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Howard I Maibach - One of the best experts on this subject based on the ideXlab platform.

  • Percutaneous Penetration of Methyl Nicotinate from Ointments Using the Laser Doppler Technique: Bioequivalence and Enhancer Effects
    Journal of Pharmacokinetics and Pharmacodynamics, 2006
    Co-Authors: Yvonne Remane, Claudia S. Leopold, Howard I Maibach
    Abstract:

    Laser Doppler flowmetry (LDF) may be used to quantify erythema response as a result of an increased cutaneous microcirculation induced by Methyl Nicotinate (MN). Bioequivalence of a test and a standard preparation (vehicles: light mineral oil and medium chain triglycerides, respectively) was confirmed according to the pilot study of the FDA Guidance for Industry “Topical dermatologic corticosteroids: In Vivo bioequivalence” applying the staggered application and synchronized removal method for one defined concentration. Furthermore, the influence of penetration enhancers (5% w/w DiMethylsulfoxide (DMSO) and 10% w/w diethylene glycol monoethyl ether) on MN penetration was investigated. It was shown that DMSO and diethylene glycol monoethyl ether altered cutaneous microcirculation and thus MN penetration in comparison to the standard formulation. However, true penetration enhancement could only be proved with diethylene glycol monoethyl ether resulting from an improved drug solubility in the skin which was confirmed by attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR). Increased MN penetration by DMSO was only caused by thermodynamic effects, i.e. a decreased drug solubility in the vehicle.

  • clinical microneedle injection of Methyl Nicotinate stratum corneum penetration
    Skin Research and Technology, 2005
    Co-Authors: Raja K Sivamani, Boris Stoeber, Gabriel C Wu, Hongbo Zhai, Dorian Liepmann, Howard I Maibach
    Abstract:

    Background/purpose: In recent years, microneedles were proposed as a method to painlessly deliver drugs past the stratum corneum. Microneedles have been fabricated in several designs, but limited studies have tested microneedle injections in humans. In this work, we compare microneedle injections with topical application (TA) to investigate if microneedles enhance in vivo drug delivery past the stratum corneum. Method: In vitro tests were used to measure microneedle pressures and injection volumes. In vivo microneedle injections were performed on the volar forearm of 11 healthy volunteers. Two sets of microneedles, pointed and symmetric, were used to develop microneedle/syringe apparatuses that were used to inject approximately 1 μL of 0.1 M Methyl Nicotinate, and were compared against TA. A Laser Doppler Perfusion Monitor was used to record maximum blood flow and the time to maximum blood flow at the treatment sites. Results: Pointed and symmetric microneedle-injected sites showed a significantly faster time to maximum blood flow than TA. The pointed microneedle injections also resulted in a higher maximum blood flux. Volunteers reported feeling pressure but no pain from the microneedles during the injections. Conclusion: The microneedles aid in bypassing the stratum corneum and enhance drug delivery through it. The design of the microneedle influences its delivery capabilities, because the pointed microneedles seem to be less susceptible to clogging during the injection.

  • effect of lipophilic vehicles on in vivo skin penetration of Methyl Nicotinate in different races
    International Journal of Pharmaceutics, 1996
    Co-Authors: Claudia S. Leopold, Howard I Maibach
    Abstract:

    Studies on racial differences in percutaneous penetration have mainly focused on measurements of either the pharmacodynamic response of a drug or skin reactivity to irritants. In order to clarify the contribution of the barrier stratum corneum to the overall drug penetration rate in different races, an in vivo permeability study was conducted with Methyl Nicotinate as the model drug. Four races (Caucasians, Hispanics, Blacks, Asians) were investigated. The drug was dissolved in various lipophilic vehicles (dimethicone 100, light mineral oil, isopropyl myristate, medium chain triglycerides) at concentrations that provide equal drug escaping tendencies. Drug solutions were applied to the upper arms of 48 subjects (four races with 12 subjects each) with a glass chamber system. To avoid drug depletion, drug disappearance rates were measured under steady-state conditions by the so-called difference method. Drug flux among the four races increases in the following order: Blacks < Asians < Caucasians < Hispanics. The effect of race almost reaches significance level (P = 0.067). Fisher's PLSD post-hoc procedure indicated a significant difference between drug penetration in Hispanics and Blacks (P = 0.009) suggesting structural or functional differences in the stratum corneum. Enhancement factors were calculated from the steady-state flux values, (i.e. drug disappearance rates per area unit) for each race. Significant enhancing effects (P = 0.0001) were observed with the vehicles isopropyl myristate and mineral oil with all races.

  • cutaneous responses to topical Methyl Nicotinate in human forearm and vulvar skin
    Journal of Dermatological Science, 1991
    Co-Authors: Peter Elsner, Howard I Maibach
    Abstract:

    Abstract In order to identify and define differences in percutaneous absorption and microcirculatory sensitivity between forearm and vulvar skin we studied the response of human forearm and vulvar (labium majus) skin to topical Methyl Nicotinate (MN) in 11 healthy premenopausal volunteers. MN-induced erythema was assessed by laser Doppler velocimetry (LDV). The following parameters were compared: 1) basal cutaneous blood flow, 2) the time to peak response, 3) the magnitude of LDV peak response, 4) the area under the LDV resonse-time curve and 5) the decay time to 75% of peak response. Basal cutaneous blood flow at the vulva was higher than at the forearm (P The results indicate that the MN-induced vasodilatation is less intense and lasts shorter in vulvar compared to forearm skin.

  • percutaneous penetration of Methyl Nicotinate at three anatomic sites evidence for an appendageal contribution to transport
    Skin Pharmacology and Physiology, 1991
    Co-Authors: Howard I Maibach
    Abstract:

    Percutaneous absorption of the vasodilator Methyl Nicotinate (MN) was evaluated in human volunteers at three anatomic sites (forehead, forearm and palm) using the technique of laser Doppler flowmetry

M. Vairamani - One of the best experts on this subject based on the ideXlab platform.

  • Identification and quantification of Methyl Nicotinate in rice (Oryza sativa L.) by gas chromatography–mass spectrometry☆
    Food Chemistry, 2007
    Co-Authors: B Muralidhararao, U Saradhi, N Shobharani, G Ramanjaneyulu, Shashi Prabhakar, G Prasad, M. Vairamani
    Abstract:

    During the course of analysis of popular rice varieties cultivated in India towards identification of their aroma compounds, Methyl Nicotinate (MN), a medicinal and flavour additive compound, was identified for the first time in rice samples. A simple direct solvent extraction method using 300mg of the sample is developed to extract MN in rice samples and detected by capillary gas chromatography–mass spectrometry analysis. Quantitative analysis of MN is performed for polished rice, brown rice and rice bran samples from five rice varieties that are widely produced in India by using GC–MS operating under SIM mode (m/z 106). The quantity of MN is in the range of 0.63–1.30μg/g, 1.37–3.99μg/g and 1.87–12.04μg/g for polished rice, brown rice and rice bran samples, respectively. Breeding programmes for rice with high concentrations of MN can be greatly facilitated by establishing the concentrations of the MN in new cultivars. This method is more economic with less time consumption and enables fast screening of a large number of samples.

  • identification and quantification of Methyl Nicotinate in rice oryza sativa l by gas chromatography mass spectrometry
    Food Chemistry, 2007
    Co-Authors: U Saradhi, G Ramanjaneyulu, Shashi Prabhakar, Shobha N Rani, G S V Prasad, M. Vairamani
    Abstract:

    During the course of analysis of popular rice varieties cultivated in India towards identification of their aroma compounds, Methyl Nicotinate (MN), a medicinal and flavour additive compound, was identified for the first time in rice samples. A simple direct solvent extraction method using 300 mg of the sample is developed to extract MN in rice samples and detected by capillary gas chromatography-mass spectrometry analysis. Quantitative analysis of MN is performed for polished rice, brown rice and rice bran samples from five rice varieties that are widely produced in India by using GC-MS operating under SIM mode (m/z 106). The quantity of MN is in the range of 0.63-1.30 μg/g, 1.37-3.99 μg/g and 1.87-12.04 μg/g for polished rice, brown rice and rice bran samples, respectively. Breeding programmes for rice with high concentrations of MN can be greatly facilitated by establishing the concentrations of the MN in new cultivars. This method is more economic with less time consumption and enables fast screening of a large number of samples.

  • analytical nutritional and clinical methods identification and quantification of Methyl Nicotinate in rice oryza sativa l by gas chromatography mass spectrometry q
    2007
    Co-Authors: Shobha N Rani, Shashi Prabhakar, M. Vairamani
    Abstract:

    During the course of analysis of popular rice varieties cultivated in India towards identification of their aroma compounds, Methyl Nicotinate (MN), a medicinal and flavour additive compound, was identified for the first time in rice samples. A simple direct solvent extraction method using 300 mg of the sample is developed to extract MN in rice samples and detected by capillary gas chromatography–mass spectrometry analysis. Quantitative analysis of MN is performed for polished rice, brown rice and rice bran samples from five rice varieties that are widely produced in India by using GC–MS operating under SIM mode (m/z 106). The quantity of MN is in the range of 0.63–1.30 lg/g, 1.37–3.99 lg/g and 1.87–12.04 lg/g for polished rice, brown rice and rice bran samples, respectively. Breeding programmes for rice with high concentrations of MN can be greatly facilitated by establishing the concentrations of the MN in new cultivars. This method is more economic with less time consumption and enables fast screening of a large number of samples.

Jonathan Hadgraft - One of the best experts on this subject based on the ideXlab platform.

  • Skin permeability data: Anomalous results
    International Journal of Pharmaceutics, 1998
    Co-Authors: I.tuncer Degim, W. John Pugh, Jonathan Hadgraft
    Abstract:

    Abstract Analysis of published skin permeation data has shown that a few compounds appear to have anomalous skin permeability coefficients. These include penetrants such as naproxen, atropine and nicotine. The permeabilities of these materials were re-determined together with aspirin, benzoic acid, diclofenac, ibuprofen and Methyl Nicotinate. The results are discussed in conjunction with published regression analyses and compared with values predicted by estimating the octanol–water partition coefficients using commercial software packages.

  • percutaneous absorption of Methyl Nicotinate
    International Journal of Pharmaceutics, 1995
    Co-Authors: C Lafforgue, I Eynard, F Falson, A C Watkinson, Jonathan Hadgraft
    Abstract:

    Abstract The percutaneous absorption of Methyl Nicotinate was measured in vitro across hairless rat skin. The Methyl Nicotinate was applied in vehicles containing propylene glycol dipelargonate, Labrafac Hydrophile® and Transcutol®. In vitro experiments were analysed using solutions to Fick's laws of diffusion in order to determine permeation parameters.

  • Phonophoresis of Methyl Nicotinate: A Preliminary Study to Elucidate the Mechanism of Action
    Pharmaceutical Research, 1993
    Co-Authors: James C. Mcelnay, Heather A. E. Benson, Robin Harland, Jonathan Hadgraft
    Abstract:

    The skin penetration enhancement effect of ultrasound (phonophoresis) on Methyl Nicotinate was investigated in 10 healthy volunteers in a double-blind, placebo-controlled, crossover clinical trial. Each treatment consisted of the application of ultrasound massage (3.0 MHz, 1.0 W/cm^2 continuous output) or placebo massage (0 MHz) for 5 min to the forearms of the volunteers, followed by a standardized application of Methyl Nicotinate at intervals of 15 sec, 1 min, and 2 min postmassage. Percutaneous absorption of Methyl Nicotinate was monitored using laser Doppler velocimetry. Ultrasound treatment applied prior to Methyl Nicotinate led to enhanced percutaneous absorption of the drug, for example, ultrasound treatment data versus control data at 2 min showed significant increases (P < 0.05; analysis of variance) in the peak blood flow (125.8 ± 12.0 vs 75.3 ± 10.4% flux) and in the area under the curve for blood flow (2630.3 ± 387.5 vs 1567.6 ± 183.5% flux · min). The results of this study suggest that ultrasound affects the skin structure to provide skin penetration enhancement. This finding is consistent with the proposed hypothesis that phonophoresis acts by disordering the structured lipids in the stratum corneum.

  • surfactant effects in percutaneous absorption i effects on the transdermal flux of Methyl Nicotinate
    International Journal of Pharmaceutics, 1992
    Co-Authors: Paul Ashton, Kenneth A Walters, Keith Roger Brain, Jonathan Hadgraft
    Abstract:

    Abstract We have investigated the effects of a series of surfactants on the permeability of human skin in vitro using Methyl Nicotinate as a model drug. The surfactants used were cetyl triMethyl ammonium bromide, sodium lauryl sulphate, decyl Methyl sulphoxide and Brij 36T. These surfactants have a linear alkyl chain of 10–12 units linked to different hydrophilic groups. We found that while the ionic surfactant exerted a greater effect on the flux of Methyl Nicotinate, the nonionic surfactants had a smaller but more immediate effect on the flux. This is consistent with the hypothesis that for compounds to disturb the permeability barrier of the stratum corneum they must first penetrate it themselves. Ionic compounds can be expected to penetrate this lipophilic barrier more slowly than nonionic compounds of a similar structure and therefore will take longer to elicit their effects.

Suojiang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • aluminum deposition from lewis acidic 1 butyl 3 Methylimidazolium chloroaluminate ionic liquid bmim cl alcl3 modified with Methyl Nicotinate
    ChemElectroChem, 2015
    Co-Authors: Qian Wang, Bin Chen, Qinqin Zhang, Xingmei Lu, Suojiang Zhang
    Abstract:

    The potentiostatic electrodeposition of aluminum (Al) on copper (Cu) substrates from [Bmim]Cl/AlCl3(33.3/66.7mol%) ionic liquid (IL) containing different concentrations of Methyl Nicotinate (MN) was studied at 303K. It was found that the grain size of the deposits decreased from micron-sized to nanoscale and the preferred Al(200) crystallographic orientation became stronger when increasing the concentration of MN from 2 to 8 mmolL(-1). At a modest potential, a mirror-bright Al coating could be obtained when the concentration of MN was no less than 4mmolL(-1). Furthermore, atomic force microscopy and cyclic voltammetry were used to investigate the effect of MN on the electrodeposition of Al, which demonstrated that MN acted simultaneously as a brightener and a leveling agent by adsorbing on the electrode surface, producing Al coatings with a highly uniform and smooth surface.

  • Aluminum Deposition from Lewis Acidic 1‐Butyl‐3‐Methylimidazolium Chloroaluminate Ionic Liquid ([Bmim]Cl/AlCl3) Modified with Methyl Nicotinate
    ChemElectroChem, 2015
    Co-Authors: Qian Wang, Bin Chen, Qinqin Zhang, Xingmei Lu, Suojiang Zhang
    Abstract:

    The potentiostatic electrodeposition of aluminum (Al) on copper (Cu) substrates from [Bmim]Cl/AlCl3(33.3/66.7mol%) ionic liquid (IL) containing different concentrations of Methyl Nicotinate (MN) was studied at 303K. It was found that the grain size of the deposits decreased from micron-sized to nanoscale and the preferred Al(200) crystallographic orientation became stronger when increasing the concentration of MN from 2 to 8 mmolL(-1). At a modest potential, a mirror-bright Al coating could be obtained when the concentration of MN was no less than 4mmolL(-1). Furthermore, atomic force microscopy and cyclic voltammetry were used to investigate the effect of MN on the electrodeposition of Al, which demonstrated that MN acted simultaneously as a brightener and a leveling agent by adsorbing on the electrode surface, producing Al coatings with a highly uniform and smooth surface.

  • Electrodeposition of Bright Al Coatings from 1-Butyl-3-Methylimidazolium Chloroaluminate Ionic Liquids with Specific Additives
    Journal of The Electrochemical Society, 2015
    Co-Authors: Qian Wang, Bin Chen, Qinqin Zhang, Xingmei Lu, Suojiang Zhang
    Abstract:

    The electrodeposition of aluminum (Al) on copper (Cu) substrate was investigated in [Bmim] Cl/AlCl3 (33.3/66.7 mol%) ionic liquid using three pyridine derivatives, nicotinic acid, Methyl Nicotinate, and 3-Methyl pyridine as additives at 303 K, respectively. It was found that bright Al coatings could be electrodeposited with nicotinic acid and Methyl Nicotinate as additives. SEM and XRD characterizations revealed that the bright coatings were very smooth, composed of nanocrystalline and with a strong (200) preferential orientation. By contrast, a matte and lusterless Al coating was obtained from the ionic liquid with 3-Methyl pyridine. Furthermore, the effect of the three additives was investigated by means of cyclic voltammetry, chronopotentiometry and Raman spectroscopy. It was demonstrated that nicotinic acid and Methyl Nicotinate could absorb on electrode surface more easily and thus served as very effective brighteners producing highly uniform and smooth Al coatings. However, 3-Methyl pyridine had no such effect. (C) The Author(s) 2015. Published by ECS. All rights reserved.

Shigehiro Konaka - One of the best experts on this subject based on the ideXlab platform.

  • conformational studies by 1h nmr in a nematic solvent Methyl isoNicotinate Methyl Nicotinate and Methyl picolinate
    Journal of Molecular Structure, 1999
    Co-Authors: Hajime Kiyono, Hiroshi Takeuchi, Kaori Inoue, Shigehiro Konaka
    Abstract:

    Abstract The structures of Methyl isoNicotinate (MI), Methyl Nicotinate (MN) and Methyl picolinate (MP), i.e., 4-, 3-, and 2-pyridinecarboxylic acid Methyl esters, were studied by 1 H−NMR at 296 K using nematic liquid–crystal solvent ZLI 1167. Conformational analysis was performed according to the model of Emsley, Luckhurst and Stockley to take account of the correlation between rotation and internal rotation. Only the conformer with a planar skeleton was detected for MI but s- trans and s- cis conformers were found for MN and MP. The relative abundance of the s- trans form was determined to be 64(2) and 68(2)% for MN and MP, respectively, which are in agreement with those determined by gas-phase electron diffraction. The positions of the ring protons of MI in ZLI 1167 agree with those in the gas phase within experimental errors. In the case of MN and MP, however, observed direct coupling constants between the ring protons are in poor agreement with those calculated from the gas-phase structures due to the deformation of the pyridine rings in ZLI 1167.

  • structure determination of Methyl Nicotinate and Methyl picolinate by gas electron diffraction combined with ab initio calculations
    Journal of Physical Chemistry A, 1998
    Co-Authors: Hajime Kiyono, Hiroshi Takeuchi, Ryosuke Tatsunami, Teruyo Kurai, Toru Egawa, Shigehiro Konaka
    Abstract:

    The molecular structures of isomers, Methyl Nicotinate and Methyl picolinate, have been studied by gas electron diffraction. The samples were heated to 341-343 K by using a high-temperature nozzle to get enough vapor pressure. HF/6-31G* ab initio calculations were carried out, and structural constraints were taken from their results. Vibrational amplitudes and shrinkage corrections were calculated from the harmonic force constants given by normal coordinate analyses. The principal structural parameters of the s-trans conformer of Methyl Nicotinate are as follows (angle brackets mean averaged values): 〈rg(N-C)〉 ) 1.337(7) A; 〈rg(C-C)ring〉 ) 1.402(3) A; rg(Cring-C(dO)) ) 1.480(12) A; rg(CdO) ) 1.199(7) A; 〈rg(C-O)〉 ) 1.380(11) A; ∠RCNC ) 119.0(14)°; 〈∠RNCC〉 ) 122.8(11)°; ∠R(Nd)C-Cring-C(dO) ) 118.3(12)°; ∠RCring-CdO ) 121.5(12)°; ∠RCring-C-O ) 115.6(10)°. Those of the s-trans conformer of Methyl picolinate are as follows: 〈rg(N-C)〉 ) 1.344(7) A; 〈rg(C-C)ring〉 ) 1.398(4) A; rg(Cring-C(dO)) ) 1.497(11) A; rg(CdO) ) 1.209(7) A; 〈rg(CO)〉 ) 1.380(11) A; ∠RCNC ) 117.2(12)°; 〈∠RNCC〉 ) 123.9(12)°; ∠RN-C-C(dO) ) 115.1(10)°; ∠RCringCdO ) 121.0(12)°; ∠RCring-C-O ) 115.1(12)°. The structural parameters of the two isomers and Methyl isoNicotinate have been compared and their similarity and differences have been discussed.

  • conformational studies by liquid crystal nmr and ab initio calculations Methyl Nicotinate and Methyl isoNicotinate
    Journal of Molecular Structure, 1992
    Co-Authors: Hideki Kurokawa, Hiroshi Takeuchi, Shigehiro Konaka
    Abstract:

    Abstract Conformational properties of Methyl Nicotinate and Methyl isoNicotinate have been studied by liquid crystal 1 H-NMR spectroscopy combined with ab initio calculations. The solvent used is a mixture of 80 mol.% of EBBA and 20 mol.% of MBBA.Ab initio calculations have been performed with 4-21G and MINI-4 basis sets to estimate molecular structures and the potential functions for internal rotation. Some structural parameters and the energy difference between rotational isomers have been refined by using observed dipolar coupling constants. The correlation between internal rotation and reorientational molecular motion has been taken into account according to the theory of Emsley, Luckhurst and Stockley. The parameters of the mean external potential are found to take similar values for Methyl Nicotinate and Methyl isoNicotinate. The energy difference of the two stable conformers of Methyl Nicotinate is in agreement with the analysis neglecting the correlation between the two motions.