Molecular mechanism of ion-pair releasing from acrylic pressure sensitive adhesive containing carboxyl group: Roles of doubly ionic hydrogen bond in the controlled release process of bisoprolol ion-pair

Low drug load, high retention mometasone furoate cream with polyglyceryl - 3 oleate as a chemical enhancer: Formulation development, in vivo and in vitro evaluation and molecular mechanisms

The study aimed to create a low loading, high retention, easier to apply O/W mometasone furoate (MF) cream using a chemical enhancer (CE) approach to provide more options for patients with atopic dermatitis (AD) and to investigate molecular mechanisms of its increased release and retention. A Box-Behnken design determined the optimal formulation based on stability and in vitro skin retention. Evaluations included appearance, rheological properties, irritation, in vivo tissue distribution and pharmacodynamics. Molecular mechanisms of enhanced release were studied using high-speed centrifugation, molecular dynamics and rheology. The interaction between the CE, MF and skin was studied by tape stripping, CLSM, ATR-FTIR and SAXS. The formulation was optimized to contain 0.05% MF and used 10% polyglyceryl-3 oleate (POCC) as the CE. There was no significant difference from Elocon® cream in in vivo retention and pharmacodynamics but increased in vivo retention by 3.14-fold and in vitro release by 1.77-fold compared to the basic formulation. POCC reduced oil phase cohesive energy density, enhancing drug mobility and release. It disrupted skin lipid phases, aiding drug entry and formed hydrogen bonds, prolonging retention. This study highlights POCC as a CE in the cream, offering insights for semi-solid formulation development.

Ionic liquids as the effective technology for enhancing transdermal drug delivery: Design principles, roles, mechanisms, and future challenges

Ionic liquids (ILs) have been proven to be an effective technology for enhancing drug transdermal absorption. However, due to the unique structural components of ILs, the design of efficient ILs and elucidation of action mechanisms remain to be explored. In this review, basic design principles of ideal ILs for transdermal drug delivery system (TDDS) are discussed considering melting point, skin permeability, and toxicity, which depend on the molar ratios, types, functional groups of ions and inter-ionic interactions. Secondly, the contributions of ILs to the development of TDDS through different roles are described: as novel skin penetration enhancers for enhancing transdermal absorption of drugs; as novel solvents for improving the solubility of drugs in carriers; as novel active pharmaceutical ingredients (API-ILs) for regulating skin permeability, solubility, release, and pharmacokinetic behaviors of drugs; and as novel polymers for the development of smart medical materials. Moreover, diverse action mechanisms, mainly including the interactions among ILs, drugs, polymers, and skin components, are summarized. Finally, future challenges related to ILs are discussed, including underlying quantitative structure-activity relationships, complex interaction forces between anions, drugs, polymers and skin microenvironment, long-term stability, and in vivo safety issues. In summary, this article will promote the development of TDDS based on ILs.

Ionic Liquid Transdermal Patches of Two Active Ingredients Based on Semi-Ionic Hydrogen Bonding for Rheumatoid Arthritis Treatment

Rheumatoid arthritis (RA) is a chronic autoimmune disease that leads to deformities and disabilities in patients. Conventional treatment focuses on delaying progression; therefore, new treatments are necessary. The present study reported a novel ionic liquid transdermal platform for efficient RA treatment, and the underlying mechanism was elucidated using FTIR, 1H-NMR, Raman, XPS, and molecular simulations. The results showed that the reversibility of the semi-ionic hydrogen bonding facilitated high drug loading and enhanced drug permeability. Actarit's drug loading had an approximately 11.34-times increase. The in vitro permeability of actarit and ketoprofen was improved by 5.46 and 2.39 times, respectively. And they had the same significant effect in vivo. Furthermore, through the integration of network pharmacology, Western blotting (WB), and radiology analyses, the significant osteoprotective effects of SIHDD-PSA (semi-ionic H-bond double-drug pressure-sensitive adhesive transdermal patch) were revealed through the modulation of the JAK-STAT pathway. The SIHDD-PSA significantly reduced paw swelling and inflammation in the rat model, and stimulatory properties evaluation confirmed the safety of SIHDD-PSA. In conclusion, these findings provide a novel approach for the effective treatment of RA, and the semi-ionic hydrogen bonding strategy contributes a new theoretical basis for developing TDDS.

Design of a tulobuterol patch with improved mechanical properties: effect of transdermal permeation enhancers on the release process of metal ligand-based acrylic pressure-sensitive adhesives

The aim of this study was to design a tulobuterol (TUL) patch with good penetration behavior and mechanical properties. Particular attention was paid to the effect of transdermal permeation enhancers on the release process of metal ligand-based acrylic pressure-sensitive adhesive (AA-NAT/Fe3+). The type and dosage of the enhancers were screened by in vitro transdermal penetration in rat skin. The optimized formulation was evaluated in a pharmacokinetic study in rats. Furthermore, the molecular mechanism by which Azone (AZ) improves the release rate of TUL from AA-NAT/Fe3+ was investigated by FT-IR, shear strength test, rheological study, and molecular simulation. As a result, the optimized formula using AA-NAT/Fe3+ showed better mechanical properties compared to commercial products. Meanwhile, the AUC0-t and Cmax of the optimized patch were 1045 ± 89 ng/mL·h and 106.8 ± 28.5 ng/mL, respectively, which were not significantly different from those of the commercial product. In addition, AZ increased the mobility of the pressure-sensitive adhesive (PSA) rather than decreasing the drug-PSA interaction, which was the main factor in enhancing TUL release from the patch. In conclusion, a TUL transdermal drug delivery patch was successfully developed using metal-coordinated PSA, and a reference was provided for the design of metal-coordinated acrylic PSA for transdermal patch delivery applications.

Rhamnose-PEG-induced supramolecular helices: Addressing challenges of drug solubility and release efficiency in transdermal patch

Transdermal drug delivery systems (TDDS) demand both high drug loading capacity and efficient delivery. In order to improve both simultaneously, this study aims to develop a novel rhamnose-induced pressure-sensitive adhesive (HPR) by dispersing the drug in the supramolecular helical structure. Ten model drugs, categorized as acidic and basic compounds, were chosen to understand the characteristics of the HPR and its inner mechanism. Notably, it enhanced drug loading by 1.41 to 5 times over commercially available pressure-sensitive adhesives Duro-Tak@ 87-4098 and Duro-Tak@ 87-2287, in addition to increasing drug release efficiency by a factor of about 5. Pharmacokinetic evaluation demonstrated that the HPR group had >4-fold (Tulobuterol TUL) and 3-fold (Diclofenac DIC) more area under the blood drug concentration curve (AUC) than the commercial TUL and DIC patches in the absence of added excipients and a significantly prolonged mean residence time (MRT) of >4-fold (TUL) and 3-fold (DIC), demonstrating the potential for highly efficacious and prolonged dosing. Furthermore, its safety and mechanical properties meet the requisite standards. Mechanistic inquiries unveiled that both acidic and basic drugs establish hydrogen bonds with HPR and become encapsulated within supramolecular helical structures. The supramolecular helical structures, significantly elevated both the enthalpy of the drug-HPR and entropy of the drugs release, thereby substantially enhancing drug delivery efficiency. In summary, HPR enabled a significant simultaneous enhancement of drug loading and drug delivery, which, together with its unique spatial structure, would contribute to the development of TDDS. In addition, the establishment of rhamnose-induced supramolecular helical structures would provide innovative pathways for different drug delivery systems.

Probing the mechanism of release process from metal coordination-based acrylic pressure-sensitive adhesives: Synergistic effect of coordination and hydrogen bonding for controlled drug release

Hydrogen bonding, ionic interactions, and dipole-dipole interactions have been extensively studied to control drug release from patches. However, metal coordination bonding has not been fully explored for the control of transdermal drug release. In this study, metal coordination-based acrylic pressure-sensitive adhesives (PSAs) were designed and synthesized in order to systemically elucidate the effect of metal coordination on drug release from acrylic PSAs. Ketoprofen (KET) and donepezil (DNP) were selected as model drugs. Results showed that the burst release rate of KET was controlled by N-[tris(hydroxymethyl)methyl]acrylamide (NAT) and Fe3+, while the DNP release rate had no significant changes. It was found that the PSA-drug interaction, rather than the molecular mobility of PSA, played a dominant role in the controlled release process of KET. The hydrogen bond interaction between NAT and KET controlled the release process, while the coordination bond interaction between Fe3+ and KET further slowed down the release of KET. In conclusion, it was found that the controlled release of KET was achieved by the synergistic effect of coordination bonding and hydrogen bonding, which opens up a facile but powerful avenue for the design of brand-new controlled release systems and new opportunities for their application in transdermal drug delivery.

Ternary Deep Eutectic Solvents System of Colchicine, 4-Hydroxyacetophenone, and Protocatechuic Acid and Characterization of Transdermal Enhancement Mechanism

This study aimed to prepare colchicine (CO), 4-hydroxyacetophenone (HA), and protocatechuic acid (CA) contained in transdermal rubber plasters into a more releasable and acrylate pressure-sensitive adhesive (PSA) to optimize traditional Touguling rubber plasters (TOU) with enhanced transdermal permeability by using deep eutectic solvents (DES) technology. We compared the difference in the release behavior of CO between rubber plaster and PSA, determined the composition of the patch through pharmacodynamic experiments, explored the transdermal behavior of the three components, optimized the patch formula factors, and improved the penetration of CO through the skin. We also focused on elucidating the interactions among the three components of DES and the intricate relationship between DES and the skin. The melting point of DES was determined using DSC, while FTIR, 13C NMR, and ATR-FTIR were used to explore the intricate molecular mechanisms underlying the formation of DES, as well as its enhancement of skin permeability. The results of this investigation confirmed the successful formation of DES, marked by a discernible melting point at 27.33°C. The optimized patch, formulated with a molar ratio of 1:1:1 for CO, HA, and CA, significantly enhanced skin permeability, with the measured skin permeation quantities being 32.26 ± 2.98 µg/cm2, 117.67 ± 7.73 µg/cm2, and 56.79 ± 1.30 µg/cm2 respectively. Remarkably, the optimized patch also demonstrated similar analgesic and anti-inflammatory effects compared to commercial diclofenac diethylamide patches in different pharmacodynamics studies. The formation of DES altered drug compatibility with skin lipids and increased retention, driven by the interaction among the three component molecules through hydrogen bonding, effectively shielding the skin-binding sites and enhancing component permeation. In summary, the study demonstrated that optimized DES patches can concurrently enhance the penetration of CO, HA, and CA, thereby providing a promising approach for the development of DES in transdermal drug delivery systems. The findings also shed light on the molecular mechanisms underlying the transdermal behavior of DES and offer insights for developing more effective traditional Chinese medicine transdermal drug delivery systems.

The tumor-enriched small molecule gambogic amide suppresses glioma by targeting WDR1-dependent cytoskeleton remodeling

Glioma is the most prevalent brain tumor, presenting with limited treatment options, while patients with malignant glioma and glioblastoma (GBM) have poor prognoses. The physical obstacle to drug delivery imposed by the blood‒brain barrier (BBB) and glioma stem cells (GSCs), which are widely recognized as crucial elements contributing to the unsatisfactory clinical outcomes. In this study, we found a small molecule, gambogic amide (GA-amide), exhibited the ability to effectively penetrate the blood-brain barrier (BBB) and displayed a notable enrichment within the tumor region. Moreover, GA-amide exhibited significant efficacy in inhibiting tumor growth across various in vivo glioma models, encompassing transgenic and primary patient-derived xenograft (PDX) models. We further performed a genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) knockout screen to determine the druggable target of GA-amide. By the combination of the cellular thermal shift assay (CETSA), the drug affinity responsive target stability (DARTS) approach, molecular docking simulation and surface plasmon resonance (SPR) analysis, WD repeat domain 1 (WDR1) was identified as the direct binding target of GA-amide. Through direct interaction with WDR1, GA-amide promoted the formation of a complex involving WDR1, MYH9 and Cofilin, which accelerate the depolymerization of F-actin to inhibit the invasion of patient-derived glioma cells (PDCs) and induce PDC apoptosis via the mitochondrial apoptotic pathway. In conclusion, our study not only identified GA-amide as an effective and safe agent for treating glioma but also shed light on the underlying mechanisms of GA-amide from the perspective of cytoskeletal homeostasis.

Realizing zero-order controlled transdermal drug permeation through competing doubly ionic H-bond in patch

Transdermal drug delivery system (TDDS) was an effective way to realize controlled drug delivery. However, realizing zero-order controlled drug skin delivery was still challenging in the drug-in-adhesive patch. This study provided a strategy to accomplish this delivery form by stabilizing the drug concentration in adhesive through concentration-dependent competitive interaction. Clonidine (CLO) and Granisetron (GRA) were chosen as the model drugs which were of high skin permeability, and polydimethylaminoethyl acrylate (EA) as an excipient to interact with hydroxyphenyl adhesive (HP). Drug release, permeation and pharmacokinetic study were conducted to evaluate the controlled effect of HP-EA. The molecular interaction was characterized by FT-IR, 1H NMR and XPS. Dynamic simulation and molecular docking further clarified the competitive interaction involved in the release process. Both the drug skin permeation study of CLO and GRA patch based on the HP-EA adhesive showed good zero-order fitting with r of 0.994 and 0.998, compared with non-functional adhesive (0-PSA). Furthermore, the pharmacokinetic study of the CLO patch showed a plateau phase for around 52 h without influencing the area under concentration-time curve (AUC), indicating that the HP-EA could realize zero-order drug skin delivery. The mechanism study revealed that EA serving as a 'buffer component' promoted the conversion of the ionic CLO to the neutrals the as the neutrals released, which stabilized '1% neutrals CLO concentration'. In conclusion, the drug delivery system based on the concentration-dependent competitive interaction broadened our understanding of the molecular mechanisms involved in zero-order controlled release in transdermal patches which would promote the development of zero-order drug delivery in TDDS.

Combination of ion-pair strategy and chemical enhancers for design of dexmedetomidine long-acting patches: Dual action mechanism induced longer controlled release and better delivery efficiency

The purpose of this study was to prepare a dexmedetomidine (Dex) 72 h long-acting patch by the combined use of ion-pair strategy and chemical enhancers (CEs), and to investigate molecular mechanisms of drug-loading enhancement and controlled release. The formulation of patch was optimized by single-factor investigation and Box-Behnken design. The pharmacokinetics, analgesic pharmacodynamics and irritation of the formulation were evaluated, respectively. Moreover, the effects of ion-pairs and CEs on the patch were characterized by DSC, rheology study, FTIR, and molecular docking, and the effects on the skin were evaluated by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), Raman study, and molecular dynamics, respectively. The optimized formulation was 17.00 % (w/w) Dex-NA (Naphthoic acid), 7.20 % Polyglyceryl-3 dioleate (POCC), 25-AAOH as pressure sensitive adhesives (PSA) and 66.50 μm in thickness. Compared with the control group (C_max = 62.02 ± 16.55 ng/mL, MRT_0-t = 26.74 ± 1.27 h), the pharmacokinetics behavior of the optimization group was more stable and durable (C_max = 31.22 ± 13.26 ng/mL, MRT_0-t = 33.62 ± 1.62 h). Besides, it also showed good analgesic effect and no obvious irritation. The results indicated that Dex-NA both increased the drug-PSA interactions and inhibited the penetration of the drug into the skin. POCC increased the molecular mobility of the PSA and disrupted skin lipids thereby improving the drug penetration rate. In summary, the Dex long-acting patch was developed, which provided a reference for the combined application of ion-pair strategy and CEs in other long-acting transdermal delivery.

High drug-loading and controlled-release hydroxyphenyl-polyacrylate adhesive for transdermal patch

Long-acting transdermal drug delivery system (TDDS) requires high drug-loading and drug controlled-release. To simultaneously improve drug-polymer miscibility and realize drug controlled-release, this work aimed to develop a new pressure sensitive adhesive modified with hydroxyphenyl (HP-PSA) by introducing doubly ionic H-bond into drug-PSA interaction. Eight model drugs divided into R₃N, R₂NH and no N type were chosen to understand the characteristics of the HP-PSA and inner mechanism. The results showed that the doubly ionic H-bond between R₃N and R₂NH type drugs and HP-PSA, differing from the ionic bond and neutral H-bond, was a reversible and relatively strong interaction. It could significantly enhance their drug-loading by 1.5 to 7 times and control drug release rate to its 1/5 to 1/2 without altering its total release properties, outperforming the commercial Duro-Tak® 87-2510 and Duro-Tak® 87-2852 adhesives. According to the pharmacokinetics results, the high drug-loading patches based on HP-PSA achieved a sustainable plasma drug concentration avoiding burst release, and over 2 times area under concentration-time curve (AUC) as well as 6 times mean residence time (MRT) revealed its potential to realize long-acting drug delivery. Additionally, its safety and mechanical features were satisfied. The mechanism study showed that the repulsion of the ionic drugs in HP-PSA increased drug-loading, and the relatively strong interaction could also control drug release. The incomplete H-bond transfer determined its reversibility, thus making the drug release percentage up to that of non-functional PSA. In conclusion, the high drug-loading efficiency and drug controlled-release capacity of HP-PSA, as well as its unique interaction, would contribute to the development of TDDS. Moreover, the construction of the doubly ionic H-bond would provide further inspiration for various drug delivery systems in the non-polar environment.

Mechanistic Study of Release Characteristics of Two Active Ingredients in Transdermal Patch Containing Lidocaine-Flurbiprofen Ionic Liquid

Ionic liquids (ILs) have been proven to be an efficient technology for enhancing drug skin permeability. However, the question of whether the two components of ILs are released synchronously in transdermal preparations has remained unclear. Thus, this study aimed to investigate the release characteristics of two components of ILs and their underlying molecular mechanism. The ILs containing flurbiprofen (FLU) and lidocaine (LID) were synthesized and characterized. The four typical acrylates pressure sensitive adhesives (PSAs) with different functional groups were synthesized and characterized. The effects of PSAs on the release characteristics of two components of ILs were investigated by drug release tests and verified by skin permeation experiments. The action mechanisms were revealed by FTIR, Raman, dielectric spectrum, and molecular docking. The results showed that the average release amount of FLU (0.29 μmol/cm2) and LID (0.11 μmol/cm2) of ILs in the four PSAs was significantly different (p < 0.05), which illustrated that the two components did not release synchronously. The PSA−none and PSA−OH with low permittivity (7.37, 9.82) interacted with drugs mainly by dipole-dipole interactions and hydrogen bonds. The PSA−COOH and PSA−CONH2 with high permittivity (11.19, 15.32) interacted with drugs mainly by ionic bonds and ionic hydrogen bonds. Thus, this study provides scientific guidance for the application of ILs in transdermal preparations.

Spatial-thermodynamic understanding of stabilization mechanism using computational approaches and molecular-level elucidation of the mechanism of crystal transformation in polymorphic irbesartan nanosuspensions

Irbesartan polymorphisms possess low solubility properties, nanosuspensions represent a method for improving the dissolution. Stabilizers are significant constituents of nanosuspensions. Herein we presented computational research on screening stabilizers and exploring stabilization mechanisms. The crystal transformation mechanism was also investigated. Soluplus-P407 and TPGS-HPMCE5 were screened by spatial conformation and thermodynamic energy analyses. The prepared nanosuspensions improved the dissolution properties of bulk drugs at pH 1.2, 4.5, 6.8. The nanosuspensions stabilization mechanism was analyzed by Molecular docking, Molecular dynamics simulations, Fourier transform infrared spectroscopy and Raman spectroscopy. It might be relate to the decreased enthalpy and Gibbs free energy which were determined by the synergy of external and internal energy factors. The X-ray powder diffraction, differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy showed the crystal structures. The irbesartan B form was transformed in a Soluplus-P407-B/TPGS-HPMCE5-B physical mixture, but not in an SDS (-OH free)-B physical mixture. The intra-proton transfer induced by -OH on the stabilizer might be the transformation mechanism.

Management of hypertension associated with cardiovascular failure

Hypertension (HT) treatment should focus on the prevention of new-onset heart failure (HF) or its exacerbation due to the increasing trend of HF incidence in Japan. According to the SPRINT trial, strict control of blood pressure (BP) of approximately 120 mmHg suppresses the progression of HF stages A and B to a more severe stage. However, in stages C and D, the target value for BP reduction differs depending on whether HF is HF reduced ejection fraction (EF) (HFrEF) or HF preserved EF (HFpEF). Additionally, the relationship between BP control and the prognosis of HF mostly showed the J-curve phenomenon in both HFrEF and HFpEF; however, patients with HFpEF need a lower target BP value than those with HFrEF. One reason is that vascular failure is associated with the pathophysiology of HF. Therefore, it is important to utilize an antihypertensive treatment strategy that considers vascular insufficiency. In addition, the presence or absence of compelling indications is important for the selection of antihypertensive (with cardioprotective effects for HF) medications. The uptitration of cardioprotective medications such as angiotensin-converting enzyme inhibitors/angiotensin II type 1a receptor blockers and beta-blockers is recommended in patients with HFrEF; however, it is often not practically possible to increase the dosage. In these cases, the use of medications in combination with other medication classes is also useful. Moreover, it is also useful to properly use medications of the same class considering their onset of action and half-life in the blood. It is still unclear how cardioprotective medications are used in patients with HFrEF, especially on certain age groups. The optimal initiation and continuation of cardioprotective medications should be carefully determined.

The enhancing effect and promoting mechanisms of the stereoisomeric monoterpene alcohol esters as enhancers for drugs with different physicochemical properties

To explore the structure-activity connections of amphiphilic permeation enhancers containing the length of the hydrophobic chains as well as the properties of the polar head, O-acylgeraniol and O-acylnerol derivatives were synthesized from geraniol/nerol (cis-isomer of geraniol) and pharmaceutical excipient acids in this research. Their promotion of the percutaneous absorption of three drugs as the model, flurbiprofen (FP), isosorbide dinitrate (ISDN) and donepezil (DNP), which were selected based on their physicochemical properties, was tested by in vitro skin penetration and in vivo. Molecular simulation, ATR-FTIR, CLSM and histological observation were implement to evaluate the mode of action of the enhancers. The results indicated that (E)-3,7-dimethyl-2,6-octadien-1-yl tetradecanoate (GER-C14, trans-) achieved the highest enhancement ability for the three drugs; additionally, the in vivo results obtained were in good correlation with the in vitro data. Molecular docking results suggested that enhancers loosen the hydrogen bonds between ceramides, and the results of molecular simulation indicated that GER-C14, NER-C14 could insert into the middle of the lipid bilayer to form an independent phase. According to ATR-FTIR and histological evaluation, the enhancers extracted lipids and influenced the protein region, thereby disturbing the skin array. In addition, CLSM described the dynamic effects of enhancers on lipids between stratum corneum (SC) cells. In conclusion, GER-C14 had a better penetration promotion effect, which broadened our understanding of stereoisomeric penetration enhancers.

A molecular mechanism investigation of the transdermal/topical absorption classification system on the basis of drug skin permeation and skin retention

A transdermal/topical absorption classification system for the characterization of the systemic or local delivery of drugs is the theoretical basis for the design and evaluation of transdermal/topical formulations. A classification system was established on the basis of the in vitro and in vivo skin permeation/retention behaviors of 12 model drugs. Drug skin penetration/retention exhibited a significant correlation with physicochemical parameters (log K_O/W, molecular weight, polar surface area, and polarizability). Four representative model drugs were selected to clarify the molecular mechanisms of drug skin permeation/retention behaviors. The excellent lipid-disrupting effect and enhanced partitioning exhibited by propranolol (high permeation-high retention) and zolmitriptan (high permeation-low retention) via the formation of moderate H-bonds with skin lipids were proven by ATR-FTIR (Δν_asCH2 > 2 cm^-1), Raman spectra (ΔLPP, SPP > 0.2 nm), and X-ray scattering (lipid crystallization) and were supported by ¹³C NMR results. The low lipid miscibility of zolmitriptan (ΔH_{zolmitriptan-lipid} = 126.92 J/g) caused the low skin retention of this drug. High polarizabiltiy (α = 38.5 × 10^-24 cm³) and low H-bond forming capability (E_H-bond = 0 kcal/mol) restricted terbinafine (low permeation-high retention) in terms of partitioning (k_D-SC = 0.09). Diclofenac (low permeation-low retention) stabilized skin lipids through the formation of strong H-bonds and exhibited excessive drug-lipid miscibility (ΔH_{diclofenac-skin} = -128.73 J/g), thus restricting its skin absorption. This classification system reflects the most essential drug skin absorption characteristics and provides a theoretical basis for the design of transdermal/topical formulations.

Effect of the combination of permeation enhancer and ion-pairs strategies on transdermal delivery of tofacitinib

The aim of the present study was to develop a tofacitinib (TOF) transdermal patch by the combination of ion-pairs and chemical permeation enhancer strategies. And a theory of controlled release of chemical permeation enhancers by counterion was proposed on the basis of in vitro skin permeation and skin retention study. Through the in vitro skin permeation study, the formulation factors such as counterion, pressure sensitive adhesive (PSA), drug loading and patch thickness were investigated, and the optimized patch (6.5% LA-TOF, 15% POCC and thickness = 50 μm) was evaluated by the pharmacokinetic study. The AUC_0-t of the optimized patch was 529.89 ± 45 h ng/mL. Special attention has been paid to the molecular mechanism of the effects of counterion concentration on the release and permeation enhancement effect of penetration enhancer. FTIR study, ¹³C NMR, XPS and molecular modeling were conducted to investigate the molecular interaction between POCC and LA. Raman Imaging and ATR-FTIR were used to explore the POCC content in the skin and the interference degree to lipid. The results revealed that a strong hydrogen bond appeared between LA and the hydroxyl group of POCC, which inhibited the release of POCC, thus reducing the lipid disturbance and permeation enhancement effect of POCC. In conclusion, this TOF patch was successfully developed. The effect of counterion on permeation enhancers was clarified at molecular level, and these results provided references for the development of TOF patch.

Development of gliclazide ionic liquid and the transdermal patches: An effective and noninvasive sustained release formulation to achieve hypoglycemic effects

Ionic liquids (IL) technology provides a useful platform to achieve the topical delivery of therapeutic agents, because of its capability to improve skin permeability. While the majority of the researches aimed to achieve local action by topical IL delivery, systemic action of therapeutic agents by local topical application has rarely been reported. In the present work, Gliclazide (GLI), a second-generation sulfonylurea drug was transformed into an IL with tributyl(tetradecyl)phosphonium for the first time. The physicochemical properties of this IL were systematically characterized by DSC, TGA, FT-IR, NMR, and HPLC. The transdermal patch based on this IL was further prepared using DURO-TAK®87-4098. The fabricated gliclazide based ionic liquid [P_6,6,6,14][GLI] transdermal patch displayed satisfactory in vitro and in vivo performance. The [P_6,6,6,14][GLI] patch released 88.17% of the loaded drug within a 3-day period in the in vitro dissolution test, confirming its sustained release property. Meanwhile, GLI effectively permeated through the artificial skin from [P_6,6,6,14][GLI] transdermal patch in the in vitro skin permeation test, with the permeation rate and lag time of 16.571 ± 0.328 μg/cm²/h and 3.027 ± 0.154 h respectively. The [P_6,6,6,14][GLI] transdermal patch showed favorable PK profile in rat as compared with GLI oral suspension. The relative bioavailability of GLI reached 92.06% of GLI oral suspension, while the C_max was significantly reduced. Most importantly, [P_6,6,6,14][GLI] transdermal patch demonstrated superior hypoglycemic effect to the oral suspension both in the fasted and fed condition, confirming the feasibility of systemic action by local topical delivery of IL. In addition, the [P_6,6,6,14][GLI] transdermal patch caused no skin irritation based on histopathological analysis.

Development of long-acting rivastigmine drug-in-adhesive patch utilizing ion-pair strategy and characterization of controlled release mechanism

The purpose of present study was to develop a long-acting drug-in-adhesive patch of rivastigmine (RVS) to achieve controlled release under high drug loading. Formulation factors including ion-pair, pressure sensitive adhesive (PSA), drug-loading and permeation enhancers were investigated through in vitro skin permeation experiments. Optimized patch was evaluated by pharmacokinetic study. The mechanism of controlled release was studied by FTIR, Raman, DSC, rheology study and molecular modeling. The optimized patch composed of RVS-SA (equal to 30% RVS), 15% POCC as permeation enhancer and AAOH as PSA matrix. The RVS in optimized patch was basically permeated at a uniform rate, and the ratio of the skin permeation amount (2803.38 ± 153.85 μg/cm²) in 72 hours to that of the control group (1000.89 ± 62.45 μg/cm²) was 2.8. The plasma concentration of RVS was stable for 72 hours in vivo (AUC_optimized = 5721.30 ± 1994.87 h ng/mL, MRT_0-t = 29.55 ± 2.49 h), and C_max was significantly controlled. The results of the study on the controlled release mechanism showed that the addition of counter ion formed hydrogen bonds with RVS and PSA respectively, which reduced the fluidity and molecular mobility of PSA, and enhanced the interaction between RVS and PSA, thus achieving the purpose of long-acting effect. In conclusion, long-acting drug-in-adhesive patch of RVS was developed, and provided a new idea for the long term drug delivery of Alzheimer's disease.

Probing Dynamic Behavior of Chemical Enhancers Passing In and Out of the Stratum Corneum and Modulation by Biodegradable Enhancer

Chemical enhancers (CEs) decreased the barrier of the stratum corneum (SC) to enhance drug permeation. This was a "dynamic" behavior, which involved three processes including passing in, acting on, and passing out of the SC. However, compared with mature "static" researches about acting on the SC, the other two processes were poorly understood. This work aimed to probe the dynamic behavior of CEs and modulate it for satisfactory effectiveness. The investigating method of CEs' dynamic behavior was established to obtain the rate of CEs passing in and out of the SC. An analysis attribution was conducted to obtain the possible reasons for the quite different dynamic behavior of CEs based on log P, solubility parameter, and minimum binging energy. It demonstrated the rate of CEs passing in and out of the SC was dependent on CE affinity with the SC and the interaction between CEs and the SC, respectively. The relevance between CEs' dynamic behavior and the extent of decreasing SC barrier was confirmed by transepidermal water loss (TEWL). The higher rate of CE passing in the SC and a lower rate of passing out of the SC may contribute to an increased concentration of CEs in the SC, leading to a stronger ability to decrease the SC barrier. More importantly, two biodegradable CEs (Leu-Dod and Ser-Dod) of dodecanol were synthesized and achieved a modulation of its dynamic behavior to obtain more satisfactory effectiveness of enhancing drug permeation. This work was meaningful for the guidance of rationally promoting CEs' effectiveness from a dynamic perspective, which was an unprecedented attempt in this field.

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.

Enhanced Drug Loading in the Drug-in-Adhesive Transdermal Patch Utilizing a Drug-Ionic Liquid Strategy: Insight into the Role of Ionic Hydrogen Bonding

Though pharmaceutical polymers were widely used in inhibiting drug recrystallization via strong intermolecular hydrogen and ionic bonds, the improved drug stability was achieved at the cost of the drug release rate or amount in the drug-in-adhesive transdermal patch. To overcame the difficulty, this study aimed to increase drug loading utilizing a novel drug-ionic liquid (drug-IL) strategy and illustrate the underlying molecular mechanism. Here, naproxen (NPX) and triamylamine (TAA) were chosen as the model drug and corresponding counterion, respectively. In addiiton, carboxylic pressure-sensitive adhesive (PSA) was chosen as the model polymer. The drug-IL (NPX-TAA) was synthesized and characterized by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and proton nuclear magnetic resonance. The miscibility between NPX-TAA and PSA was assessed using microscopy study, X-ray diffraction, fluorescence spectroscopy, and solubility parameter calculation. In addition, molecular mechanisms of crystallization inhibition were revealed by FT-IR, Raman spectroscopy, DSC, X-ray photoelectron spectroscopy (XPS), and molecular docking. Finally, the release pattern of the high load patch of NPX-TAA was evaluated using in vitro drug release and verified by a skin permeation experiment. The results showed that drug loading in PSA was increased by 5.0 times, which was caused by the synergistic effect of strong ionic hydrogen bonding (the decreased intensity and blue shift of the O-H peak of COOH in PSA) formed between NPX-TAA and PSA-COO^- and normal hydrogen bonding (red shift of the C═O peak in PSA) formed between NPX-TAA and the carbonyl group of PSA. In addition, -NH⁺ of TAA was confirmed as the molecular basis of ionic hydrogen bonding through new peak appearance (binding energy: 400.0 eV) in XPS spectra. Moreover, high drug release percent (80.8 ± 1.8%) was achieved even at high drug loading compared with the control group (72.4 ± 2.2%). Thus, this study introduced an effective drug-IL method to enhance drug loading capacity and illustrated the brand-new action mechanism, which provided a powerful instrument for the development of a high drug loading-high release patch.

Prediction of the physical stability of amorphous solid dispersions: relationship of aging and phase separation with the thermodynamic and kinetic models along with characterization techniques

Introduction: Solid dispersion has been considered to be one of the most promising methods for improving the solubility and bioavailability of insoluble drugs. However, the physical stability of solid dispersions (SDs), including its aging and recrystallization, or phase separation, has always been one of the most challenging problems in the process of formulation development and storage.Areas covered: The high energy state of SDs is one of the primary reasons for the poor physical stability. The factors affecting the physical stability of SDs have been described from the perspective of thermodynamics and kinetics, and the corresponding theoretical model is put forward. We briefly summarize several commonly used techniques to characterize the thermodynamic and kinetic properties of SDs. Specific measures to improve the physical stability of SDs have been proposed from the perspective of prescription screening, process parameters, and storage conditions.Expert opinion: The separation of the drug from the polymer, the formation, and migration of drug crystals will cause the SDs to shift toward the direction of energy reduction, which is the intrinsic cause of instability. Furthermore, computational simulation can be used for efficient and rapid screening suitable for the excipients to improve the physical stability of SDs.

Bisoprolol transdermal patch improves orthostatic hypotension in patients with chronic heart failure and hypertension

β blockers (BBs) play an important role in heart failure (HF) treatment. However, orthostatic hypotension (OH) is sometimes caused by BBs. The bisoprolol transdermal patch works more slowly and is long acting compared with the bisoprolol fumarate tablet. The risk of OH may be reduced by using the bisoprolol transdermal patch. We evaluated 57 consecutive patients who were taking the bisoprolol fumarate tablet for chronic HF with hypertension from November 2016 to September 2017. We switched the patients to the bisoprolol transdermal patch. Because 12 of 57 subjects could not continue using the bisoprolol transdermal patch, we analyzed the remaining 45 patients. We investigated BP, blood tests, and changes in BP from supine to standing positions before and after 6 months of switching from tablet to patch. OH was diagnosed by observing a systolic/diastolic BP drop of at least 20/10 mmHg or an absolute systolic BP (sBP) of <90 mmHg from the standing position. No significant changes were observed in the BP and BPs from supine to standing positions, whereas log brain natriuretic peptide was significantly reduced after switching from patch to tablet (2.102 to 2.070pg/dl, P = .039). OH, which occurred in originally 17 patients, showed improvement and eventually appeared in 4 patients. In these patients, changes in BP from supine to standing positions were also significantly improved (changes in sBP, -11 to -6mmHg, P = .016). This study demonstrated that switching from the bisoprolol fumarate tablet to transdermal patch reduced the morbidity of OH in HF patients.

Unconventional Passive Enhancement of Transdermal Drug Delivery: toward a Mechanistic Understanding of Penetration Enhancers Releasing from Acrylic Pressure-Sensitive Adhesive of Patches

PURPOSE

Penetration enhancers (PEs) enhancing efficacy depends on two processes: PEs release from patches and action on skin. Compared with their action on skin, PEs release process was poorly understood. Therefore, the purpose of this study was to make a mechanistic understanding of PEs release from acrylic pressure-sensitive adhesive of patches and propose an unconventional enhancement of PEs efficacy.

METHODS

PEs efficacy was evaluated both in drug permeation study and drug pharmacokinetic study. Confocal Raman spectroscopy was employed to observe PEs release behavior by mapping PEs dynamic distribution in skin. The mechanism of PEs release behavior was provided from molecular interaction and rheology using FT-IR, molecular docking, molecular dynamic simulation and rheometer, separately.

RESULTS

The release behavior of PEs themselves greatly restricted their efficacy. By using PEG 400, an improvement of oleic acid (OA) release behavior was achieved, and the efficacy of OA was significantly enhanced with enhancing ratio (ER) from 2.69 to 4.10 and AUC_last from 1574 ± 87 to 2664 ± 249 ng·h/mL, separately. The improvement of OA release behavior was primarily resulted from reduction of the interaction between OA and adhesive, which was caused by other small molecules with a strong ability in forming hydrogen bonds with adhesive. Also, the rigidity of adhesive was a factor in affecting PEs release behavior.

CONCLUSIONS

An unconventional passive enhancement of transdermal drug delivery was achieved via improving PEs themselves releasing from acrylic pressure-sensitive adhesive. Graphical abstract Influence of PEs release behavior on drug permeation through skin and molecular mechanism.

Mechanism and Improved Dissolution of Glycyrrhetinic Acid Solid Dispersion by Alkalizers

The purpose of this study was to increase the dissolution of glycyrrhetinic acid (GA) by preparing ternary solid dispersion (TSD) systems containing alkalizers, and to explore the modulating mechanism of alkalizers in solid dispersion systems. GA TSDs were prepared by hot melt extrusion (HME) with Kollidon^® VA64 as the carrier and L-arginine/meglumine as the alkalizers. The in vitro release of the TSD was investigated with a dissolution test, and the dissociation constant (pKa) was used to describe the ionization degree of the drug in different pH buffers. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectra, X-ray photoelectron spectroscopy (XPS), and a molecular model were used for solid-state characterizations and to study the dissolution mechanism of the TSDs. It was evident that the dissolution of GA significantly increased as a result of the TSD compared to the pure drug and binary solid dispersion. SEM, DSC, and XPRD data showed that GA transformed into an amorphous form in TSD. As illustrated by FTIR, Raman, XPS, and molecular docking, high binding energy ion-pair complexes formed between GA and the alkalizers during the process of HME. These can destroy the H-bond between GA molecules. Further, intermolecular H-bonds formed between the alkalizers and Kollidon^® VA64, which can increase the wettability of the drug. Our results will significantly improve the solubility and dissolution of GA. In addition, the lower pKa value of TSD indicates that higher ionization is beneficial to the dissolution of the drug. This study should facilitate further developments of TSDs containing alkalizers to improve the dissolution of weakly acidic drugs and gain a richer understanding of the mechanism of dissolution.

Probing the Role of Ion-Pair Strategy in Controlling Dexmedetomidine Penetrate Through Drug-in-Adhesive Patch: Mechanistic Insights Based on Release and Percutaneous Absorption Process

The purpose of present study was to develop a controlled release drug-in-adhesive patch for transdermal delivery of dexmedetomidine (Dex) using ion-pair technique. Based on the in vitro transdermal experiment, the role of ion-pair on the Dex release behavior and percutaneous absorption process was also investigated. Fourier transform infrared spectroscopy (FTIR), molecular modeling, differential scanning calorimetry (DSC), and rheological test were conducted to probe the effect of ion-pair on the Dex release from patch. Besides, the tape stripping test, attenuated total reflectance Fourier transform infrared (ATR-FTIR), and molecular simulation were carried out to elaborate the action of ion-pair on the Dex percutaneous permeation process. Results showed that the optimized patch prepared with Dex-salicylic acid (SA) showed zero-order skin permeation profile within 24 h; Dex-SA had greater hydrogen bonding formation potential with pressure sensitive adhesive (PSA) than Dex, which resulted in the decrease in the formation ability of free volume of PSA and the increase with the improvement of mechanical strength and chain stiffness of PSA and thus controlled the release rate of Dex from transdermal patch. Besides, the physicochemical properties of Dex such as molecular weight and octanol/water partition coefficient were changed after forming ion-pair with SA, which decreased the permeation ability of Dex. In conclusion, a controlled release drug-adhesive patch for Dex was developed and the mechanism study of ion-pair on the Dex release and percutaneous permeation process was proposed at molecular level.