Effect of pH and solubility on in vitro skin penetration of methotrexate from a 50% v/v propylene glycol-water vehicle

Biotin receptor-targeting nanogels loaded with methotrexate for enhanced antitumor efficacy in triple-negative breast cancer in vitro and in vivo models

High-dose methotrexate (MTX) chemotherapeutic applications confront drug specificity and pharmacokinetic challenges, which can be overcome by utilizing targeted drug delivery systems. In the present study, biotin-PEG conjugated nanogels of carboxymethyl polyethyleneimine (Biotin-PEG-CMPEI) were developed for active targeted delivery of MTX in triple negative breast cancer (TNBC). TEM and DLS analyses revealed uniform, discrete, and spherical particles with a mean hydrodynamic diameter of about 100 nm and ζ-potential of + 15 mV (pH = 7.4). Biotin-PEG-CMPEI nanogels exhibited a zero-order MTX release kinetics at pH = 7.5 and a swelling-controlled release at pH = 5.5. In 4 T1 cells treated with the MTX-loaded Biotin-PEG-CMPEI, the IC₅₀ was reduced by about 10 folds compared to the free drug, while the unloaded nanogels showed no significant toxicity. In the model mice, the group treated with the MTX-loaded Biotin-PEG-CMPEI had a lower tumor volume and mortality rate animal model when compared to free drug. Additionally, histopathological analyses showed that the group treated with the MTX-loaded nanogels had less lung metastasis and glomerular damage caused by MTX. Overall, the MTX-loaded Biotin-PEG-CMPEI targeted directly against overexpressed biotin receptors in TNBC have been shown to improve the MTX safety and therapeutic efficacy.

Nitric Oxide-Releasing Emulsion with Hyaluronic Acid and Vitamin E

S-Nitrosoglutathione (GSNO) is a naturally available S-nitrosothiol that can be incorporated into non-toxic formulations intended for topical use. The value of nitric oxide (NO) delivered topically relates to its well-studied physiological functions such as vasodilation, angiogenesis, cell proliferation and broad-spectrum antibacterial activity. Previously reported topical NO-releasing substrates include polymeric materials that exhibit non-toxic behaviors on dermal tissue such as polyethylene glycol. However, they do not serve as humectants nor provide vitamins to the skin. In this study, GSNO was added to an emulsion that was fortified with α-tocopheryl acetate (vitamin E) and hyaluronic acid. The average total NO content for the NO-releasing emulsion was 58 ± 8 μmol g⁻¹ at 150 °C and the cumulative NO release over 53 h at physiological temperature (37.4 °C) was 46 ± 4 μmol g⁻¹. The GSNO concentration in the lotion was optimized in order to reach a pH value similar to that of human skin (pH 5.5). The viscosity was analyzed using a rotational viscometer for the S-nitrosated and the non-nitrosated emulsions to obtain a material that can be readily spread on dermal tissue. The viscosity values obtained ranged from 7.88 ± 0.99 to 8.50 ± 0.36 Pa s. Previous studies have determined that the viscosity maximum for lotions is 100 Pa s. A low viscosity increases the diffusion coefficient of active ingredients to the skin given that they are inversely proportional as described by the Einstein–Smoluchowski equation. The effect of the S-nitrosated and non-nitrosated emulsions on adult human dermal fibroblasts (HDFs) was assessed in comparison to untreated HDFs using Colorimetric Cell Viability Kit I-WST-8. The findings indicate that neither the S-nitrosated nor non-nitrosated emulsions induced cytotoxicity in HDFs.

S-Nitrosoglutathione (GSNO) is a naturally available S-nitrosothiol that can be incorporated into non-toxic formulations intended for topical use.

Toxicity, Biocompatibility, pH-Responsiveness and Methotrexate Release from PVA/Hyaluronic Acid Cryogels for Psoriasis Therapy

Poly(vinyl alcohol)/hyaluronic acid cryogels loaded with methotrexate were studied. The physical⁻chemical characterization of cryogels was performed by FT-IR spectroscopy, scanning electron microscopy, differential scanning calorimetry and dynamic mechanical thermal analysis. Acute toxicity and haematological parameters were determined by "in vivo" tests. The biocompatibility tests proved that the obtained cryogels showed significantly decreased toxicity and are biocompatible. The pH-responsiveness of the swelling behaviour and of the methotrexate release from the poly(vinyl alcohol)/hyaluronic acid (PVA/HA) cryogels were studied in a pH interval of 2⁻7.4. A significant change in properties was found at pH 5.5 specific for treatment of affected skin in psoriasis disease.

Synergistic effect of iontophoresis and soluble microneedles for transdermal delivery of methotrexate

The aim of this study was to investigate the transdermal iontophoretic delivery of methotrexate, alone or in combination with microneedles, in-vitro and in-vivo using intracutaneous microdialysis in the hairless rat. The average depth of the microdialysis probe in the skin was found to be 0.54 mm. Methotrexate was stable in the presence of an applied electric field as determined by cyclic voltammetry. A current density of 0.4 mA cm−2 applied for 60 min was used in combination with maltose microneedles to enhance delivery of methotrexate across the skin. Delivery was enhanced by iontophoresis and microneedles, both in-vitro and in-vivo. A synergistic 25-fold enhancement of delivery was observed in-vivo when a combination of microneedles and iontophoresis was used compared with either modality alone.

Dermal and transdermal delivery of an anti-psoriatic agent via ethanolic liposomes

The aim of the current investigation is to evaluate the transdermal potential of novel vesicular carrier, ethosomes, bearing methotrexate (MTX), an anti-psoriatic, anti-neoplastic, highly hydrosoluble agent having limited transdermal permeation. MTX loaded ethosomes were prepared, optimized and characterized for vesicular shape and surface morphology, vesicular size, entrapment efficiency, stability, in vitro human skin permeation and vesicle-skin interaction. The formulation (EE(9)) having 3% phospholipid content and 45% ethanol showing the greatest entrapment (68.71+/-1.4%) and optimal nanometric size range (143+/-16 nm) was selected for further transdermal permeation studies. Stability profile of prepared system assessed for 120 days revealed very low aggregation and growth in vesicular size (8.8+/-1.2%). MTX loaded ethosomal carriers also provided an enhanced transdermal flux of 57.2+/-4.34 microg/cm(2)/h and decreased lag time of 0.9 h across human cadaver skin. Skin permeation profile of the developed formulation further assessed by confocal laser scanning microscopy (CLSM) revealed an enhanced permeation of Rhodamine Red (RR) loaded formulations to the deeper layers of the skin (170 microm). Also, the formulation retained its penetration power after storage. Vesicle skin interaction study also highlighted the penetration enhancing effect of ethosomes with some visual penetration pathways and corneocytes swelling, a measure of retentive nature of formulation. Our results suggests that ethosomes are an efficient carrier for dermal and transdermal delivery of MTX.

Evaluation of the pH effect of formulations on the skin permeability of drugs by biopartitioning micellar chromatography

Dermal absorption of chemicals is an area of increasing interest for the pharmaceutical and cosmetic industries, as well as in dermal exposure and risk assessment processes. Biopartitioning micellar chromatography (BMC) is a mode of reversed phase micellar chromatography that has proved to be useful in the description and prediction of several pharmacological properties of xenobiotics including oral drug absorption, ocular and skin drug permeability. The present paper deals with the application of biopartitionig micellar chromatography to evaluate the pH effect on the skin permeability of twelve non-steroidal anti-inflammatory drugs and lidocaine. For this purpose the BMC retention of the whole set of compounds at several pHs between 3.5 and 8 was obtained. Using the BMC retention-permeability model previously reported, the permeability of the compounds at different pH values was estimated. The predicted permeability values at different pH values for ketoprofen, lidocaine, salicylic acid and ibuprofen agree with those experimental reported in literature for these compounds using excised human and rat skin.

Deformable liposomes for dermal administration of methotrexate

Deformable liposomes were prepared to investigate the effectiveness of dermal administration of methotrexate (MTX). The phospholipids used to prepare the liposomes were soybean lecithin (PC) or hydrogenated lecithin (HPC) and dipotassium glycyrrhizinate (KG) as surfactant. The lipid/KG ratio (w/w) was 2:1 and 4:1. Liposomes size, entrapment efficiency and MTX release through dialysis membrane were determined and the interaction between MTX and liposomes was investigated using differential scanning calorimetry. The MTX amount permeated through pig skin were three- to four-fold higher using liposomes containing KG compared to those from water solution or normal liposomes. No significant differences were observed between PC-KG liposomes and HPC-KG liposomes. At the end of the skin permeation assay using deformable liposomes, up to 50% of the administered dose was found in the skin. This capability depends on the self-regulating carrier deformability. These results suggest that liposomes containing KG may be of value for the topical administration of MTX in the treatment of psoriasis.

Ionisation and the effect of absorption enhancers on transport of salicylic acid through silastic rubber and human skin

PURPOSE

to investigate if salicylic acid (SA)-permeation through excised human skin (HS) and silastic rubber (SR) conforms to the pH-hypothesis and to assess the influence of a range of absorption enhancers on the transport of SA with and without a transmembrane pH-gradient.

METHODS

Franz cells were used to study SA permeation from solutions and saturated suspensions. McIlvaine buffers were used to maintain transmembrane pH-gradients. Membrane pretreatment was used to study the action of absorption enhancers.

RESULTS

the flux of SA from solutions was dependent upon the vehicle pH and permeant concentration was directly related to the degree of ionisation of the solute. Flux from suspensions was independent of pH, since the level of unionised drug, the predominant diffusing species, was maintained at the intrinsic saturated solubility at all pH values. The observed SA flux enhancement across human skin without a transmembrane pH-gradient was not significantly different from the enhancement with a pH-gradient for all of the absorption enhances used, except for dodecylamine.

CONCLUSIONS

the results showed that SA permeation conformed to the p H-partition hypothesis. The evidence from absorption-enhancer pretreatment demonstrated that, under certain conditions, the transdermal penetration enhancement of a number of topical enhancing compounds, including Azone and oleic acid can be explained without recourse to ion-pair phenomena.

Influence of counter ions on the skin permeation of methotrexate from water--oil microemulsions

The influence on the permeation of methotrexate across intact hairless mouse skin of different counter ions added to water--oil (w/o) microemulsions containing lecithin, as surfactant, and water--propylene glycol at different pH values, as internal phase, was studied. As counter ions, monooctyl phosphate, monodecyl phosphate, monodecyl glycerophosphate, taurodeoxycholate, dodecyl sulfate and dioctyl sulfosuccinate were used. At pH 4.0, the transport of methotrexate was enhanced by the counter ions and a marked increase in the flux of the drug was measured when dodecyl sulfate and dioctyl sulfosuccinate were used. At pH 5.0 only a slight increase of the flux was observed. The increased permeation was attributed to the lipophilization of methotrexate as a consequence of ion pair formation.

Mechanism of the enhancement effect of n-octyl-beta-D-thioglucoside on the transdermal penetration of fluorescein isothiocyanate-labeled dextrans and the molecular weight dependence of water-soluble penetrants through stripped skin

To clarify the mechanism of the enhancing effect of n-octyl-beta-D-thioglucoside (OTG), which acts as a potent enhancer for skin penetration of peptides and water-soluble penetrants, the in vitro penetration of macromolecules [fluorescein isothiocyanate-labeled dextrans (FTIC-dextrans)] was evaluated with hairless rat skin and stripped skin. The FITC-dextrans (MW, 4400, 9600, and 69,000 Da, referred to as FD-4, FD-10, and FD-70, respectively) penetrated more easily in the presence of OTG (1.5%), with high fluxes equivalent to those through stripped skin. This result indicated that the enhancement effect of OTG on the penetration of macromolecules through the stratum corneum was extensive, and the barrier function of the corneum was nearly eliminated by the OTG treatment. OTG significantly solubilized the stratum corneum proteins and ceramides during the initial time stage. Scanning electron microscopic observations demonstrated that OTG treatment dramatically changed the cell membrane (i.e., exfoliation of cell membranes and dissociation of adherent cornified cells), suggesting a significant disturbance of the cohesive laminae and barrier functions. The extent of dissociation of cell membranes increased with treatment time, without significant changes in the cell junctions. These results clarify that the enhancement mechanism of OTG was different from that of laurocapram and other lipophilic enhancers. The permeability of polar solutes with differing molecular sizes (MW, 180-69,000 Da) through stripped skin was size dependent (r = 0.997, p < 0.001). However, the viable epidermis and dermis restricted the penetration of macromolecules, such as FD-70.