[Clinical effect of salicylic acid and high dose urea applied according to the standardized New German Formulary].
OBJECTIVE
To determine whether salicylic acid and high dose urea in five different NRF (New German Formulary) formulations have an effect on stratum corneum.


METHODS
20 healthy volunteers had their stratum corneum blacked with silver nitrate and a photographic developer, and a chromameter (a*-value) was used to determine the amount of discoloration produced by the study products and the drug free vehicles after 24 hours semiocclusive application and 24 hours later. The change in fingerpad ridge width produced by the study formulations and drugfree vehicles was determined at the same time, using the Hikoscope Dermatoscope after 30 and 35 minutes' use under an occlusive dressing. The results obtained with the two methods were correlated.


RESULTS
All study formulations were effective. There were differences in the time course of the effects on the stratum corneum. The fingerpad ridge width method is not a measure of keratolytic activity because there were no significant correlations between the results obtained with the two methods. Also, 40% urea was keratolytic in the silver nitrate test, but had no effect of fingerpad ridge width.


CONCLUSIONS
All NRF study formulations were effective in the stratum corneum. The fingerpad ridge width method is not a measure of keratolytic activity but rather of an other unknown effect of salicylic acid.
Gloor
M
M
Hautklinik am Klinikum der Stadt Karlsruhe GmbH, Germany. max@prof-gloor.de
Fluhr
J
J
Wasik
B
B
Gehring
W
W
D000287:Administration, Topical; D000328:Adult; D000891:Anti-Infective Agents, Local / Q000737:chemistry; D005260:Female; D005569:Formularies as Topic; D005858:Germany; D006801:Humans; D007641:Keratolytic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D020156:Salicylic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D012835:Silver Nitrate / Q000737:chemistry; D012867:Skin / Q000187:drug effects*; D014508:Urea / Q000008:administration & dosage / Q000494:pharmacology*
D000891:Anti-Infective Agents, Local; D007641:Keratolytic Agents; D014508:Urea; D012835:Silver Nitrate; D020156:Salicylic Acid