Effects of iontophoresis and chemical enhancers on the transport of lidocaine and nicotine across the oral mucosa

Purpose: To analyze the effects of chemical enhancers and iontophoresis on the buccal transmucosal delivery of lidocaine and nicotine. Methods: Porcine oral mucosal samples were pretreated with chemical enhancers before conducting 8-hr Franz diffusion-cell experiments. In studies addressing the influence of iontophoresis on molecular transport, the current density was set at 0.3 mA/cm ². Data were analyzed using graphical and non-linear regression optimization techniques. Results: Both permeation enhancement techniques promote drug transport. In the absence of electricity, the flux increased as high as 4- and 200-fold, relative to a control, in the case of lidocaine hydrochloride (LHCl) and nicotine hydrogen tartrate (NHT) gel formulations, respectively. The combination of iontophoresis and chemical enhancers produced an even higher flux compared to the original passive diffusion process: up to 8-fold for LHCl and 450-fold forNHT.Mostly, the current helped to decrease the response time. However, a balance should be maintained between reaching a high delivery rate and reducing the time it takes to attain a desired flux value. In addition, the influence of chemical enhancers was drug-specific. Conclusions: The estimation of model parameters allows for a systematic approach to the design of chemical and physical penetration enhancers for transmucosal drug delivery.