Abstract
This article presents the development and evaluation of a new
topical formulation of diclofenac diethylamine (DDA) as a locally applied
analgesic lotion. To this end, the lotion formulations were formulated with equal
volume of varying concentrations (1%, 2%, 3%, 4%; v/v) of permeation enhancers,
namely propylene glycol (PG) and turpentine oil (TO). These lotions were
subjected to physical studies (pH, viscosity, spreadability, homogeneity, and accelerated
stability), in vitro permeation, in vivo animal studies and sensatory
perception testing. In vitro
permeation of DDA from lotion formulations was evaluated across polydimethylsiloxane
membrane and rabbit skin using Franz cells. It was found that PG and TO content influenced
the permeation of DDA across model membranes with the lotion containing 4% v/v
PG and TO content showed maximum permeation enhancement of DDA. The flux values
for L4 were 1.20 ± 0.02 μg.cm-2.min-1 and 0.67 ± 0.02 μg.cm-2.min-1 for
polydimethylsiloxane and rabbit skin, respectively. Flux values were
significantly different (p < 0.05)
from that of the control. The flux enhancement ratio of DDA from L4 was
31.6-fold and 4.8-fold for polydimethylsiloxane and rabbit skin, respectively. In the in vivo animal testing, lotion with 4%
v/v enhancer content showed maximum anti-inflammatory and analgesic effect without
inducing any irritation. Sensatory perception tests involving healthy
volunteers rated the formulations between 3 and 4 (values ranging between -4 to
+4, indicating very bad to excellent respectively). It was concluded that the
DDA lotion containing 4% v/v PG and TO exhibited the best performance overall
and that this specific formulation should be the basis for further clinical
investigation.