administration
- explain frequency and duration of us
- any special warnings ex: **how should it be used during pregnancy (usually shouldn’t)
- therapeutic goals and outcomes
- signs of an adverse response, and what to do if something goes wrong
- when should treatment be discontinued?
