Transdermal Iontophoretic Delivery of Propofol: A General Anaesthetic in the Form of its Phosphate Salt

The main objective of this study was to investigate the feasibility of delivery of propofol phosphate (PP), a prodrug of propofol, via transdermal route using iontophoresis in combination with chemical permeation enhancers (CPEs). PP, a prodrug, was synthesized and its structure was characterized. In vitro passive and iontophoretic drug transport studies were carried out using Franz diffusion cell across freshly excised hairless rat skin at different concentrations of PP in combination with CPE. Among all the CPEs screened, 0.1% sodium dodecyl sulfate (SDS) increased the passive transdermal flux to 13.43 ± 0.73 μg/(cm2 h) from 8.52 ± 0.82 μg/(cm2 h) (control). Cathodal iontophoresis in combination with 0.1% SDS synergistically enhanced the flux [249.24 ± 6.12μg/(cm2 h)] of PP. The Pharmacokinetic studies were performed in rat model to assess the feasibility of transdermal delivery of PP. The amount of propofol present in plasma samples in control group (passive) was below the detectable levels at all the time points during the study. The plasma concentration-time profile of iontophoresis group of rats was fit to a noncompartmental model and the pharmacokinetic parameters were calculated. These studies suggest the plausibility of achieving therapeutically relevant levels of propofol when delivered via transdermal route by combining iontophoresis with CPE.