Ointments, Creams, Gels

Functions of Topical Dermatologicals

Designed to deliver drug to the skin (target organ)

Topical dermatologicals can be

• Protectants (Creates layers over the skin - SPF40)

• Humectants (Like moisturizers and retrieves it from outside)

• Emollients (Dissolves into the skin, oil based)

• Vehicles for medication transport 

Transdermal Products

Deliver drug percutaneously for entry into systemic circulation (the skin is not the intended target)

Advantages of Topical Dermatologicals

• Drug goes to site of action

• Minimal amount of drug needed

• Low risk of systemic adverse events

Disadvantages of Topical Dermatologicals

• Absorption of drug

• Skin thickness varies

• Skin irritation

• Application process

Ointments

Semisolid preparations intended for external application to the skin or mucous membranes that soften or melt at body temperature

• Semisolid plastic flow characteristics

• Resistance to flow drops as applications continues

• 4 main categories of ointment bases

Oleaginous Bases (Hydrocarbon Base)

• Emollient, Protective, and Occlusive effects

• Immiscible with water

• Aqueous preparations can not be incorporated; very small amounts of alcohol can be absorbed

• Levitating agents such as mineral oil, can be used when drug to incorporate is a powder

  • Petrolatum, USP; White Petrolatum, USP

The two absorption bases

• Anhydrous Absorption Bases

• Emulsion Base

• Occlusive, but not the same degree as oleaginous bases

• Not easily removed - external phase of emulsion is oil

Anhydrous Absorption Bases

Permit incorporation of aqueous solutions resulting in Water/Oil emulsions

• Ex. Aquabase

Emulsion Bases

Permit incorporation of additional quantities of aqueous solutions

• Ex. Nivea

Emulsion  

Fine dispersion of minute droplets of one liquid in another which is not soluble or miscible 

Stable Emulsion

A wide variety of emulsifiers are used in pharmacy to prepare emulsions such as creams and lotions

• Emulsifying wax

• Cetearyl alcohol

• Ploysorbate 20

• Ceteareth 20

Water Removable Bases

• Oil in water (O/W) emulsions resembling creams

• External phase of emulsion is water - easily removed from skin (water washable)

• Absorb serous discharges

  • Ex. Dermabase

Water soluble bases

• Do not contain oleaginous components

• Can contain and absorb water

• Water washable

• Greaseless

• Used in incorporation of solid drug substances

  • Ex. Polybase

Factors to be considered with the selection of the appropriate base

• Release rate of drug from ointment

• Topical or percutaneous drug absorption

• Occlusion of moisture from skin

• Stability of the drug

• Removal by washing with water

• Characteristics of the surface for application

Incorporation Method

Ingredients are mixed until uniform mixture

• Mortar and Pestle (M&P)

• Electronic M&P

• Spatula and Tile

• Ointment Mil

Incorporation of solids into base

• Communication & Levigation

• Geometric dilution

Incorporation of liquids into base

• Consider ointment base capacity to accept liquids

• Ointment mill video

Methods of How to prepare ointments

• Incorporation method

• Fusion method

Fusion Method

Components are melted and allowed to congeal under constant stirring

• (70 degree C - 75 degree C) For emulsions, the 2 phases should be at the same temperature

• Water/Oil: add water slowly to the oil phase

• Oil/Water: add oil slowly to the aqueous phase

• Heat susceptible or volatile substances - add last (cooler)

Ointment Compendial Requirements

• Microbial Content

• USP Minimum Fill Test <755>

• Stability <795>

USP Minimum Fill Test <755>

When product is <60 g or mL/unit, “for a test of 10 units”: 

• The average content of 10 units must not be less than 100% of the labeled amount

• None of the units tested may contain less than 90% of the labeled amount

Stability <795>

“For water containing topical/dermal/mucosal liquid or semisolid formulations BUD is no later than 30 days

Packaging, Labeling, and Storage

• Jars: Glass & Plastic

• Tubes

• Syringes: Individually dosed

• Labeling

  • Dual Labels

• Storage

  • Store in a cool place

Creams

Opaque, soft solids or thick liquids intended for external application, consisting of medicaments dissolved or suspended in water-soluble or vanishing cream bases

Semi-solid, pseudoplastic flow

Will not flow under force of gravity but small force will initiate flow

The term “cream”

Traditionally applied to semisolids that possess a relatively soft, spreadable consistency formulated as either water-in-oil or oil-in-water emulsions

More recently, restricted to products consisting of oil-in-water emulsions

Term “cream” most frequently applied to soft cosmetically acceptable types of preparations

Gels

Semisolid systems consisting of dispersions of small or large molecules in an aqueous liquid vehicle rendered jelly-like through the addition of a gelling agent-carboxymethylcellulose

Applications include:

• Oral

• Topical

• Intranasal

• Vaginal

• Rectal

The Types of Gels

• Single Phase

• Two Phase

Gel Single Phase

• Gels in which the macromolecule are uniformly distributed throughout a liquid with no apparent boundaries between the dispersed macromolecules and the liquid

• Usually involve organics

Gel Two Phase 

• When the gel mass consists of floccules of small distinct particles

• Usually involve inorganics

• Milk of Magnesia is an example (MG Hydroxide gel)

Gel Composition

Gelling Agent:

• Synthetic Macromolecules (Carbomers, Cellulose derivatives)

• Natural hums (Arabic Gum, Tragacanth)

• Alginic acid (Alginate, Brown Algae)

• Water

• Cosolvents

• Preservatives

• Stabilizers

Pastes

• Thick, stiff ointments that do not ordinarily flow at body temperature, and therefore serve as protective coatings over the areas to which they are applied

• Usually > 20% solids 

• Semisolid, dilatant flow

  • Resistance to flow increased with increased force of application

Plasters

Solid or semisolid preparations that cannot be spread at room temperature

• Ex. Salicylic acid 40% plaster

Lotions

Intertriginous areas - two skin rub together such as axilla of the arm, anogential region, skin folds of the breasts and fingers/toes

Creams

Moist, weeping lesions

Ointments

Dry, scaly lesions

Ophthalmic Ointments and Gels

• Short residence time after application

• Sterile

• Nonirritating 

• Soften at body temperature

Nasal Ointments and Gels

• Local and systemic effects

• Rich blood supply in nasal lining

Rectal Ointments, Creams, Gels

• Anorectal pruritus

• Inflammation

• Hemorrhoids

Vaginal Ointments, Creams, Gels

• Anti-infectives

• Hormones

• pH modifiers 

• Spermicides 

Nasal Ointments and Gels

The nose internal surface is coated with a thin layer of mucus to protect the respiratory system from bacteria.

Some drugs moisturize the nasal passage or act as decongestants

Some drugs are inhaled nasally for central effect such as butorphanol (Stadol)

Vaccines and other polypeptides/proteins might be successfully administered nasally

Rectal Preparations - Topical

Products treat local conditions on anorectal pruritus, and hemorrhoids

Bases used include combinations of PEG300 and 3350, emulsion cream bases using white petrolatum and mineral oil as well as other ingredients including antibacterials

Application externally with a finger, or internally for hemorrhoids with an applicator

Vaginal Preparations

The vaginal surface is lined with squamous epithelium cells and mucus

Products are used to treat infections, endometrial atrophy, and contraception

Antibiotics and antifungal are used - nystatin, clotrimazole, and miconalzole

Estrogen cream for post menopausal women