Abstract:
Background: Transdermal drug delivery is a sustain drug delivery method to treat inflammatory
conditions. Thespesia populnea plant has been used in Ayurveda to treat inflammatory conditions.
Thus, a transdermal patch was formulated as a convenient method to treat inflammation with this
plant.
Objective: To develop a transdermal patch containing ethanolic bark extract of T. Populnea
Method: The crude ethanolic bark extract was obtained from the Soxhlet extraction. The
maximum effective, non-toxic concentration (MEC) was evaluated using Human Red Blood Cell
(HRBC) membrane stabilization and brine shrimp toxicity assays. Eleven patch bases (PA1-PA11)
were developed by varying ratios of hydroxypropyl methyl cellulose (HPMC) and sodium
alginate. Folding endurance, surface pH, thickness and moisture content were evaluated to select
the best patch base. The MEC was incorporated to the most stable bases and transdermal patches
(TPA) were formulated using solvent casting method. Compatibility between the polymers and the
crude extract was investigated using Fourier Transform Infrared (FTIR) spectroscopy. In vitro
drug release was evaluated for 8 hours. HRBC assay and the brine shrimp assay were conducted
for the released samples collected at define time duration. Skin irritation and different physico
chemical properties were evaluated on the TPAs.
Results: The MEC was 5 mg/mL. PA1 and PA3 were selected as the best bases according to the
physicochemical properties. TPA1 and TPA3 had a thickness of 0.32±0.01 and 0.39±0.01 mm, pH
6.9±0.5 and 7.1±0.5, and weight uniformity of 0.19 and 0.21 g, with a folding endurance >243 and
>260, moisture content of 6.31 and 5.71%, respectively. Both patches were reddish-brown,
translucent, flexible and slightly smooth with a faint camphoraceous odor. However, TPA1
showed a steady release kinetics over the release period and revealed a maximum inhibition of
58.48 ± 0.42% after 5 hours, whereas TPA3 did not show drug release over the time. TPA1 did
not exhibit any in vitro toxicity and no oedema or allergic reactions 24 hours post-application. No
phase separation or defects were observed in TPA1 during stability period at room temperature
and 45°C.
Conclusion: TPA1 was the most stable transdermal patch that can be optimized in future as a
commercial product.
