Buxton: Principles of Topical Treatments Flashcards
In what two ways do the active ingredients in topicals penetrate the skin?
transepidermally or transfollicularly
What are some different “vehicles” of topical drugs?
powder paste shake lotion ointment hydrophilic ointment, cream or lotion water
When do you use topicals?
If a patient has a skin disorder covering <30% of the body, a topical medication may be considered
What are 3 main ways to ensure that you choose the right vehicle for a topical?
patient’s skin type
degree of acuity of the disease
nature of the lesions
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)
creams, lotions, shake lotions; ointments or pastes
Degree of acuity: Acute inflammatory processes are best treated with (blank). If the lesions are weeping, use (blank).
creams or lotions; shake lotions
What type of topical should you use for acute erythema?
shake lotion, lotion, or cream
What type of topical should you use for vesicles?
shake lotion, gel, lotion
What type of topical should you use for blisters?
wet dressings, shake lotions
What type of topical should you use for erosions?
powder, shake lotions
What type of topical should you use for crusts?
ointment
These are some topical agents you might see
keratolytic agents cytotatic agents antibiotics, antifungals, antivirals corticosteroids combination products nonsteroidal antiinflammatory agents sunscreens
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.
Class 1 is the weakest: hydrocortisone, prednisolone
Class 4 is the strongest: Clobetasol 17-propionate
Side effects of topical corticosteroids:
Epidermis? Hair follicles? Dermis? Pigmentation? Vessels?
atrophy of epidermis steroid acne around hair follicles atrophy and striae of the dermis hypopigmentation erythema and telangiectases
help prevent infections caused by bacteria that get into minor cuts, scrapes, and burns
topical antibiotics
Most topical antibiotics are directed against which bacteria?
S. aureus and Strep pyogenes
Classes of topical antibiotics
Cell wall synthesis inhibitors Ribosome function inhibitors Sulfa drugs Burn treatment agents Miscellaneous
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
Mupirocin
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.
Polymyxin B
**in neosporin
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.
Bacitracin A
**also in neosporin
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
Gramicidin
How is Gramicidin administered? How does it work?
topically; believed to work at the cytoplasmic membrane, forming small pores that cause leakage of essential cations from the cytoplasm
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
neomycin
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.
Silver sulfadiazine
Used to treat acne; Exact antibacterial mechanism is unknown, but presumably involves oxidation of essential bacterial structures.
benzoyl peroxide
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.
Clindamycin
When would you want to use an ointment?
erosions and crusts
When would you not want to use an ointment?
acute erythema
vesicles
blisters
