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Regenthal, Ralf; Krueger, Mario; Koeppel, Claus; Preiss, R

doi:10.1023/a:1009935116877

Cited by 239 publications

(77 citation statements)

References 5 publications

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“…Despite high interindividual variability, the trough values were similar to previously reported plasma levels 24 h after oral administration of 12.5-50 mg HCTZ and 50-300 mg IRBE (12-500 and 120-750 ng mL -1 , respectively). However, it should be emphasized that these concentration ranges were estimated from published concentration-time profiles, because residual concentrations during chronic administration of HCTZ-IRBE fixed-dose combinations have never been reported in the literature [31,32]. These results suggested no difference in residual plasma concentrations if HCTZ and IRBE are administered alone or in combination.…”

Section: Application To Patient Samplesmentioning

confidence: 93%

HPLC–DAD Analysis of Hydrochlorothiazide and Irbesartan in Hypertensive Patients on Fixed-Dose Combination Therapy

et al. 2011

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Hydrochlorothiazide (HCTZ) and the angiotensin II type 1 receptor antagonist (ARB) irbesartan (IRBE) are well-known antihypertensive drugs, frequently administered as a low-dose combination in a single pill. In this work, a simple, sensitive, and selective high-performance liquid chromatographic (HPLC) method with diodearray detection was developed for simultaneous determination of HCTZ and IRBE levels in the plasma of hypertensive patients given a fixed combination of 12.5 mg HCTZ and 300 mg IRBE. Compounds were extracted from acidified plasma samples with 3 mL ethyl acetate, and eluted at 6 and 19 min from a C 4 column by elution with an acetonitrile-phosphate buffer (pH 3.6) mobile-phase gradient at a flow rate of 1 mL min -1 . The assay was linear over the ranges 2.5-500 and 20-4,000 ng mL -1 for HCTZ and IRBE, respectively. Overall intra-assay and inter-assay variation were within acceptance limits. Limits of quantification were 2.5 and 20 ng mL -1 for HCTZ and IRBE, respectively. Plasma samples remained stable for 12 h at room temperature, through three thaw-freeze cycles, and for 2 and 7 months at -20°C. In hypertensive patients, residual concentrations were 22.3 ± 6.0 and 241.8 ± 39.0 ng mL -1 for HCTZ and IRBE, respectively. There was no interference from other co-administered drugs. Despite the different physicochemical properties of HCTZ and IRBE, our method enables accurate measurement of both drugs for assessment of compliance by patients treated by fixed-dose combination therapy with HCTZ-IRBE.

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Section: Application To Patient Samplesmentioning

confidence: 93%

HPLC–DAD Analysis of Hydrochlorothiazide and Irbesartan in Hypertensive Patients on Fixed-Dose Combination Therapy

et al. 2011

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“…The drug concentration was titrated according to recommended therapeutic plasma concentrations; concentrations were 0.10mg/mL for benztropine (therapeutic range 0.01-0.18mg/mL) and 0.2 mg/mL for promethazine (therapeutic range 0.05-0.4mg/ mL) 50,51 Drugs in these concentrations were added directly to the circulating Krebs solution, and 5 minutes was allowed for equilibration of the drug level throughout the solution. After this, 30 times the original dose was added, to reach a concentration above the therapeutic range, designated as the supratherapeutic experiment.…”

Section: Anticholinergic Drugsmentioning

confidence: 99%

“…For benztropine, this was 0.03mg, to reach a final concentration of 0.0301mg/L (toxic plasma concentration 0.0139mg/L). 50 For promethazine, this The frequency spectrum plot shows the most salient frequency -that is, the frequency with the highest amplitude, to choose the predominant frequency and amplitude. This allows elimination of other signals that contribute to 'noise' in the graph of diameter change over time, which ideally should be sinusoidal in shape.…”

Section: Anticholinergic Drugsmentioning

confidence: 99%

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Analysis of spatiotemporal pattern and quantification of gastrointestinal slow waves caused by anticholinergic drugs

et al. 2017

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ABSTRACT. Anticholinergic drugs are well-known to cause adverse effects, such as constipation, but their effects on baseline contractile activity in the gut driven by slow waves is not well established. In a video-based gastrointestinal motility monitoring (GIMM) system, a mouse's small intestine was placed in Krebs solution and recorded using a high definition camera. Untreated controls were recorded for each specimen, then treated with a therapeutic concentration of the drug, and finally, treated with a supratherapeutic dose of the drug. Next, the video clips showing gastrointestinal motility were processed, giving us the segmentation motions of the intestine, which were then converted via Fast Fourier Transform (FFT) into their respective frequency spectrums. These contraction quantifications were analyzed from the video recordings under standardised conditions to evaluate the effect of drugs. Six experimental trials were included with benztropine and promethazine treatments. Only the supratherapeutic dose of benztropine was shown to significantly decrease the amplitude of contractions; at therapeutic doses of both drugs, neither frequency nor amplitude was significantly affected. We have demonstrated that intestinal slow waves can be analyzed based on the colonic frequency or amplitude at a supratherapeutic dose of the anticholinergic medications. More research is required on the effects of anticholinergic drugs on these slow waves to ascertain the true role of ICC in neurologic control of gastrointestinal motility.

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“…It must be taken into account that the serum concentration of mefenamic acid after therapeutic treatment is four times higher (40 µmol L -1 ). 28 Although it is known that mefenamic acid is bound to albumin in in vivo human plasma, it should be understood that therapeutic levels are the steady state concentrations necessary to be reached for the drug to exert a significant clinical benefit. Although reports on the interaction of mefenamic acid on human erythrocytes and cell membranes are very scanty, it has been reported that mefenamic acid affected in vitro the permeability of gastric mucosal cells in a 1 to 10 mmol L -1 concentration.…”

Section: Figurementioning

confidence: 99%

Molecular interactions of mefenamic acid with lipid bilayers and red blood cells

Suwalsky¹,

Manrique-Moreno²,

Howe³

et al. 2011

J. Braz. Chem. Soc.

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O ácido mefenâmico é um anti-inflamatório não esteroidal (NSAID), também prescrito no tratamento da dor. No presente trabalho, os efeitos estruturais na membrana de eritrócitos humanos e de modelos moleculares foram investigados. Esta última foi composta em bicamadas construídas de dimiristoilfosfatidilcolina (DMPC) e dimiristoilfosfatidiletanolamina (DMPE), classes de lipídios encontrados nas porções interna e externa do eritrócito e da maioria das membranas celulares, respectivamente. Este artigo apresenta evidências de que o ácido mefenâmico interage com as membranas das células vermelhas, como segue: (i) em estudos de microscopia eletrônica de varredura (SEM) em eritrócitos humanos, foi observado que a droga induziu mudanças na forma, produzindo estomatócitos; (ii) estudos de difração de raios X mostraram que a droga interagiu com bicamadas de DMPC e efeitos de perturbação um pouco menores, em DMPE, foram detectados; (iii) medições de FT-IR mostraram que NSAID induziu a fluidização das cadeias acílicas de ambos, DMPC e DMPE; (iv) a espectroscopia de transferência de energia por ressonância Förster (FRET) indicou uma rápida intercalação do ácido mefenâmico nas cadeias hidrofóbicas do lipossoma DMPC.Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID), also prescribed to treat pain. In the present work, the structural effects on the human erythrocyte membrane and molecular models have been investigated. The latter consisted in bilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), classes of lipids found in the outer and inner moieties of the erythrocyte and most cell membranes, respectively. This report presents evidence that mefenamic acid interacts with red cell membranes as follows: (i) in scanning electron microscopy (SEM) studies on human erythrocytes it has been observed that the drug induced shape changes, forming stomatocytes; (ii) X-ray diffraction showed that the drug interacted with DMPC bilayers; somewhat lower perturbing effects on DMPE were detected; (iii) FT-IR measurements showed that NSAID induced fluidization of both DMPC and DMPE acyl chains; (iv) Förster resonance energy transfer spectroscopy (FRET) indicated a rapid intercalation of the mefenamic acid into DMPC liposome hydrophobic chains.

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Untitled

Cited by 239 publications

References 5 publications

HPLC–DAD Analysis of Hydrochlorothiazide and Irbesartan in Hypertensive Patients on Fixed-Dose Combination Therapy

HPLC–DAD Analysis of Hydrochlorothiazide and Irbesartan in Hypertensive Patients on Fixed-Dose Combination Therapy

Analysis of spatiotemporal pattern and quantification of gastrointestinal slow waves caused by anticholinergic drugs

Molecular interactions of mefenamic acid with lipid bilayers and red blood cells

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