Design of Two Liquid Ibuprofen-Poloxamer-Limonene or Menthol Preparations for Dermal Administration

First report on QSAR modelling for chemical penetration enhancement ratio (ER) of different FDA-approved drugs in Poloxamer 407: A next step towards better skin permeability of drugs

Poloxamer 407 is a versatile excipient that enhances drug solubilization and prolongs drug release. Poloxamers are non-ionic tri-block copolymers composed of a central hydrophobic chain of polyoxypropylene flanked by two hydrophilic chains of polyoxyethylene. Various researchers have utilized Poloxamer 407 in topical and transdermal drug delivery systems, and it has also been reported to enhance skin permeability. The present investigation was conducted to predict the structural features of drugs that contribute to increased skin permeation in the presence of Poloxamer 407 as a polymer or carrier system. This was achieved using a multiple linear regression-based quantitative structure-activity relationship (QSAR) model developed with six molecular descriptors. The statistical outcomes (r2 = 0.872, Q2F1 = 0.805, Q2F2 = 0.804, and Q2F3 = 0.821) demonstrated the model's strong internal and external predictive capability. The model was further validated using various criteria to ensure its reliability. Additionally, an ex vivo study was performed on selected drugs (Voriconazole, Terbinafine, Ketoconazole, Pantoprazole, Sumatriptan, Sitagliptin, and Rabeprazole) to evaluate the predictive power of the developed 2D-QSAR model. The results of this study (experimental enhancement ratio, ER) were found to be highly correlated with the predicted ER values from the model. This QSAR-based prediction study highlights the potential for forecasting the skin penetration abilities of various drug classes in the presence of Poloxamer 407. It also provides a foundation for designing pharmaceutical dosage forms with improved skin permeability, which could aid in the treatment of skin-related conditions and other diseases.

Deep Eutectic Solvent Formulations and Alginate-Based Hydrogels as a New Partnership for the Transdermal Administration of Anti-Inflammatory Drugs

The transdermal administration of nonsteroidal anti-inflammatory drugs (NSAIDs) is a valuable and safer alternative to their oral intake. However, most of these drugs display low water solubility, which makes their incorporation into hydrophilic biopolymeric drug-delivery systems difficult. To overcome this drawback, aqueous solutions of bio-based deep eutectic solvents (DES) were investigated to enhance the solubility of ibuprofen, a widely used NSAID, leading to an increase in its solubility of up to 7917-fold when compared to its water solubility. These DES solutions were shown to be non-toxic to macrophages with cell viabilities of 97.4% (at ibuprofen concentrations of 0.25 mM), while preserving the anti-inflammatory action of the drug. Their incorporation into alginate-based hydrogels resulted in materials with a regular structure and higher flexibility. These hydrogels present a sustained release of the drug, which is able, when containing the DES aqueous solution comprising ibuprofen, to deliver 93.5% of the drug after 8 h in PBS. Furthermore, these hydrogels were able to improve the drug permeation across human skin by 8.5-fold in comparison with the hydrogel counterpart containing only ibuprofen. This work highlights the possibility to remarkably improve the transdermal administration of NSAIDs by combining new drug formulations based on DES and biopolymeric drug delivery systems.

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.