A monolithic drug-in-adhesive patch of methoxyflavones from Kaempferia parviflora: In vitro and in vivo evaluation

The aim of this study was to design and develop a suitable monolithic drug-in-adhesive type patch of methoxyflavones from Kaempferia parviflora (K. parviflora) using acrylic polymer Durotak® 87-2852. The absence of interaction between components in K. parviflora extract and the adhesive polymer was confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Thirteen K. parviflora patches with different extract loading and permeation enhancers were prepared by the solvent evaporation technique. All formulations showed good physicochemical properties, good stability and satisfactory adhesive properties. The effect of K. parviflora loading and permeation enhancers on methoxyflavones transport across porcine ear skin was also evaluated. The permeation of methoxyflavones increased with the amount of K. parviflora. Among the permeation enhancers investigated, oleic acid increased permeation flux of total methoxyflavones by 1.25 fold compared to the control; whereas menthol shortened the lag time. When oleic acid and menthol were combined, the maximum flux of methoxyflavones and shortest lag time were observed, suggesting a synergistic effect of menthol with oleic acid. The optimal patch formulation contained 15% K. parviflora, 3% oleic acid and 3% of menthol, and this was evaluated via an in vivo pharmacokinetic study using rats. The maximum plasma drug concentration (Cmax) of total methoxyflavones was 218.08 ng/ml with Tmax at 8 h. The concentrations of methoxyflavones in plasma continued to increase until the end of the experiment, indicating a sustained release into the systemic circulation.

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