Desirable Properties of Barrier Function in Skin Care

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Questions and Answers

What is the primary mechanism of action of Azone in enhancing skin permeation?

Promotion of significant hydration of the stratum corneum

Disruption of the lipid bilayer of the stratum corneum (correct)

Mild keratolytic effect on the stratum corneum

Fluidization and solubilization of intercellular lipids

What is a common side effect of using DMSO at high concentrations?

Erythema and stinging sensation (correct)

Mild keratolytic effect on the stratum corneum

Fluidization and solubilization of intercellular lipids

Disruption of the lipid bilayer of the stratum corneum

What is a characteristic of 2-Azone as a permeation enhancer?

Requires high concentrations (>60%) to be effective

Irritating to human skin

Non-effective at low concentrations

Very effective at low concentrations (1-5%) (correct)

What is a mechanism of action of urea as a permeation enhancer?

Promoting significant hydration of the stratum corneum Signup and view all the answers

What is a characteristic of surfactants as permeation enhancers?

They solubilize the drug within the core of their micelles Signup and view all the answers

What is a common use of urea in pharmaceutical preparations?

As a permeation enhancer in transdermal drug delivery Signup and view all the answers

What is a limitation of using cationic surfactants as permeation enhancers?

They can cause damaging effects to the skin Signup and view all the answers

What is a similarity between DMF and DMAC?

They have similar mechanisms of action to DMSO Signup and view all the answers

What is the main advantage of iontophoresis over passive transdermal systems?

It eliminates the use of chemical skin enhancers Signup and view all the answers

What is the principle of iontophoresis based on?

Electrostatic repulsion rule Signup and view all the answers

What type of drug molecules can iontophoresis allow for transdermal permeation?

Charged and ionized molecules Signup and view all the answers

What is the main disadvantage of iontophoresis systems?

They are much more complicated systems Signup and view all the answers

What is the term for the process of positively charged drug ions being repelled into the skin?

Anodal iontophoresis Signup and view all the answers

What is the method of permeation that uses a low voltage external electric current?

Iontophoresis Signup and view all the answers

What is the benefit of synthesizing piperazinyl alkyl ester prodrugs of ketorolac?

It enhances the skin permeation Signup and view all the answers

What is the characteristic of iontophoresis that makes it a non-invasive method?

It is a needle-free method Signup and view all the answers

What is the main advantage of anionic surfactants compared to cationic surfactants?

They cause less skin irritation Signup and view all the answers

Which of the following is a main disadvantage of ionic surfactants?

They are powerful irritants and cause skin water loss Signup and view all the answers

What is the order of decreased skin irritation among surfactants?

Cationic SAA > Anionic SAA > Non-ionic SAA Signup and view all the answers

What is the main effect of skin hydration on drug permeation?

It increases permeation of both hydrophilic and lipophilic APIs Signup and view all the answers

Which of the following increases skin hydration?

Skin moisturizers Signup and view all the answers

What is the main effect of solvents on the skin?

They swell the polar pathway Signup and view all the answers

Which of the following is an example of non-ionic surfactants?

Pluronic F127 Signup and view all the answers

What plays a major role in successful transdermal drug permeation?

Drug-related physicochemical properties Signup and view all the answers

What is the primary reason for aprotic solvents being effective permeation enhancers?

They are able to form hydrogen bonds with other molecules having hydrogen atoms Signup and view all the answers

What is the result of aprotic solvents undergoing intercellular hydrogen bonding with proteins within the skin?

Denaturation of keratinocytes within the stratum corneum Signup and view all the answers

What is the characteristic of aprotic solvents that makes them unable to form hydrogen bonds with themselves?

Absence of hydrogen atoms on their Oxygen or Nitrogen atoms Signup and view all the answers

What is the result of aprotic solvents penetrating into lipids of the horny layer?

Lipid fluidization and disruption of the highly ordered structure of lipid packing of the stratum corneum bilayer Signup and view all the answers

What is the primary advantage of aprotic solvents as permeation enhancers?

They are able to dissolve anything and everything Signup and view all the answers

What is the characteristic of DMSO that makes it an extremely powerful aprotic solvent?

It is able to dissolve anything and everything Signup and view all the answers

What is the primary requirement for a permeation enhancer to be effective?

It should have a unidirectional flow and cause no leakage of body fluids Signup and view all the answers

What is the characteristic of an ideal permeation enhancer?

It should have a unidirectional flow and cause no leakage of body fluids Signup and view all the answers

What is a major advantage of iontophoresis in transdermal patches?

It eliminates the use of chemical skin enhancers, reducing irritation and toxic side effects. Signup and view all the answers

What is the primary mechanism of action of electroporation?

The high voltage electric current produces temporary and momentary hydrophilic pores in the stratum corneum. Signup and view all the answers

What is a key difference between iontophoresis and phonophoresis?

Iontophoresis can be used in transdermal delivery of ionic drugs only, while phonophoresis enhances permeation of both ionic and non-ionic drugs. Signup and view all the answers

What is the typical duration of the high voltage electric current in electroporation?

10 microseconds to 100 milliseconds Signup and view all the answers

What is a characteristic of microneedles?

They are arrayed on a patch and pierce the upper epidermis, creating hollow pores for drug delivery. Signup and view all the answers

What is a disadvantage of iontophoresis compared to phonophoresis?

Iontophoresis is limited to aqueous media only. Signup and view all the answers

What is a type of drug that can be delivered using electroporation?

Peptide hormones such as vasopressin and calcitonin. Signup and view all the answers

What is the material used to make microneedles?

Silicon. Signup and view all the answers

Study Notes

Ideal Properties of Chemical Permeation Enhancers

Barrier function of the skin should be diminished with no loss of electrolytes or body fluids
Unidirectional flow with no leakage of body fluids
Acceptable upon usage (spreadable and leaves a good skin feel)
Easily formulated into different semisolid dosage forms

Examples of Chemical Permeation Enhancers

Aprotic Solvents

Most effective permeation enhancers
Accelerate skin penetration of many compounds (steroids, antibiotics)
Examples: Dimethylsulfoxide (DMSO), Dimethylformamide (DMF), Dimethylacetamide (DMAC)
Mechanism of action: Formation of hydrogen bonds with intercellular proteins, leading to denaturation of keratinocytes within the stratum corneum

Azone

Smooth, oily, hydrophobic liquid
Non-irritating to human skin
Capable of enhancing percutaneous penetration of many compounds
Mechanism of action: Disrupts the highly ordered lipid packing of the lipid bilayer

Urea

Promotes transdermal drug permeation by:
- Promoting significant hydration of the stratum corneum
- Forming diffusive channels within the skin layers
- Causing mild stratum corneum disruption
Advantages: Very effective at low concentrations, non-toxic, and biodegradable

Surfactants or Surface Active Agents (SAA)

Disrupt the lipid bilayer of the stratum corneum by fluidizing and solubilizing intercellular lipid
Modify the barrier function of the stratum corneum, enhancing drug permeation
Examples:
- Cationic surfactants (e.g., Cetyl trimethyl ammonium bromide)
- Anionic surfactants (e.g., Sodium lauryl sulphate and diacetylsulphosuccinate)
- Non-ionic surfactants (e.g., Pluronic F127, Pluronic F68, and Tween 80)

Skin Hydration

Hydration of the stratum corneum increases permeation of both hydrophilic and lipophilic APIs
Skin hydration opens up the dense, compact structure of the stratum corneum, leading to swelling of skin cells and tissues

Other Solvents

Increase penetration by swelling the polar pathway
Examples: Polyols (alcohols, e.g., methanol and ethanol), propyleneglycol, and glycerol

Physical Permeation Enhancer Methods

Iontophoresis

Definition: Permeation of ionized drug molecules through intact skin membranes using a low-voltage external electric current
Mechanism of action: Electrostatic repulsion rule, repelling charged drug ions into the skin
Advantages:
- Non-invasive
- Rapid onset of action
- Enhanced transdermal delivery for a broad range of APIs
- Eliminates the use of chemical skin enhancers in transdermal patches
Disadvantages:
- Complicated systems
- Restricted to aqueous media

Electroporation

Definition: Enhancement of drug permeation through the skin by application of a high-voltage electric current
Mechanism of action: Temporary hydrophilic pores created in the stratum corneum, allowing passage of large drug molecules
Examples: Peptide hormones (e.g., vasopressin, neurotensin, and calcitonin)

Microneedle Array

Definition: Array of micronsized needles applied on a patch (10 to 200 μm in height and 10 to 50 μm in width)
Mechanism of action:
- Microneedle arrays pierce the upper epidermis, creating hollow pores for drug entry
- Painless due to short length, avoiding nerve endings in the upper dermis

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Description

This quiz covers the ideal characteristics of a substance that can repair the skin's natural barrier function, including diminishing electrolyte loss, being spreadable, and being easily formulated into various semisolid dosage forms.