Dermatology Quiz: Skin Functions and Treatments

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Questions and Answers

Why should topical retinoids be avoided during pregnancy?

Because they can cause erythema.

Because they are teratogenic. (correct)

Because they can cause photosensitivity.

Because they can cause dry, irritated, and peeling skin.

Which of these is not an effect of benzoyl peroxide?

Inhibition of protein synthesis. (correct)

Antiseptic.

Keratolytic.

Inhibition of P.acnes growth.

Penicillins are primarily used to treat which skin condition?

Acne.

Viral infections.

Fungal infections.

Deep skin infections. (correct)

Which of these is not a function of the skin?

It converts testosterone to dihydrotestosterone. Signup and view all the answers

Which enzyme do imidazoles and triazoles inhibit?

14-α-sterol demethylase. Signup and view all the answers

What is the main sterol in fungal membranes?

Ergosterol. Signup and view all the answers

Which layer of the skin provides the main barrier to absorption?

The stratum corneum. Signup and view all the answers

What is the mechanism of action of allylamines?

They inhibit squalene epoxidase and prevent ergosterol synthesis. Signup and view all the answers

Which of these topical corticosteroids is classed as 'potent'?

Clobetasol propionate 0.05%. Signup and view all the answers

What is tachyphylaxis?

A decrease in response to a drug following repeated administration. Signup and view all the answers

Which of these statements about allylamines is true?

They bind well to the stratum corneum. Signup and view all the answers

How can tachyphylaxis to topical corticosteroids be managed?

By instituting 'weekend therapy' or 'pulse therapy'. Signup and view all the answers

What is the mechanism of action of acyclovir?

It is an analogue of guanine which inhibits the viral DNA topoisomerase enzyme. Signup and view all the answers

Which two families of receptors are activated by retinoids?

Retinoic acid receptors and retinoid X receptors. Signup and view all the answers

Which of these conditions are topical retinoids not suitable to treat?

Dry skin. Signup and view all the answers

Which receptors, when blocked, does not completely relieve itching?

H1 receptors. Signup and view all the answers

Study Notes

Skin Function

Skin acts as a drug delivery portal to other tissues.
Skin excretes drugs via sweat
Skin has diseases & conditions requiring treatment.
Skin does not convert testosterone to dihydrotestosterone.

Skin Anatomy

The stratum corneum is the main barrier to absorption.

Topical Corticosteroids

Potency classification determines safety for long-term use.
Mild potency safest for long-term use, face, and thinner skin.
Potent corticosteroids include:
- Clobetasol propionate 0.05%

Tachyphylaxis

Decrease in response to a drug following repeated administration.
Can be managed using 'weekend therapy' or 'pulse therapy'.

Side Effects of Topical Corticosteroids

Skin thinning and atrophy.
Hirsutism
Photosensitivity.
Tachyphylaxis is not a side effect.

Topical Antihistamines

Block H1 and H2 receptors.
Blocking only H2 receptors does not completely relieve itching.

Retinoids

Activate retinoic acid receptors and retinoid X receptors.
Not suitable to treat:
- Dry skin
- Sunburn
- Pregnancy
Should be avoided during pregnancy because they are teratogenic.

Benzoyl Peroxide

Antiseptic
Inhibits P.acnes growth
Not a keratolytic.

Penicillins

Prevent the formation of the protein supports of bacterial cell walls.
Treat deep skin infections.
Do not treat fungal or viral infections.

Imidazoles and Triazoles

Inhibit 14-α-sterol demethylase.
Used to treat fungal infections.

Ergosterol

Main sterol in fungal membranes.

Allylamines

Inhibit squalene epoxidase and prevent ergosterol synthesis.
Second-line treatment for fungal infections.

Acyclovir

Analogue of guanine that inhibits the viral DNA topoisomerase enzyme.
Treats viral infections.

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Description

This quiz covers essential topics related to skin functions, anatomy, and treatments, including topical corticosteroids and antihistamines. Learn about the role of skin in drug delivery and the effects of various treatments on skin health. Test your knowledge on important dermatological concepts.