Development of lapachol topical formulation: anti-inflammatory study of a selected formulation

This study aimed at developing a topical formulation of lapachol, a compound isolated from various Bignoniaceae species and at evaluating its topical anti-inflammatory activity. The influence of the pharmaceutical form and different types of emulsifiers was evaluated by in-vitro release studies. The formulations showing the highest release rate were selected and assessed trough skin permeation and retention experiments. It was observed that the gel formulation provided significantly higher permeation and retained amount (3.9-fold) of lapachol as compared to the gel-cream formulation. Antinociceptive and antiedematogenic activities of the most promising formulation were also evaluated. Lapachol gel reduced the increase in hind-paw volume induced by carrageenan injection and reduced nociception produced by acetic acid (0.8% in water, i.p.) when used topically. These results suggest that topical delivery of lapachol from gel formulations may be an effective medication for both dermal and subdermal injuries.