Mechanistic investigation and reversible effect of 2-isopropyl-5-methylcyclohexyl heptanoate on thein vitropercutaneous absorption of indomethacin

Fu'cupping Physical Permeation-Enhancing Technique Enhances the Therapeutic Efficacy of Corydalis yanhusuo Gel Plaster

Corydalis yanhusuo, a traditional Chinese medicine, is widely used to treat various pains, and its active ingredients are alkaloids. This study aimed to develop a new type of transdermal gel plaster containing the extract of C. yanhusuo. Studies have shown that Fu'cupping physical permeation-enhancing technique can promote the penetration of alkaloids and improve the efficacy of drugs. A transdermal gel plaster containing the extract of C. yanhusuo was prepared and optimized using an orthogonal experimental design. The skin permeation ability of the gel plaster was studied in vitro, while the anti-inflammatory and analgesic effects of the prepared patch alone or with Fu'cupping physical permeation-enhancing technique were evaluated in a rat model. The formulation of a gel plaster containing C. yanhusuo extract was successfully prepared with an optimized composition consisting of glycerin (15 g), sodium polyacrylate (2 g), silicon dioxide (0.3 g), ethanol (2 g), aluminum oxide (0.1 g), citric acid (0.05 g), the C. yanhusuo extract (3 g), and water (15 g). The cumulative transdermal permeation of dehydrocorydaline, corypalmine, tetrahydropalmatine, and corydaline in 24 h was estimated to be 569.7 ± 63.2, 74.5 ± 13.7, 82.4 ± 17.2, and 38.9 ± 8.1 µg/cm2, respectively. The in vitro diffusion of dehydrocorydaline and corydaline followed the zero-order kinetics profile, while that of corypalmine and tetrahydropalmatine followed a Higuchi equation. The prepared gel plaster significantly reduced paw swelling, downregulated inflammatory cytokines, and mitigated pain induced by mechanical or chemical stimuli. The Fu'cupping physical permeation-enhancing technique further improved the anti-inflammatory and analgesic effects of the patch. The combined application of the Fu'cupping physical permeation-enhancing technique and the alkaloid gel plaster may be effective against inflammation and pain.

Transdermal Enhancement Strategy of Lappaconitine: Alteration of Keratin Configuration by Counter-Ion

The objective of this study was to develop a lappaconitine (LA) transdermal patch with counter-ion to increase the transdermal permeability of the drug, and a theory of counter-ion altering the conformation of the skin keratin was put forward based on the in vitro skin permeation study and physicochemical properties of ion-pairs. Formulation factors including pressure sensitive adhesives (PSAs), drug-loading, counter-ions and molar ratios of counter-ion were screened by in vitro skin permeation study. The optimized formulation was composed of 7% LA, 1.5 mole cinnamic acid and AAOH (PSA containing hydroxyl group synthesized by our laboratory) as an adhesive matrix. The optimized patch was evaluated by the pharmacokinetic and analgesic pharmacodynamic studies. AUC_0-t and pain inhibition ratio of the optimized patch were 2450.40 ± 848.52 h ng/mL and 81.18%, which showed good absorption into the skin and excellent analgesic effect. The mechanism of facilitated transdermal drug permeation by counter-ion was investigated by ATR-FTIR, thermal analysis, FTIR, XPS and molecular docking. The results indicated that after the formation of ion-pairs, the excess counter-ions would alter the conformation of the skin keratin, thus increasing the transdermal penetration of LA. In conclusion, the LA patch was successfully optimized, and the effect of counter-ions on the skin was clarified at the molecular level. These findings provided additional references for the application of counter-ion in the transdermal drug delivery system.

An investigation on percutaneous permeation of flurbiprofen enantiomers: The role of molecular interaction between drug and skin components

This work aimed to investigate skin permeation profiles of chiral flurbiprofen and clarify the molecular mechanism of transdermal permeation difference of enantiomers. The in vitro transdermal permeation of enantiomers through rat skin was studied by diffusion cells. Physicochemical parameters of model chiral drugs were determined. Molecular interaction between chiral flurbiprofen and ceramides of skin was investigated by FTIR, ¹³C NMR and molecular docking. The skin permeation mechanism of chiral drugs was characterized by ATR-FTIR, Raman spectra, DSC and molecular dynamic simulation. The results showed that the amount of the permeation and retention amount of (S)-flurbiprofen was 1.5 times over that of (R)-flurbiprofen. And it was proven that the difference was not induced by physicochemical properties but the molecular interaction between drug-skin components. (S)-flurbiprofen was easy to form stronger hydrogen bonding with -CONH group of skin lipids due to its steric configuration, which disturbed lipids arrangement more easily according to the results of ATR-FTIR (Δν_asCH₂ = 1.00 cm^-1), Raman spectra (ΔI₂₈₈₂/I₂₈₅₃ = 0.32) and the DSC (ΔT_{m stratum corneum} = 11.75 °C). It was demonstrated more obvious effect on the second structure of keratin by ATR-FTIR study (Δ Amide I = 3.60 cm^-1 and Δ Amide II = 3.38 cm^-1). Better compatibility between (S)-flurbiprofen and lipids was confirmed quantificationally by thermodynamic analysis. In conclusion, the higher interaction between (S)-flurbiprofen and skin components, the higher skin permeation, which contributes to decrease the administration dose and increase the therapeutic effect.

Alternative therapy of rheumatoid arthritis with a novel transdermal patch containing Siegesbeckiae Herba extract

ETHNOPHARMACOLOGICAL RELEVANCE

Siegesbeckiae Herba (SiH) is a traditional anti-rheumatic herbal medicine in China. A SiH derived product, Phynova Joint and Muscle Relief Tablets™, has been granted the UK license in 2015. Although transdermal delivery provides better patient compliance and relative constant plasma drug concentration, the feasibility of transdermal delivery of SiH was not clear.

AIM OF THE STUDY

The aim of the present study was to develop a novel transdermal patch containing SiH extract for alternative therapy of rheumatoid arthritis.

MATERIALS AND METHODS

SiH extract containing 48.5% (w/w) of kirenol was prepared from Siegesbeckia pubescens Makino. Then transdermal patches containing SiH extract were prepared by the solvent evaporation technique. The formulation of the transdermal patch was optimized based on the in vitro skin permeation experiment. Finally, the anti-inflammatory and analgesic activity of the optimal patch were evaluated by chronic inflammation model induced by complete Freund's adjuvant (CFA) and writhing model induced by acetic acid, separately.

RESULTS

Oleic acid (OA) showed the maximum permeation enhancement effect with the enhancement ratio (ER) values of 3.32. Therefore, OA was used as a permeation enhancer in the transdermal patch. The optimal formulation consisted of SiH extract (10% of the matrix, w/w), OA (10% of the matrix, w/w), DURO-TAK® 87-2287 (pressure sensitive adhesive matrix) and Scotchpak™ 9701 (backing layer). The optimal transdermal patch containing SiH extract significantly reduced the degree of paw swelling and number of writhing in inflammation model and writhing model, respectively.

CONCLUSIONS

The developed transdermal patch containing Siegesbeckiae Herba extract showed good anti-inflammatory and analgesic effects, which demonstrated a great potential for alternative therapy of rheumatoid arthritis.

Pomegranate Seed Oil Enhances the Percutaneous Absorption of trans-Resveratrol

Pomegranate seed oil (PSO) is primarily composed of unsaturated fatty acids, implying its potential application as a transdermal enhancer. In this study, the function of PSO in prompting the percutaneous absorption of resveratrol was examined and compared with isopropyl palmitate (IP). IP of 10% enhanced the cumulative permeation amount of resveratrol by 50% but did not influence the permeation velocity. Though 2.5% and 5.0% IP accelerated the penetration process of resveratrol, they had no discernable impact on total permeation amount. In contrast, the cumulative percutaneous amount of the drug with 2.5%, 5.0% and 10% PSO was 1.25, 2.25, and 3.14-fold that of resveratrol alone, respectively. Moreover, PSO of different concentrations speeded up resveratrol to permeate through skin in the whole process, exhibiting its superior capacity over IP in enhancing the transdermal absorption of resveratrol. IP of 2.5% substantially augmented resveratrol retention in stratum corneum (SC), epidermis, and dermis (p < 0.05) while 2.5% PSO only increased the drug detaining in SC. Involvement of oils also aided in resveratrol diffusion within skin. The study demonstrates that both IP and PSO prompted the percutaneous transport of resveratrol. PSO presents more promising opportunities in serving as a percutaneous enhancer for transdermal preparations.

Monocyclic monoterpenes as penetration enhancers of ligustrazine hydrochloride for dermal delivery

The purpose of this study was to explore the enhancing effects and the mechanism of monocyclic monoterpene penetration enhancers (menthol and menthone) on the transdermal absorption of ligustrazine hydrochloride (LH). Franz-type diffusion cells were used to determine percutaneous parameters of LH in vitro and surface changes of porcine skin were studied by a scanning electron microscope (SEM). The effects of promoters on the biophysical natures of stratum corneum (SC) were researched by Fourier transform-infrared (FT-IR). Penetration parameters of menthol (p < 0.01) and menthone groups (p < 0.05) were greater than those of the control; morphological changes of skin monitored by SEM demonstrated that the menthone group had the most disruption and desquamation of SC flakes, which resulted from extracted lipids. FT-IR measurements showed menthone had the greatest changes in peak shift and peak area, which resulted from C-H stretching vibrations of SC lipids. The results suggest that the penetration mechanism might include disturbing and extracting SC lipids and the hydrogen bond connection.

The effect of ion-pair formation combined with penetration enhancers on the skin permeation of loxoprofen

CONTEXT

Loxoprofen (LOXO) is a non-steroidal anti-inflammatory drug. Repeated oral administrations induce gastrointestinal side effects. Patches are a promising alternative.

OBJECTIVE

The aim of this study was to investigate the effects of organic amines on the skin permeation of LOXO and finally design a patch with a comparable permeation profile and pharmacodynamic effects to the commercial LOXONA® plaster.

MATERIALS AND METHODS

The effects of organic amines were assessed by flux values of LOXO from isopropyl myristate (IPM), using horizontal diffusion cell and rabbit skin. FTIR spectroscopy was used to confirm ion-pair formation. Anti-inflammatory and analgesic activity assessments were performed in the adjuvant arthritis rat model and acetic acid-induced writhing syndrome in mouse, separately.

RESULTS AND DISCUSSION

Results showed that triethylamine (TEA) was the most potential candidate in IPM, with the highest flux of 499.75 ± 32.40 µg/cm(2)/h. In patch, the highest flux of 369.37 ± 34.32 µg/cm(2)/h was still obtained by LOXO-TEA. Combined with penetration enhancers, the cumulative amounts were further increased in presence of 5% IPM, which exhibited a flux of 840.04 ± 66.38 µg/cm(2)/h as two times of the commercial one. Ultimately, anti-inflammatory and analgesic activity assessment presented that a comparable pharmacodynamic activity with the commercial one could be obtained by the patch we designed. Additionally, we also found that LOXO patch applied topically exerted a systemic effect, and the effect was dose-dependent.

CONCLUSION

It was feasible for LOXO patch design by combination of ion-pair technology and chemical enhancers.