Topical DDS Flashcards
What does topical refer to?
Application of the drug locally
-mostly skin
-membranes
-mouth
-eye
-nasal
Topical DDS: Ointments, Cream, Gel, Pastes, Lotions
Difference between dermatological skin products and Transdermal drugs?
dermatological skin products mostly work topically on the skin (inflammation, psoriasis, actinic keratosis), Transdermal will go into the blood (systemically)
Analgesics often work on joint muscles, still considered topical (grey area - bc the blood may take it there)
What are the routes that deliver topical preparations?
-Dermatological: ALL - TOPICAL or SYSTEMIC
-Nasal (rich blood supply): Ointment, Gel - mostly topical, also systemic
-Rectal: Ointment, Gel, Cream -> perianal and anal canal
-Vaginal: Ointment, Gel, Cream, Foam
(Otics and Ophtalmics can also be considered topical bc there is no high Bioavailability on those routes)
Rectal indications:
Anorectal pruritus, inflammation, hemorrhoids
Vaginal indications:
Anti-infectives, hormones, pH modifiers, spermicides
Definition of Ointments or Ointment Bases
Ointment Bases: Mixture of Oil, water, and different excipients + DRUG
-Semisolid preparations for external use to the skin or mucous membranes
-melt at body temperature
Characteristics of od ideal Ointments
-Spread easily, Non-gritty (should be fine)
-semisolid plastic flow: often stiff -> shear and yield value need to be crossed for the ointment to spread, can also be pseudoplastic if the yield value doesn’t exist that much
Types of Ointment Bases: USP Classification
OLEAGINOUS BASES
-Water insoluble and Not water washable
-Oily greasy, and Occlusive (Emollient) -> it forms a layer and prevents the water from evaporating from the skin (no dehydration)
-Lack of cosmetic appeal
-Applied on dry skin bc of emollient effect, Not applied on hairy areas
Examples of Oleaginous Bases
-Hydrocarbons: Mineral oils, petrolatums, paraffins, waxes
-oils: Castor oil, cottonseed oil, olive oil
-Synthetic esters and alcohols: Glyceryl monostearate, butyl stearate, isopropyl lanolate, cetyl alcohol, stearyl alcohol
-White petrolatum (refined Vaseline, used in LAB to make Zinc oxide paste)
!!-White ointment: A mixture of white wax and petrolatum
Types of Ointment Bases:
ABSORPTION BASES - Type A
Bases that can form w/o Emulsions
-Anhydrous, it has oily ingredients (petrolatum, waxes) and an emulsifying agent -> which can absorb excretes from wounds or edema
-Can absorb water (to create a w/o emulsion), but has NO WATER
-Water insoluble and Not water washable
-Oily, occlusive, and lacks cosmetic appeal
Examples of Absorption Bases
!!-Anhydrous Lanolin (woot fat)
-Hydrophilic petrolatum
-Aquaphor -> contains Petrolatum, Lanolin alcohol (EMULSIFIER)
Aquabase generic for Aquaphor
Types of Ointment Bases:
ABSORPTION BASES - Type B
Absorption Bases that are w/o Emulsions - it has oil, water, and an emulsifier -> also used for weeping wounds to absorb excretes
-Water insoluble and Not water washable
-Can absorb water and contains water
-Easy to spread and Cosmetically elegant
-Occlusive
Examples: !!Hydrous Lanolin, Nivea, Eucin (these products have water as excipient)
How can you contain water, and absorb water, but also be water insoluble?
Water removable Bases
called CREAM
-o/w emulsion (w/o also possible) often called a CREAM -> oil, emulsifier, and water as the external phase
-Easily washed from the skin, can absorb serous
discharges
-not as occlusive
-humectant: help moisturize by adding water (different to Emollient in w/o ointments)
Example: Hydrophilic ointment, USP
Watersoluble Bases
-Water soluble and water washable
-Can absorb water
-Anhydrous or hydrous
-no oil phase, easy to remove
Examples: Composed of polyethylene glycols (PEGs; Macrogols)
MW varies depending on the number of polymers (PEG 400 liquid - PEG 8000 solid, would be melted before use)
Criteria on how to choose the appropriate Base
*Release rate -> water-soluble drugs wouldn’t want to leave the base
*Topical or percutaneous drug absorption -> some drugs are absorbed better, hence go deeper f.e. Steroids have better absorption in oleaginous base than in creams
* Occlusion -> for dry skin
* Stability of drug -> if not stable in water don’t use o/w
* Effect of drug on ointment base -> drug and base shouldn’t be complexing or reacting in a way that it hinders the drug
* Easily removable?
* Characteristics of surface for application
Applications to prepare Ointments:
-Ointment Slab/Pill Tile/Spatula
-Mortar/Pestle (not preferred bc of losses)
-Unguator
-Ointment Mill
Compounding Ointment:
-When working with solids (like powder), the first step is to LEVEGATE (reduce particle size w/ liquid) with f.e. glycerin and SPATULATION
-Then add the semisolids (LAB example: Lanolin and petroleum by geometric dilution)
Compounding Cream:
The oily phase may have solids that need to be melted -> start with the material with the highest melting point, then continue with solids with lower MP
-water phase has to be a few degrees higher
-W/O: add water slowly; O/W: add oil slowly
-Cooling with constant stirring -> promoteS the fusing of the oil and water phase and the formation of the cream
-HEAT: prevent evaporation of water, and be careful w/ heat-labile drugs and excipients (degradation)
Selection of Levegation Agent:
-For W/O Emulsion bases, Oleaginous, Absorption: Mineral Oil
-For O/W Emulsion bases, water-soluble bases:
Glycerin/Propylene Glycol/Water
Ointment Packaging and Storage
Jars: Glass, Plastic - Do not pour in while hot!
Disp. Jars: Plastic
Tubes: Plastic, tin, aluminum
Syringes: Individually dosed, good protection of the product
Store in a cool place and avoid the extreme temperature (no fridge)
Definition of creams
semisolid preparations with medicinal agents
dissolved or dispersed in a W/O or an O/W emulsion (w/o are often creams)
Characteristics: Semisolid, Pseudoplastic flow (viscosity reduces as you apply shear), small force will initiate flow
For skin, rectal, and vaginal
Difference between Ointments and creams:
Ointments: w/o
Creams: mostly o/w, Pseudoplastic flow, easier to spread and to remove
Definition of Pastes
Thick, stiff ointments, don’t flow at room temperature -> protective coatings, so the skin doesn’t get any rashes
-Semisolid, plastic flow with definite yield value (harder to spread)
-Some may have dilatant flow (resistance to flow increased with the increased force of application)
Definition of Lotions
-Aqueous preparations -> need insoluble material for external application without friction
-Newtonian and free-flowing (better flowing than creams), flows under gravity
-No yield value
-also refer to o/w and w/o emulsions
->preferred in surfaces that rub against each other with more friction
