DƯỢC LÍ Goodman & Gilman's The Pharmacological Basis of Therapeutics 12th, 2010

Table 65–2
Vehicles for Topically Applied Drugs
CREAM OINTMENT GEL/FOAM LOTION/SOLUTION/FOAM
Physical basis Oil in water emulsion Water in oil Water-soluble Solution-dissolved drug
emulsion
base
Lotion-suspended drug
Aerosol propellant with drug
Foam drug with surfactant as
foaming agent and propellant
Solubilizing >31% water (up to 80%) <25% water Contains water- May be aqueous or alcoholic
medium
soluble polyethylene
glycols
Pharmacological Leaves concentrated drug Protective oil Concentrates drug
advantage at skin surface film on skin at surface after
evaporation
Advantages for Spreads and removes Spreads easily Nonstaining Low residue on scalp
patient easily Slows water Greaseless
No greasy feel evaporation Clear appearance
Gives a cooling
effect
Locations on Most locations Avoid Foams well for scalp Solutions and foams are well
body intertriginous and other hairy accepted on scalp
areas
locations
Disadvantages Needs preservatives Greasy to very Needs preservatives
greasy
High alcohol can
Stains clothes be drying
Occlusion Low Moderate to high
Increases skin
moisture
Composition Requires humectants Needs surfactants Microspheres or
issues (glycerine, propylene to prevent phase microsponges can
glycol, polyethylene separation be formulated in
glycols) to keep moist Hydrocarbon gels
when applied
(VASELINE)
Oil phase with long-chain
alcohol for stability and
smooth feel
Has absorption bases—
hydrophilic petrolatum
glucocorticoids. Absorption varies among body areas;
the steroid is selected on the basis of its potency, the
site of involvement, and the severity of the skin disease.
Often, a more potent steroid is used initially, followed
by a less potent agent. Most practitioners
become familiar with at least one glucocorticoid in
each class to facilitate selection of the appropriate
strength of therapy. Twice-daily application of topical
glucocorticoids is sufficient, and more frequent application
does not improve response (Green et al., 2005).
In general, only nonfluorinated glucocorticoids should
be used on the face or in occluded areas such as the
axillae or groin.
Intralesional preparations of glucocorticoids
include insoluble preparations of triamcinolone acetonide
(KENALOG-10) and triamcinolone hexacetonide