An HPLC Method for the Separation and Simultaneous Determination of Antihistamines,Sympathomimetic Amines and Dextromethorphan in Bulk Dpug Material and Dosage Forms

Abstract

A high-performance liquid chromatography (HPLC) method for the simultaneous determination of bamipine, phenylephrine or (phenylpropanolamine, ephedrine) and dextromethorphan has been developed. The method proved suitable for the analysis of the compounds in various pharmaceutical formulations. From the sample solutions no interference was observed on the chromatographs. The accuracy of the assay has been assessed. Recovery studies have been also carried out by adding known quantities of the active ingredients to placebo samples (spiking recoveries).     

Separation of chiral drugs with sulfobutylether-β-cyclodextrin bycapillary zone electrophoresis

IntroductionChaedcyclodextrlnswerefirstIntroducedby几rabelforchlralseparationofamlnoacids,andthechargedCDcommonlyusednowdaysarecarboxymethyl－p－CD（CM－p－CD）,p－CD－phosphate,Y－CD－phosphate,sulfobutylether－p－cyclodextrln（SBE－p－CD）etc．...     

Sensitive determination of fluphenazine at a dodecanethiol self-assembled monolayer-modified gold electrode, and its electrocatalysis to phenylephrine

Fluphenazine, an important tranquilizer, was found to undergo effective accumulation on dodecanethiol (DDT) self-assembled monolayer modified gold electrode (i.e. DDT/Au) and generated two anodic peaks at about 0.7 and 0.79 V (vs. SCE) in 0.05 M Na₂B₄O₇ (pH = 9.3) buffer solution. Sensitive and quantitative measurement of fluphenazine based on the former anodic peak was established under optimum conditions. The peak current was linear to fluphenazine concentration in the range from 5 × 10⁻⁷ to 5 × 10⁻⁵ M, with a detection limit of 5 × 10⁻⁹ M. This method was successfully applied to the determination of fluphenazine in drug tablets and proved to be reliable compared with UV spectrophotometry. In the presence of fluphenazine, the electrochemical oxidation of phenylephrine was catalyzed. The DDT self-assembled monolayer was characterized by Fourier transform infrared spectroscopy, surface Raman spectroscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and electrochemical probing.     

Computationally-designed phenylephrine prodrugs – a model for enhancing bioavailability

DFT calculations at B3LYP 6-31G (d,p) for intramolecular proton transfer in a number of Kirby's enzyme models demonstrated that the driving force for the proton transfer efficiency is the distance between the two reactive centres (r_GM) and the attack angle (α); and the rate of the reaction is linearly correlated with r_GM² and sin (180°- α). Based on these results three phenylephrine prodrugs were designed to provide phenylephrine with higher bioavailability than their parent drug. Using the experimental t_1/2 (the time needed for the conversion of 50% of the reactants to products) and EM (effective molarity) values for these processes the t_1/2 values for the conversion of the three prodrugs to the parent drug, phenylephrine were calculated. The calculated t_1/2 values for ProD 1 and ProD 2 were very high (145 days and several years, respectively) whereas that of ProD 3 was found to be about 35 hours. Therefore, the intra-conversion rates of the phenylephrine prodrugs to phenylephrine can be programmed according to the nature of the prodrug linker.     

基于离子液体促进的手性配体交换毛细管电泳法分离分析去氧肾上腺素光学异构体

基于非手性离子液体对手性配体交换的促进作用,建立了一种测定去氧肾上腺素手性异构体的毛细管电泳分离分析方法。在系统优化了电泳条件后,采用20 kV的分离电压、25 ℃的毛细管柱温、254 nm的检测波长以及5 s的压力(3447 Pa)进样时间,在添加4.0 mmol/L Cu(Ⅱ)、8.0 mmol/L L-脯氨酸(L-Pro)和15 mmol/L氯化-1-丁基-3-甲基咪唑([BMIM]Cl)的20 mmol/L Tris-H₃PO₄缓冲溶液(pH 5.4)中,R-去氧肾上腺素和S-去氧肾上腺素的分离度为1.42,峰面积与质量浓度分别在12.5~150.0 mg/L和15.0~150.0 mg/L范围内有线性关系。将该方法用于加标血液和尿液样品中R和S型去氧肾上腺素的测定,尿液中的加标回收率为93.7%~108.2%,相对标准偏差在3.18%(n=3)以内;血液中的加标回收率为91.4%~113.1%,相对标准偏差在4.82%(n=3)以内。     

Potentiometric sensor for phenylephrine based on phenylephrine-tetraphenylborate lipophilic salt

Phenylephrine (PE) ion-selective electrode based on incorporation of phenylephrine-tetraphenylborate lipophilic salt in plasticized PVC matrices is constructed. The electrode shows near Nernstian response over the concentration range 1.5 × 10^–4-10^–1 M in solutions of pH 2.9–8.0 at 25°C. The electrode resists the effect of heat in the temperature range 25–55°C exhibiting an isothermal temperature coefficient of 0.0007 V/°C. The selectivity of the electrode for PE towards large number of inorganic cations, sugars and amino acids is investigated. Determination of PE in an eye-drops pharmaceutical preparation is carried out using the proposed electrode as potentiometric sensor.     

Pre-column derivatization method for determining phenylephrine in human plasma and its application in a pharmacokinetic study

In the present study, a rapid derivatization liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated to evaluate phenylephrine in human plasma. The plasma samples were processed to precipitate the proteins, followed by derivatization of the phenylephrine in the plasma with dansyl-chloride solution and extraction with methyl tert-butyl ether–n-hexane (2:1, v/v). The treated samples were analyzed on a Gemini C₁₈ column with 3 min gradient elution, and sensitive detection was achieved with a Waters TQ-s. The method gave linear results over a concentration range from 0.020 to 10.0 ng/ml. The lower limit of quantification was 0.020 ng/ml. Intra- and inter-day precision was <15%, and accuracy was 95.0–105.3%. The validated LC–MS/MS method was successfully applied in the pharmacokinetic analysis of phenylephrine in Chinese subjects with common cold after a single-dose administration of 5, 10 or 20 mg phenylephrine. This pre-column derivatization method may also be applied for the analysis of endogenous hormones such as norepinephrine and adrenaline in a biological matrix.     

Analysis of methyldopa in the presence of phenylephrine using electrocatalytic effect of a ferrocene derivative at a surface of feather like La3+/ZnO nano‐flowers modified carbon paste electrode

The purpose of the present study was to introduce a newly designed approach for simultaneous determination of methyldopa and phenylephrine using modified carbon paste electrode with feather like La³⁺/ZnO nano‐flowers and N‐(ferrocenylmethylidene) fluoren‐2‐amine (La³⁺/ZnONFMF2ACPE). According to the results from the electrochemical experiments, oxidation current of methyldopa on the modified electrode surface was incremented and its oxidation occurred at a potential about 110 mV less positive than that of an unmodified carbon paste electrode. A linear response was observed for the electrode at different methyldopa concentrations (0.2 to 500.0 μM). The existence of phenylephrine did not induce any change in the modified electrode sensitivity to methyldopa, indicating that they could be measured simultaneously or independently. Real human body samples were used to test our technique efficacy in detecting methyldopa and phenylephrine.     

Chromatographic separation and analysis of chloropheniramine maleate, methscopolamine nitrate and phenylephrine hydrochloride in sustained release capsules

Summary A high performance liquid chromatographic method has been developed for the simultaneous determination of chlorpheniramine maleate (CPM), methscoplamine nitrate (MSN) and phenylephrine hydrochloride (PEH) in sustained release capsules. The separation was carried out on a reverse-phase CN-column with use of a mobile phase consisting of 70% (v/v) solution of acetonitrile in water containing 2% (v/v) acetic acid and 0.005M sodium 1-hepatane sulfonate at a flow rate of 2 mL min⁻¹. The eluted peaks were detected at 262 nm. The method is sensitive, accurate and rapid and can be used in the routine analysis of the mixture of the three compounds.