Formulation and evaluation of transdermal drug-delivery system of isosorbide dinitrate / Formulação e avaliação de sistema transdérmico droga-entrega de dinitrato de isossorbida

The purpose of this study was to develop a reservoir-type transdermal delivery system for isosorbide dinitrate (ISDN). The developed patch consisted of five layers from bottom to top, namely, a temporary liner, an adhesive layer, a rate-controlling membrane, a reservoir and a backing. The effects of chemical penetration enhancers, reservoir materials and rate-controlling membranes on the release behaviour of ISDN from the transdermal patch were studied, and the in vitro release of ISDN from the developed patch was studied and compared with the commercially available ISDN patch. The results showed that there was no significant difference in permeation rates between the developed reservoir-type patch and the commercially available ISDN patch (p> 0.05). Moreover, the cumulative release ratio of the commercially available ISDN patch in 48 h was up to 89.8%, whereas the developed patch was only 34.9%, which meant the sustained release time of the developed patch was much longer than the commercially available ISDN patch, and would promote the satisfaction of the patient...

O objetivo do presente estudo foi desenvolver um sistema de liberação transdérmico do tipo reservatório para o dinitrato de isossorbida (ISDN, abrevitura em Inglês). A formulação transdérmica desenvolvida constou de cinco camadas de baixo para cima, ou seja, um revestimento temporário, uma camada adesiva, uma membrana controladora da taxa de liberação, um reservatório e um reforço. Estudaram-se os efeitos dos potenciadores de penetração química, materiais do reservatório e membranas de controle da taxa de liberação no comportamento da formulação transdérmica de dinitrato de isossorbida. A liberação in vitro da formulação transdérmica de dinitrato de isossorbida desenvolvida foi estudada em comparação com a formulação de dinitrato de isossorbida disponível comercialmente. Os resultados mostraram que não existem diferenças significativa nas taxas de permeação entre o tipo de reservatório desenvolvido e o de dinitrato de isossorbida desenvolvido comercialmente (p>0,05). Ademais, a taxa de liberação cumulativa da formulação de dinitrato de isossorbida disponível comercialmente em 48 horas foi de até 89,8% e a da formulação desenvolvida, de apenas de 34,9%, o que provou que a liberação sustentada da formulação desenvolvida foi muito maior do que a de dinitrato de isossorbida desenvolvida comercialmente, o que promoveria a satisfação do paciente...

CGRP mediate the isosorbide-5-mononitrate cardiovascular response in healthy Chinese male volunteers through a XOR-independent pathway.

OBJECTIVES: This study was designed to determine whether xanthine oxidoreductase (XOR) is involved in Isosorbide- 5-mononitrate (IS-5-MN) metabolism, and to elucidate the role of the neuropeptide calcitonin gene-related peptide (CGRP) in the IS-5-MN response. METHODS: In 15 Chinese volunteers, we observed the relationship between baseline XOR-mRNA expression in peripheral blood mononuclear cells (PBMCs) and the response to 20 mg IS-5-MN. IS-5-MN pharmacokinetics profiles, changes in plasma concentrations of CGRP, and CGRPmRNA expression in PBMCs were assessed in vivo and in vitro. RESULTS: Individuals with a lower baseline XOR-mRNA expression showed lower plasma XOR activity and significantly greater changes in SBP (ΔSBP) after IS-5-MN administration. Individuals with a lower baseline XOR-mRNA expression also showed significantly greater increases in plasma concentrations of CGRP. There were no differences in IS-5-MN AUC between the two groups. IS-5-MN significantly up-regulated the expression of CGRP α- and CGRP ß-mRNA in PBMCs, which were not affected by the XOR inhibitor allopurinol. CONCLUSIONS: Our study suggests that CGRP may contribute to the response to IS-5 MN in a XOR-independent pathway.

Pharmacokinetic properties of isosorbide-5-mononitrate under fasting and fed conditions in healthy male subjects.

OBJECTIVE: This study was performed to compare the pharmacokinetic properties and relative bioavailability of two isosorbide-5-mononitrate (5-ISMN) sustained-release drugs in healthy Korean subjects under fasting and fed conditions. METHODS: A total of 60 healthy volunteers (30 each in the fasting and fed arms of the study) were enrolled in the study and were randomized to treatment. After the administration of a single dose of one of the investigational products, blood samples were collected at specific time intervals from 0 to 36 hours. The plasma concentrations of 5-ISMN were measured by LC-MS/MS. The pharmacokinetic parameters were calculated, and the 90% confidence intervals (CIs) of the geometric mean ratio (test/reference) of the parameters were obtained by analysis of variance on logarithmically transformed data. RESULTS: The corresponding 90% CIs of AUClast and Cmax for the test/reference geometric mean ratio were 90.75 - 98.44% and 92.28 - 98.33%, respectively, under fasting conditions. In the fed state study, the 90% CIs for the geometric mean ratio of test to reference drugs were 94.79 - 103.33% for AUClast and 99.86 - 108.02% for Cmax. CONCLUSION: The test product is equivalent to the reference product in subjects under fasting and fed conditions within the Korean regulatory bioequivalence criteria. Both formulations were safe and well tolerated, and there were no noteworthy differences in the safety profiles between the test and reference drugs.

Combined isosorbide dinitrate and ibuprofen as a novel therapy for muscular dystrophies: evidence from Phase I studies in healthy volunteers.

We designed two Phase I studies that assessed healthy volunteers in order to evaluate the safety and to optimize the dosing of the combination of the drugs isosorbide dinitrate, a nitric oxide donor, and ibuprofen, a nonsteroidal antiinflammatory drug. We designed these studies with the aim of designing a Phase II trial to evaluate the drugs' efficacy in patients affected by Duchenne muscular dystrophy. For the first trial, ISOFEN1, a single-dose, randomized-sequence, open-label, active control, three-treatment cross-over study, was aimed at comparing the pharmacokinetics of ibuprofen 200 mg and isosorbide dinitrate 20 mg when given alone and concomitantly. The pharmacokinetics of ibuprofen given alone versus ibuprofen given concomitantly with isosorbide dinitrate were similar, as documented by the lack of statistically significant differences in the main drug's pharmacokinetic parameters (time to maximal concentration [Tmax], maximal concentration [Cmax], area under the curve [AUC]0-t, and AUC0-∞). Similarly, we found that the coadministration of ibuprofen did not significantly affect the pharmacokinetics of isosorbide dinitrate. No issues of safety were detected. The second trial, ISOFEN2, was a single-site, dose titration study that was designed to select the maximum tolerated dose for isosorbide dinitrate when coadministered with ibuprofen. Eighteen out of the 19 enrolled subjects tolerated the treatment well, and they completed the study at the highest dose of isosorbide dinitrate applied (80 mg/day). One subject voluntarily decided to reduce the dose of isosorbide dinitrate from 80 mg to 60 mg. The treatment-related adverse events recorded during the study were, for the large majority, episodes of headache that remitted spontaneously in 0.5-1 hour - a known side effect of isosorbide dinitrate. These studies demonstrate that the combination of isosorbide dinitrate and ibuprofen does not lead to pharmacokinetic interactions between the two drugs; they also demonstrate that the combination of isosorbide dinitrate and ibuprofen has optimal tolerability and safety profiles that are similar to those previously reported for isosorbide dinitrate and ibuprofen given alone.

Evaluation of novel immediate-/controlled-release tablets of isosorbide-5-mononitrate (5-ISMN): in vitro-in vivo correlation.

The aim of the present study was to develop the novel immediate-controlled release (ICR) tablets of isosorbide-5-mononitrate (5-ISMN) composed of an osmotic pump tablet core coated with an immediate-release layer. The novel ICR tablets of 5-ISMN could release drug quickly and continuously through a semi-permeable membrane (SPM) composed of ethylcellulose (EC)/polyethylene glycol (PEG) 4000 and cellulose acetate (CA)/PEG4000. Release tended to decrease with storage time. However, the drug release rates changed little for the SPM composed of EC/PVP K30. The weight loss test also confirmed these results. The major release mechanism was diffusion according to the Higuchi equation. The relative bioavailability of the ICR tablets compared to the reference formulation in the single and multiple dose regiments were 90.9 and 111.2%, respectively. They were both bioequivalent to the reference formulation. In vitro-in vivo correlation (IVIVC) studies demonstrated that the dissolution in vitro simulated the absorption in vivo well. In general, 5-ISMN ICR tablets composed of an osmotic pump tablet core and an immediate-release layer may be promising in providing immediate and constant drug delivery with minimum fluctuations during long storage time.

A simple and sensitive gas chromatography method for determination of isosorbide dinitrate and its metabolites in human plasma: application to pharmacokinetics study on oral spray.

A sensitive method for the simultaneous determination of isosorbide dinitrate (ISDN) and its mononitrate metabolites, isosorbide 2-mononitrate and isosorbide 5-mononitrate (IS-2-MN and IS-5-MN), in human plasma was developed using capillary gas chromatography with electron-capture detection, whereas 1,2,4-butanetriol trinitrate was used as internal standard. The analytes were extracted with a simple liquid-liquid extraction from plasma and separated on a DB-1 column. The results of method validation demonstrated that the calibration curves were linear in range of 2-60 ng/mL for ISDN and IS-5-MN, 1-20 ng/mL for IS-2-MN, respectively. The precision (RSD%) was less than 15%, and the lower limit of quantitation was identifiable and reproducible at 2 ng/mL for ISDN and IS-5-MN, 1 ng/mL for IS-2-MN. The analytes in plasma were stable after being stored for more than 30 days and after 2 freeze-thaw cycles (-20 to 25°C). And then this method was successfully applied to a pharmacokinetic investigation on isosorbide dinitrate oral spray in healthy volunteers.

[The effects and its mechanism of N-arginine chitosan as transdermal enhancer].

The purpose of this study is to investigate the penetration effects and mechanism of N-arginine chitosan (ACS). This novel transdermal enhancer with a mimetic structure of cell-penetration peptides was synthesized by introducing hydrophilic arginine groups to the amino-group on chitosan's side chain. The structure of ACS was confirmed by FT-IR, 1H NMR and element analysis. In addition, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used to study the protein conformation and the water content of stratum corneum, and the result suggested that ACS can change the orderly arrangement of the molecules in the stratum corneum, making the stack structure of keratin become loose. And ACS can increase the water content of the stratum corneurn. Inverted fluorescence microscope and flow cytometry were used to examine penetration effect of ACS on Hacat cell. The result confirmed that the uptake of ACS was enhanced with increased substitution degree of arginine by 4-8 folds compared to chitosan. In vitro penetration studies on three electrical types of drugs were carried out using three model drugs of negatively charged aspirin, positively charged terazosin and neutral drug isosorbide mononitrate by the method of Franz diffusion cells. The results showed that ACS has obviously penetration of the negatively charged drug aspirin, and certain penetration of neutral drug issorbide mononitrate, but inhibition of positively charged terazosin. In vivo imaging technology research results show that the ACS can significantly enhance the fluorescence intensity of morin, which is the auto-fluorescence anionic drug. These obtained results suggested that ACS, as a promising transdermal enhancer, can change the structure of the keratinocytes and analog penetrating peptides promote absorption, but have certain selectivity for the drug.

A novel permeation enhancer: N-succinyl chitosan on the intranasal absorption of isosorbide dinitrate in rats.

The purpose of this paper is to study the potential of N-succinyl chitosan as a novel permeation enhancer for the intranasal absorption of isosorbide dinitrate (ISDN). A series of N-succinyl chitosan (NSCS) with different degree of succinylation (DS) and molecular weight were synthesized. An in situ nasal perfusion technique in rats was utilized to investigate the effect of NSCS substitution degree, NSCS molecular weight and concentration on the intranasal absorption of ISDN. The absorption enhancing effect of NSCS was compared with that of chitosan. It was found that all the NSCS investigated improved the intranasal absorption of ISDN remarkably. Better promoting effect was observed for 0.1% NSCS 50 (63) compared with 0.5% chitosan 50. In nasal ciliotoxicity test, both NSCS and chitosan investigated showed good safety profiles. Thereafter, in vivo studies of the selected formulations were carried out in rats and the pharmacokinetic parameters were calculated and compared with that of intravenous injection. Both in situ and in vivo studies demonstrated that NSCS is more effective than chitosan in promoting intranasal absorption of ISDN. Taking both absorption enhancing and safety reason into account, we suggest NSCS is a promising intranasal absorption enhancer.

In vitro dissolution and in vivo bioequivalence evaluation of two brands of isosorbide 5-mononitrate sustained release tablets.

The purpose of the present study was to test a sustained release-tablet newly formulated with synthetic paraffin and compare its bioequivalence to that of the Imdur® Long-Acting tablet, based on the guidelines of the Korean Food and Drug Administration.Dissolution test was performed in 4 different dissolution media. A LC/MS/MS method of isosorbide 5-mononitrate in human plasma was validated. In vivo bioequivalence tests of the 2 isosorbide 5-mononitrate tablets were performed in both preprandial and postprandial states.A comparative dissolution test gave similar results for both tablets in all dissolution media tested: 40% dissolution in pH 1.2 at 2 h and 80% dissolution in pH 4.0, pH 6.8, or water at 10 h. In a bioequivalence study to compare 2 tablets, the mean total area under the curve (AUCt) and peak concentration (Cmax) in the fasted state were 8 476.0 ng · h/mL and 540.4 ng/mL, respectively, for the Imdur® Long Acting Tablet 60 mg, and 8 701.4 ng · h/mL and 564.2 ng/mL, respectively, for the test tablet. The mean AUCt and Cmax in the fed state were 8 793.5 ng · h/mL and 559.9 ng/mL, respectively, for the Imdur® Long-Acting tablet 60 mg, and 8 639.8 ng · h/mL and 617.9 ng/mL, respectively, for the test tablet. The 90% confidence intervals using log transformed data were within the acceptable range of 0.8 - 1.25.Based on these statistical analyses, we conclude that the test tablet is bioequivalent to the Imdur® Long-Acting tablet 60 mg in both the preprandial and postprandial states.

In vitro and in vivo evaluation of novel osmotic pump tablets of isosorbide-5-mononitrate containing polyvinyl pyrrolidone (PVP) for controlled release.

A novel osmotic pump tablet with ethyl cellulose (EC) and polyvinyl pyrrolidone (PVP) as the semipermeable membrane and isosorbide-5-mononitrate (5-ISMN) as the model drug was formulated in this study. Zero order release kinetics were attained by avoiding aging during storage. Drug release increased with an increase in the percentage of PVP K30 in the semipermeable membrane. However, drug release decreased with increased coating weight. Drug release rates decreased continuously for tablets coated with EC/PEG4000 and cellulose acetate (CA)/PEG4000. This tendency was more marked with longer storage time. However, there was little change in drug release rates for tablets with a semipermeable membrane of EC/PVP K30 at 6, 12 or 24 months. The weight loss test also validated the results mentioned above. The relative bioavailability of the osmotic-pump tablets against the reference formulation in single and multiple dose regimens was 116.7 and 106.5, respectively. This means that the bioavailability of osmotic pump tablets using PVP as the plasticiser was equal to that of the reference formulation. In general, 5-ISMN osmotic pump tablets with a semipermeable membrane composed of EC/PVP K30 may be useful in providing constant drug delivery with minimum fluctuations during longer storage time.

Usefulness of rat skin as a substitute for human skin in the in vitro skin permeation study.

Sprague-Dawley (SD) rats are broadly used in preclinical studies for drug development, so a lot of information for the rats can be obtained especially from pharmacokinetic, pharmacological and toxicological studies. The purpose of this study was to clarify whether SD rat skin can be used to predict human skin permeability. In vitro permeation studies of the three model drugs, nicorandil, isosorbide dinitrate, and flurbiprofen, through human skin and SD rat skin were performed using Franz-type diffusion cells. The permeation rates of the three model drugs through human skin and SD rat skin were determined, and their variations were evaluated. The inter-individual variations in SD rat skin permeability of the three model drugs were much lower than that in human skin permeability, although the permeation rates of the three model drugs through the SD rat skin were about twice those through human skin. In addition, no difference in the skin permeability coefficients of the three model drugs was obtained between fresh SD rat skin and frozen SD rat skin. The markedly smaller variation in the permeability through SD rat skin compared with that through human skin indicated that in vitro permeation studies using SD rat skin would be especially useful for evaluating differences in the skin permeability of the three model drugs as well as for predicting human skin permeability.

Study on dissolution and absorption of four dosage forms of isosorbide mononitrate: level A in vitro-in vivo correlation.

The objective of the present study was to develop a novel in vitro system to simulate the process of dissolution and permeation of oral solid dosage forms in vivo, and to establish a correlation between in vitro permeation and in vivo absorption that could predict the bioavailability (BA) and bioequivalence (BE) of congeneric products. The in vitro dissolution and absorption kinetics of four dosage forms of isosorbide mononitrate (ISMN) were evaluated by the USP basket/paddle system and drug dissolution/absorption simulating system (DDASS). The corresponding pharmacokinetic study was performed in beagle dogs. A comparative study was carried out between the classical and the novel method to estimate the effectiveness of the modified DDASS in simulating the course of dissolution and absorption in vivo. Indeed, the correlation coefficients of in vitro dissolution and in vivo absorption obtained from DDASS and dogs were higher. Moreover, a higher level A in vitro-in vivo correlation (IVIVC) between DDASS permeation and dog absorption was established, with correlation coefficients of 0.9968, 0.9872, 0.9921, and 0.9728. The DDASS method was more accurate at modeling the process of dissolution and absorption in vivo for both immediate-release (IR) and sustained-release (SR) dosage forms of ISMN.

Variation assessment for in vitro permeabilities through Yucatan micropig skin.

The purpose of this study was to evaluate the variations in the in vitro Yucatan micropig (YMP) skin permeabilities of drugs and to clarify whether YMP skin can be used to predict human skin permeability. In vitro permeation studies of the three model drugs, nicorandil, isosorbide dinitrate and flurbiprofen, through YMP skin were performed using Franz-type diffusion cells. The permeation rates of the three model drugs were determined, and their variations were evaluated. The inter-individual variations in YMP skin permeability for the three model drugs were smaller than that in human skin permeability, and the permeation rates of the three model drugs through the YMP skin were approximately half that through human skin. In addition, the intra-individual variations in YMP skin permeability for nicorandil and flurbiprofen were much smaller than the inter-individual variations in YMP skin. The inter- and intra-regional variations in YMP skin permeability were very small. The markedly smaller variation in the permeability through YMP skin as compared with that through human skin indicated that in vitro permeation studies using YMP skin would be particularly useful for evaluating differences in the skin permeability of the three model drugs as well as for predicting human skin permeability.

Comparison of different absorption enhancers on the intranasal absorption of isosorbide dinitrate in rats.

The objective of this work was to study the influence of different absorption enhancers on the intranasal absorption of isosorbide dinitrate (ISDN). First of all, an in situ nasal perfusion technique in rats was used to investigate the effect of pH, concentration of drug solution and different absorption enhancers on the intranasal absorption of ISDN. The absorption enhancers investigated include hydroxypropyl-beta-cyclodextrin (HP-beta-CD), chitosans (CS) of different molecular weight, and poloxamer 188. All of them enhanced the intranasal absorption of ISDN remarkably. It was found that poloxamer 188 had better permeation enhancing effect than that of HP-beta-CD and CS of the same concentration. Thereafter, in vivo behaviors of the selected formulations were studied in rats and the pharmacokinetic parameters were calculated and compared with that of intravenous injection. Both in situ and in vivo studies demonstrated that poloxamer 188 played a key role in promoting intranasal absorption of ISDN. In nasal ciliotoxicity test, all the absorption enhancers investigated showed good safety profiles. Taking both enhancing effect and safety into account, we suggest poloxamer 188 is the most promising as an intranasal absorption enhancer.

Comparison of intracoronary adenosine and isosorbide dinitrate on no-reflow/slow flow during rotational atherectomy.

OBJECTIVE: To compare the effect of intracoronary adenosine and isosorbide dinitrate (ISDN) on no-reflow/slow flow during high-speed rotational atherectomy (HSRA) in patients with complex coronary artery disease (CAD). METHODS AND RESULTS: Medical records from consecutive patients diagnosed with complex CAD between November 2002 and March 2006 who underwent HSRA at the Tri-Service General Hospital, National Defence Medical Centre in Taipei, Taiwan, were included in this study. Patients in the adenosine group (n=32) received a 50 microg intracoronary adenosine bolus prior to the initiation of burr rotation and during each ablation. Patients in the ISDN group (n=58) received a 0.5 mg intracoronary ISDN bolus at comparable time points. Angiographic success was achieved in 100% of patients in the adenosine group and 98.3% (57/58) in the ISDN group.The procedural success rates were 96.9% (31/32) in the adenosine group and 89.7% (52/58) in the ISDN group. One patient (3.1%) from the adenosine group and six patients (10.3%) from the ISDN group experienced no-reflow/slow flow (P = 0.414). No in-hospital mortality occurred and target vessel revascularization was unnecessary. CONCLUSIONS: Intracoronary administration of either adenosine or ISDN during HSRA appears safe and administration of either agent may be effective in decreasing the incidence of no-reflow/slow flow during HSRA. Further large, prospective, randomized, placebo-controlled trials are required.

Design and evaluation of pH-independent pulsatile release pellets containing isosorbide-5-mononitrate.

A three-layered, pH-independent pulsatile release pellets system containing isosorbide-5-mononitrate (ISMN) was studied. The process of the heart disease such as angina has a close relationship to the chronobiology, which gives rise to the need of a pulsatile drug deliver system for the anti-anginal drug. In this study, pellets containing ISMN were firstly prepared as the core, and then layered with a swelling layer followed by an water-insoluble control layer. The core pellets were formulated with microcrystalline cellulose (MCC) and lactose, and were prepared by extrusion-spheronization. The preparation was optimized by Box-Behnken experimental design, when taking the MCC/lactose ratio as swell as the operating conditions of extrusion-spheronization as variables. The experimental results demonstrated the relationships between formulation, operation and properties of the product, and meanwhile provided optimized values for the parameters. The core pellets were coated by a fluidized bed coater, and pellets with various coating types and coating levels were studied by in vitro dissolution tests. The effects of both swelling layer and control layer on the lag time and the drug release time were studied, in order to predetermine the lag time and release time. The pellets were also evaluated in vivo by studying the pharmacokinetics after oral administration in beagle dogs. The pellets achieved a lag time of 4.1 h in vivo, which had a good consistency with the in vitro results, and the relative bioavailability was nearly 100% comparing to the normal tablets.

Development of monolithic osmotic pump tablet system for isosorbide-5-mononitrate delivery and evaluation of it in vitro and in vivo.

The objective of this study is to develop the monolithic osmotic pump tablet system (MOTS) containing isosorbide-5-mononitrate (5-ISMN), and to evaluate its in vitro and in vivo properties. The influences of tablet formulation variables, size and location of the delivery orifice, membrane variables, and pH value of the dissolution medium on 5-ISMN release from MOTS have been investigated. These results demonstrated that the tablet core played an important role in MOTS, and membrane variables could affect the 5-ISMN release rate. The optimal formulation of 5-ISMN MOTS was determined by uniform design. Furthermore, the dog pharmacokinetics and relative bioavailability of the test formulation (5-ISMN MOTS) have been compared with the reference formulation (Imdur: 60 mg/tablet, a sustained release, SR, tablet system) following an oral single dose of 60 mg given to each of six Beagle dogs. The mean drug fraction absorbed by the dog was calculated by the Wagner-Nelson technique. The results showed that drug concentration in plasma could be maintained more stable and longer after the administration of 5-ISMN MOTS compared with the matrix tablets of Imdur, and a level A "in vitro-in vivo correlation" was observed between the percentage released in vitro and percentage absorbed in vivo. It is concluded that 5-ISMN MOTS is more feasible for a long-acting preparation than 5-ISMN SR tablet system as once-a-day treatment, and it is very simple in preparation, and can release 5-ISMN at the rate of approximately zero order for the combination of hydroxypropylmethyl cellulose as retarder and NaCl as osmogent.

Effect of several electrolyzed waters on the skin permeation of lidocaine, benzoic Acid, and isosorbide mononitrate.

The effects of several electrolyzed waters were evaluated on the permeation of model base, acid and non-ionized compounds, lidocaine (LC), benzoic acid (BA), and isosorbide mononitrate (ISMN), respectively, through excised hairless rat skin. Strong alkaline-electrolyzed reducing water (ERW) enhanced and suppressed the skin permeation of LC and BA, respectively, and it also increased the skin permeation of ISMN, a non-ionized compound. On the contrary, strong acidic electrolyzed oxidizing water (EOW) enhanced BA permeation, whereas suppressing LC permeation. Only a marginal effect was observed on the skin permeation of ISMN by EOW. These marked enhancing effects of ERW on the skin permeation of LC and ISMN were explained by pH partition hypothesis as well as a decrease in skin impedance. The present results strongly support that electrolyzed waters, ERW and EOW, can be used as a new vehicle in topical pharmaceuticals or cosmetics to modify the skin permeation of drugs without severe skin damage.

Effect of oral organic nitrates on expression and activity of vascular soluble guanylyl cyclase.

BACKGROUND AND PURPOSE: The regulation of vascular soluble guanylyl cyclase (sGC) expression by nitric oxide (NO) is still under discussion. In vitro, NO has been shown to downregulate the expression of sGC but it is unclear if this mechanism is operative in vivo and occurs during nitrate treatment. EXPERIMENTAL APPROACH: We investigated whether high dose isosorbide mononitrate (ISMN) or pentaerythrityl tetranitrate (PETN) treatment changes vascular sGC expression and activity in vivo. New Zealand White rabbits received a standard diet, 2 or 200 mg ISMN kg(-1) d(-1) for 16 weeks, and C57BL/6 mice received a standard diet, 6, 60 or 300 mg PETN kg(-1) d(-1) for four weeks. Absorption was checked by measuring the plasma levels of the drug/metabolite. KEY RESULTS: Western blots of rabbit aortic rings showed similar protein levels of sGC alpha1- (P=0.2790) and beta1-subunits (P=0.6900) in all groups. Likewise, ANOVA showed that there was no difference in the expression of sGC in lungs of PETN-treated mice (P=0.0961 for alpha1 and P=0.3709 for beta1). The activities of isolated sGC in response to SNAP (1 microM-1 mM) were identical in aortae of ISMN-treated rabbits (P=0.0775) and lungs of PETN-treated mice (P=0.6348). The aortic relaxation response to SNAP slightly decreased at high ISMN but not at high PETN. CONCLUSIONS AND IMPLICATIONS: These data refute the hypothesis that therapeutic treatment with long acting NO donors has a significant impact on the regulation of vascular sGC expression and activity in vivo.