title: Differential effects of some natural compounds on the transdermal absorption and penetration of caffeine and salicylic acid.
abstract: Many natural products have the potential to modulate the dermal penetration of topically applied drugs and chemicals. We studied the effect of five natural compounds (hydroxycitronellal, limonene 1,2-epoxide, terpinyl acetate, p-coumaric acid, transferrulic acid) and ethanol on the transdermal penetration of two marker drugs ((14)C-caffeine and (14)C-salicylic acid) in a flow through in vitro porcine skin diffusion system. The parameters of flux, permeability, diffusivity, and percent dose absorbed/retained were calculated and compared. The dermal absorption of (14)C-caffeine was significantly higher with terpinyl acetate and limonene 1,2-epoxide as compared to ethanol; while dermal absorption of (14)C-salicylic acid was significantly greater with hydroxycitronellal and limonene 1,2-epoxide as compared to ethanol. A 10-fold increase in flux and permeability of caffeine with terpinyl acetate was observed while limonene increased flux of caffeine by 4-fold and permeability by 3-fold. Hydroxycitronellal and limonene increased salicylic acid's flux and permeability over 2-fold. The other natural compounds tested did not produce statistically significant effects on dermal penetration parameters for both caffeine and salicylic acid (p≥0.05). These results emphasize the differential effects of natural substances on the transdermal penetration of hydrophilic (caffeine) and hydrophobic (salicylic acid) drugs.
authors: Institute of Computational Comparative Medicine, Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
authors: Faqir
authors: F
authors: Muhammad
authors: Institute of Computational Comparative Medicine, Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA. Electronic address: jriviere@vet.k-state.edu.
authors: Jim E
authors: JE
authors: Riviere
mesh_terms: D000818:Animals; D001688:Biological Products / Q000737:chemistry / Q000494:pharmacology*; D002110:Caffeine / Q000737:chemistry / Q000493:pharmacokinetics*; D002250:Carbon Radioisotopes; D004058:Diffusion; D004305:Dose-Response Relationship, Drug; D005260:Female; D015394:Molecular Structure; D010539:Permeability / Q000187:drug effects; D020156:Salicylic Acid / Q000737:chemistry / Q000493:pharmacokinetics*; D012869:Skin Absorption / Q000187:drug effects*; D013329:Structure-Activity Relationship; D013552:Swine
chemical_list: D001688:Biological Products; D002250:Carbon Radioisotopes; D002110:Caffeine; D020156:Salicylic Acid
keywords: Drugs; Natural substance; Penetration; Skin