3.2: Topical Drug Delivery II

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Questions and Answers

What is a characteristic of hydrocarbon (oleaginous) bases in ointments?

They are primarily water-based.

They are greasy and insoluble in water. (correct)

They can easily absorb water.

They contain a high percentage of surfactants.

Which of the following statements accurately describes absorption bases?

They can absorb water due to surfactants. (correct)

They do not enhance drug delivery.

They are entirely water-soluble.

They form water-in-oil emulsions only in a dry environment.

What effect do hydrocarbon bases primarily have on skin contact?

They cause dehydration of the skin.

They provide a continuous, greasy, and water-repellent barrier. (correct)

They form a greasy but water-absorbent film.

They quickly evaporate, enhancing drug permeation.

Which of the following is considered an emulsion base in ointment formulations?

Hydrous lanolin Signup and view all the answers

What is a common disadvantage of using ointments based on hydrocarbon bases?

They tend to feel greasy and may stain clothing. Signup and view all the answers

Which of the following does NOT describe a property of absorption bases?

Greasiness is absent. Signup and view all the answers

What distinguishes water-in-oil emulsions from other ointment bases?

They contain oil as the external phase. Signup and view all the answers

What therapeutic effect do ointments generally provide when applied to the skin?

They enhance drug permeation. Signup and view all the answers

What is the primary characteristic of lotions compared to other topical dosage forms?

They have a continuous aqueous phase. Signup and view all the answers

What therapeutic effect do lotions provide upon application?

They leave a thin film that cools and soothes the skin. Signup and view all the answers

What type of instability can lotions experience?

Chemical, physical, and microbiological instability. Signup and view all the answers

In what form are active drugs typically found in gels?

Suspended or dissolved in the liquid phase. Signup and view all the answers

What is a common property of gels in topical applications?

They consist of a liquid phase trapped in a solid structure. Signup and view all the answers

Which of the following is NOT typically an example of a lotion?

Iodine tincture. Signup and view all the answers

What type of vehicle do topical solutions typically use?

Aqueous vehicles, sometimes with alcohol. Signup and view all the answers

Which statement about patient acceptance of lotions is accurate?

Lotions are highly acceptable due to their ease of application. Signup and view all the answers

Which of the following polymers is used in gels but is not a polysaccharide?

Carbomer Signup and view all the answers

What characteristic does a gel possess that aids in drug delivery?

Porous matrix film Signup and view all the answers

Which of the following gels is designed specifically for joint pain relief?

Voltaren Gel Signup and view all the answers

What is a key advantage of using ethanol in gel formulations?

It enhances drug penetration into the skin. Signup and view all the answers

Which of the following is a common application of collagen-based gels?

Sealing small wounds Signup and view all the answers

Benzoyl peroxide gel is primarily used for which of the following conditions?

Acne treatment Signup and view all the answers

Which property is NOT typically associated with gelling polymers?

Thermal sensitivity Signup and view all the answers

What is a notable difference between gels like hand sanitizer and gels used for acne treatment?

Acne treatment gels contain antibiotics. Signup and view all the answers

What is a primary characteristic of Eucerin compared to anhydrous absorption bases?

Moderately good emollient properties Signup and view all the answers

How do oil-in-water emulsion bases differ from water-in-oil emulsion bases regarding transepidermal water loss?

They do not block transepidermal water loss Signup and view all the answers

Which of the following statements is true about water-soluble bases?

They can be irritating to wounds Signup and view all the answers

What is a common therapeutic property of pastes used in dermatological applications?

They absorb fluid and have high protective value Signup and view all the answers

What is the primary reason hydrophilic ointment is often referred to as vanishing cream?

It evaporates, leaving a thin transparent film Signup and view all the answers

Which ingredient is commonly used in ointments classified as pastes?

Petrolatum Signup and view all the answers

What distinguishes water-washable bases from other formulations?

They allow easy removal with water Signup and view all the answers

How do the protective properties of anhydrous absorption bases compare to those of Eucerin?

Anhydrous bases are more protective than Eucerin Signup and view all the answers

What is the primary function of castor oil when added to pyroxylin?

To soften the pyroxylin and ensure it remains in place. Signup and view all the answers

Which topical dosage form is specifically designed to be cut to fit the treatment area?

Plasters. Signup and view all the answers

What type of topical dosage form allows for non-rubbing application, particularly useful for irritated areas?

Aerosols. Signup and view all the answers

Which of the following is NOT a benefit of wet dressings?

Provide a protective barrier against pathogens. Signup and view all the answers

What characteristic do foams have that differentiates them from other topical forms?

They are gas-propelled liquids or solids. Signup and view all the answers

Which of the following excipients is used to prevent rancidity in hydrocarbon formulations?

Butylated hydroxytoluene (BHT). Signup and view all the answers

What is one drawback of foams as a topical dosage form?

They tend to break down quickly. Signup and view all the answers

What type of antimicrobial preservative is commonly found in water-containing dosage forms?

Benzalkonium chloride. Signup and view all the answers

Which type of moisturizer primarily inhibits transepidermal water loss?

Occlusives Signup and view all the answers

What is a significant drawback of using humectants in low humidity environments?

They may draw water from the skin. Signup and view all the answers

What does the fingertip unit measurement represent?

The quantity from fingertip to the index finger's first crease. Signup and view all the answers

Which of the following is a characteristic of co-solvents?

They enhance drug solubility and prevent precipitation. Signup and view all the answers

What is the recommended time frame for applying moisturizers after bathing?

Within 3 minutes of bathing. Signup and view all the answers

Which ingredient is commonly used as a humectant?

Glycerin Signup and view all the answers

Which of the following is NOT a property of occlusive agents?

They enhance drug penetration. Signup and view all the answers

What is the purpose of using a thin film of moisturizer during application?

To achieve effective hydration without excess product. Signup and view all the answers

Study Notes

Topical Drug Delivery - Semisolids

Semisolids include ointments, intended for skin or mucous membrane application.
Ointments contain a medicinal substance.
Classifications based on interaction with water:
- Hydrocarbon (oleaginous) bases: greasy, insoluble in water, anhydrous, do not absorb water.
  - Examples: White Petrolatum USP (Vaseline), White Ointment USP (wax added for stiffness/smoothness).
  - Properties: form an adherent, continuous, greasy, water-repellent film, good occlusiveness (blocks water loss), emollient effect (softens skin), enhance drug permeation, prolonged contact time.
  - Patient aspects: greasy/unpleasant, not water washable, can stain.
- Absorption bases: greasy, anhydrous, can absorb water due to surfactants, typically form water-in-oil emulsions with added water.
  - Examples: lanolin, hydrophilic petrolatum USP (Aquaphor).
  - Properties: somewhat occlusive, less greasy than hydrocarbon bases, readily absorbed.

Topical Drug Delivery - Liquids

Lotions are fluid emulsions or suspensions for external application.
Continuous phase is typically aqueous.
Examples: Calamine lotion, clotrimazole lotion, selenium sulfide lotion, Cetaphil (oil-in-water emulsion).
Properties: non-occlusive, evaporates, cools/soothes skin, suitable for large areas, non-greasy-highly acceptable.

Topical Drug Delivery - Pastes

Pastes are ointments with high percentages (20-50%) of fine powder.
Base is usually petrolatum.
Examples of powders: Zinc oxide, talc, starch, bentonite.
Properties: thick, protective film, less greasy than corresponding base without powder, absorptive, stiff.

Topical Drug Delivery - Aerosols

Aerosols are drug/propellant blends for spray application.
Useful for areas where rubbing is irritating (e.g., sunburns).
Examples: antifungal spray powders, sunburn products (e.g., Solarcaine).

Topical Drug Delivery - Plasters

Plasters are solid/semisolid adhesive masses spread on backing material for prolonged external application.
Similar to patches but can be shaped to the treatment area.
Example: Salicylic acid plaster (Mediplast).

Topical Drug Delivery - Wet Dressings

Aqueous solutions applied as a dressing (e.g., gauze, linens).
Solutions are typically astringents or antiseptics.
Benefits: cleanse wounds of exudates, help with wound healing, maintain drainage, remove exudates/secretions.
Example: Aluminum acetate.

Topical Drug Delivery - Foams

Foams are gas-propelled liquids/solids, resemble shaving cream consistency.

Topical Dosage Form Excipients

Antioxidants prevent rancidity (e.g., BHT, BHA, Vitamin E).
Antimicrobial preservatives prevent microbial growth (e.g., benzalkonium chloride, parabens, benzoic acid).
Waxes increase stiffness/reduce tackiness (e.g., beeswax, cetyl esters wax, cetyl alcohol).
Moisturizers hydrate skin:
- Occlusive (inhibit water loss: petrolatum, Aquaphor).
- Non-occlusive (e.g., dimethicone, other silicones).

Topical Drug Considerations

Thin films are sufficient for most applications but diaper rash pastes use thicker films.
Fingertip unit-measurement method estimates product dosage.
Cleanse/dry treatment area, apply shortly after bathing/showering.
Use gentle rubbing/massage motions for application.
Avoid excessive amounts (especially in children) due to increased drug penetration.
Exercise caution in thin-skinned areas and intertriginous areas (skin-on-skin contact) due to increased drug penetration.

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Description

Explore the world of semisolids in topical drug delivery. This quiz covers ointments, their classifications based on water interaction, and different types of bases used. Understand the properties, patient considerations, and examples of hydrocarbon and absorption bases.