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?

    <p>Promoting significant hydration of the stratum corneum</p> Signup and view all the answers

    What is a characteristic of surfactants as permeation enhancers?

    <p>They solubilize the drug within the core of their micelles</p> Signup and view all the answers

    What is a common use of urea in pharmaceutical preparations?

    <p>As a permeation enhancer in transdermal drug delivery</p> Signup and view all the answers

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

    <p>They can cause damaging effects to the skin</p> Signup and view all the answers

    What is a similarity between DMF and DMAC?

    <p>They have similar mechanisms of action to DMSO</p> Signup and view all the answers

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

    <p>It eliminates the use of chemical skin enhancers</p> Signup and view all the answers

    What is the principle of iontophoresis based on?

    <p>Electrostatic repulsion rule</p> Signup and view all the answers

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

    <p>Charged and ionized molecules</p> Signup and view all the answers

    What is the main disadvantage of iontophoresis systems?

    <p>They are much more complicated systems</p> Signup and view all the answers

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

    <p>Anodal iontophoresis</p> Signup and view all the answers

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

    <p>Iontophoresis</p> Signup and view all the answers

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

    <p>It enhances the skin permeation</p> Signup and view all the answers

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

    <p>It is a needle-free method</p> Signup and view all the answers

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

    <p>They cause less skin irritation</p> Signup and view all the answers

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

    <p>They are powerful irritants and cause skin water loss</p> Signup and view all the answers

    What is the order of decreased skin irritation among surfactants?

    <p>Cationic SAA &gt; Anionic SAA &gt; Non-ionic SAA</p> Signup and view all the answers

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

    <p>It increases permeation of both hydrophilic and lipophilic APIs</p> Signup and view all the answers

    Which of the following increases skin hydration?

    <p>Skin moisturizers</p> Signup and view all the answers

    What is the main effect of solvents on the skin?

    <p>They swell the polar pathway</p> Signup and view all the answers

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

    <p>Pluronic F127</p> Signup and view all the answers

    What plays a major role in successful transdermal drug permeation?

    <p>Drug-related physicochemical properties</p> Signup and view all the answers

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

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

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

    <p>Denaturation of keratinocytes within the stratum corneum</p> Signup and view all the answers

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

    <p>Absence of hydrogen atoms on their Oxygen or Nitrogen atoms</p> Signup and view all the answers

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

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

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

    <p>They are able to dissolve anything and everything</p> Signup and view all the answers

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

    <p>It is able to dissolve anything and everything</p> Signup and view all the answers

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

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

    What is the characteristic of an ideal permeation enhancer?

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

    What is a major advantage of iontophoresis in transdermal patches?

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

    What is the primary mechanism of action of electroporation?

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

    What is a key difference between iontophoresis and phonophoresis?

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

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

    <p>10 microseconds to 100 milliseconds</p> Signup and view all the answers

    What is a characteristic of microneedles?

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

    What is a disadvantage of iontophoresis compared to phonophoresis?

    <p>Iontophoresis is limited to aqueous media only.</p> Signup and view all the answers

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

    <p>Peptide hormones such as vasopressin and calcitonin.</p> Signup and view all the answers

    What is the material used to make microneedles?

    <p>Silicon.</p> 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.

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