RESUMEN
The reduction-cascade of PETN is described as a combination of cyclic-voltammetric measurements and analytical results together with synthesis of PETN-metabolites; furthermore the electroreduction of pentaerythityldinitrate (PEDN) in the presence and absence of cystine as well as cystine and electrogenerated superoxide-radicalanions to elucidate the interaction of PETN with thiol-species. PETN was recognized as precursor for a initial radicalic process, followed by intermediate formation of pentaerythityltrinitratealdehyde (PENA) inside a self-reducing nitrate-system with NO as final product, which may explain its special position in comparison with other pharmaceutically applied nitratestructures. It could be proved, that a cystine-pool reacts as a selective moderator inside the reduction of PEDN without being interfered by O2.-, yielding pentaerythitylmononitrate (PEMN) meanwhile in the absence of cystine only pentaerythrite (PE) is formed.
Asunto(s)
Tetranitrato de Pentaeritritol/química , Cistina/química , Electroquímica , Indicadores y Reactivos , Oxidación-Reducción , Superóxidos/químicaRESUMEN
Pentaerithrityltetranitrate (PETN) is an organic nitrate ester with high selectivity to venous vessels and little development of tolerance. Here we report experimental results concerning the hemodynamic and antiischemic effects of intravenously administered PETN. The experiments were performed with anesthetized, open-chest minipigs (25 to 35 kg body weight [bw]). PETN (0.125, 0.25, 0.5 mg/kg bw, i.v.) dose-dependently decreased left ventricular systolic pressure without change in peripheral vascular resistance. A reflex increase in heart rate returned to normal within 20 minutes (0.125 and 0.25 mg/kg). PETN (0.5 mg/kg) also transiently (10 minutes) decreased left ventricular contractility. In additional experiments, myocardial infarction was induced by LAD occlusion (1 hour), followed by reperfusion (3 hours). PETN (0.6 mg/h, i.v.) was administered starting 20 minutes before ischemia until the end of reperfusion. While PETN did not cause hemodynamic changes, infarct size was significantly decreased compared with vehicle (56 +/- 6% vs 83 +/- 3% of area at risk, p < 0.05). Regional contractile function (ultrasound crystals) was completely abolished during ischemia and did not recover during 3 hours reperfusion in control hearts. However, PETN-treated pigs showed partial functional recovery (19 +/- 5%, p < 0.05 vs vehicle) during the first hour of reperfusion. Histologic evaluation revealed a decreased number of granulocytes accumulated in the ischemic myocardium of PETN-treated animals. Accordingly, in-vitro experiments showed a reduction by PETN of the adherence of HL-60 cells differentiated to granulocytes to vascular smooth muscle cells. Therefore, PETN reduced infarct size and improved myocardial function after LAD occlusion and reperfusion. It is concluded that the intravenous administration of PETN might be of advantage in the treatment of acute myocardial ischemia.
Asunto(s)
Circulación Coronaria/efectos de los fármacos , Hemodinámica/efectos de los fármacos , Infarto del Miocardio/patología , Tetranitrato de Pentaeritritol/farmacología , Animales , Infusiones Intravenosas , Daño por Reperfusión Miocárdica/patología , Miocardio/patología , Porcinos , Porcinos EnanosRESUMEN
Assay methods based on gas chromatography/mass spectroscopy (GC-MS) may be used to measure PE1N (pentaerithrityl mononitrate, CAS 1607-00-7), PE2N (pentaerithrityl dinitrate, CAS 1607-01-8) and intermediate pentaerithrityltrinitrate (PE3N, CAS 1607-17-6) in human plasma. Based on this method a simplified method to quantify the metabolites of PETN (pentaerithrityl tetranitrate, CAS 78-11-5, Pentalong) is described. In the present study a consistent method to extract the metabolites of human plasma and following derivatisation is described. Since PE1N can be quantified up to 150 ng/ml, PE2N and PE3N up to 30 ng/ml in human plasma, a dilution of the plasma samples can be avoided. The mean recovery rate is not so high as in other described methods, and inaccuracy is about 10%. Therefore a calibration range between 0.2-30 ng/ml of PE2N and 1-150 ng/ml of PE1N has to be considered. The described method offers an alternative and applicable option to quantify the PETN-metabolites and elucidate their part as NO-donors.
Asunto(s)
Eritritol/análogos & derivados , Tetranitrato de Pentaeritritol/sangre , Vasodilatadores/sangre , Biotransformación , Calibración , Eritritol/sangre , Cromatografía de Gases y Espectrometría de Masas , Humanos , Tetranitrato de Pentaeritritol/análogos & derivados , Tetranitrato de Pentaeritritol/farmacocinética , Vasodilatadores/farmacocinéticaRESUMEN
Anti-ischemic therapy with organic nitrates is complicated by tolerance. Induction of tolerance is incompletely understood and likely multifactorial. Recently, increased production of reactive oxygen species (ROS) has been investigated, but it has not been clear if this is a direct consequence of the organic nitrate on the vessel or an in vivo adaptation to the drugs. To examine the possibility that nitrates could directly stimulate vascular ROS production, we compared the development of nitrate tolerance with the formation of ROS induced by pentaerithrityltetranitrate (PETN) or nitroglycerin (GTN) in vitro in porcine smooth muscle cells, endothelial cells, washed ex vivo platelets and whole blood. By examining cGMP formation, it was found that 24-hr treatment with GTN but not PETN induced significant nitrate tolerance, which was prevented by parallel treatment with Vit C. Incubation of vascular cells acutely with 0.5 mM GTN doubled the rate of ROS generation, whereas PETN had no such effect. The rate of ROS (peroxynitrite and O2) formation detected by specific spin traps in tolerant smooth muscle cells, treated for 24 hr with 0.01 mM GTN, was substantially higher (30.5 nM/min) than in control cells acutely treated with 0.5 mM GTN (25 nM/min). In contrast to PETN, GTN induces nitrate tolerance and also increases the formation of ROS both in vascular cells and in whole blood. ROS formation is minimally stimulated by PETN comparable to data obtained in Vit C-suppressed GTN tolerance. ROS formation induced by organic nitrates seems to be a key factor in the development of nitrate tolerance.
Asunto(s)
Nitratos/metabolismo , Nitratos/farmacología , Nitroglicerina/metabolismo , Tetranitrato de Pentaeritritol/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Animales , Plaquetas/efectos de los fármacos , Plaquetas/metabolismo , Células Cultivadas , GMP Cíclico/metabolismo , Tolerancia a Medicamentos , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Radical Hidroxilo/metabolismo , Músculo Liso Vascular/citología , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/metabolismo , Detección de Spin , Superóxidos/metabolismo , PorcinosRESUMEN
Up to now, there has been no data available on the pharmacokinetics of pentaerythrityl tetranitrate (PETN, CAS 78-11-5) and its metabolites, pentaerythrityl-trinitrate (PE-tri-N), pentaerythrityl-dinitrate (PE-di-N), pentaerythrityl-mononitrate (PE-mono-N) in human plasma. Therefore, in order to determine PETN and its metabolites in plasma sensitive and highly selective GC/MS methods had to be developed and validated. PETN and its metabolite PE-tri-N were validated in the concentration range 50 pg/ml to 10 ng/ml. Isosorbide dinitrate (ISDN) was used as the internal standard and the analytes were extracted with dichloromethane from the plasma. The mass spectrometric tests were carried out using chemical ionization in the negative mode (NlCl) with the application of ammonia as a reagent gas. The nitrate ion m/z 62 was determined in the analytes and internal standard. The accuracy of the mean of the quality control samples during the three days (between days) was between 100 and 110% (PETN), as well as 90 and 106% (PE-tri-N). After an oral application of 100 mg PETN in a pilot study, unchanged PETN and PE-tri-N was measured in plasma. Both metabolites PE-di-N and PE-mono-N were validated at the concentration range of 0.25 ng/ml to 25 ng/ml plasma. After extraction, these analytes were derivatized with BSTFA (N,O-bis[trimethylsilyl]trifluoro-acetamide). The applied internal standard was isosorbide-5-mononitrate (IS-5-MN). The mass spectrometric tests were carried out in the same manner as for PETN and PE-tri-N with chemical ionization in the NlCl mode. The detected masses were m/z 324 for PE-di-N, m/z 351 for PE-mono-N and m/z 217 for IS-5-MN. The accuracy of the mean of the quality control samples during 5 days were between 104 and 107% (PE-di-N) and 102 and 106% (PE-mono-N). The maximum concentration of these analytes in the subject samples were on the average all over 5 ng/ml plasma after the oral administration of 100 mg PETN.
Asunto(s)
Tetranitrato de Pentaeritritol/sangre , Vasodilatadores/sangre , Calibración , Cromatografía de Gases y Espectrometría de Masas , Humanos , Tetranitrato de Pentaeritritol/farmacocinética , Vasodilatadores/farmacocinéticaRESUMEN
Two preparations containing 100 mg pentaerithyrityl tetranitrate (PETN, CAS 78-11-5) each were administered to 24 healthy male volunteers in an open randomised two-way cross-over design. The test preparation was a commercially available 50 mg tablet (Pentalong 50 mg Tabletten, 2 tablets per dose), the reference preparation was an aqueous suspension prepared immediately before application from the same 25% PETN/lactose trituration as was used for manufacturing the tablets. Blood samples were withdrawn pre-dose and at 14 time points within 24 h after dosing. The resulting plasma was analysed by a GC/MS method developed on purpose. Since in a pilot study not a single one of 120 plasma samples contained concentrations of unchanged PETN or of its metabolite pentaerithrityl trinitrate (PE-tri-N, CAS 1607-17-6) above the quantification limit of 50 pg/ml, the samples of this study were assayed for the metabolites pentaerithrityl dinitrate (PE-di-N, CAS 1607-01-8) and pentaerithrityl mononitrate (PE-mono-N, CAS 1607-00-7) only. -Mean peak levels of 17 ng/ml and 7.5 ng/ml PE-di-N were reached ca. 3 h after application of tablets or trituration. The plasma elimination half-life was 4-5 h. Average maximum PE-mono-N levels of 79 ng/ml (tablets) and 35 ng/ml (trituration) were observed at 7 h p. appl. They declined with a half-life of 10-11 h. The relative bioavailability of the tablets as determined by means of the AUC of PE-di-N is 280-290%. This high value is explained by the specific properties of drug liberation and dissolution from the preparations used.
Asunto(s)
Tetranitrato de Pentaeritritol/análogos & derivados , Glicoles de Propileno/farmacocinética , Vasodilatadores/farmacocinética , Adulto , Disponibilidad Biológica , Biotransformación , Estudios Cruzados , Cromatografía de Gases y Espectrometría de Masas , Semivida , Humanos , MasculinoRESUMEN
Topical glucocorticoids still belong to the most important medications available in dermatotherapy. The clinical use of topical glucocorticoids, however, nowadays is limited by the fear of side-effects both systemic and local, especially skin atrophy. The purpose of this study was to assess the atrophogenicity potential of newly developed topical glucocorticoids which were said to show an increased benefit-risk ratio. The test preparations comprised mometasone furoate, the corresponding vehicle, prednicarbate and hydrocortisone. They were applied once or twice daily for 6 weeks in healthy volunteers. Skin thickness was assessed weekly by using high frequency pulsed ultrasound. Clinically, none of the volunteers showed any sign of overt skin atrophy. Skin thickness, however, was reduced to a certain extent with all trial preparations including the base preparation. As to be expected from previous experiments the results for hydrocortisone and prednicarbate did not differ significantly from the ones for the base preparation. Interestingly, the same applied to mometasone furoate. These findings, together with the other available data, give evidence of an increased benefit-risk ratio as compared to previous medium potent topical glucocorticoids. This might be of particular interest facing psoriasis vulgaris where an antiproliferative activity of a drug is needed.
Asunto(s)
Antiinflamatorios/efectos adversos , Hidrocortisona/efectos adversos , Prednisolona/análogos & derivados , Pregnadienodioles/efectos adversos , Piel/efectos de los fármacos , Administración Tópica , Adulto , Antiinflamatorios/administración & dosificación , Atrofia/inducido químicamente , Método Doble Ciego , Femenino , Humanos , Hidrocortisona/administración & dosificación , Masculino , Persona de Mediana Edad , Furoato de Mometasona , Pomadas , Prednisolona/administración & dosificación , Prednisolona/efectos adversos , Pregnadienodioles/administración & dosificación , Piel/patologíaRESUMEN
BACKGROUND AND OBJECTIVE: Previous studies have suggested that endothelin (ET)-1 with its marked vasoconstrictive potency may play a role in the induction of coronary artery spasms. Furthermore, it was demonstrated using in-vitro vessel preparations that the secretion of ET-1 by the vascular endothelium is enhanced in the presence of atherosclerotic alterations. The objective of the present study was to investigate a) the effects of ergometric exercise on ET-1 plasma concentrations in 10 patients with coronary artery disease (CAD) as compared to an age and sex matched control group and b) the modulatory role of the orally administered organic nitrate, pentaerithrityltetranitrat (PETN), in patients with CAD. PATIENTS AND METHODS: 10 male patients with CAD confirmed by coronarography and 10 male healthy controls underwent a bicycle ergometry according to the WHO-standards upt to 125 watts. Venous blood samples for determination of ANP and ET-1 plasma concentrations were drawn in supine position directly before and 5 min after ergometric exercise. Subsequently, patients were randomized and treated for 3 days in a crossover design either with placebo or PETN (150 mg b.i.d.). RESULTS: Basal plasma levels of ET-1 were 6.1 +/- 0.7 pg/ml (patients) and 5.5 +/- 0.6 pg/ml (controls), resp. (n.s.). After ergometric exercise ET-1 plasma concentrations rose significantly (7.3 +/- 0.9 pg/ml; p < 0.05) in the placebo-treated patient group, whereas they remained constant (5.5 +/- 0.7 pg/ml) in the PETN-treated patient group. Blood pressure and heart rate were not modified by the PETN-treatment. ET-1 plasma levels remained unaffected by ergometric exercise in controls. DISCUSSION: In contrast to healthy controls ergometric exercise induced an increase in ET-1 plasma concentrations in patients with CAD that may be potentially harmful by promoting coronary vasospasms. The almost complete blunting of the ET-1-increase in the presence of PETN-therapy may result from local-hemodynamic effects of the organic nitrate; it may be hypothesized that the nitrate-induced rise in local NO-concentrations counteracts ET-secretion. The findings of the present study are in accordance with the beneficial clinical effects of organic nitrates in patients with CAD.
Asunto(s)
Enfermedad de la Arteria Coronaria/sangre , Endotelinas/sangre , Ejercicio Físico/fisiología , Tetranitrato de Pentaeritritol/uso terapéutico , Administración Oral , Análisis de Varianza , Enfermedad de la Arteria Coronaria/tratamiento farmacológico , Endotelinas/efectos de los fármacos , Humanos , Masculino , Persona de Mediana Edad , RadioinmunoensayoRESUMEN
Previous studies suggest that ET-1 plays a role in induction of coronary artery disease (CAD). It was shown that secretion of endothelin-1 (ET-1) by the vascular endothelium is enhanced in atherosclerotic alterations and may be antagonized by EDRF. The objective of the present study was to investigate the effects of ergometric exercise on plasma ET-1 concentrations, and the potential modulatory role of LDL cholesterol, and the effects of an orally administered nitrate, PETN, in patients with CAD. Ten men with CAD and 10 healthy men underwent bicycle ergometry according to the WHO-standards. Venous blood samples for determination of ET-1 concentrations were drawn directly before and 5 min after ergometric exercise. Patients were randomized and treated for 72 h in a crossover design either with placebo or pentaerithrityltetranitrate (PETN). After 72 h the identical ergometric protocol was repeated. Basal plasma levels of ET-1 were 6.1 +/- 0.7 pg/ml (patients) and 5.5 +/- 0.6 pg/ml (controls) (n.s.). After ergometric exercise ET-1 plasma concentrations rose significantly (7.3 +/- 0.9 pg/ml; p < 0.05) in the patient group under placebo treatment, whereas they remained constant (5.5 +/- 0.7 pg/ml) with PETN treatment. ET-1 levels remained unaffected by ergometric exercise in healthy controls. Mean LDL cholesterol plasma levels in patients with CAD were 156 +/- 8 mg% and 152 +/- 7 mg% in healthy controls. In the patient group there was a significant (p < 0.002) positive correlation between the exercise-induced increase in ET-1 and the LDL cholesterol plasma concentrations (r = 0.85). Blood pressure and heart rate were not modified by PETN treatment. In patients with CAD bicycle ergometry induced an increase in ET-1 plasma concentrations. The positive correlation with the LDL cholesterol plasma levels indicates that LDL cholesterol is involved in regulation of ET-1 secretion in vivo. PETN therapy completely abolished the exercise-induced increase in ET-1 plasma levels. This may result from local hemodynamic effects of the nitrate; hypothetically a nitrate-induced rise in the local NO concentrations can be considered. The clinical implications of these findings remain elusive. However, the findings of the present study are in accordance with the beneficial clinical effects of nitrates in patients with CAD.
Asunto(s)
LDL-Colesterol/sangre , Enfermedad Coronaria/sangre , Endotelinas/sangre , Ejercicio Físico , Tetranitrato de Pentaeritritol/farmacología , Vasodilatadores/farmacología , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Loratadine, a new nonsedating histamine H1-antagonist, has been shown to inhibit immunologic release of inflammatory mediators in addition to its H1-receptor blocking properties. After oral administration, the agent is metabolized primarily to desethoxycarbonyl-loratadine (DCL). The basic piperidine, DCL, is readily soluble in water, whereas the nonbasic urethane, loratadine, is insufficiently soluble in water for some in vitro investigations. Therefore we used the metabolite, DCL, to study its influence on in vitro leukocyte histamine release (LHR) in 24 allergic and 22 nonallergic subjects. IgE-mediated and calcium ionophore A23187-induced LHR were inhibited by DCL in a dose-dependent fashion (values of drug concentration to induce 30% inhibition after stimulation with inhalant antigen, anti-IgE, concanavalin A, and calcium ionophore A23187 were 6, 8, 5, and 11 mumol/L, respectively). Higher concentrations of DCL caused mediator release in all subjects (n = 45, 30 mumol/L DC: 11% +/- 2% LHR, 100 mumol/L DCL: 35% +/- 1% LHR), abolishing any inhibitory effect of the drug. Rapid onset of inhibition by 10 mumol/L DCL was found in kinetic studies (n = 10). The inhibition of anti-IgE-induced histamine secretion was synergistically increased by simultaneous preincubation of DCL with the potent histamine H2-agonist, FRA-19. Additional data indicate that the inhibition of LHR by DCL might involve biochemical events that occur after cellular Ca++ influx because LHR induced by N-formyl-methionyl-leucyl-phenylalanine or the phorbol ester, 12-O-tetradecanoyl phorbol-12-acetate, was not significantly affected by DCL.
Asunto(s)
Basófilos/efectos de los fármacos , Basófilos/inmunología , Antagonistas de los Receptores Histamínicos H1/farmacología , Liberación de Histamina/efectos de los fármacos , Loratadina/análogos & derivados , Calcimicina/farmacología , Concanavalina A/farmacología , Liberación de Histamina/inmunología , Humanos , Inmunoglobulina E/metabolismo , Técnicas In Vitro , Loratadina/farmacología , N-Formilmetionina Leucil-Fenilalanina/farmacología , Rinitis Alérgica Estacional/inmunología , Acetato de Tetradecanoilforbol/farmacologíaRESUMEN
A total of 166 patients with non-small cell lung cancer (NSCLC) were included in two multicenter trials testing different treatment regimens. In study I, 116 patients received 4 cycles of aggressive polychemotherapy consisting of cis-platinum 100 mg/m2 (day 1), etoposide 100 mg/m2 (days 4-6), and vindesine 3 mg/m2 (day 1) (CEV); patients without distant metastases subsequently received chest irradiation with 50 Gy. In study II, 50 patients were treated with monochemotherapy consisting of etoposide 250 mg/m2 (days 1-3), and ifosfamide 5 g/m2 as 24-h infusion (day 29). While this program was repeated in responders with extensive disease (ED), patients with limited disease (LD) subsequently received chest irradiation with 50 Gy using 20 mg/m2 cis-platinum weekly as a radiosensitizer. Response rates (CR + PR) to chemotherapy were higher in study I than in study II, and were 26% (CR 3%) vs. 8% (CR 0%) for all patients, 18% (CR 0%) vs. 4% (CR 0%) for ED, and 45% (CR 11%) vs. 13% (CR 0%) for LD. The increase in response rates by radiotherapy was marginal in study I (CR + PR 47%, CR 18%), but remarkable in study II (CR + PR 42%, CR 29%). While median survival was slightly longer in study I than in study II for ED (7.7 vs. 6.6 months) and LD (14.4 vs. 12.0 months), the 2-year survival rate was in favor of study II (10% vs. 25%). Toxicity was clearly more pronounced in study I, including 3 lethal complications and 16 discontinuations of therapy due to side effects or refusal. Thus, while in ED the efficacy of both treatment regimens was very restricted, in LD radiotherapy with cis-platinum as a radiosensitizer achieved a relatively high 2-year survival rate which justifies further testing of this treatment strategy.