Topical Preparations Flashcards
Advantages of topical preparations: (4)
non invasive
easy dose withdrawal in case of adverse reactions
convenient
avoid hepatic first pass metabolism
Disadvantages of topical preparations: (3)
low skin permeability
skin irritation
difficult to determine dose accurately
How is dose administered via topicals?
Using fingertip unit
Ointment..
drug dissolved or dispersed in greasy base
can be difficult to spread, but promotes skin hydration
Creams..
semi-solid emulsion
longer residence time than lotion, excellent patient acceptability, easily washable
Gel..
viscous liquid, clear
forms a film on skin when dried
Lotion…
water based
high spreadibility, suitable on hairy skin, short residence time
primarily used for cleansing or disinfection
Foam…
dispersion of gas within a liquid
foam generated during use
Spray…
liquid droplets in gas - aerosol
without direct skin contact
rapid and even coverage of large surface area
Patch…
solid dosage form containing drug on an adhesive film
accurate dosing, protection of formulation
Cellular layers of the skin: (3)
epidermis
dermis
hypodermis
Factors affecting dermal drug transport:
age
disease - broken skin, thickened skin
drug properties
Midrodialysis
invasive treatment
where a semi permeable tube is inserted surgically below the skin
Tape stripping
stratum corneum progressively removed by tape
Shunt pathway
through hair follicles and sebaceous glands
