Skin Anatomy and Transdermal Delivery

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Questions and Answers

Which pH level is mentioned as being below which the growth of certain bacteria is suppressed?

5.5 (correct)

5.0

4.5

6.0

What role does glutathione play in the skin?

It serves as a natural sunscreen.

It maintains normal conditions of the skin. (correct)

It regulates pH levels.

It acts as a preservative.

What is the main function of the stratum corneum in the skin?

Regulation of blood circulation.

Mechanical and physical barrier. (correct)

Storage of fat deposits.

Synthesis of vitamin D.

What characteristics should substances have for effective transdermal delivery?

Good aqueous and lipid solubility. Signup and view all the answers

What innate immune component is found in the stratum corneum to combat microbes?

Antimicrobial peptides (AMPs) Signup and view all the answers

What role does the stratum corneum play in skin physiology?

It serves as a permeability barrier. Signup and view all the answers

How many layers of corneocytes are typically found in the stratum corneum?

18–20 layers Signup and view all the answers

What is the main consequence of the stratum corneum's acidification?

Enhanced antimicrobial defense Signup and view all the answers

What is the typical size of substances that cannot penetrate the stratum corneum?

500 Da Signup and view all the answers

What is the composition of the lipids in the stratum corneum?

About 13 species of lipids Signup and view all the answers

Which of the following is NOT a function of the stratum corneum?

Facilitating nutrient absorption Signup and view all the answers

What are the rapidly dividing cells in the hair follicle matrix called?

Keratinocytes Signup and view all the answers

Which factor can lead to reversible hair loss?

Severe stress Signup and view all the answers

What is one advantage of using transdermal delivery instead of injections?

Transdermal delivery is often less painful. Signup and view all the answers

What role do non-ionic surfactants play in the formulation of proniosomes?

They enhance drug permeation. Signup and view all the answers

How can patches improve drug administration compared to traditional methods?

Patches allow for controlled release and higher drug loading. Signup and view all the answers

What is a primary characteristic of berberine as a drug?

It has low solubility and low permeability. Signup and view all the answers

What is a benefit of using nanoparticles in drug delivery?

Nanoparticles can enhance drug stability and reduce side effects. Signup and view all the answers

In the context of liposomes, what factor primarily affects permeation and stability?

The charge of the lipids used. Signup and view all the answers

Which of the following is NOT a characteristic of proniosomes?

Reduce contact time. Signup and view all the answers

What is one of the additional control methods that can be used in drug delivery systems?

Using chemical interactions. Signup and view all the answers

What is the primary benefit of transdermal delivery for patients who cannot swallow?

It avoids metabolism by the liver. Signup and view all the answers

Which of the following factors does NOT influence the steady state flux (J) in transdermal drug delivery?

Patient's age Signup and view all the answers

Which route of transdermal penetration is the least significant for drug delivery?

Transappendageal route Signup and view all the answers

Which type of transdermal delivery technology utilizes lipid bilayers surrounding an aqueous core?

Liposomes Signup and view all the answers

What characterizes ethosomes compared to conventional liposomes?

Enhanced delivery of hydrophilic drugs Signup and view all the answers

What is the main role of mucin in the formulation of beclomethasone-loaded liposomes?

It prolongs formulation permanence at the application site. Signup and view all the answers

Which substance is NOT a typical component of ethosomes?

Sucrose Signup and view all the answers

What is the primary application of minoxidil in relation to transdermal delivery?

Hair growth stimulation Signup and view all the answers

In the context of skin penetration, which characteristic of drugs can complicate transdermal delivery?

Hydrophilicity of the substance Signup and view all the answers

What method can be used to enhance drug delivery across the skin barrier?

Using edge activators in transfersomes Signup and view all the answers

Which of the following is NOT an entry site for transdermal drug delivery?

Nails Signup and view all the answers

How does the introduction of edge activators impact transfersomes?

Increases vesicle deformability Signup and view all the answers

Which statement correctly describes the significance of the stratum corneum in transdermal delivery?

It serves as the primary barrier to drug delivery. Signup and view all the answers

Which of the following is indicative of the particle size in beclomethasone loaded liposomes enriched with mucin?

Polydispersity Signup and view all the answers

What is the primary function of the adhesive in a transdermal patch?

To ensure the patch stays in place Signup and view all the answers

Which factor does NOT influence the permeation of trazodone across the skin?

Temperature of application Signup and view all the answers

What component is commonly used in film-forming agents for transdermal applications?

Polyethylene glycol Signup and view all the answers

What is the primary mechanism by which iontophoresis enhances drug delivery?

Uses an electric current to drive charged particles across the skin Signup and view all the answers

Which of the following techniques is suitable for delivering larger molecules like DNA?

Thermal ablation Signup and view all the answers

Which of the following vehicles is used in a permeation enhancer for transdermal drug delivery?

Both volatile and non-volatile vehicles Signup and view all the answers

What is the role of microneedles in drug delivery?

To penetrate the skin and facilitate drug penetration Signup and view all the answers

In the context of drug formulations, what does a permeation enhancer do?

Promotes drug diffusion through biological barriers Signup and view all the answers

What kind of materials can be used for hollow microneedles?

A variety of polymers including biocompatible ones Signup and view all the answers

How does electrophoresis generate drug delivery across the skin?

By applying high voltage to create transient pores Signup and view all the answers

Which of these is NOT a common film-forming agent for transdermal applications?

Sodium chloride Signup and view all the answers

What is the main advantage of using microneedles compared to traditional injections?

They are pain-free and minimally invasive Signup and view all the answers

What is one disadvantage of using iontophoresis for drug delivery?

It can only deliver small molecules Signup and view all the answers

What is the purpose of gelling agents in transdermal formulations?

To control release and provide texture Signup and view all the answers

Study Notes

Skin Anatomy and Physiology

The skin consists of hair follicles, which contain keratinocytes that produce the keratinized hair shaft.
Melanocytes in the hair follicle contribute melanin, providing hair color.
Hair loss can be temporary, often due to stress, trauma, or hormonal changes.

Stratum Corneum Characteristics

Composed of corneocytes stacked in 18–20 layers, forming a dynamic barrier rather than a fixed one.
Mortar lipids in the stratum corneum provide a permeability barrier.
Acts to prevent dehydration and maintain body temperature by blocking substances larger than 500 Da.

Skin Barrier and Permeability

Acidification of the stratum corneum enhances antimicrobial defenses against specific bacteria.
Contains vitamin E (α- and γ-tocopherol), ascorbic acid, and glutathione, contributing to skin homeostasis.
Antimicrobial peptides (AMPs) serve to combat various microbes present in the skin.

Transdermal Delivery Overview

Medications can be absorbed through the skin or mucosal membranes, allowing effects elsewhere in the body.
Useful for patients unable to swallow or when drugs are heavily metabolized in the liver (e.g., anti-nausea drugs, hormone therapy).
Flux of drugs through the skin is determined by factors such as concentration, permeability coefficient, and skin thickness.

Routes of Skin Entry

Cells in the skin, hair follicles and glands, and pores between cells serve as entry points for substances.
Transcellular route: Requires substances to be lipid-soluble to pass through cell membranes.
Transappendageal route: Minimal contribution to overall permeability, primarily utilized by specific treatments like Minoxidil.

Transdermal Delivery Technologies

Passive Technologies: Nanocarriers enhance drug delivery by increasing surface area and bioavailability while decreasing toxicity.
- Liposomes/Magnetosomes: Contain aqueous cores and lipid bilayers; useful for targeted drug release.
- Ethosomes: Modified liposomes improving the transport of both hydrophilic and hydrophobic drugs through skin layers.

Specific Formulations

Beclomethasone Loaded Liposomes: Enhanced with mucin to prolong retention in the application area.
Transfersomes: Modified for better skin permeability, used in patches like TransdermScop.

Advanced Drug Delivery Systems

Polymer Matrix Diffusion-Controlled System: Consists of solid drugs in polymer matrices for sustained release.
Film Forming Agents: Create a film upon solvent evaporation, enabling localized drug delivery.

Innovative Techniques

Iontophoresis: Uses small electric currents to drive charged particles through the skin; effective for small molecules (<7,000 Da).
Electrophoresis: High voltages create transient pores, enhancing transport through the skin.
Microneedles: Arrays of micron-scale needles that can be solid, dissolvable, coated, or hollow, allowing effective drug delivery into the dermis.

Emerging Research and Applications

The use of microneedles for the delivery of poorly soluble drugs like teriflunomide is being explored for its effectiveness, combining in vitro and in vivo assessments for final formulation selection.### Targeted Delivery and Nanoparticles
Targeted delivery aims to minimize side effects by directing drugs specifically to affected areas.
Nanoparticles enhance drug characteristics such as solubility, permeability, and stabilizing effects.
Solid lipid nanoparticles can improve the transdermal delivery of drugs like teriflunomide in rheumatoid arthritis management.

Transdermal Delivery Systems

Hollow microneedles enable non-invasive transdermal delivery, providing a pain-free alternative to injections.
Transdermal gels, such as those used for berberine—a drug known for low solubility—facilitate sustained release and improved patient compliance.
Proniosomes enhance drug permeability, shelf life, and contact time, addressing challenges in drug delivery.

Patches as Delivery Methods

Transdermal patches can offer prolonged contact time, resulting in controlled release of the medication.
High drug loading in patches reduces frequency of administration, improving patient adherence.
Non-ionic surfactants can aid in forming proniosomes and act as permeation enhancers, optimizing drug absorption.

Alternative Formulations

Liposomes may also serve as delivery vehicles, with their charge influencing permeation and stability.
Different lipid charges in formulations can affect drug release through complexation or chemical interactions.
Additional control methods in drug delivery enhance customization tailored to specific therapeutic needs.

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Description

This quiz explores the anatomy and physiology of the skin, focusing on the role and composition of the stratum corneum. It also covers the skin barrier's function and permeability, along with the main methods of transdermal permeation. Perfect for those studying dermatology or pharmacology.