Transdermal Drug Delivery Quiz
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Questions and Answers

Which of the following is NOT a characteristic of the transepidermal pathway?

  • It involves diffusion through the cells of the epidermis.
  • It is accessible to both lipophilic and hydrophilic drugs. (correct)
  • It is the most common route for drug penetration.
  • It is also known as the intracellular pathway.

    • What is the approximate thickness of the epidermis on the palms and soles?

  • 1.5 mm (correct)
  • 5 mm
  • 0.5 mm
  • 0.05 mm

    • Which of the following routes is primarily used by polar molecules?

  • Subcutaneous tissues
  • Transappendageal route (correct)
  • Transepidermal pathway
  • Systemic effect

    • What is the primary mechanism of drug transport through the transappendageal route?

    <p>Passive diffusion</p> Signup and view all the answers

    What is the significance of the stratum corneum in relation to drug penetration?

    <p>It provides a barrier to drug penetration.</p> Signup and view all the answers

    What is a key advantage of Transdermal Drug Delivery (TDD) compared to oral drug administration?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is NOT a function of the skin as described in the text?

    <p>Hormonal regulation</p> Signup and view all the answers

    What is the primary mechanism by which drugs are delivered through the skin in Transdermal Drug Delivery (TDD)?

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

    The first commercially available prescription patch approved by the FDA in 1979 was for the treatment of what condition?

    <p>Motion sickness</p> Signup and view all the answers

    What does the term "first-pass effect" refer to in the context of drug delivery?

    <p>The initial breakdown of a drug by enzymes in the liver</p> Signup and view all the answers

    Which of the following is NOT a disadvantage of transdermal drug delivery?

    <p>Requires a high drug load/concentration</p> Signup and view all the answers

    What is the primary advantage of transdermal drug delivery as compared to oral drug delivery?

    <p>Minimize inter-/intra-patient variation</p> Signup and view all the answers

    What is the approximate thickness of human skin?

    <p>0.5 mm</p> Signup and view all the answers

    Which of the following is NOT a benefit of transdermal drug delivery?

    <p>Easily and rapidly identified in emergency situations</p> Signup and view all the answers

    What level of effect can transdermal drugs have?

    <p>Effect on the skin surface, the dermis, systemic circulation and other tissues, depending on the drug properties</p> Signup and view all the answers

    Which of these is NOT a true statement about transdermal drug delivery?

    <p>Transdermal drug delivery is typically faster acting than oral drug delivery</p> Signup and view all the answers

    Which layer of the skin is the epidermis?

    <p>Outermost layer</p> Signup and view all the answers

    Which of the following is an example of a transdermal patch that is known for its relatively fast onset?

    <p>Nitroglycerin patch</p> Signup and view all the answers

    What is the rate limiting step in transdermal drug delivery?

    <p>Transport through the stratum corneum</p> Signup and view all the answers

    Which transport process involves the movement of substances across skin cell membranes?

    <p>Transcellular transport</p> Signup and view all the answers

    Which component of a transdermal patch primarily controls the release rate of the drug?

    <p>Drug reservoir</p> Signup and view all the answers

    Under what circumstance can a transdermal patch typically be cut?

    <p>When it is properly designed for cutting</p> Signup and view all the answers

    What does the LogP ratio measure in relation to transdermal drug delivery?

    <p>The hydrophilicity and lipophilicity of a compound</p> Signup and view all the answers

    Which of the following is NOT a factor that can influence drug absorption through transdermal patches?

    <p>Drug expiration date</p> Signup and view all the answers

    Which type of implant is controlled by the rate at which a drug diffuses through a membrane?

    <p>Diffusion-controlled implant</p> Signup and view all the answers

    What is percutaneous absorption?

    <p>Absorption of substances through the skin</p> Signup and view all the answers

    What is the ideal log P range for transdermal drug delivery?

    <p>1 to 3</p> Signup and view all the answers

    Which component of the stratum corneum is NOT typically included?

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

    Which factors affect the rate limiting step of systemic absorption?

    <p>Hydration of the skin and formulation influence</p> Signup and view all the answers

    What is the primary composition of the stratum corneum?

    <p>15-25 layers of skin cells</p> Signup and view all the answers

    What range of molecular weight (MW) is generally ideal for drugs intended for transdermal delivery?

    <p>100-800</p> Signup and view all the answers

    What is the effect of skin hydration on drug permeability?

    <p>Hydration increases permeability</p> Signup and view all the answers

    What does the surface area of a transdermal patch influence?

    <p>Drug absorption rate</p> Signup and view all the answers

    What is a key attribute of a transdermal drug delivery formulation?

    <p>Consistent temperature regulation</p> Signup and view all the answers

    Study Notes

    Transdermal Drug Delivery (TDD)

    • Transdermal drug delivery diffuses medication through the skin into the bloodstream for systemic circulation and a therapeutic effect.
    • The first commercially available transdermal patch was approved in 1979 for motion sickness.
    • The skin has three major layers: epidermis, dermis, and subcutaneous tissue.
    • The rate-limiting step for transdermal drug delivery is the stratum corneum, a semi-permeable membrane.
    • The stratum corneum is composed of keratinized tissue, various layers, cells, and lipids.
    • Transdermal drug delivery can be through transcellular/intracellular pathways, or intercellular spaces. Transappendageal pathways are less significant, occurring via skin appendages like hair follicles. This takes 0.1% of the skin surface.
    • Log P ratio: The ideal log P range for transdermal drugs is 1-3. A higher log P suggests the drug is more hydrophobic.
    • Biological factors, like skin age and condition, can affect drug absorption. Chronic use of certain medications can increase penetration.

    Objectives

    • Identify the major skin layers & the rate-limiting step of transdermal drug delivery.
    • Understand the different transport methods (transcellular/intracellular, intercellular and transappendageal).
    • Explain the components and attributes of transdermal patches that affect drug penetration.
    • Distinguish dissolution vs diffusion-controlled implants and identify their respective advantages and disadvantages.
    • Explain LogP and its range and implications.

    Questions to ask yourself

    • What is the largest organ of the body? (Skin)
    • What does percutaneous absorption mean? (Absorption through the skin)
    • Can drug concentrations be measured within a membrane? (Potentially)
    • What is the dosage? (Dosage/units)

    Advantages of Transdermal Drug Delivery

    • Rapid termination of drug effects
    • Avoidance of the first-pass metabolism in the liver
    • Reduced variability in drug levels
    • Lower administered doses
    • Non-invasive
    • Minimized inter/intra-patient variations
    • Predictable and extended duration of a drug's activity

    Disadvantages of Transdermal Drug Delivery

    • Poor penetration through the skin of most drugs, causing slow onset of action.
    • Local irritation
    • Poor adhesion
    • Requires high drug concentration.

    Factors Affecting Transdermal Drug Absorption

    • Hydration of the skin (increased hydration improves permeability)
    • Skin temperature
    • Penetration enhancers
    • Drug/skin interaction
    • Drug/vehicle interactions
    • Exposure time
    • Solubility in both lipids and water

    Components of a TDD System

    • Polymer matrix/drug reservoir
    • Drug
    • Permeation enhancers (e.g., surfactants)
    • Pressure-sensitive adhesive
    • Backing laminates
    • Release liner
    • Excipients
    • Plasticizers and solvents

    Types of Transdermal Patches

    • Reservoir system: Drug reservoir between backing layer and controlling membrane.
    • Matrix system: Homogeneous dispersion of drug in a polymer matrix.
    • Micro-reservoir system: Combination of reservoir and matrix systems.

    Clinical Considerations & Safety Issues

    • Application site, rotation, avoiding irritated/broken skin.
    • Removing a patch, avoiding chewing or consumption, potential permanent skin changes.

    Rate-Limiting Step

    • Stratum Corneum (outer skin layer) acts as a semi-permeable membrane. Contains keratin, lipids (fatty acids, cholesterol) and water.

    Fick's Law of Diffusion

    • Describes how drugs diffuse through a membrane based on factors like membrane thickness, surface area, and concentration differences.

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    Related Documents

    Transdermal Drug Delivery (TDD) PDF

    Description

    Test your knowledge on transdermal drug delivery mechanisms and characteristics with this insightful quiz. Explore topics such as drug penetration, epidermis thickness, and advantages over oral administration. Ideal for students and professionals in pharmacology and dermatology.

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