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*