Pharmacology

Question 1

main routes for drug administration in the skin

Answer 1

1. topical
2. transdermal
3. subcutaneous
4. other epithelial routes e.g. airways, conjunctival sac, nasal mucosa and vagina

Question 2

model of the stratum corneum

Answer 2

Brick and Mortar model

Question 3

drug delivery diffusion routes

Answer 3

intercellular
transcellular
transappendageal

Question 4

vehicles

Answer 4

lotions (most water content)
creams
ointments
gels
pastes
powders
foams

Question 5

describe lotion formula

Answer 5

suspension/solution of medication in water (if containing alcohol it can sting)

Question 6

when are lotions used?

Answer 6

hair-bearing areas

Question 7

creams formulation

Answer 7

semisolid emulsion of oil in water, containing emulsifier and preservative

Question 8

are creams cosmetically acceptable

Answer 8

yes, non-greasy

Question 9

describe ointments

Answer 9

semisolid grease, less cosmetically acceptable

Question 10

gels formulation

Answer 10

thickened aqueous solutions containing high molecular weight polymers e.g. methylcellulose

Question 11

pastes formulation

Answer 11

semisolids finely powdered material (ZNO). stiff, greasy and often used in bandages

Question 12

describe foams

Answer 12

colloid with two or three phases

Question 13

types of topical therapies

Answer 13

1. emollients
2. topical steroids
3. anti-infective
4. antipruritic
5. keratolytic

Question 14

describe emollients

Answer 14

used in dry/scaly conditions
300-500g per week
applied after bathing in direction of hair growth

Question 15

describe topical steroids

Answer 15

vasoconstriction and anti-inflammation
range from mild to very potent
whole body application is 20-30g

Question 16

Adverse of topical steroids

Answer 16

thinning of skin
purpura
rosacea
telangiectasia
systemic absorption (Cushing's)
tachyphylaxis

Question 17

types of anti-infectives

Answer 17

antiseptics (iodine, hydrogen peroxidetriclosan and chlorhexidine)
antiviral
antifungals e.g. nystatin, clotrimazole or ketoconazole.

Question 18

examples of antipruritics

Answer 18

methanol
capsaicin
phenol
crotamiton

Question 19

function of keratolytics

Answer 19

soften keratin

Question 20

role of calcineurin inhibitors

Answer 20

suppress lymphocyte activation

Question 21

factors that increase partitioning into the skin

Answer 21

• hydration of the skin by occlusion

- inclusion of excipients (increases solubility of hydrophobic drugs)

Question 22

factors that affect absorption into the skin

Answer 22

nature of skin (site, hydration, thickness)
drug preparation (concentration, salt, vehicle)

Question 23

describe the subcutaneous route

Answer 23

needle into adipose tissue

Question 24

how does the drug enter the systemic circulation by subcutaneous route

Answer 24

via capillaries or lymphatic vessels

Question 25

disadvantage of subcutaneous route

Answer 25

slow absorption (can be a good thing)
limited volume injected

Question 26

why is the skin a good route for drug administration

Answer 26

• simple and non-sterile
• steady state plasma concentration
• avoids first pass metabolism
• drug absorption can be terminated rapidly

Question 27

disadvantages of skin as a route of administration

Answer 27

only limited numbers can diffuse across the epidermis

Question 28

describe transdermal drug delivery

Answer 28

adhesive patch

Question 29

role of enhancers in an adhesive patch

Answer 29

interact with lipid matrix to increase permeability