The effect of temperature on the diffusion of lidocaine base

The inherent barrier properties of the skin present a major problem for
the transdermal delivery of drugs. Due to the selectively permeable nature of the
skin compounds need to be relatively lipophilic with a molecular weight below
500 Da for passive permeation (Finnin et al 1999). Temporary application of heat
is a non-invasive method that has been shown to increase systemic drug delivery
(Ashburn et al 2003). A rise in skin temperature causes an increase in drug
diffusivity throughout the vehicle and temporarily alters the barrier properties of
the skin, resulting in enhanced diffusion (Akomeah et al 2004). However, little
work has been conducted on the effect of membrane temperature on diffusion of
a compound with an inverse relationship between solubility and temperature, for
example lidocaine. Therefore, the aim of this study was to show that an increased
membrane temperature can enhance the diffusion of lidocaine