Pre-Treatment with Aloe vera Juice Does Not Enhance the in vitro Permeation of Ketoprofen across Skin

Background/Aims: The potential of pre-treating skin with Aloe vera juice as a penetration enhancer was evaluated in vitro using ketoprofen as model permeant. Methods: To excised porcine skin mounted in Franz diffusion cells was applied either: (1) commercial Aloe vera; (2) commercial Aloe vera followed by massaging; (3) previously boiled commercial Aloe vera; (4) water (negative control); (5) tea tree oil (positive control). After 1 h, the pre-treatment was removed and the skin dosed with a saturated solution of ketoprofen in polyethylene glycol 400; the appearance of drug in the receptor phase was then monitored by HPLC. Results: No statistically significant differences in the transdermal delivery of ketoprofen were observed between water and all the Aloe vera pre-treatments (p > 0.05). The tea tree oil pre-treatment was significantly different to all others (p < 0.05). Conclusion: Aloe vera appears to have no value as a penetration enhancer when used as a pre-treatment, although the data indirectly support the mechanism of action proposed previously, work when used ‘within-vehicle’. Handling household products containing Aloe vera appears not to leave the user at elevated risk of subsequent absorption of exogenous chemicals.