The influence of the acyl chain on the transdermal penetration-enhancing effect of synthetic phytoceramides.

BACKGROUND/AIMS: The skin has become very attractive as a route for drug administration. Optimization of topical drug formulations by the addition of penetration enhancers may facilitate the passage of drugs through the stratum corneum. METHODS: In this paper, the skin penetration effect of phytosphingosine and 9 derived phytoceramides (PCERs) on 3 transdermal model drugs (i.e. caffeine, testosterone, ibuprofen) was investigated via Franz diffusion cell experiments using split-thickness human skin. Azone was included as a positive control. RESULTS: The main finding in our study was that the PCERs exerted a compound-dependent penetration-enhancing effect. Some of the investigated PCERs exhibited a penetration-enhancing ratio of more than 2 (mean ± SE): for caffeine PCER1 (2.48 ± 0.44), PCER2 (2.75 ± 0.74), PCER3 (2.62 ± 0.93) and PCER6 (2.70 ± 0.45) and for testosterone PCER1 (2.08 ± 0.56), PCER2 (2.56 ± 0.13), PCER3 (3.48), PCER4 (2.53), PCER5 (2.04 ± 0.14), PCER6 (2.05 ± 0.48) and PCER10 (4.84 ± 0.79), but none of them had an influence on ibuprofen. CONCLUSION: The investigated PCERs exhibited a penetration-enhancing effect on caffeine and testosterone but not on ibuprofen.

Risk evaluation of impurities in topical excipients: The acetol case.

Pharmaceutical excipients for topical use may contain impurities, which are often neglected from a toxicity qualification viewpoint. The possible impurities in the most frequently used topical excipients were evaluated in-silico for their toxicity hazard. Acetol, an impurity likely present in different topical pharmaceutical excipients such as propylene glycol and glycerol, was withheld for the evaluation of its health risk after dermal exposure. An ex-vivo in-vitro permeation study using human skin in a Franz Diffusion Cell set-up and GC as quantification methodology showed a significant skin penetration with an overall Kp value of 1.82×10-3 cm/h. Using these data, limit specifications after application of a dermal pharmaceutical product were estimated. Based on the TTC approach of Cramer class I substances, i.e. 1800 µg/(day∙person), the toxicity-qualified specification limits of acetol in topical excipients were calculated to be 90 µg/mL and 180 µg/mL for propylene glycol and glycerol, respectively. It is concluded that setting specification limits for impurities within a quality-by-design approach requires a case-by-case evaluation as demonstrated here with acetol.

Skin penetration enhancing properties of the plant N-alkylamide spilanthol.

ETHNOPHARMACOLOGICAL RELEVANCE: Plants are often used for skin diseases in different ethnopharmacological systems. Local and systemic effects of topically applied compounds can be significantly increased by plant constituents having skin penetration enhancers. MATERIALS AND METHODS: In this study, we examined the proposed penetration enhancing properties of spilanthol, an N-alkylamide abundantly present in several Asteraceae plants like Spilanthes acmella L., on three model drugs (caffeine, testosterone and ibuprofen). Moreover, as plants are frequently contaminated with toxic environmental substances, the mutual influence on the transdermal behavior between spilanthol and six model mycotoxins (aflatoxin B1, ochratoxin A, fumonisin B1, citrinin, zearalenone, T-2 toxin) was investigated. RESULTS: Spilanthol exhibits component and concentration dependent penetration enhancing effects. No significant penetration enhancing effect for ibuprofen has been observed, but with increasing spilanthol concentration (from 0 up to 1w/V%), the permeability of caffeine increased, resulting in an enhancing ratio (ER) of 4.60. For testosterone, a maximal penetration enhancing concentration of 0.5% spilanthol was found (ER=4.13). Next to its beneficial applicability to increase local as well as systemic pharmacological effects of dermally co-administrated drug, this N-alkylamide negatively influences human health risk if spilanthol containing formulations are polluted with mycotoxins: the presence of spilanthol (0.3w/V%) induced a significant increase of permeability coefficient Kp of five investigated mycotoxins, with ER values ranging between 1.57 and 6.37. On the other hand, mycotoxins themselves do not significantly influence the transdermal behavior of spilanthol. CONCLUSIONS: The existence of a significant mutual influence of compounds towards skin penetration should always be considered during the development or as part of the functional quality evaluation of topical products.

A critical quality parameter in quantitative fused-core chromatography: The injection volume.

As part of the method development, the injection volume as a critical quality attribute in fast fused-core chromatography was evaluated. Spilanthol, a pharmaceutically interesting N-alkylamide currently under investigation in our laboratory, was chosen as the model compound. Spilanthol was dissolved in both PBS and MeOH/H2O (70/30, v/v) and subsequently analyzed using a fused-core system hereby selecting five chromatographic characteristics (retention time, area, height, theoretical plates and symmetry factor) as responses. We demonstrated that the injection volume significantly influenced both the qualitative and quantitative performance of fused-core chromatography, a phenomenon which is confounded with the nature of the used sample solvent. From 2 µL up to 100 µL injection volume with PBS as solvent, the symmetry factor decreased favorably by 20%. Moreover, the theoretical plates and the quantitative parameters (area and height) increased up to 30%. On the contrary, in this injection volume range, the theoretical plates for the methanol-based samples decreased by more than 60%, while the symmetry factor increased and the height decreased, both by 30%. The injection volume is thus a critical and often overlooked parameter in fused-core method description and validation.

Androgenic and spermatogenic activity of alkylamide-rich ethanol solution extract of Anacyclus pyrethrum DC.

Anacyclus pyrethrum (A. pyrethrum) has been used as Vajikaran Rasayana (aphrodisiac) in traditional Indian ayurvedic medicine to treat male sexual dysfunction, including infertility. Aphrodisiac activity may be due to an increase in the production or effect of androgens, so this study sought to evaluate the androgenic and spermatogenic potential of the alkylamide-rich ethanol solution extract. Male Wistar strain rats weighing between 150 and 180 g were completely randomized divided into five groups. The ethanol solution extract of A. pyrethrum was administered to groups of rats in 50, 100, and 150 mg/kg doses for a period of 28 days, and the action was compared with control and testosterone-treated rats. Thirteen N-alkylamides were detected in the extract by using HPLC/UV/electrospray ionization mass spectrometry method. Extract administration at all the doses produced significant increase in body weight, sperm count, motility, and viability along with serum testosterone, luteinizing hormone, and follicle-stimulating hormone concentrations. Histoarchitecture of testis revealed increased spermatogenic activities. Seminal fructose content was also significantly increased after 28 days of treatment. Our results suggest that the ethanol solution extract of the roots of A. pyrethrum has androgenic potential and may improve male fertility by enhancing spermatogenesis.

Improved positive electrospray ionization of patulin by adduct formation: usefulness in liquid chromatography-tandem mass spectrometry multi-mycotoxin analysis.

Several sensitive methods have been developed for patulin determination; however, mass spectrometric (MS) detection of this toxin in the positive electrospray ionization (ESI(+)) mode is not straightforward. Furthermore, the combined determination of patulin with other mycotoxins in one single run has not been reported yet. The present paper demonstrates the formation and use of a methanol adduct of patulin in ESI(+). A study of the fragmentation pathway confirmed the authenticity of the patulin adduct, while the use of ion trap and high resolution Orbitrap mass spectrometry allowed reliable assignment of the patulin fragment ions. Exploiting the formation of the methanol adduct, patulin has been successfully included in a single run multi-mycotoxin liquid chromatography tandem mass spectrometric (LC-MS/MS) method in support of ex vivo-in vitro biomedical studies.

LC-MS N-alkylamide profiling of an ethanolic Anacyclus pyrethrum root extract.

An N-alkylamide profiling from an ethanolic Anacyclus pyrethrum DC. root extract was performed using a gradient reversed phase high performance liquid chromatography/UV/electrospray-ionization ion-trap mass spectrometry (HPLC/UV/ESI-MS) method on an embedded polar column. MS1 and MS2 fragmentation data were used for identification purposes while UV was used for quantification. Thirteen N-alkylamides (five N-isobutylamides, three N-methyl isobutylamides, four tyramides and one 2-phenylethylamide) were detected. Six of them, identified as undeca-2E,4E-diene-8,10-diynoic acid isobutylamide, undeca-2E,4E-diene-8,10-diynoic acid N-methyl isobutylamide, tetradeca-2E,4E-diene-8,10-diynoic acid tyramide, deca-2E,4E-dienoic acid N-methyl isobutylamide, tetradeca-2E,4E,XE/Z-trienoic acid tyramide and tetradeca-2E,4E,XE/Z,YE/Z-tetraenoic isobutylamide, are novel compounds which have never been reported before from Anacyclus pyrethrum.

Human skin penetration of selected model mycotoxins.

Dermal exposure data for mycotoxins are very scarce and fragmentary, despite their widespread skin contact and hazard toxicity. In this study, the transdermal kinetics of aflatoxin B1 (AFB1), ochratoxin A (OTA), fumonisin B1 (FB1), citrinin (CIT), zearalenone (ZEA) and T-2 toxin (T-2) were quantitatively evaluated, using human skin in an in vitro Franz diffusion cell set-up. All mycotoxins penetrated through the skin, except for FB1, which showed concentrations in the receptor fluid below the LoD, resulting in a K(p)<3.24×10(-6)cm/h. OTA showed the highest permeation (K(p)=8.20×10(-4)cm/h), followed by CIT (K(p)=4.67×10(-4)cm/h). AFB1 and ZEA showed lower permeability rates (K(p)=2.11 and 2.33×10(-4)cm/h, respectively). T-2 was found to have the lowest permeability (K(p)=6.07×10(-5)cm/h). From literature-based mycotoxin-concentrations, dermal contact surface, exposure time and apparent K(p)'s obtained in this study, the daily dermal exposure (DDE) in two industrial and one residential scenario was estimated. Dermal exposure to the DNA-reactive genotoxic carcinogenic AFB1 can lead to a health risk for agricultural workers which are exposed to a mycotoxin contaminated solution in a worst case situation. For all the other investigated mycotoxins, no significant health risk is calculated after dermal contact in neither agricultural nor residential environments.

Alkamid database: Chemistry, occurrence and functionality of plant N-alkylamides.

ETHNOPHARMACOLOGICAL RELEVANCE: N-Alkylamides (NAAs) are a promising group of bioactive compounds, which are anticipated to act as important lead compounds for plant protection and biocidal products, functional food, cosmeceuticals and drugs in the next decennia. These molecules, currently found in more than 25 plant families and with a wide structural diversity, exert a variety of biological-pharmacological effects and are of high ethnopharmacological importance. However, information is scattered in literature, with different, often unstandardized, pharmacological methodologies being used. Therefore, a comprehensive NAA database (acronym: Alkamid) was constructed to collect the available structural and functional NAA data, linked to their occurrence in plants (family, tribe, species, genus). MATERIALS AND METHODS: For loading information in the database, literature data was gathered over the period 1950-2010, by using several search engines. In order to represent the collected information about NAAs, the plants in which they occur and the functionalities for which they have been examined, a relational database is constructed and implemented on a MySQL back-end. RESULTS: The database is supported by describing the NAA plant-, functional- and chemical-space. The chemical space includes a NAA classification, according to their fatty acid and amine structures. CONCLUSIONS: The Alkamid database (publicly available on the website http://alkamid.ugent.be/) is not only a central information point, but can also function as a useful tool to prioritize the NAA choice in the evaluation of their functionality, to perform data mining leading to quantitative structure-property relationships (QSPRs), functionality comparisons, clustering, plant biochemistry and taxonomic evaluations.

Stability of extemporaneously prepared cytarabine, methotrexate sodium, and methylprednisolone sodium succinate.

PURPOSE: The short-term stability of extemporaneously prepared triple intrathecal therapy, containing cytarabine, methotrexate sodium, and methylprednisolone sodium succinate, was evaluated. METHODS: Three batches of triple intrathecal solution were prepared using commercially available products and stored in three different packaging materials (plastic syringe system, brown glass vials, and brown glass vials filled with metal needles). The solutions were protected from light and stored at 5 °C, 25 °C, and 40 °C or exposed to ultraviolet and visible light at 25 °C, compliant with the International Conference on Harmonisation. Samples were taken immediately before and after 4, 8, 24, 32, and 48 hours of storage. Simultaneous high-performance liquid chromatography- ultraviolet light/diode array detector assay of cytarabine, methotrexate sodium, and methylprednisolone sodium succinate was performed using a fused-core stationary phase and an acetonitrile-based gradient. First-order kinetic degradation values were calculated, and temperature dependence was evaluated using the Arrhenius equation. RESULTS: Cytarabine was stable under all storage conditions. Methotrexate sodium displayed significant degradation after light exposure but remained stable under the other storage conditions. Methylprednisolone sodium succinate was found to be the most labile component in the triple intrathecal solution. Temperature-dependent degradation was observed, resulting in 46% degradation after 48 hours at 40 °C. Two degradants were formed: methylprednisolone and methylprednisolone hydrogen succinate. Packaging material and batch-to-batch variability did not significantly influence the stability of the triple intrathecal solution. CONCLUSION: Triple intrathecal solution of cytarabine, methotrexate sodium, and methylprednisolone sodium succinate was stable for up to 12 hours when stored at 5 °C and protected from light.

Spilanthes acmella ethanolic flower extract: LC-MS alkylamide profiling and its effects on sexual behavior in male rats.

According to Indian Systems of Medicine, Spilanthes acmella (L.) Murr. (Family - Asteraceae), is considered effective in the treatment of sexual deficiencies especially due to ageing. In the present study, characterization of ethanolic extracts of the Spilanthes acmella flower and its effect on general mating pattern, penile erection and serum hormone levels of normal male Wistar albino rats were investigated and compared with sildenafil citrate. In vitro nitric oxide release was also investigated in human corpus cavernosum cell line. As N-alkylamides are a promising group, their profiling was performed using a gradient reversed phase high performance liquid chromatography/electrospray ionization ion trap mass spectrometry (HPLC/ESI-MS) method on an embedded polar column. MS(1) and MS(2) fragmentation data were used for identification purposes. For assessment of sexual behavior, animals were divided into five groups of eight male rats. The extracts (50, 100 and 150mg/kgbodyweight/day) and sildenafil citrate (5mg/kgbodyweight/day) (positive control) were administered orally for 28 days. The behavioral and sexual parameters were observed at days 0, 15, 28 and after a lapse of 7 and 14 days of discontinuance of drug treatment. Five N-isobutylamides, one 2-methylbutylamide and one 2-phenylethylamide were identified. The orally administered extract had a dose dependent positive effect on mounting frequency, intromission frequency and ejaculation frequency and the most significant effects (p<0.05) were observed at 150mg/kg treatment, even after a lapse of 7 and 14 days of discontinuance of drug treatment. A dose dependent effect was also observed on the FSH, LH and testosterone serum levels. With 150mg/kg of ethanolic extract the values for FSH, LH and testosterone were 3.10±0.25mlU/ml, 6.87±0.18mlU/ml and 3.72±0.12ng/ml, respectively. In vitro nitric oxide release was 21.7±2.9µM, which was significantly higher compared to the control group (p<0.01). Sildenafil citrate exhibited also a significant effect on NO release, but no effect on hormone levels of rats was observed. The aphrodisiac potential of an ethanolic Spilanthes acmella extract was demonstrated in vitro and in vivo. N-Alkylamides might attribute to the improved sexual potential. Study lends support to the traditional utilization of S. acmella as a sexual stimulating agent.

Vancomycin release from poly(D,L-lactic acid) spray-coated hydroxyapatite fibers.

The influence of the poly(D,L-lactic acid) (PDLLA) coating thickness on the in vitro vancomycin release from a hydroxyapatite (HA) carrier was studied. Microporous HA fibers with a porosity of 51 v% and an average pore diameter of 1.0 µm were fabricated by a diffusion-induced phase separation technique. They were loaded with 38 mg vancomycin hydrochloride (VH)/gHA, and their cylindrical shape enabled the application of the spray coating technique for the deposition of uniform PDLLA coating thicknesses, varying from 6.5 µm to 28 µm. The resulting in vitro VH release varied from a complete release within 14 days for 6.5 µm coatings to a release of 23% after 28 days for 28 µm coatings. It was clear that the VH release rate from a HA fiber can be adjusted by varying the PDLLA coating thickness. Microbiological tests of these fibers against a methicillin-resistant Staphylococcus aureus (MRSA) isolate pointed to the importance of the initial burst release and confirmed that the released antibiotics had the potential to interfere with S. aureus biofilm formation.

A new discriminative criterion for the development of Franz diffusion tests for transdermal pharmaceuticals.

PURPOSE: In vitro skin/membrane permeation profiling of topical pharmaceuticals is an important overall quality attribute in the evaluation of product consistency and it is also used for IVIVR (in vitro - in vivo relationship) purposes in product development and change control. Franz diffusion cell (FDC) experiments are emerging as a generally accepted methodology in this field, where the choice of operational conditions requires a data-supported justification towards the discriminating power of the test. A response function is therefore proposed to objectively quantify the discriminating power. METHODS: We evaluated the usefulness of the proposed response function by studying one of the operational conditions, i.e. the influence of receptor medium composition, on the FDC in vitro penetration behaviour of the model compound testosterone formulated in four different topical preparations, using both artificial membranes and dermatomed human skin. RESULTS: From the obtained cumulative amount of testosterone in the receptor fluid versus time curves, the permeability coefficient Kp of testosterone from each formulation was calculated. The evaluation of the discriminating power of the different media was performed using our new objective response function based upon an equal spread criterion of normalised Kp values. CONCLUSION: We demonstrated significant differences in discriminating power between the different media used, with the overall best results obtained with hydroxypropyl-beta-cyclodextrine (HPBCD) containing media. The proposed new criterion was found to be useful for the rational design of an in vitro diffusion test for transdermal pharmaceuticals.