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Flashcards in Pharmacology Deck (54)
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1

What aare adjacent corneocytes held together by?

corneodesmosomes

2

What is conventional transdermal drug delivery driven by?

diffusion

3

What is Fick's Law?

Rate of absorption (flux) is equal to the permeability coefficient times the concentration of drug

4

What are the important factors in the role of the vehicle?

The solubility of the drug in vehicle (Cy)
Maximising the movement of the drug from vehicle to the atratum corneum (drug must escape from vehicle)

5

What is the permeability coefficient (Km) described as?

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

6

What is the purpose of excipients?

They are put into the vehicle to enhance the solubitliy of the drug and so enhance absorption

7

Why might excess, non-dissolved drug be included into transdermal patches?

increases duration of effectiveness nad porvides a constant rate of delivery- dissolved drug that is removed by absorption is replaced by undissolved drug maintaining a fairly constant soluble concentration

8

Why are topically applied drugs generally poorly absorbed?

only a small fraction partitions into the stratum corneum

9

Name some factors that can improve partitioning

hydration of the skin by occlusion (increases the reservoir with which the drug can be absorbed)
inclusion of excipients which also increase the solubility of hydrophobic drugs

10

What are the factors that affect the absorption of topically applied drugs in drug preparation?

drug conc.
the drug salt (different salts can have varying potencies)
the vehicle (can affect how active a drug is)

11

What do glucocorticoids combine with in the cytoplasm?

GRalpha

12

What does combination of steroid with GRalpha cause the dissociation of?

inhibitory heat shock proteins
(they were previously joined to GRalpha but steroid kicks it out)

13

What does the steroid and GRalpha do in the nucleus?

bind to the glucocorticoid response elements which switches on or off transcription of specific

14

Where is subcutaneous drug delivered?

adipose tissue just beneath teh surface of the skin

15

How does subcutaneous drug reach systemic circulation?

diffuses into capillaries or lymphatics

16

What are some advantages to subcut drug administration?

absorption is relatively slow (poor vascular supply)
can be used to introduce a depot of drug under the skin that is very slowly released into the circulation

17

What is an advantage of subcut drug administration?

injection volume is limited

18

What is the skin a good route for a systemic effect?

avoids first pass metabolism
drug absorption can be terminated rapidly

19

What makes a drug suitable for transdermal drug delivery?

low molecular weight
moderately lipophilic
potenet
relatively brief half life

20

What is iontophoresis

application of low voltage electrical pulses to the skin via a surface electrode over a prolonged period of time can drive low molecular mass molecules (of the same charge) through the skin- move away from the same charge

21

What is electroporation?

very brief high volatge pulses lead to "pore" formation

22

What is sonophoresis?

use of ultrasound to increase skin permeability

23

What is a cream?

semisolid emulsion of oil in water

24

Creams contain both an emulsifier and a..

preservative

25

Due to their high water content, creams do what to the skin?

cool and moisturise

26

What is an ointment?

semisolid grease/oil (soft paraffin)

27

Do ointments contain preservative?

no

28

Why do ointments help to moisturise the skin?

occlusive- restrict transepidermal water loss

29

What is a lotion?

a liquid formulation- suspension or solution of medication in water, alcohol or other liquids

30

What areas are lotions used to treat?

scalp and other hair-bearing areas