Skin pharmacology Flashcards
(60 cards)
What pharmologcial methods can we use to treat skin conditions?
Topical
Systemic
Drugs that induce reactions in the skin, e.g. psoralen
What ways can we use the skin to deliver drugs to the body?
Transdermal application
Topical
What is the difference between transdermal and topical administration?
Transdermal: application of drug to the skin with the intent that the drug will act elsewhere in the body
Topical: application of the drug to the damaged skin, the drug acts locally
What methods of transdermal administration are there?
Transdermal patch: a sticker
Iontopheresis: use of electric currents to get the drug through the skin
Micro-needles: the future, tiny needles that help drug bypass the skin barrier
How do transdermal patches work?
Apply to skin, the drug passes through the skin slowly providing a slow release of the drug over a long time period
The skin is a highly effective barrier, how does the drug get across it from a transdermal patch?
The drugs used need to be lipophilic
The stratum corneum (outer layer) is lipid rich, so the drug can get through it and into the body
What features must a drug given transdermically have?
Lipid soluble
High affinity
What are the advantages of transdermal patches?
This route bypasses the first-pass effect
Self-administration
Lasts over long periods of time
What is the first-pass effect?
When a drug is given orally, its concentration is greatly reduced because it is metabolised by the liver before it can act
What drugs are given transdermically?
HRT Contraception Nicotine replacement Angina Pain relief
What drug is used to treat angina transdermically?
GTN: glyceryl trinitrate
Name some factors that affect the delivery of the drug via a transdermal patch?
The skin type
How much fact there is
The placement of the patch
Body temperature
How does glyceryl trinitrate help treat angina?
Nitroglycerin converts to NO
Affects the smooth muscle
A vasodilator
More blood flow to heart, less ischaemia and pain
What drug is often given for pain relief via a transdermal patch?
Fentanyl, an opiate
What are the side effects of fentanyl?
Fever
Breathing problems
These usually resolve when you take off the patch
In what ways is a fentanyl transdermal patch better and worse than oral morphine?
Better:
- much lower dose is required to get the same effect
- great for chronic pain due to slow release
Worse:
- slow onset of action
What is iontopheresis?
A transdermal patch that uses electrical currents to get the drug in through the skin more efficiently
What are micro-needles?
Apart from sounding really cute!
They are tiny needles that allow the drug to pass the skin barrier and get into the body
Currently in development still
What forms can you get drugs in to give topically?
Ointment: made with grease
Pastes: powder suspended in ointment
Cream: made with water and grease
Lotion: liquid, wet
Which form of topical drug is best for very potent drugs that may cause damage to surrounding healthy tissue?
Pastes: they stay where they are put
What do emollients do to the skin?
Hydrate, soothe, reduce itching
They can help repair the damaged epithelial barrier
What is the benefit of having urea in an emollient?
Urea dissolves the intercellular matrix of the cells of the stratum corneum, promoting desquamation of scaly skin,
It helps to soften hyperkeratotic areas.
Name some ‘barrier cream’?
What do they do?
Silicones and Zinc oxide
They help create a barrier on the skin, to prevent pathogens and allergens getting in
When given topically, what does salicylic acid do?
What type of drug is it?
Facilitates breakdown of keratin to soften skin
It is a keratolytic
