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Flashcards in Pharmacology Deck (56):
1

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

2

Drug administration via the skin can be used to treat systemic disease. True or false

True

3

What are the 3 major routes of administration for skin

Topical
Transdermal
Subcutaneous/ depot

4

What kind of effect do topical treatments have

local effect but also can treat underlying tissues

5

What type of effects do subcutaneous and transdermal treatments have

systemic effects (often prolonged)

6

What route of administration is required to reach the skin barrier

Depot injection

7

What is the single most important barrier to drug penetration

The stratum corneum

8

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

9

What are the corneocytes suspended in?

Lipids in lamellar structures / layers

10

What are the bricks in the Brick and Mortar Model

Corneocytes

11

What are adjacent corneocytes held together by? Where are these found?

corneodesmosomes (intercellular junctions)
living more inner layers of the skin

12

What is the mortar made up of?

intracellular lipids in an intensely hydrophobic environment

13

What is the ratio of different lipid content in the stratum corneum and why is this important?

1:1:1
any change in this can cause major changes to the skin

14

What can the mortar act as?

A reservoir for lipid-soluble drugs (topical steroids)

15

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.

16

What is meant by topical route of administration

when a drug is applied directly to the surface of the skin

17

When are topical drugs used?

superficial skin disorders - psoriasis and eczema
skin infections
itching
dry skin
warts

18

Name some vehicles for topical routes of admisistration

ointments
creams
gels
lotions
pastes
powders

19

What dictates the choice of the vehicle

1. Physicochemical properties of the drug
2. the clinical condition

20

What types of drugs are applied to relieve itching

H1 recepto antagonists

21

What is oftenused to treat dry skin

Moisturising agents

22

How do warts arise

Abnormal division of keratinocytes

23

What is the point in having vehicles

A vehicle which may be suitable for wet/ oozing skin is probably not suitable for dry skin

24

Drug absorption across the skin is a passive process. true or false

true

25

what can be described by Fick's first law of diffusion

The rate of absorption of a drug across the skin

26

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

27

What is Km

the equilibrium solubility of the drug in the stratum corneum relative to its solubility in the vehicle

28

A very soluble drug will penetrate easily. true or false

false

29

What type of base is vest for a lipothilic drug

Hydrophilic base

30

What tends to break down the permeability barrier

hydration

31

Are hydrophilic or lipothilic drugs better for absorption

lipothilic

32

What provides the driving force for absorption

The soluble fraction of a drug

33

Inclusion of what can enhance solubility and absorption

The inclusion of exipients

34

Give an example of an excipient

propylene glycol

35

Why are topically applied drugs generally poorly absorbed

Only a small fraction partitions into the stratum corneum

36

What does an increased partitoning result from

a reduction in the barrier function of the stratum corneum

37

What can be used to increase the solubility of hydrophobic drugs

Inclusion of excipients

38

Name some factors that influence the absorption of topically applied drugs

The nature of the skin - the thickness
Hydration of the skin
Integrity of the epidermis
Drug concentration
The drug salt
The vehicle

39

Why can a pharmacist not substitute the vehicle

It has been prescribed just as much as the drug itself

40

Why might a cream be used rather than an ointment

For cosmetic reasons

41

Glucocorticosteroids signal via what and specifically what

Nuclear receptors - GRalpha

42

What is meant by Subcutaneous Route

Drug delivered by a needle into the adipose tissue just beneath the surface of the skin

43

What are some advantages of administering a drug subcutaneously

Absorption is relatively sore due to poor vascular supply
Route of adminsitration for many protein drugs (insulin)
Suitable for administration fof depot of drug under the skin that

44

What is the main disadvantage of using subcutaneous route of administration

Injection volume is limited

45

What are 4 advantages of a drug being administered topically for a systemic affect

Simple and non-sterile technique
Steady-state plasma concentration over a prolonged period of time
Avoids first pass metabolism
terminated rapidly

46

What is meant by transdermal drug delivery

Drug is incorporated into a n adhesive patch and applied to the epidermis

47

What 4 types of drugs is Trasdermal drug delivery useful for

low molecular weight
moderately lipophilic
potent
realtively brief half life

48

What are some advantages of using transdermal drug delivery

Relatively few drugs are suitable
Chance of allerfies and cost

49

Name some drugs wihch are administered transdermally

nicotine
GTN
fentanyl
estradiol

50

WHat is the puropse of using chemical enhancements in transdermal drug delivery

Increases permeability
Low cost
Can be incorporated into vehicles

51

What are some disadvantages of transdermal drug delivery

Skin irritation/ toxicity
Not effective for highly water soluble drugs

52

What agents tend to be used to enhance

Water - prolonged occlusion
A variety of solvents and surfactants (ethanol, and sodium dodecyl sulphate

53

What is iontophoresis

application of low voltage electrical pulses to the skin via a surface electrode over a prolonged period of time

54

What is meant by electroporation

very brief high voltage pulses lead to pore formation. Has the potential for the delivery of hydrophilic and changed molecules into the skin

55

what is sonophoresis

the use of ultrasound to increased skin permeability

56

How do microneedles work

they punch microscopic holes i nthe skin - largely experimental