In vitro percutaneous absorption data for model chemicals in Rhinella marina: chemicals formulated in penetration enhancers ethanol or propylene glycol

Brief description

Effect of penetration enhancers on the percutaneous absorption kinetics of caffeine, benzoic acid, and ibuprofen through isolated skin from the terrestrial toad Rhinella marina.

Full description

Previous studies by the authors measured in vitro absorption kinetics of model chemicals through Rh. marina skin when the chemicals were formulated as saturated solutions in Amphibian Ringers Solution. However, many chemicals are formulated in solutions containing penetration enhancers. No data exists to quantify the effect of penetration enhancers on absorption kinetics through frog skin, nor is there information of how these enhancers effect frog skin structure. This dataset provides in vitro absorption kinetics for three model chemicals - benzoic acid, caffeine, and ibuprofen – formulated in either 1/10/30% v/v ethanol or 20% PG solution. Franz-type diffusion cells were used to measure absorption, and chemical content was quantified using validated HPLC methods. Additionally, the impact on frog skin due to exposure to these penetration enhancers was characterised using differential scanning calorimetry (DSC) and histology. 

Each chemical was formulated as a saturated solution (infinite dose) in one of the enhancers and applied to the external skin surface. Diffusion through the skin was measured over a period of four to six hours. Chemical flux was determined from the steady-state slope of the cumulative absorption vs time plot. Skin samples for DSC experiments and histology were either freshly excised, or exposed to one of the following for a period of six hours: ARS, 1/10/30% v/v ethanol, 20% v/v PG.

Data includes a spreadsheet (comma-separated values / .csv file) providing individual animal information (including animal ID, sex, weight, and from which body regions each skin sample was obtained), penetration enhancer identification, chemical information (including name and concentration) and absorption data including chemical content at each sample time and calculated flux and Kp values. DSC and histology are available by contacting the author.

Column headings for the spreadsheet are explained below:

AnimalID: individual animal identifier

Sex: animal sex 

Weight: frog weight in grams

Region: primary skin region (dorsal=D/ ventral=V) of skin sample

SubRegion: Identifies if ventral samples are thoracic (T) or pelvic (P) in origin. Dorsal samples remain coded as “D”

LeftRightMid: identifies if samples taken from left (L), right (R) or on the midline (M)

Solvent: enhancer used (1/10/30% v/v ethanol or 20% PG)

Chemical: chemical applied to the skin (caffeine/benzoic acid/ibuprofen)

Conc: concentration of chemical applied (microgram/ml)

Flux: steady-state flux of the chemical

Kp: permeability coefficient of the chemical (Kp=Conc/Flux)

t=0 through t=6: concentration (microgram/ml) of chemical in receptor fluid at each sampling time (hr)