TITLE:
Transdermal Delivery of Gabapentin: Effect of Cosolvent and Microemulsion on Permeation through the Rat Skin
AUTHORS:
Chika J. Mbah, Charles O. Nnadi
KEYWORDS:
Transdermal Delivery, Cosolvent System, Microemulsion, Gabapentin
JOURNAL NAME:
Pharmacology & Pharmacy,
Vol.5 No.5,
May
13,
2014
ABSTRACT: The objective of
the present study was to examine the influence of cosolvent system and micro-emulsion
formulation on in-vitro skin permeation of gabapentin, furthermore,
to characterize the physicochemical properties of drug-loaded oil-in-water
(o/w) and water-in-oil (w/o) cremophor 40-based microemulsions in comparison to
the blank counterparts. The cosolvent system prepared by homogenous mixing is
composed of ethanol-water and propylene glycol-water mixture (90:10, 80:20, 70:30
v/v) respectively. The microemulsion consisted of coconut oil, water and
mixture of cremophor 40 (surfactant) and ethanol (cosurfactant) and was
prepared by aqueous phase titration method. Physicochemical properties of
microemulsions were determined using reported procedures. Transdermal flux for
gabapentin was studied in-vitro using
modified Franz diffusion cells. The physicochemical properties of drug-loaded
microemulsions and their blank counterparts were generally alike, however,
slight variation in pH and viscosity was observed probably due to the intrinsic
properties of the drug. The ethanol-water system (70:30 v/v) gave higher flux
for gabapentin when compared to propylene glycol-water system (70:30 v/v). The
w/o microemulsion formulations resulted in, higher flux for gabapentin when
compared to o/w formulations. FTIR spectra of the untreated stratum corneum,
when compared to cosolvent system and microemulsion treated stratum corneum,
suggest the mechanism of permeation to be disruption of lipid bilayers and
keratin denaturation of the stratum corneum. The results show that
incorporation of gabapentin into microemulsions did not change the
microemulsion type. The in vitro permeation data obtained from
experimental work suggest that the cosolvent system (ethanol-water 70:30 v/v)
and w/o microemulsion formulations respectively, can be successfully used as
potential vehicles in developing transdermal therapeutic systems for
gabapentin.