COMPARISONS OF THE HISTOLOGICAL MORPHOLOGY AND IN VITRO PERCUTANEOUS ABSORPTION OF CAFFEINE IN SHED SNAKE SKIN AND HUMAN SKIN

The employment of excised skin (human or animal) mounted in diffusion cells is frequently used for the characterization of biopharmaceutical properties of topical semisolids dosage forms.  Reptile skin from snake appears to be a useful alternative to other animal and human skins in assessing the potential for transdermal drug delivery. The aim of the study was to compare human and snake skin from a histological point of view. Furthermore the absorption of caffeine, as a hydrophilic model substance, was compared on snake shed skins (two anatomical locations; ventral and dorsal), from three different species, Python regius , Epicrates maurus colombianus , Lampropeltis triangulum campbelli , and human skin.  Snake skin shows histological similarity to human Stratum corneum in term of thickness and composition. Regarding the absorption, the cumulative amount of caffeine increased linearly with time through the dorsal and ventral shed skins of all 3 species. Except for Lampropeltis triangulum campbelli ventral skin, the caffeine permeation behavior obtained on all snake shed skins evaluated was in a similar range as on human skin. One main advantage of shed skin, is that snakes molt regularly and can provide many sheds, that can be obtained without sacrificing the animals. Key words: caffeine; transdermal; shed skin; in vitro ; snake; topical formulation PRIMERJAVA HISTOLOSKE ZGRADBE TER PERKUTANE ABSORPCIJE KOFEINA IN VITRO V LEVKU KAC IN CLOVESKI KOŽI Povzetek: Koža (cloveskega ali živalskega izvora) se pogosto uporablja kot orodje za proucevanje biofarmacevtskih lastnosti topikalnih zdravil. Koža kac bi lahko bila uporabna alternativa drugim živalskim kožam in cloveski koži pri oceni sposobnosti prenosa zdravil preko kože. Cilj studije je bil histoloska primerjava cloveske in kacje kože ter primerjava absorpcije kofeina kot hidrofilne modelne snovi na levkih kac iz dorzalnega in ventralnega podrocja treh razlicnih vrst kac: kraljevega pitona ( Python regius ), mavricnega udava ( Epicrates maurus colombianus ), mlecne kace ( Lampropeltis triangulum campbelli ). Kacja koža je histolosko podobna cloveski glede debeline in sestave roženi plasti ( stratum corneum ). Glavna prednost levitve kac je, da se dogaja veckrat, kar omogoca pridobitev vec levkov, ki se jih lahko pridobi brez žrtvovanja živali. Rezultati so pokazali, da se je skupna kolicina kofeina scasoma linearno povecevala v dorzalnih in ventralnih levkih pri vseh treh vrstah kac, razen na na ventralnem podrocju levka mlecne kace ( Lampropeltis triangulum campbelli ), pri katerem je bila prehodnost kofeina podobna kot pri prehodu skozi clovesko kožo. Kljucne besede : kofein; transdermalno; levek; in vitro ; kaca; topikalni pripravek