Buxton: Principles of Topical Treatments

Question 1

In what two ways do the active ingredients in topicals penetrate the skin?

Answer 1

transepidermally or transfollicularly

Question 2

What are some different “vehicles” of topical drugs?

Answer 2

powder
paste
shake lotion
ointment
hydrophilic ointment, cream or lotion
water

Question 3

When do you use topicals?

Answer 3

If a patient has a skin disorder covering <30% of the body, a topical medication may be considered

Question 4

What are 3 main ways to ensure that you choose the right vehicle for a topical?

Answer 4

patient’s skin type
degree of acuity of the disease
nature of the lesions

Question 5

Skin type: About 50% of individuals have oily skin or seborrhea. They do better with (blank) while the ones with dry skin do better with (blank)

Answer 5

creams, lotions, shake lotions; ointments or pastes

Question 6

Degree of acuity: Acute inflammatory processes are best treated with (blank). If the lesions are weeping, use (blank).

Answer 6

creams or lotions; shake lotions

Question 7

What type of topical should you use for acute erythema?

Answer 7

shake lotion, lotion, or cream

Question 8

What type of topical should you use for vesicles?

Answer 8

shake lotion, gel, lotion

Question 9

What type of topical should you use for blisters?

Answer 9

wet dressings, shake lotions

Question 10

What type of topical should you use for erosions?

Answer 10

powder, shake lotions

Question 11

What type of topical should you use for crusts?

Answer 11

ointment

Question 12

These are some topical agents you might see

Answer 12

keratolytic agents
cytotatic agents
antibiotics, antifungals, antivirals
corticosteroids
combination products
nonsteroidal antiinflammatory agents
sunscreens

Question 13

Topical corticosteroids can be ranked from Class 1 to Class 4. Which is the weakest? Give an example. Which is the strongest? Give an example.

Answer 13

Class 1 is the weakest: hydrocortisone, prednisolone

Class 4 is the strongest: Clobetasol 17-propionate

Question 14

Side effects of topical corticosteroids:

Epidermis?
Hair follicles?
Dermis?
Pigmentation?
Vessels?

Answer 14

atrophy of epidermis
steroid acne around hair follicles
atrophy and striae of the dermis
hypopigmentation
erythema and telangiectases

Question 15

help prevent infections caused by bacteria that get into minor cuts, scrapes, and burns

Answer 15

topical antibiotics

Question 16

Most topical antibiotics are directed against which bacteria?

Answer 16

S. aureus and Strep pyogenes

Question 17

Classes of topical antibiotics

Answer 17

Cell wall synthesis inhibitors
Ribosome function inhibitors
Sulfa drugs
Burn treatment agents
Miscellaneous

Question 18

Isolated from Pseudomonas fluorescens
Works against Gram-positive bacteria only
Can be used to treat MRSA (although resistance is rising)
Ester linkage is rapidly hydrolyzed hepatically, thus precluding utility as an oral or intravenous antibiotic.
Inhibits bacterial isoleucyl-tRNA synthetase

Answer 18

Mupirocin

Question 19

Member of the lipopeptide class of antibiotics.
Only active against gram negative bacteria (P. aeruginosa, E. coli, K. pneumoniae), while daptomycin is used to treat gram positive bacteria
Highly nephrotoxic and are thus only used topically.
Bind the the lipopolysaccharide in the outer membrane, thus destroying OM integrity.
Bind to the cytoplasmic membrane (to the phosphatidylethanolamine) and make the membrane more permeable.

Answer 19

Polymyxin B

**in neosporin

Question 20

Primarily used against gram positive bacteria S. aureus and Streptococci spp.
Most gram negative organisms are resistant.
Interferes with bacterial cell wall synthesis.
Acts by blocking a step in the process whereby the key subunits are transferred from the cytoplasm.

Answer 20

Bacitracin A

**also in neosporin

Question 21

Small peptide
Some are cyclic, others are linear
Commercially, it is a mixture of compounds
It is a powerful antibacterial agent, with braod range against Gram + and Gram - microorganisms

Answer 21

Gramicidin

Question 22

How is Gramicidin administered? How does it work?

Answer 22

topically; believed to work at the cytoplasmic membrane, forming small pores that cause leakage of essential cations from the cytoplasm

Question 23

Extremely nephrotoxic, thus limiting its use to a topical antibiotic
Has excellent activity against gram negative bacteria and partial activity against gram positive strains.
Like other aminoglycosides, works by binding to the bacterial 30S ribosomal subunit, thus inhibiting protein synthesis

Answer 23

neomycin

Question 24

Sulfa drug works by interfering with the biosynthesis of folic acid.
Heavy metals, like silver, seem to be toxic to bacteria, probably due to their ability to denature proteins through reaction with disulfide bonds.
Used to treat burn patients.

Answer 24

Silver sulfadiazine

Question 25

Used to treat acne; Exact antibacterial mechanism is unknown, but presumably involves oxidation of essential bacterial structures.

Answer 25

benzoyl peroxide

Question 26

Commonly used topically in the treatment of acne.
A member of the lincosamide class of antibacterial agents and acts at the bacterial ribosome.
Commonly used to treat aerobic Gram-positive bacteria.

Answer 26

Clindamycin

Question 27

When would you want to use an ointment?

Answer 27

erosions and crusts

Question 28

When would you not want to use an ointment?

Answer 28

acute erythema
vesicles
blisters