Dermal Flashcards
Compounds causing chemical burns
ammonia, calcium oxide, HCl, HF (also hypocalcemia), sodium hydroxide, toluene
ethylene oxide, methyl bromide, some fluorine containing hydrocarbons
solvents cause chemical burns by delipidation of the skin
Contact allergens
nickel, chromium
aminoglycosides, sulfonamides, benzocaine
p-Phenylenediamine (hair dyes), epoxy resins (latex)
Pentadecylcatechol (uroshiol) - poison ivy, poison oak, poison sumac
Phototoxicity
chemicals most often absorb light in UVA range (290-700 nm)
psoralens (lime juice, celery; intercalate with DNA), PAHs, tetracyclines, sulfonamides, sulfonyureas, thiazides, furocoumarins
occurs more often than photoallergy
Photoallergy
type IV hypersensitivity
halogenated salicylanilides (removed from market; used as positive controls), fragrances (6-methylcoumarin, sandalwood oil), drugs (chlorpromazine, diphenhydramie, sulfanilamide), sunscreen ingedients (PABA, oxybenzone)
Photoallergy generally is distinguishable from phototoxicity because the former results from delayed hypersensitivity, and amounts of chemical too low to give a toxic response still suffice to elicit allergy.
Klaassen, Curtis D.; Watkins, John B.. Casarett & Doull’s Essentials of Toxicology, Third Edition (Lange) . McGraw-Hill Education. Kindle Edition.
Murine Local Lymph Node (LLNA)
measures sensitization from induction phase
topical treatment of the ear
injection of radiolabeled thymidine or Brdu
Advantages of transdermal drug delivery
steady infusion for extended periods (typically 1 to 7 days) thereby avoiding large variations in plasma concentration
preventing exposure to the acidic pH of the stomach
avoiding biotransformation in the gastrointestinal tract or from first-pass removal by the liver.
Klaassen, Curtis D.; Watkins, John B.. Casarett & Doull’s Essentials of Toxicology, Third Edition (Lange) . McGraw-Hill Education. Kindle Edition.
Arsenic
altered skin pigmentation, hyperkeratosis of the palms and soles, impaired circulation reflecting endothelial cell damage (“black foot” disease), and carcinoma (skin, lung, bladder, liver, and other organs).
Generation of ROS in target cells is another proposed mechanism of arsenic’s carcinogenicity, and its other pathological effects.
Klaassen, Curtis D.. Casarett & Doull’s Toxicology: The Basic Science of Poisons, 9th Edition (p. 972). McGraw-Hill Education. Kindle Edition.
Draize test for irritation
produces few false negatives (type II errors), but many false positives (type I errors).
0.5 ml (liquid) or 0.5 g (solid) of the target material is applied to a 1×1″ gauze patch onto abraded and intact skin for 24 hours.
After 24 hours, the patches are removed and scored for the following endpoints: erythema and edema
Klaassen, Curtis D.. Casarett & Doull’s Toxicology: The Basic Science of Poisons, 9th Edition (p. 957). McGraw-Hill Education. Kindle Edition.
Psoralens
chemicals producing phototoxicity without production of singlet oxygen. Psoralens intercalate within DNA to form covalent adducts, and cross-link when activated by UVA.
in lime and celery
Klaassen, Curtis D.. Casarett & Doull’s Toxicology: The Basic Science of Poisons, 9th Edition (p. 964). McGraw-Hill Education. Kindle Edition.
