LAUSR

Percutaneous caffeine intake would be a good strategy for evading any potential gastrointestinal irritation, as long as the issue of taste can be set aside; therefore, caffeine spray preparations have been made commercially available in recent years. Some have raised concerns regarding not only the psychostimulant action of caffeine by systemic exposure, but also the dermalprotective effect invoked by topical application. Absorption of pharmacologically active substances through the skin also has many advantages compared to oral administration; namely, substances can be applied to large areas at a time, and a relatively safe low peak concentration can be obtained due to slow but sustained absorption. Firstpass metabolism can also be circumvented, and interindividual variability might be lower.[1] Research on percutaneous caffeine absorption has been conducted primarily using a diffusion cell system in porcine and human skins.[2-4] Mixtures of ethanol and water, or ethanol and propylene glycol, have been used as vehicles to prepare the caffeine solution.[5] Muhammad and Riviere studied the effects of nontoxic terpenes on the penetration levels of caffeine in porcine skin. Among them, terpinyl acetate (TA) improves the penetration level 10fold, compared to the control group.[2]