Salicylic acid penetration rate

The lipid composition of the SC varies between the different regions of the body. A study by Elias et al. demonstrated a quantitative relationship between the rate of percutaneous transport of salicylic acid across the SC at two different body sites (abdomen and leg) and the lipid weight percent at the corresponding sites. The results showed that the lower the lipid content, the higher the penetration rate of salicylic acid, which appeared to be in line with the role of the lipid pathway to the non-polar solute pene-tration.f A more in-depth study by Lampe et al. also found the same variations in lipid weight percent, with face > abdomen > leg > plantar SC in the exact inverse of their known permeability. ... 

Benzoic Acid. Bcn/oic acid possesses appreciable antifungal effects, but it cannot penetrate the outer layer of the skin in infected areas. Therefore, benzoic acid when u.sed as an antifungal agent must be admixed with a kcratolytic agent. Suitable mixtures arc benzoic acid and. salicylic acid and benzoic acid and resorcinol. An old preparation that is. still in u.se is Whitfield s Ointment. USP. litis ointment contains benzoic acid. 6%, and. salicylic acid, 6%, in a petrolatum base. The cure rates from preparations like thc.se are low. 

The kinetic model has been used to analyze percutaneous penetration rate data for nine molecules aspirin, benzoic acid, caffeine, chloramphenicol, dlethyltoluamlde, nitrobenzene, salicylic acid ( ) and the methyl and benzyl esters of nicotinic acid ( 9 ). Experimentally, the chemicals ( C-labelled) were applied topically In acetone to the ventral forearm of human volunteers and the urinary excretion of radioactivity was then measured over a five day period ... 

To be effective, a locally applied corticosteroid must penetrate into the skin. The rate and extent of penetration is determined for a large extent by the formulation of the base. By adding penetration enhancers such as salicyl acid or urea the penetration of the active substance is enhanced. In this way a class I or II corticosteroid containing preparation becomes more effective. 

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