The effects of plain and liposome-associated articaine with transmembrane pH gradient on humam keratinocytes (HaCaT) viability and IL-6 expression

Articaine is not encapsulated in significant proportion in liposomes without transmembrane pH gradient. The aim of this study was to perform the initial characterization of a formulation of articaine in unilamelar liposome with transmembranarpH gradient and to observe its effects on human keratinocytes (HaCaT) regarding cellular viability and liberation of interleukin 6 (IL-6) in comparison to plain articaine. HaCaT cells were exposed to plain articaine solutions and liposomal suspensions (0.1%, 0.2% and 0.3% articaine concentrations) and to the controls (saline, liposomal suspension and culture medium). Cell viability (MTT reduction - spectrophotometry) was evaluated at 10 min and 4h after exposure to the treatments; IL-6 was determined after 4 h of cell treatments. Cell viability results were submitted to Kruskal-Wallis test, followed by Dunn post-hoc test; IL-6 results were analyzed by Kruskal-Wallis and Student-Newman-Keuls tests. Significance was set at 5%. Liposome vesicles remained intact after articaine loading and presented encapsulation efficiency of 18.95%. Liposome without anesthetic presented polydispersity index of 0.2 ± 0.0, while liposomes with articaine showed values of 0.56 ± 0.03 to 0.66 ± 0.10. Zeta potentials varied from -10.5 ±0.9 to -21.2 ± 0.9 mV and vesicle sizes from 622 ± 71.5 to 796 ± 111.95 nm. Cell viability decreased after 10 min exposure to the liposomal formulations (with and without articaine) in relation to the other treatments (p<0.05); liposomal formulations did not differ from each other (p>0.05). No differences were found among the other treatments (p>0.05), which did not interfere in cell viability after this exposure time. After 4h exposure cell viability was diminished by all liposomal formulations and by 0.2% and 0.3% plain articaine (p<0.05), except for control groups and 0.1% plain articaine (p>0.05). IL-6 release was not affected by liposomal formulations (p>0.05); all concentrations of plain articaine increased IL-6 release in relation to the controls and to each correspondent liposomal formulation (p<0.05). In conclusion, liposome with transmembrane pH gradient increases articaine encapsulation in relation to that described in the literature, however it presented intrinsic in the model evaluated (AU)