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Fitzpatrick's Dermatology, 9th Edition (Chapter-based Decks) > 183: Principles of Topical Therapy > Flashcards

183: Principles of Topical Therapy Flashcards

1
Q

What are the three key steps involved in topical therapy?

A
  1. Topical application
  2. Percutaneous absorption
  3. Binding of the active molecule to its target site
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2
Q

What factors influence adherence to prescribed medicines in chronic conditions?

A

Adherence is influenced by:
- Primary nonadherence: Patients do not fill their prescription or initiate treatment.
- Secondary nonadherence: Patients initiate treatment but use the medication poorly, including poor execution and early discontinuation.
- Tachyphylaxis: Result of nonadherence rather than loss of corticosteroid receptor function.

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3
Q

How does the Law of Diffusion relate to topical medications?

A

The Law of Diffusion states that compounds applied topically to the skin surface migrate along concentration gradients.

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4
Q

What are Fick’s Laws and their relevance to drug diffusion?

A

Fick’s Laws describe the diffusion of uncharged compounds across a membrane or barrier:
- Fick’s First Law: Steady-state flux of a compound is proportional to the concentration gradient and diffusion coefficient.
- Fick’s Second Law: Predicts the flux of compounds under non-steady-state conditions.

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5
Q

What is the significance of the three-compartment model in cutaneous drug delivery?

A

The three-compartment model includes:
1. Skin surface
2. Stratum corneum
3. Viable tissue
The formulation acts as a reservoir from which the compound must be released.

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6
Q

What is the relationship between absorption rates and the efficacy of topical medications?

A

Topical medications generally have a poor total absorption and a slow absorption rate. However, low absorption does not necessarily translate into low efficacy.

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7
Q

A patient uses a topical corticosteroid intermittently and discontinues early. What is the likely outcome, and what term describes this behavior?

A

The likely outcome is reduced therapeutic efficacy due to poor adherence. This behavior is termed secondary nonadherence.

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8
Q

How does the diffusion coefficient influence the time it takes for a molecule to migrate along a path length?

A

The relationship between the time it takes for a molecule to migrate along a path length and its diffusion coefficient is governed by Fick’s Second Law.

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9
Q

What is the range of nonadherence to prescribed medicines in chronic conditions?

A

Between 30% and 50%.

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10
Q

What is primary nonadherence?

A

When patients do not fill their prescription or initiate treatment.

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11
Q

What is secondary nonadherence?

A

When patients initiate treatment but use the medication poorly, including poor execution and early discontinuation of treatment.

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12
Q

What does tachyphylaxis refer to in the context of medication adherence?

A

It refers to the result of nonadherence rather than loss of corticosteroid receptor function.

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13
Q

What does the Law of Diffusion state regarding topical compounds?

A

Compounds applied topically to the skin surface migrate along concentration gradients.

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14
Q

What does Fick’s First Law describe?

A

The steady-state flux of a compound is proportional to the concentration gradient and the diffusion coefficient.

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15
Q

What is the role of the formulation in cutaneous delivery of applied drugs?

A

The formulation acts as a reservoir from which the compound must be released for absorption.

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16
Q

How does low absorption of topical medicines relate to their efficacy?

A

Low absorption does not necessarily translate into low efficacy; topical corticosteroids can be effective due to their inherent potency.

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17
Q

What factors can affect the diffusion of compounds within skin compartments?

A

Factors affecting diffusion include:
- Disease state: Changes in skin condition can alter permeability.
- Pharmacologic activity: The nature of the drug or its excipients can influence absorption.
- Concentration gradient: Compounds may diffuse down their concentration gradient.

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18
Q

What is the significance of the reservoir in topical formulations?

A

The reservoir refers to the amount of active ingredient that remains in contact with nonvolatile constituents after application.

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19
Q

How can topical formulations be differentiated based on their intended action?

A

Topical formulations can be differentiated based on:
1. Surface retention: Products designed to remain on the skin surface.
2. Compartment delivery: Formulations intended to deliver compounds to skin compartments.
3. Transdermal migration: Formulations that migrate across the skin into the central compartment.

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20
Q

What are the key factors to consider when selecting a formulation for topical application?

A

Key factors include:
- Thermodynamic activity: The activity of the active ingredient.
- Incorporation amount: The amount of compound that can be included in the formulation.
- Stability: The stability of the formulation on the skin surface.
- Partition coefficient: The balance between the vehicle and stratum corneum.
- Enhancer activity: The ability of the formulation to enhance absorption.

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21
Q

What role does the stratum corneum play in percutaneous absorption?

A

The stratum corneum is the primary barrier limiting percutaneous absorption.

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22
Q

How do hair follicles contribute to the storage of topically applied substances?

A

Hair follicles serve as a reservoir for topically applied substances, with the following characteristics:
- Storage capacity: They can store compounds applied to the skin.

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23
Q

A patient with eczematous skin applies a topical formulation. What factors might influence the reservoir effect of the active ingredient in this scenario?

A

Eczematous skin has increased scaliness, which enhances the reservoir effect by trapping the active ingredient.

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24
Q

A patient applies a topical drug containing alcohol. What changes might occur on the skin surface, and how could this affect drug absorption?

A

Alcohol in the formulation may evaporate rapidly, leading to increased concentrations of nonvolatile substances on the skin surface.

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25
Q

What is the relationship between the thermodynamic activity of a compound and percutaneous absorption?

A

Percutaneous absorption is proportional to the thermodynamic activity of the compound.

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26
Q

What is drug compounding?

A

The process of combining or altering ingredients to create tailored medication.

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27
Q

What is a significant pathway for compounds across the stratum corneum?

A

Localization of compounds in the corneocytes, more prevalent in the upper layers (stratum disjunctum).

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28
Q

What is the optimum size of particles for penetration into hair follicles?

A

300 to 600 nm.

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29
Q

What are the pathways for drug delivery through hair follicles and their significance?

A

Nanoparticles are stored 10x longer in hair follicles than in the stratum.

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30
Q

How do hair follicles contribute to storage of topically applied substances?

A

Hair follicles act as a reservoir for topically applied substances, with the highest reservoir capacity in the scalp, followed by the forehead and calf.

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31
Q

What are the pathways for drug delivery through hair follicles?

A

Nanoparticles are stored 10x longer in hair follicles than in the stratum corneum. Hair follicles are surrounded by blood capillaries, making them important for drug delivery.

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32
Q

How does skin metabolism affect the bioavailability of topical medications?

A

Alterations in skin metabolism can impact the risk of topical exposure to carcinogens and diseases like hirsutism and acne. Metabolic activity is found in various skin layers.

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33
Q

What factors influence the resorption of compounds through the skin?

A

Resorption is related to the surface area of exchanging capillaries and their blood flow, which can be influenced by temperature, humidity, and vasoactive compounds.

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34
Q

What pathologic processes can reduce skin barrier function?

A

Reduced skin barrier function has been observed in conditions such as ichthyoses, psoriasis, atopic dermatitis, and contact dermatitis.

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35
Q

What is the significance of the stratum corneum in drug absorption?

A

The stratum corneum acts as a rate-limiting barrier to percutaneous drug delivery, determining the extent of compound penetration.

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36
Q

How does the therapeutic efficacy of hydrocortisone differ in a patient with psoriasis?

A

In psoriasis, structural alterations in the stratum corneum may increase the percutaneous absorption of hydrocortisone, enhancing its therapeutic efficacy.

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37
Q

Why might a transdermal formulation of nitroglycerin have reduced systemic bioavailability?

A

Cutaneous metabolism reduces the systemic bioavailability of transdermal nitroglycerin due to metabolic activity in the skin.

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38
Q

How might ichthyosis affect drug absorption?

A

Ichthyosis involves reduced skin barrier function, which can enhance percutaneous absorption of topical medications.

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39
Q

How does occlusion of the skin affect permeability of corneocytes?

A

Occlusion leads to swelling of corneocytes, increasing their permeability to substances.

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40
Q

Why might nanoparticles be advantageous for drug delivery into hair follicles?

A

Nanoparticles can be stored 10 times longer in hair follicles than in the stratum corneum, making them efficient carriers.

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41
Q

How do stem and dendritic cells in hair follicles influence drug delivery?

A

Stem and dendritic cells are important for regenerative medicine and immunomodulation, making hair follicles significant for drug delivery.

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42
Q

What is the role of the viable epidermis in drug dilution after percutaneous absorption?

A

The viable epidermis dilutes compounds due to its larger volume compared to the stratum corneum.

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43
Q

How do vasoactive compounds influence resorption of topically applied drugs?

A

Vasoactive compounds can directly influence skin blood flow, affecting the resorption of drugs.

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44
Q

What is the impact of structural alterations in the stratum corneum on barrier function?

A

Structural alterations can reduce the barrier function of the stratum corneum, enhancing percutaneous absorption.

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45
Q

What is the role of mixed-function monooxygenases in skin metabolism?

A

Mixed-function monooxygenases are involved in the oxidation of polycyclic aromatic hydrocarbons and can be induced by xenobiotics.

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46
Q

How does the size of the dermal compartment influence metabolism?

A

The large size of the dermal compartment may result in a significant role in the metabolism of topicals.

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47
Q

How do dendritic cells in hair follicles contribute to drug delivery?

A

Dendritic cells are important for immunomodulation, making hair follicles significant for drug delivery.

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48
Q

What is the impact of temperature and humidity on skin blood flow?

A

Changes in temperature and humidity can directly influence skin blood flow, affecting drug resorption.

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49
Q

How does mixed-function monooxygenases presence influence drug metabolism?

A

They are involved in the metabolism of xenobiotics, influencing the bioavailability and efficacy of drugs.

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50
Q

What is the significance of hair follicles in drug delivery?

A

Hair follicles serve as efficient carrier systems for drug delivery due to their longer storage of nanoparticles.

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51
Q

How does skin barrier function vary among different body sites?

A

Skin barrier function varies with the order: arm ~ abdomen > postauricular > forehead.

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52
Q

What is the role of viable tissue in drug absorption?

A

Viable tissue allows for substantial dilution of compounds from the stratum corneum.

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53
Q

What factors influence skin metabolism?

A

Skin metabolism can be influenced by diseases, topical exposure to carcinogens, and various compounds.

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54
Q

What is the relationship between skin blood flow and drug absorption?

A

Total blood flow to the skin can vary significantly, affecting the uptake of compounds.

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55
Q

How does aging affect skin barrier recovery?

A

Aged individuals may have reduced recovery of barrier activity after perturbation.

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56
Q

What is the impact of skin surface microorganisms on metabolism?

A

They contribute to metabolic activity, important for the metabolism of topically applied compounds.

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57
Q

What is the rate-limiting barrier to percutaneous drug delivery?

A

The stratum corneum acts as the rate-limiting barrier to percutaneous drug delivery.

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58
Q

What happens to compounds that remain in the skin for longer periods?

A

They undergo significantly more metabolism.

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59
Q

What are the implications of hair follicles in drug delivery systems?

A

Hair follicles serve as efficient carriers due to longer nanoparticle storage and their close network of blood capillaries.

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60
Q

How does skin metabolism influence systemic bioavailability?

A

Skin metabolism can significantly reduce the systemic bioavailability of topical medications.

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61
Q

What factors influence the rate of resorption of compounds through the skin?

A

The rate of resorption is influenced by blood flow, temperature, humidity, and vasoactive compounds.

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62
Q

What pathologic processes can reduce skin barrier function?

A

Conditions like ichthyoses, psoriasis, and atopic dermatitis can lead to reduced skin barrier function.

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63
Q

How does the stratum corneum act as a rate-limiting barrier?

A

It serves as a rate-limiting barrier due to its high resistance to diffusion.

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64
Q

What are the main components of the stratum corneum?

A

The stratum corneum is composed of ceramides, free fatty acids, and cholesterol in a 1:1:1 molar ratio.

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65
Q

What are the two main routes for drug permeation through the stratum corneum?

A

The two main routes are transepidermal and transappendageal pathways.

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66
Q

Which pathway is considered the most important for cutaneous drug delivery?

A

The intercellular pathway is considered the most important route.

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67
Q

How does diseased skin affect the barrier function of the stratum corneum?

A

Diseased skin may have an altered stratum corneum, changing the barrier function.

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68
Q

What effect do solvents, surfactants, and alcohols have on the stratum corneum?

A

They denature the cornified layer and increase penetration.

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69
Q

How much can simple hydration enhance the absorption of topical steroids?

A

Simple hydration can enhance absorption by 4-5 times.

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70
Q

What happens to the skin barrier architecture with abnormal epidermal proliferation?

A

It disrupts the skin barrier architecture, enhancing percutaneous absorption.

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71
Q

What is the significance of the intercellular pathway in cutaneous drug delivery?

A

The intercellular pathway is considered the most important route for cutaneous drug delivery.

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72
Q

How does the stratum corneum composition influence drug penetration?

A

Variations in the composition of ceramides, free fatty acids, and cholesterol can affect drug penetration.

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73
Q

What is the impact of hydration on the absorption of topical steroids?

A

Simple hydration enhances the absorption of topical steroids by 4-5 times.

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74
Q

How does the presence of alcohol in a topical formulation affect the stratum corneum?

A

Alcohol can denature the cornified layer, increasing penetration.

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75
Q

What is the effect of abnormal epidermal proliferation on percutaneous absorption?

A

It disrupts the skin barrier architecture, enhancing percutaneous absorption.

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76
Q

How does the presence of eczematized skin alter the barrier function?

A

Eczematized skin has a reduced barrier function, allowing for increased penetration.

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77
Q

What is the significance of the transepidermal route in drug permeation?

A

The transepidermal route is key for drug permeation as molecules pass between corneocytes.

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78
Q

How does the presence of surfactants in a topical formulation affect drug absorption?

A

Surfactants can denature the cornified layer, increasing penetration.

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79
Q

How does the presence of ceramides in the stratum corneum influence its barrier function?

A

Ceramides play a crucial role in maintaining the barrier function.

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80
Q

What is the significance of the transappendageal pathway in drug delivery?

A

The transappendageal pathway provides an alternative route for drug delivery.

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81
Q

What is the impact of stratum corneum thickness on drug penetration?

A

Thinner areas of the stratum corneum allow for greater absorption.

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82
Q

How does the presence of sebaceous glands in hair follicles affect drug delivery?

A

Sebaceous glands facilitate drug delivery through the transappendageal pathway.

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83
Q

What is the composition of the stratum corneum?

A

It is composed of ceramides, free fatty acids, and cholesterol in a 1:1:1 molar ratio.

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84
Q

What percentage of the stratum corneum is made up of ceramides, cholesterol, and free fatty acids?

A

50% ceramides, 35% cholesterol, and 15% free fatty acids.

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85
Q

How does simple hydration of the stratum corneum affect the absorption of topical steroids?

A

It enhances the absorption of topical steroids by 4-5 times.

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86
Q

What are the two main routes for drug permeation through the stratum corneum?

A
  1. Transepidermal pathway: Molecules pass between corneocytes via the intercellular micropathway or through the cytoplasm of dead keratinocytes and intercellular lipids (transcellular micropathway).
  2. Transappendageal pathway: Involves the flow of molecules through eccrine glands and hair follicles via associated sebaceous glands.

The intercellular pathway is considered the most important route for cutaneous drug delivery.

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87
Q

How does the condition of the stratum corneum affect drug absorption in diseased skin?

A

In diseased skin, the stratum corneum may have an altered state (increased, decreased, or absent), which changes the body’s barrier function. Specific effects include:

  • Abraded/eczema skin: Acts as less of a barrier.
  • Solvents, surfactants, and alcohols: Denature the cornified layer, increasing penetration and enhancing absorption of topical medications.
  • Hydration: Simple hydration of the stratum corneum can enhance absorption of topical steroids by 4-5 times.
  • Abnormal epidermal proliferation: Disrupts the skin barrier architecture, enhancing percutaneous absorption.
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88
Q

What is the composition of the stratum corneum?

A

The stratum corneum is composed of:
- 50% ceramides (with acylceramides being the most abundant)
- 35% cholesterol
- 15% free fatty acids

The thickness of the stratum corneum and its composition can influence drug penetration, which varies depending on the body site.

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89
Q

What is the role of the stratum corneum in percutaneous drug delivery?

A

The stratum corneum acts as a rate limiting barrier to percutaneous drug delivery, with thickness affecting drug penetration depending on the body site.

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90
Q

What are the two main routes of drug permeation through the stratum corneum?

A

The two main routes of permeation are:
1. Transepidermal - molecules pass between corneocytes via intercellular pathways or through the cytoplasm of dead keratinocytes and intercellular lipids.
2. Transappendageal/shunt route - flow of molecules through eccrine glands and hair follicles via associated sebaceous glands.

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91
Q

How does hydration of the stratum corneum affect drug absorption?

A

Hydration of the stratum corneum increases the absorption of topical steroids by 4-5 times, enhancing drug penetration and efficacy.

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92
Q

What are the advantages of using occlusion techniques in topical therapy?

A

The advantages of occlusion techniques include:
1. Increased hydration of the stratum corneum, limiting rub off and wash off of the drug.
2. Increased drug delivery by 10 times.
3. Rapid onset and increased efficacy of the medication.

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93
Q

What are some disadvantages of occlusion techniques in topical therapy?

A

Disadvantages of occlusion techniques include:
1. Rapid reappearance of drug adverse effects.
2. Potential to promote infection, folliculitis, or miliaria.
3. Topical anesthetics can hasten absorption to skin and bloodstream, causing complications such as:
- Lidocaine - cardiac toxicity
- Prilocaine - methemoglobinemia.

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94
Q

What is the composition ratio of ceramides, free fatty acids, and cholesterol in the stratum corneum?

A

1:1:1 ratio of ceramides, free fatty acids (FFA), and cholesterol.

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95
Q

What is the most important route for cutaneous drug delivery?

A

The intercellular pathway of the trans epidermal route.

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96
Q

What can alter the barrier function of the stratum corneum?

A

Diseased skin can have altered stratum corneum, which may be increased, decreased, or absent.

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97
Q

What is the effect of solvents and surfactants on drug absorption?

A

They can increase drug penetration and absorption by denaturing the cornified layer.

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98
Q

How does occlusion enhance drug absorption and what are the potential disadvantages of this technique?

A

Occlusion enhances drug absorption by:
1. Increasing stratum corneum hydration, which limits rub off and wash off of the drug, thereby enhancing penetration.
2. Increasing drug delivery by 10x, leading to rapid onset and increased efficacy.

However, the potential disadvantages include:
- Rapid reappearance of drug adverse effects.
- Increased risk of infection, folliculitis, or miliaria.
- Topical anesthetics can hasten absorption to the skin and bloodstream, causing complications such as:
1. Lidocaine – cardiac toxicity
2. Prilocaine – methemoglobinemia.

99
Q

What is the effect of multiple daily applications of topical medications on drug penetration compared to once daily application?

A

Multiple daily applications yield minimum penetration increases compared to once daily application.

100
Q

What is the Fingertip Unit (FTU) and how is it related to the application of topical medications?

A

The Fingertip Unit (FTU) is the amount of topical medication dispensed from a 5mm diameter nozzle onto the tip of the palmar aspect of the index finger to the distal interphalangeal joint skin crease. 1 FTU = 500mg of topical agent = 2% BSA.

101
Q

What miscellaneous factors can increase drug absorption from topical medications?

A

Factors that can increase drug absorption include:
1. Vigorous rubbing - increases surface area of skin covered and blood supply to the local area, causing a local exfoliative effect.
2. Presence of hair follicles - can enhance absorption.
3. Reduced particle size of active ingredient - increases the surface area for absorption.

102
Q

What are the characteristics and uses of powders in topical formulations?

A

Powders in topical formulations:
- Characteristics:
- Absorb moisture and decrease friction.
- Adhere poorly to the skin, limited to cosmetic and hygienic purposes.
- Uses:
- Commonly used in intertriginous areas and feet.
- Adverse Effects (AE):
- Caking, crusting, irritation, granuloma formation, inhalation.
- Examples:
- Zinc oxide (antiseptic and covering properties)
- Talc (lubricating and drying properties)
- Stearate (improved adherence to the skin)
- Calamine (astringent to relieve pruritus).

103
Q

What are the main characteristics and uses of ointments in topical formulations?

A

Ointments are semisolid preparations that use petrolatum-based vehicles capable of providing hydration, occlusion, and lubrication.
- Characteristics:
- Increase drug potency due to their ability to enhance permeability.
- Indicated for conditions affecting glabrous skin (palms and soles) and lichenified areas.
- Categories:
- Hydrocarbon bases/Oleaginous bases/Emollients:
1. Prevent evaporation of moisture in the skin.
2. Generally stable and do not contain preservatives.
3. Cannot absorb aqueous solutions, thus not used for water-soluble drugs.
4. Petrolatum is commonly used; however, it has disadvantages such as being greasy and staining clothing.

104
Q

What are the disadvantages of hydrocarbon-based ointments?

A

Hydrocarbon-based ointments, like petrolatum, are greasy, can stain clothing, and cannot absorb aqueous solutions, limiting their use for water-soluble drugs.

105
Q

What is the purpose of poultices in topical therapy?

A

Poultices are wet solid masses of particles applied to diseased skin, used as wound cleansers and absorptive agents in exudative lesions.

106
Q

What are the characteristics and uses of silicon ointments?

A

Silicon ointments are used in the treatment of diaper rash, incontinence, bedsores, and colostomy sites. They are effective due to their properties that help protect and soothe the skin.

107
Q

What are the key components and functions of absorption bases in topical formulations?

A

Absorption bases contain hydrophilic substances (e.g., Lanolin, cholesterol, sorbitan monostearate, polyglycerol alcohols) that facilitate the absorption of water-soluble drugs. Their main functions are as emollients and protectants, and they are generally greasy but easier to remove than hydrocarbon bases. Examples include anhydrous lanolin and hydrophilic petrolatum.

108
Q

What distinguishes water in oil emulsions from oil in water emulsions in topical formulations?

A

Water in oil emulsions contain <25% water with oil as the dispersion medium, while oil in water emulsions contain >31% water. Water in oil emulsions are less greasy and provide a protective film, whereas oil in water emulsions are more easily spread, water washable.

109
Q

What are protectants in topical formulations?

A

Protectants are generally greasy but easier to remove than hydrocarbon bases.

Examples include anhydrous lanolin and hydrophilic petrolatum.

110
Q

What distinguishes water in oil emulsions from oil in water emulsions?

A

Water in oil emulsions contain <25% water with oil as the dispersion medium, while oil in water emulsions contain >31% water.

111
Q

What are the properties of water soluble bases in topical formulations?

A

Water soluble bases consist primarily of various PEGs, are water soluble, do not decompose, and do not support mold growth.

112
Q

What are the characteristics of gels made from water soluble bases?

A

Gels provide faster drug release, are suitable for facial and hairy areas, and may be drying or cause stinging.

They require preservatives.

113
Q

What are the advantages of water-in-oil emulsions in topical therapy?

A

Water-in-oil emulsions are less greasy, spread easily, provide a protective oil film, and have a cooling effect.

114
Q

What are the advantages of oil-in-water emulsions in topical therapy?

A

Oil-in-water emulsions spread easily, are water-washable, less greasy, and easily removed from skin and clothing.

115
Q

What are the benefits of gels in topical therapy?

A

Gels provide faster drug release and are suitable for facial and hairy areas.

116
Q

What are the disadvantages of gels in topical therapy?

A

Gels lack protective properties, can be drying, and may cause stinging.

117
Q

What are silicon ointments used for?

A

Silicon ointments are used for diaper rash, incontinence, bedsores, and colostomy sites.

118
Q

What do absorption bases contain?

A

Absorption bases contain hydrophilic substances such as lanolin, cholesterol, and polyhydric alcohols.

119
Q

What is the water content in water in oil emulsions?

A

Water in oil emulsions contain less than 25% water.

120
Q

What is the function of surfactants in water in oil emulsions?

A

Surfactants help disperse the oil in the water phase and improve stability.

121
Q

What is the primary characteristic of oil in water emulsions?

A

Oil in water emulsions contain more than 31% water.

122
Q

What do humectants in oil in water emulsions do?

A

Humectants prevent drying of the skin.

123
Q

What are water soluble bases primarily composed of?

A

Water soluble bases are primarily composed of various PEGs.

124
Q

What is a key feature of gels made from water soluble bases?

A

Gels provide a faster release of the drug independent of its water solubility.

125
Q

What is a potential drawback of gels made from water soluble bases?

A

They can be drying or cause stinging if they contain high concentrations of alcohol or propylene glycol.

126
Q

What are microspheres/microsponges used for in dermatology?

A

They are used for delivering drugs like Tretinoin (Retin-A micro).

127
Q

What are the characteristics and functions of absorption bases?

A

Absorption bases contain hydrophilic substances that allow for the absorption of water-soluble drugs and serve as emollients and protectants.

128
Q

How do water in oil emulsions differ from oil in water emulsions?

A

Water in oil emulsions are less greasy and provide a protective film, while oil in water emulsions spread easily and are water washable.

129
Q

What are the advantages and disadvantages of using water soluble bases?

A

Advantages include being water soluble and non-staining. Disadvantages include poor delivery of co-formulated drugs.

130
Q

What role do humectants play in oil in water emulsions?

A

Humectants help prevent drying of the skin by attracting moisture.

131
Q

What are the characteristics of pastes in dermatological formulations?

A

Pastes incorporate powders into an ointment, serving as impermeable barriers and localizing the effect of a drug.

132
Q

What are the different types of solutions used in dermatological applications?

A

Types include Burrow’s solution, tincture, collodion, and liniment.

133
Q

What are the advantages and disadvantages of using aerosols?

A

Advantages include lack of irritation and minimal waste. Disadvantages include expense and ecological concerns.

134
Q

What are the characteristics of foams in drug delivery systems?

A

Foams are triphasic liquids that deliver a greater amount of active drug at an increased rate.

135
Q

What are shake lotions and their components?

A

Shake lotions are lotions with added powder to increase evaporation surface area, including components like zinc oxide and talc.

136
Q

What are the advantages of using foams in topical therapy?

A

Foams deliver a greater amount of active drug at an increased rate and have high compliance.

137
Q

What are the disadvantages of aerosols in topical therapy?

A

Aerosols can be expensive and may lack irritation compared to other formulations.

138
Q

What are the advantages of using pastes in topical therapy?

A

Pastes localize the effect of drugs and serve as protectants or sunblocks.

139
Q

What are the disadvantages of using pastes in topical therapy?

A

Pastes are less greasy, more drying, and less occlusive.

140
Q

What are the benefits of using suspensions (lotions) in topical therapy?

A

Suspensions are easier to apply and allow uniform coating.

141
Q

What are the disadvantages of using suspensions (lotions) in topical therapy?

A

Suspensions can be more drying and may sting eczematized or abraded skin.

142
Q

What are the advantages of using shake lotions in topical therapy?

A

Shake lotions effectively dry and cool wet and weeping skin.

143
Q

What are the disadvantages of using shake lotions in topical therapy?

A

Shake lotions tend to sediment and may become abrasive.

144
Q

What is the function of solutions in dermatological treatments?

A

Solutions dissolve substances into a homogenous clarity for effective drug delivery.

145
Q

What are the characteristics of suspensions (lotions)?

A

Suspensions are two-phased systems of insoluble drugs dispersed in a liquid.

146
Q

What is the purpose of shake lotions?

A

Shake lotions increase the surface area of evaporation, effectively drying and cooling wet skin.

147
Q

How do foams enhance drug delivery?

A

Foams deliver a greater amount of active drug at an increased rate.

148
Q

What are the advantages of using aerosols in drug delivery?

A

Aerosols allow for thin layer application with minimal waste.

149
Q

What are liposomes used for in dermatology?

A

Liposomes are used as transdermal delivery systems to enhance drug absorption.

150
Q

What are the primary functions of pastes in topical therapy?

A

Pastes localize the effect of a drug and act as impermeable barriers.

151
Q

How do solutions differ from suspensions in topical formulations?

A

Solutions are homogeneous mixtures, while suspensions are two-phased systems of insoluble drugs.

152
Q

What are the advantages and disadvantages of using foams in topical drug delivery?

A

Advantages include effectiveness and high compliance; disadvantages may include potential adverse effects.

153
Q

What is the role of shake lotions in topical therapy?

A

Shake lotions increase the surface area of evaporation, effectively drying and cooling wet skin.

154
Q

What are the clinical implications of using aerosols for drug delivery?

A

Aerosols reduce irritation and allow for minimal waste in drug application.

155
Q

What are liposomes and how do they function in drug delivery?

A

Liposomes are microscopic spheres that penetrate the skin barrier and deliver bioactive compounds.

156
Q

What are the mechanisms of chemical penetration enhancers?

A

Chemical penetration enhancers increase drug penetration through skin hydration and lipid interaction.

157
Q

What role do stabilizers play in topical formulations?

A

Stabilizers maintain the integrity of formulations, including preservatives and antioxidants.

158
Q

What are the local effects of topical medications?

A

Local effects can include irritant contact dermatitis, with higher concentrations increasing irritation risk.

159
Q

What is the mechanism of action of liposomes in transdermal delivery?

A

Liposomes penetrate the skin barrier by interacting with the lipid layer of the stratum corneum.

160
Q

What are the chemical enhancers used to increase drug penetration?

A

Chemical enhancers include water, alcohols, sulphoxides, urea, and surfactants.

161
Q

What are the physical enhancers used to increase drug penetration?

A

Physical enhancers include iontophoresis, ultrasound energy, microneedles, and microdermabrasion.

162
Q

What are the advantages of using chemical penetration enhancers?

A

They increase skin hydration and enhance drug transport.

163
Q

What are the advantages of using physical penetration enhancers?

A

They provide non-invasive methods to enhance drug delivery.

164
Q

What are the physical enhancers used to increase drug penetration in topical therapy?

A

Physical enhancers include iontophoresis, ultrasound energy (phonophoresis), microneedles, and microdermabrasion.

165
Q

What are the advantages of using chemical penetration enhancers in topical therapy?

A

Chemical enhancers increase skin hydration and interact with the polar head group of lipids to enhance drug transport.

166
Q

What are the advantages of using physical penetration enhancers in topical therapy?

A

Physical enhancers like iontophoresis and ultrasound energy facilitate drug absorption by altering the architecture of the stratum corneum.

167
Q

What are the advantages of using liposomes in transdermal delivery systems?

A

Liposomes can deliver bioactive compounds into sebaceous glands or hair follicles, with rigid liposomes penetrating better than flexible ones.

168
Q

What are liposomes and their function in drug delivery?

A

Liposomes are microscopic spheres consisting of a bilayer that encloses an inner aqueous core, designed to penetrate the skin barrier efficiently.

169
Q

What is the mechanism of action (MOA) of liposomes in drug delivery?

A

The MOA is based partly on a damaged liquid layer of the stratum corneum, allowing liposomes to penetrate efficiently into the skin.

170
Q

Can liposomes pass the skin barrier as intact structures?

A

No clear evidence suggests that liposomes can pass the skin barrier as intact structures, but intact liposomes can penetrate along the hair shaft.

171
Q

What are some examples of chemical enhancers for drug penetration?

A

Examples include water, alcohols (ethanol), sulphoxides, urea, propylene glycol, and fatty acids.

172
Q

What is the role of urea in drug penetration?

A

Urea acts as a keratolytic agent and increases the water content of the stratum corneum.

173
Q

What are physical enhancers in drug delivery?

A

Physical enhancers include iontophoresis, ultrasound energy, and microdermabrasion, which facilitate drug absorption.

174
Q

What are stabilizers in topical formulations?

A

Stabilizers are non-therapeutic agents that include preservatives, antioxidants, and chelating agents to maintain product integrity.

175
Q

What are common preservatives used in topical formulations?

A

Common preservatives include parabens, halogenated phenols, and sodium benzoate, which prevent mold and bacterial growth.

176
Q

What is the function of antioxidants in topical formulations?

A

Antioxidants prevent the vehicle from degrading via oxidation, ensuring product stability.

177
Q

What are thickening agents and their purpose in formulations?

A

Thickening agents increase the viscosity of products and help suspend ingredients in a formulation.

178
Q

What is a potential local effect of topical medications?

A

Irritant contact dermatitis, which can occur when drug penetration is less than drug concentration.

179
Q

What is the mechanism of action of liposomes in drug delivery through the skin barrier?

A

Liposomes penetrate efficiently into the skin barrier based on a damaged liquid layer of the stratum corneum, allowing for the delivery of bioactive compounds.

180
Q

What are the roles of chemical enhancers in increasing drug penetration through the skin?

A

Chemical enhancers increase drug penetration by enhancing skin hydration and interacting with the polar head group of lipids.

181
Q

How do physical enhancers like microdermabrasion facilitate drug absorption?

A

Microdermabrasion facilitates drug absorption by applying crystals to the skin, which collects skin debris under vacuum suction.

182
Q

What are the potential side effects of using preservatives in topical formulations?

A

Preservatives, such as parabens, can act as contact sensitizers and may lead to local skin reactions.

183
Q

What is the function of stabilizers in topical preparations, and what are some examples?

A

Stabilizers prevent degradation of formulations. Examples include preservatives like parabens and antioxidants like ascorbic acid.

184
Q

What is the significance of thickening agents in topical formulations?

A

Thickening agents increase the viscosity of products, helping to suspend ingredients and ensuring even distribution.

185
Q

What are the potential side effects of using topical corticosteroids?

A

Topical corticosteroids can rarely cause HPA axis suppression, growth retardation, and other systemic effects.

186
Q

What is the relationship between local penetration and concentration in allergic contact dermatitis (ACD)?

A

In allergic contact dermatitis (ACD), local penetration is more significant than concentration.

187
Q

How does percutaneous toxicity relate to the use of topical medications?

A

Percutaneous toxicity is directly related to percutaneous absorption, influenced by factors like occlusion and body site.

188
Q

What are the systemic effects of topical salicylic acid?

A

Topical salicylic acid may manifest with CNS toxicity when applied topically.

189
Q

What is the risk associated with the use of systemic calcineurin inhibitors in dermatology?

A

Systemic calcineurin inhibitors are associated with an increased risk of lymphoma and non-melanoma skin cancer (NMSC).

190
Q

What factors contribute to increased potential for toxicity in topical drug application?

A

Factors include renal and hepatic disease, higher body surface area in infants, and extensive BSA involvement.

191
Q

What are the side effects of irritant contact dermatitis (ICD) in topical therapy?

A

ICD occurs when drug penetration is less than drug concentration, causing localized irritation.

192
Q

What factors increase the risk of systemic toxicity in topical therapy?

A

Factors include occlusion, body site, frequency of use, duration of treatment, and nature of diseased skin.

193
Q

What are the risks of using topical corticosteroids in pediatric patients?

A

Risks include HPA axis suppression, growth retardation, and hyperglycemia due to increased BSA.

194
Q

What are the risks of using systemic calcineurin inhibitors in topical therapy?

A

Systemic calcineurin inhibitors increase the risk of lymphoma and non-melanoma skin cancer (NMSC).

195
Q

What are the risks of using topical corticosteroids under occlusion?

A

Risks include increased drug absorption, leading to systemic effects like HPA axis suppression.

196
Q

What is the effect of using a less concentrated preparation over a longer time in topical therapy?

A

It is efficacious while minimizing side effects.

197
Q

What substances may cause burning or stinging sensations without signs of cutaneous irritation?

A

Tacrolimus, sorbic acid, propylene glycol, benzoyl peroxide, hydroxy acids, ethanol, lactic acid, azelaic acid, benzoic acid, and tretinoin.

198
Q

What is the relationship between local penetration and concentration in allergic contact dermatitis?

A

Local penetration is greater than concentration.

199
Q

What is a potential risk associated with nitrogen mustard in dermatological treatments?

A

Increased risk of keratoacanthoma (KA), basal cell carcinoma (BCC), squamous cell carcinoma (SCC), lentigo maligna, and primary melanoma.

200
Q

What systemic effect can topical salicylic acid have?

A

It may manifest with CNS toxicity when applied topically.

201
Q

What factors can increase percutaneous toxicity in topical treatments?

A

Use of occlusion, body site, frequency of use, duration of treatment, and nature of diseased skin.

202
Q

What is a risk associated with systemic calcineurin inhibitors in dermatology?

A

Increased risk of lymphoma and non-melanoma skin cancer (NMSC).

203
Q

What can cause immunologic contact urticaria in susceptible individuals?

A

Bacitracin, when applied to diseased or abraded skin, can cause anaphylactic shock.

204
Q

What are the potential endocrine effects of topical corticosteroids?

A

They can rarely cause HPA axis suppression, growth retardation, hyperglycemia, and other systemic effects.

205
Q

What is the purpose of transdermal drugs in dermatology?

A

Topical application of therapeutic drugs serves as a delivery system for systemic therapy.

206
Q

What are the implications of using a less concentrated topical preparation over a longer duration in terms of side effects and efficacy?

A

Using a less concentrated preparation over a greater amount of time is efficacious while minimizing side effects.

207
Q

What are the potential sensory irritants in topical medications and their effects?

A

Sensory irritants may cause burning or stinging sensations without signs of cutaneous irritation.

208
Q

How does allergic contact dermatitis differ from subjective irritant contact dermatitis in terms of mechanism and effects?

A

Allergic contact dermatitis (ACD) is driven by antigen recognition, while subjective irritant contact dermatitis may cause sensations without visible irritation.

209
Q

What systemic effects can arise from the topical application of salicylic acid?

A

Topical salicylic acid may manifest with CNS toxicity when applied.

210
Q

What factors contribute to increased toxicity from percutaneous absorption of topical medications?

A

Factors include use of occlusion, body site of application, frequency of use, duration of treatment, and nature of diseased skin.

211
Q

What are the risks associated with the use of topical corticosteroids in terms of systemic effects?

A

Topical corticosteroids rarely cause systemic effects such as HPA axis suppression and growth retardation.

212
Q

What is the significance of systemic calcineurin inhibitors in relation to malignancies when used topically?

A

Systemic calcineurin inhibitors have an increased risk of lymphoma and non-melanoma skin cancer (NMSC) when used topically.

213
Q

How can transdermal drugs serve as a delivery system for systemic therapy?

A

Transdermal drugs utilize topical application to deliver therapeutic agents directly into the systemic circulation.

214
Q

What are the advantages of using hydrocortisone in topical applications?

A

Advantages include more controlled release, steady blood level profile, lack of plasma peak, and improved patient compliance.

215
Q

What are the adverse effects associated with the use of hydrocortisone adhesives?

A

Adverse effects include local irritation and allergic contact dermatitis to the adhesives.

216
Q

How does the percutaneous absorption of hydrocortisone vary by body region?

A

The percutaneous absorption of hydrocortisone varies significantly by body region, impacting treatment effectiveness.

217
Q

What are the advantages of transdermal drug delivery systems?

A

Advantages include controlled release, steady blood level profile, lack of plasma peak, and improved patient compliance.

218
Q

What are the adverse effects of transdermal drug delivery systems?

A

Adverse effects include local irritation and allergic contact dermatitis to adhesives or the drug itself.

219
Q

What are the advantages of using hydrocortisone in topical applications?

A

More controlled release, steady blood level profile, lack of plasma peak, and improved patient compliance.

220
Q

What are the adverse effects associated with hydrocortisone topical applications?

A

Local irritation and allergic contact dermatitis to the adhesives or to the drug itself.

221
Q

What are the advantages of using hydrocortisone in topical formulations?

A

More controlled release, steady blood level profile, lack of plasma peak, and improved patient compliance.

222
Q

What are the potential adverse effects associated with the use of hydrocortisone topical formulations?

A

Potential adverse effects include local irritation and allergic contact dermatitis due to adhesives.

223
Q

How does the regional variation in percutaneous absorption of hydrocortisone impact its clinical application?

A

Regional variation indicates different absorption rates, impacting treatment effectiveness and monitoring for side effects.

224
Q

What are the common components and descriptions of powders used in topical formulations?

A

Common components include zinc oxide and talc, used for cosmetic and hygienic purposes.

225
Q

What is the primary use of ointments in topical formulations?

A

Ointments are primarily used to prevent evaporation of moisture from the skin.

226
Q

How do emulsions differ based on their water content in topical formulations?

A

Emulsions can be classified as water in oil or oil in water, affecting their greasiness and application properties.

227
Q

What are the characteristics and uses of gels in topical formulations?

A

Gels are typically water-based, providing a non-greasy option for topical applications.

228
Q

What are emulsions in topical formulations?

A

Mixtures of oil in water or water in oil, used for delivering drugs.

229
Q

How do emulsions differ based on their water content in topical formulations?

A

Emulsions can be classified as:
- Water in oil (<25% water): Less greasy; easy to spread on film; provides a protective film of oil with a cooling effect.
- Oil in water (>31% water): Most commonly used to deliver a drug; easily spread, water washable, and less greasy; easily removed from the skin.

230
Q

What are the characteristics and uses of gels in topical formulations?

A

Characteristics: Organic molecules uniformly distributed in a lattice throughout the liquid; deposits drug in concentrated form.
Uses: Ideal for use in facial or hair-bearing areas; provides protective or emollient effects; may cause drying or stinging.

231
Q

What is the function of solutions in topical formulations?

A

Solutions function as astringents, counterirritants, antipyretics, and emollients, and can be aqueous, hydroalcoholic, or nonaqueous.

232
Q

What are the advantages of using aerosols in topical formulations?

A

Aerosols deliver a greater amount of drug at an increased rate, especially useful for scalp application, and allow for ease of application to hair-bearing areas.

233
Q

What are the common components of powders in topical formulations?

A

Zinc oxide and talc (magnesium silicate).

234
Q

What is the primary use of ointments in topical formulations?

A

Prevent evaporation of moisture from the skin.

235
Q

What is the function of gels in topical formulations?

A

To distribute organic molecules uniformly in a lattice throughout the liquid.

236
Q

What is the purpose of pastes in topical formulations?

A

Less greasy than ointments; used as protectants or for localizing a drug.

237
Q

What are the characteristics of solutions in topical formulations?

A

Liquid vehicles that can be aqueous or nonaqueous, used as astringents and emollients.

238
Q

What is the cooling effect of shake lotions in topical formulations?

A

They are used to dry and cool wet and weeping skin.

239
Q

What is the role of aerosols in topical formulations?

A

To deliver drugs formulated as solutions, suspensions, or powders with ease of application.

240
Q

What are the characteristics and clinical applications of powders in topical formulations?

A

Characteristics:
- Common components: Zinc oxide, talc (magnesium silicate)
- Cosmetic and hygienic purposes; ideal for intertriginous areas and feet.

Clinical Applications:
- Used for skin protection and to absorb moisture in areas prone to friction.

241
Q

How do ointments differ from creams in terms of their formulation and clinical use?

A

Ointments:
- Hydrocarbon base (e.g., petrolatum) or absorption base (e.g., lanolin derivatives).
- Prevent moisture loss; ideal for dry skin conditions.

Creams:
- Emulsions (oil in water or water in oil).
- Less greasy, easier to spread; suitable for larger areas and less occlusive than ointments.

242
Q

What is the role of gels in topical therapy, and how do they differ from ointments?

A

Role of Gels:
- Composed of water, propylene glycol, and a gelling agent (e.g., Carbopol).
- Provide a cooling effect and are less greasy.

Differences from Ointments:
- Gels are less occlusive, easier to apply, and ideal for areas that may become irritated or require a non-greasy formulation.

243
Q

What are the advantages of using aerosols in topical drug delivery?

A

Advantages of Aerosols:
- Deliver a greater amount of drug at an increased rate.
- Formulated with a pure propellant, allowing for easy application to hair-bearing areas.
- Ideal for scalp applications and can cover larger areas uniformly without direct contact.

244
Q

In what scenarios would you choose to use a paste over an ointment or cream?

A

Scenarios for Using Pastes:
- When a more drying and less occlusive formulation is needed.
- Ideal for localized treatment of conditions that may be staining or irritating, such as sunburns or rashes.
- Contains a higher concentration of active ingredients (up to 50% powder), providing a protective barrier.

Fitzpatrick's Dermatology, 9th Edition (Chapter-based Decks) (48 decks)

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