semi-solids Flashcards
layers of the skin
stratum corneum, epidermis, dermis
stratum corneum
outer layer: 40% water, 40% proteins, 20% lipids
15-25 layers of flat, nonliving cells
semipermeable, passive diffusion
dermis
vascularized, systemic absorption, hair follicles, sweat & sebaceous glands
routes of drug penetration
intercellular, intracellular, transappendageal (transfollicular)
drugs penetrate skin based on…
physiochem properties, particle size, pH of product, oil-water partition coefficient, drug concentration, skin condition
good candidates for diffusion across skin
substances with aqueous and lipid solubility
________ acts as a natural barrier limiting drug penetration
normal unbroken skin
hyperpigmentation, exposed sun-damaged skin causes
decreased penetration bc it has a thicker epidermal layer
age of skin
skin thickens with age -> decreased penetration
increased penetration is caused by
skin disorders (eczema) and a rise in skin temp
semi-solid dermatologic products
transdermal & topical
transdermal products
deliver drugs through the skin into systemic circulation (nitroglycerin ointment)
transdermal delivery
skin is not target organ, percutaneous absorption
transdermal drug delivery systems (TDDs)
ointments, creams, gels, transdermal patches
for topical products, _____ is the target organ
skin
topical drug products
treat dermal disorders (topical antibiotics), penetrate & retain in skin a while
types of topical drug products
antibiotics, antifungal, anti-infective, keratogenic, keratolytic
topical drug states of matter
liquids (solutions, suspensions, emulsions), semi-solids (ointments, creams, gels), solids (powders)
semi-solids may be applied…
to the skin, surface of eye, nasally, vaginally, rectally
all topical medications must be labeled
FOR EXTERNAL USE
types of ointments
medicated, unmedicated (physical effect), ointment bases (vehicles)
types of unmedicated ointments
protectants, emollients, lubricants, occlusives
protectants
protect injured/exposed skin surface & permit healing
emollients
soften skin or soothe irritation
lubricants
reduce the friction between surfaces
occlusives
prevent moisture in the skin from evaporation
ideal ointment base is
chemically/physically stable, nonreactive & compatible with ingredients, nontoxic/nonirritating, easy to apply/remove
ointment bases, USP
hydrocarbon (oleaginous), absorption: anhydrous and W/O emulsions, water-removable/soluble
oleaginous (hydrocarbon) bases
insoluble/immiscible with water, miscible with oil, greasy, absorb some alcoholic solutions
types of hydrocarbon ointment bases
petrolatum, white petrolatum, white & yellow ointment
petrolatum, USP (Vaselin)
purified mixture of semisolid hydrocarbons made of petroleum
color of petrolatum
yellowish to light amber
types of petrolatum
yellow petrolatum, petroleum jelly, Vaselin
white petrolatum, USP (White Vaseline)
decolorized petrolatum
types: white petroleum jelly, White Vaseline
yellow ointment, USP contains
yellow wax: 50 g
petrolatum: 950 g
white ointment, USP
used bleached or purified yellow wax
2 types of absorption bases
anhydrous & W/O bases
absorption bases are used
to incorporate limited volumes of aqueous solution into hydrocarbon base
anhydrous bases
formation of w/o emulsions, insoluble in water, emollient, greasy, absorb alcohol/some water
types of anhydrous bases
hydrophilic petrolatum (Aquabase, Aquaphor)
hydrophilic petrolatum formula
cholesterol, stearyl alcohol, white wax, white petrolatum (hydrocarbon base)—-these are emulsifiers
w/o emulsion bases
contain water & permit incorporation of additional amount of water, emollient, greasy
emulsion bases are _____ in water
insoluble
types of emulsion bases
Lanolin, USP (clean, deodorized, decolorized, waxlike); contains no more than 0.25% water
Modified Lanolin, USP (reduced contents of free lanolin; alcohols, detergents)
water-removable bases
o/w (may be diluted with aqueous or water-miscible solutions)
Hydrophilic Ointment, USP
hydrophilic ointment brands
Dermabase
Aquaphilic
hydrophilic ointment (1000g) composition
antimicrobial preservatives: methylparaben 0.25g, propylparaben 0.15g, propylene glycol 120g
emulsifiers: sodium lauryl sulfate 10g (primary), srearyl alcohol 250g (secondary)
white petrolatum 250g (oleaginous phase)
purified water 370g
water-soluble bases
lipid-free, for incorporation of aqueous solutions/solids, greaseless
example: polyethylene glycol ointment
polyethylene glycol ointment (PEG)
polymer of ethylene oxide & water
PEG with MW below 600
clear, colorless liquid
PEG with MW above 1000
waxlike, white compound
PEG ointment, NF (1000g) contains
PEG 3350 (400g)
PEG 400 (600g)
these are semisolid ointments
firmness of PEG ointment can be altered by
switching PEG 3350 with equal amount of stearyl alcohol or changing PEG 3350 & 400 proportions
incorporated medications must be
stable & compatible
incorporated meds properties
aqueous, oil, solids
oleaginous bases release
fat-soluble: limited release
water-soluble: good release
water-soluble/miscible bases release
fat-soluble: release readily
water-soluble: limited release
formulations that include liquids require
ointment base that can absorb it
solids incorporated into ointment should be
solubilized or in finest state
methods of ointment preparation
incorporation: components mixed until uniform
fusion: components combined, melted, & cooled w constant stirring until uniform
incorporation method
rubbing components together on hard surface until smooth/uniform
levigation
reducing particle size of solids by trituration, using lubricating agents such as min oil (hydrocarbon/absorption bases) & glycerin (water-removable/soluble bases)
levigation is not needed when
solid has a very fine particle size, quantity of solid is small, final product must be stiff ointment/paste, ointment base is soft
steps of incorporating solids
- trituration (reduce to fine powder in mortar)
- ointment base placed on one side of slab
- drug powder on other side of slab
- some powder mixed w portion of base until uniform (geometric dilution)
- continued until all portions uniformly blended
steps of pulverization by intervention
- material dissolved in solvent (alcohol)
- solution spread on ointment slab
- solvent allowed to evaporate, leaving thin film
4, material titrated into ingredients with spatula
steps of incorporating aqueous solution
- solution incorporated into min amount of hydrophilic base
- add mixture to hydrophobic base
