Flashcards in Pharmacology Deck (56)
What is almost as important as the type of drug chosen in producing the therapeutic effect
The vehicle in which the drug is solubilised/ delivered
Drug administration via the skin can be used to treat systemic disease. True or false
What are the 3 major routes of administration for skin
What kind of effect do topical treatments have
local effect but also can treat underlying tissues
What type of effects do subcutaneous and transdermal treatments have
systemic effects (often prolonged)
What route of administration is required to reach the skin barrier
What is the single most important barrier to drug penetration
The stratum corneum
What does the stratum corneum consist of?
Hardened, dead, keratinocytes surrounded by intercellular lipids forming 10-30 sheets of tissue that are constantly shed and renewed
What are the corneocytes suspended in?
Lipids in lamellar structures / layers
What are the bricks in the Brick and Mortar Model
What are adjacent corneocytes held together by? Where are these found?
corneodesmosomes (intercellular junctions)
living more inner layers of the skin
What is the mortar made up of?
intracellular lipids in an intensely hydrophobic environment
What is the ratio of different lipid content in the stratum corneum and why is this important?
any change in this can cause major changes to the skin
What can the mortar act as?
A reservoir for lipid-soluble drugs (topical steroids)
In what case does the drug have to travel across the stratum corneum
When you are trying to achieve either a local or a systemic effect.
What is meant by topical route of administration
when a drug is applied directly to the surface of the skin
When are topical drugs used?
superficial skin disorders - psoriasis and eczema
Name some vehicles for topical routes of admisistration
What dictates the choice of the vehicle
1. Physicochemical properties of the drug
2. the clinical condition
What types of drugs are applied to relieve itching
H1 recepto antagonists
What is oftenused to treat dry skin
How do warts arise
Abnormal division of keratinocytes
What is the point in having vehicles
A vehicle which may be suitable for wet/ oozing skin is probably not suitable for dry skin
Drug absorption across the skin is a passive process. true or false
what can be described by Fick's first law of diffusion
The rate of absorption of a drug across the skin
What are 2 important facrots relating to the role of the vehicle
Solubility of the drug in the vehicle
Maximising the movement of the drug from vehicle to the stratum corneum
What is Km
the equilibrium solubility of the drug in the stratum corneum relative to its solubility in the vehicle
A very soluble drug will penetrate easily. true or false
What type of base is vest for a lipothilic drug