In vivo Evaluation of Limonene-Based Transdermal Therapeutic System of Nicorandil in Healthy Human Volunteers

Impact of rasagiline nanoparticles on brain targeting efficiency via gellan gum based transdermal patch: A nanotheranostic perspective for Parkinsonism

Rasagiline mesylate is used as first line agent for early management of Parkinson's disease but its water soluble nature creates hurdles to cross blood brain barrier also its low oral bioavailability and rapid elimination requires frequent dosing. Thus present study aims to prepare rasagiline mesylate-nanoparticles (RM-NPs) loaded gellan gum transdermal film for non-invasive; self-administration in elderly patients. PLGA coated RM-NPs prepared by solvent evaporation technique were incorporated into film prepared by solvent casting method. Optimized films with 1.127 g gellan gum and 1.962 % linoleic acid showed enhanced ex-vivo diffusion over a period of 72 h. Comparative pharmacokinetic study revealed increased bioavailability of rasagiline on transdermal application compared to oral route. In-vivo anti-Parkinson activity estimated by behavioural and biochemical analysis indicate reserpine to interfere with monoamine storage hence resulting in development of akinesia and PD-like symptoms in rats. Brain targeting monitored by gamma imaging showed effective brain drug uptake from transdermal film which was also supported by increased brain targeting efficiency estimated from biodistribution study. Thus, the data support efficacy of gellan gum film to target drug to brain region compared to oral route and hence can be employed as a convenient approach for long-term treatment of Parkinson's disease in elderly patients.

Enantioselective penetration enhancing effect of carvone on the in vitro transdermal permeation of nicorandil

The objective was to investigate the difference in penetration enhancing effect of R-carvone, S-carvone and RS-carvone on the in vitro transdermal drug permeation. In vitro permeation studies were carried out across neonatal rat epidermis from 2%w/v HPMC (hydroxypropyl methylcellulose) gel containing 4%w/v of nicorandil (a model drug) and a selected concentration (12%w/v) of either R-carvone, S-carvone or RS-carvone against a control. The stratum corneum (SC) of rats was treated with vehicle (70%v/v ethanol-water) or ethanolic solutions of 12%w/v R-carvone, S-carvone or RS-carvone. The enhancement ratio (ER) of R-carvone, S-carvone and RS-carvone when compared to control was about 37.1, 31.2 and 29.9, respectively indicating enantioselective penetration enhancing effect of carvone enantiomers. Furthermore, there was a significant decrease in the lag time required to produce a steady-state flux of nicorandil with S-carvone when compared to R-carvone and RS-carvone. DSC and FT-IR studies indicate that the investigated enantiomers of carvone exhibit a difference in their ability to affect the cellular organization of SC lipids and proteins thereby showing enantioselective transdermal drug permeation. It was concluded that R-carvone exhibited a higher penetration enhancing activity on transdermal permeation of nicorandil when compared to its S-isomer or racemic mixture.

Percutaneous permeation enhancement by terpenes: mechanistic view

A popular approach for improving transdermal drug delivery involves the use of penetration enhancers (sorption promoters or accelerants) which penetrate into skin to reversibly reduce the barrier resistance. The potential mechanisms of action of penetration enhancers include disruption of intercellular lipid and/or keratin domains and tight junctions. This results in enhanced drug partitioning into tissue, altered thermodynamic activity/solubility of drug etc. Synthetic chemicals (solvents, azones, pyrrolidones, surfactants etc.) generally used for this purpose are rapidly losing their value in transdermal patches due to reports of their absorption into the systemic circulation and subsequent possible toxic effect upon long term application. Terpenes are included in the list of Generally Recognized As Safe (GRAS) substances and have low irritancy potential. Their mechanism of percutaneous permeation enhancement involves increasing the solubility of drugs in skin lipids, disruption of lipid/protein organization and/or extraction of skin micro constituents that are responsible for maintenance of barrier status. Hence, they appear to offer great promise for use in transdermal formulations. This article is aimed at reviewing the mechanisms responsible for percutaneous permeation enhancement activity of terpenes, which shall foster their rational use in transdermal formulations.