Pharmaceutics II: Chemical Penetration Enhancers
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Questions and Answers

What is the difference between penetration, permeation, and absorption?

  • Penetration is entering the skin, permeation is crossing the epidermis, and absorption is entering the blood supply (correct)
  • Penetration is crossing the skin, permeation is entering the epidermis, and absorption is entering the skin
  • Penetration is entering the blood supply, permeation is crossing the epidermis, and absorption is entering the skin
  • Penetration is crossing the epidermis, permeation is entering the skin, and absorption is entering the blood supply

    • What is the ideal characteristic of a chemical penetration enhancer?

  • It should be expensive and have an unpleasant odor
  • It should be inert, GRAS, and fast in action (correct)
  • It should be toxic to the skin cells
  • It should be compatible only with certain drugs

    • Which of the following is NOT a chemical skin penetration enhancer?

  • Azone
  • Fatty acids
  • Insulin (correct)
  • Dimethyl sulfoxide

    • What is the normal water content of human SC?

    <p>15-20% of tissue dry weight</p> Signup and view all the answers

    What happens to the water content of human SC under occlusion?

    <p>It increases up to 400%</p> Signup and view all the answers

    What is the purpose of using a chemical mediator?

    <p>To interact with skin cells to clear the way to the drug</p> Signup and view all the answers

    What is the function of the free form of water in the SC?

    <p>It acts as a solvent for polar permeants</p> Signup and view all the answers

    What is the purpose of hydration in enhancement of percutaneous drug permeation?

    <p>To increase the solubility of polar permeants</p> Signup and view all the answers

    What is the effect of fatty acids on the lipid bilayer of the cell membrane?

    <p>They increase the spacing between phospholipid molecules</p> Signup and view all the answers

    What is the unique feature of oleic acid that contributes to its superior skin permeation effect?

    <p>Presence of a kink in the molecule chain</p> Signup and view all the answers

    Why is butanol considered the most effective alcohol for skin permeation?

    <p>No specific reason is given in the text</p> Signup and view all the answers

    What is the effect of a 10% concentration of ethyl alcohol on biological membranes?

    <p>It dehydrates biological membranes and decreases drug permeation</p> Signup and view all the answers

    How do alcohols enhance drug permeation through the skin?

    <p>By extracting lipid fractions from the skin</p> Signup and view all the answers

    What is the concentration range for alcohols to be effective as permeation enhancers?

    <p>1-10%</p> Signup and view all the answers

    Why is ethanol commonly used in transdermal formulations?

    <p>It is the most commonly available</p> Signup and view all the answers

    How do branched alcohols, such as isopropanol, compare to linear alcohols in terms of permeation enhancement?

    <p>They are less effective</p> Signup and view all the answers

    What is the role of water in the skin?

    <p>It acts as a solvent for polar molecules and increases drug solubility</p> Signup and view all the answers

    What happens to the corneocytes when they take up water?

    <p>They swell in volume</p> Signup and view all the answers

    How does water affect the skin lipid content?

    <p>It fluidizes lipid crystalline structure</p> Signup and view all the answers

    What is the role of humectants, NMFs, and occlusive agents in the skin?

    <p>They indirectly increase skin water content</p> Signup and view all the answers

    What is the difference between hydration and moisturizing effect on the skin?

    <p>Hydration involves water, while moisturizing involves fats</p> Signup and view all the answers

    What is the role of natural moisturizing factors (NMFs) in the skin?

    <p>They bind water to skin cells and increase drug penetration</p> Signup and view all the answers

    How do NMFs prevent increased TEWL?

    <p>By retaining moisture within corneocytes</p> Signup and view all the answers

    What is the effect of water on drug permeation through the skin?

    <p>It increases drug permeation</p> Signup and view all the answers

    What is the effect of ethanol's evaporation on the drug concentration?

    <p>It increases the drug concentration</p> Signup and view all the answers

    What is the main mechanism of action of surfactants in skin permeation?

    <p>Solubilize the lipophilic API and solubilize lipids within the stratum corneum</p> Signup and view all the answers

    What is the effect of high concentration of surfactants on human skin?

    <p>It damages human skin</p> Signup and view all the answers

    What is the role of DMSO in skin permeation?

    <p>It facilitates drug partitioning from formulation to skin</p> Signup and view all the answers

    What is the effect of DMSO at low concentration on cell membranes?

    <p>It induces membrane thinning and fluidity</p> Signup and view all the answers

    What is the property of azones that makes them effective at low concentration?

    <p>High lipophilicity</p> Signup and view all the answers

    What is the primary mechanism of action of chemical enhancers in the stratum corneum?

    <p>Disruption of the lipid bilayer packing arrangement</p> Signup and view all the answers

    How do humectants facilitate skin penetration of drugs?

    <p>By pulling water from the atmosphere and binding it to corneocytes</p> Signup and view all the answers

    What is the effect of sulfoxides and azones on skin penetration of drugs?

    <p>They enhance penetration of both hydrophilic and lipophilic drugs</p> Signup and view all the answers

    What is the purpose of formulation modification in transdermal patches?

    <p>To increase the thermodynamic activity of the drug</p> Signup and view all the answers

    How do surfactants facilitate skin penetration of poorly water-soluble drugs?

    <p>By solvating poorly water-soluble drugs</p> Signup and view all the answers

    What is the primary mechanism of action of ethanol in transdermal patches?

    <p>Solvating poorly water-soluble drugs</p> Signup and view all the answers

    What is the effect of chemical enhancers on the stratum corneum?

    <p>They disrupt the lipid bilayer packing arrangement</p> Signup and view all the answers

    What is the purpose of using chemical enhancers in transdermal drug delivery?

    <p>To enhance the permeability of the stratum corneum to drugs</p> Signup and view all the answers

    Study Notes

    Chemical Penetration Enhancers

    • Terminology: Penetration refers to crossing the stratum corneum (SC), permeation refers to crossing the epidermis, and absorption refers to entering the blood supply.
    • Passive Chemical Penetration Enhancement: Uses a chemical mediator to interact with skin cells and clear the way for the drug.

    Ideal Chemical Penetration Enhancer

    • Inert: Does not react with the skin or drug.
    • GRAS (Generally Regarded as Safe): Considered safe for use.
    • Fast in Action: Quickly exerts its effect on the skin barrier.
    • Reversible Effect: The effect on the skin barrier is reversible.
    • Compatibility: Compatible with drugs and excipients.
    • Economic: Cost-effective.
    • Acceptable: Acceptable to patients in terms of odor, color, and other factors.

    Chemical Skin Penetration Enhancers

    • Types: Water, natural moisturizing factors, fatty acids, alcohols, surfactants, dimethyl sulfoxide, and azone.

    Water

    • Natural Skin Plasticizer: Renders the skin lipid content less rigid by fluidizing the lipid crystalline structure.
    • Mechanism of Action: Acts as a solvent for polar molecules, increasing drug solubility and partitioning through the skin.
    • Hydration Effect: Increases skin water content, making it more permeable to drugs.
    • Moisturizing Effect: Indirectly increases skin water content through humectants, occlusive agents, and other means.

    Natural Moisturizing Factors (NMFs)

    • Definition: Natural moisturizing factors that bind water to skin cells, increasing drug penetration through the skin.
    • Hydrating Agent: Produces hydrophilic diffusion channels through the SC.
    • Prevents TEWL (Trans Epidermal Water Loss): Retains moisture within corneocytes.

    Fatty Acids

    • Mechanism of Action: Modifies the orientation of lipid domains in the SC, causing lipid fluidization and allowing the drug to penetrate more easily.
    • Oleic Acid: Has a superior skin permeation effect due to its molecular structure, which leads to increased SC lipids fluidity.

    Alcohols

    • Best Concentration Range: 1-10% for optimal skin permeation.
    • Mechanism of Action: Solubilizes the drug, extracts lipid fraction from the skin, and increases thermodynamic activity of the drug.
    • Ethanol: Most commonly used chemical permeation enhancer in transdermal formulations.
    • Butanol: Most effective alcohol for skin permeation.

    Surfactants

    • Definition: Decreases surface tension between the formulation and skin.
    • Mechanism of Action: Solubilizes the lipophilic API and solubilizes lipids within the SC.
    • Non-Ionic Surfactants: Safest option, e.g., Polysorbate 80.
    • Anionic Surfactants: Most active, e.g., Na lauryl sulphate.

    Dimethyl Sulfoxide (DMSO)

    • Universal Solvent: Facilitates drug partitioning from the formulation to the skin.
    • Mechanism of Action: Enhances permeation of both hydrophobic and hydrophilic molecules across cell membranes.
    • Concentration Effect: Induces membrane thinning and fluidity at low concentrations, and forms transient water pores at high concentrations.

    Azone

    • Highly Lipophilic Synthetic Molecule: With a log P value of 6.2.
    • Mechanism of Action: Interacts with the lipid domains of the SC, disrupting their packing arrangement and fluidizing the lipids.
    • Effective Concentration Range: 0.1-5%.

    Summary of Passive Chemical Enhancement

    • Mechanisms: Interaction with extracellular lipid matrix, alteration of SC solvent nature, interaction with proteins, and formulation modification.
    • Enhancers: Humectants, NMFs, ethanol, surfactants, sulfoxides, and azone work through a combination of these mechanisms to improve drug delivery.

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    Description

    This quiz covers chemical penetration enhancers, including terminology, passive chemical penetration enhancement, and mechanisms of action. Learn about ideal chemical penetration enhancers and examples of marketed products.

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