Transdermal Local Anaesthetic Films of Tetracaine in Comparison to the Conventional Gel in Effective Management of Pain

Development of Bioadhesive Transdermal Patches of Bupivacaine for the Enhancement of Anaesthetic Effect: Study in Rat Model

The topical route for local anaesthesia including ointments and creams can be easily washed off by wetting agents or with contact or movement. The goal and objective of the present study was to develop and formulate a transdermal patch for local anaesthesia. These patches were formulated by solvent casting method by the use of Hydroxypropyl Methylcellulose (HPMC) polymer, different enhancers, and vasoconstrictor which is the key ingredient for enhancing aesthetic activity. Formulated patches were evaluated for the physical and physicochemical parameters like moisture content, moisture uptake, folding endurance, water vapour permeability, drug content, and drug release, and in vivo study was done on rats. Amongst all the formulations, F7 was considered the ideal formulation which is the combination of HPMC polymer, polyoxyethylene 2-oleyl ether as an enhancer, and vasoconstrictor Tetrahydrozoline. For in vivo testing Tail flick method was applied and the effect of anaesthesia was maximum as compared to other formulations. In comparison to the control formulation, there was a 2.34-fold increase in aesthetic activity. When compared to the control formulation, the F7 formulation exhibited improved and longer efficacy. A transdermal bupivacaine patch incorporating a penetration enhancer and a vasoconstrictor could be created to improve the local cosmetic effects of bupivacaine.

QbD-Based Investigation of Dermal Semisolid in situ Film-Forming Systems for Local Anaesthesia

PURPOSE

The aim of our research work was to develop dermally applicable, lidocaine hydrochloride (LID-HCl)-containing semisolid in situ film-forming systems (FFSs) using the Quality by Design (QbD) approach to increase drug permeation into the skin.

METHODS

Silicones were used to improve the properties of formulations and to increase the permeation through the skin. The QbD approach was applied to ensure quality-based development. With initial risk assessment, the critical material attributes (CMAs) and the critical process parameters (CPPs) were identified to ensure the required critical quality attributes (CQAs).

RESULTS

During the initial risk assessment, four high-risk CQAs, namely in vitro drug release, in vitro drug permeation, drying properties, and mechanical properties, and three medium-risk CQAs, namely pH, viscosity, and film appearance were identified and investigated. Moreover, four high-risk CMAs were also considered during the formulation: permeation enhancing excipients, drying excipients, film-forming excipients, and emollients. During the experiments, LID-HCl influenced these critical parameters highly, thereby reducing the drying time. The formulation containing 25% silicone showed the best mechanical properties (49 mN skin adhesion, 20.3% film flexibility, 1.27 N film burst strength), which could predict better patient adherence. In addition, in vitro permeation studies showed that formulation containing 50% silicone has the fastest permeation rate. The flux of diffused API was 6.763 µg/cm2/h, which is much higher compared to the silicone-free formulation (1.5734 µg/cm2/h), and it can already be observed in the lower part of the dermis in 0.5 hour.

CONCLUSION

Our results show that LID-HCl has great influence on the critical parameters of FFSs. The silicone content can improve the applicability of formulations and has a favorable effect on the permeation rate of LID-HCl into the skin.