Can the heptapeptide ASSIVSF of the ß2-adrenoceptor recognize ephedrine and pseudoephedrine epimers in a complex system?

Epimer separation is crucial in the field of analytical chemistry, separation science, and the pharmaceutical industry. No reported methods could separate simultaneously epimers or even isomers and remove other unwanted, co-existing, interfering substances from complex systems like herbal extracts. Herein, we prepared a heptapeptide-modified stationary phase for the separation of 1R,2S-(-)-ephedrine [(-)-Ephe] and 1S,2S-(+)-pseudoephedrine [(+)-Pse] epimers from Ephedra sinica Stapf extract and blood samples. The heptapeptide stationary phase was comprehensively characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The separation efficiency of the heptapeptide column was compared with an affinity column packed with full-length ß2-AR functionalized silica gel (ß2-AR column). The binding affinity of the heptapeptide with (+)-Pse was 3-fold greater than that with (-)-Ephe. Their binding mechanisms were extensively characterized by chromatographic analysis, ultraviolet spectra, circular dichroism analysis, isothermal titration calorimetry, and molecule docking. An enhanced hydrogen bonding was clearly observed in the heptapeptide-(+)-Pse complex. Such results demonstrated that the heptapeptide can recognize (+)-Pse and (-)-Ephe epimers in a complex system. This work, we believe, was the first report to simultaneously separate epimers and remove non-specific interfering substances from complex samples. The method was potentially applicable to more challenging sample separation, such as chiral separation from complex systems.

[Mahuang (herbaceous stem of Ephedra spp.): chemistry, pharmacodynamics, and pharmacokinetics].

The Chinese medicinal herb Mahuang is herbaceous stem of Ephedra sinica, E. intermedia, or E. equisetina(Family, Ephedraceae). In China, Mahuang has been used, all the way over a millennium, as a key component herb of many herbal medicines for management of epidemics of acute respiratory illness and is also used in officially recommended herbal medicines for COVID-19. Mahuang is the first-line medicinal herb for cold and wheezing and also an effective diuretic herb for edema. However, Mahuang can also exert significant adverse effects. The key to safety and effectiveness is rational and precise use of the herb. In this review article, we comprehensively summarize chemical composition of Mahuang and associated differences in pharmacognosy, pharmacodynamics and pharmacokinetics of Mahuang compounds, along with the adverse effects of Mahuang compounds and products. Based on full understanding of how Mahuang is used in Chinese traditional medicine, systematic research on Mahuang in line with contemporary standards of pharmaceutical sciences will facilitate promoting Chinese herbal medicines to become more efficient in management of epidemic illnesses, such as COVID-19. To this end, we recommend research on Mahuang of two aspects, i.e., pharmacological investigation for its multicompound-involved therapeutic effects and toxicological investigation for clinical manifestation of the adverse effects, chemicals responsible for the adverse effects, and conditions for safe use of the herb and the herb-containing medicines.

Therapeutic appraisal of ephedrine against rheumatoid arthritis: A new indication.

Ephedra, natural flora has been used traditionally to treat rheumatism since decades. The scientific evidence of anti-rheumatic effect of this plant has also been reported. But the anti-rheumatic activity of major constituent of this plant (ephedrine) has not been evaluated. Based on this, the current study was aimed to assess anti-arthritic activity of ephedrine by using in vitro and in vivo approaches. Correspondingly, enzyme linked immunosorbent assay was performed for the estimation of prostaglandins E2 (PGE2) and tumor necrosis factor-α (TNF-α) in serum of formaldehyde-induced arthritic animals. The results elaborated significant reduction in albumin denaturation and remarkable progress on stabilization of red blood cells outer membrane at higher concentration during in vitro experiments. The ephedrine (40mg/kg) revealed noteworthy (p<0.001) inhibition in paw swelling in animals intoxicated with albumin as well as formaldehyde as compared to animals of control group by in vivo results. In this assay, ephedrine (20 & 40 mg/kg orally) significantly suppressed the level of these inflammatory markers (PGE2 & TNF-α). Ephedrine exhibited anti-arthritic effect by decreasing pro-inflammatory cytokines (PGE2 & TNF-α). This experimental work pharmacologically supports the use of ephedrine as anti-rheumatic drug but limited to evaluate in immunological arthritic model.

Over a century since ephedrine discovery: an updated revisit to its pharmacological aspects, functionality and toxicity in comparison to its herbal extracts.

Ephedrine, a sympathomimetic amine that exhibits several adrenaline actions, is a plant alkaloid that is a common ingredient in several cold, asthma and narcolepsy treatment preparations, and in obesity management and sport medicine. Its principal action mechanism relies on its direct adrenergic actions as well as indirect role that involves the release of epinephrine and norepinephrine, thus increasing the activity of epinephrine and norepinephrine at the postsynaptic α and ß receptors. Nevertheless, its serious side effects, including stroke, heart attack, drug abuse and interactions, have never been comprehensively reviewed. We conducted a systematic review of data on ephedrine, including its occurrence in functional foods, pharmacological aspects, metabolism, pharmaco/toxicokinetics and clinical features. Furthermore, a review of ephedrine natural structural analogues with regards to their differential adrenergic receptor binding affinities, food interaction, and their impact on the pharmacokinetics and effects relative to ephedrine are presented for the first time, and in comparison to its action when present in herbs.

Therapeutic effects of Gambi-jung for the treatment of obesity.

Obesity is known as metabolic syndrome and it affects many tissues including adipose tissue, liver, and central nervous system (CVS). Gambi-jung (GBJ) is a modified prescription of Taeumjowi-tang (TJT), which has been used to treat obesity in Korea. GBJ is composed of 90% Ephedra sinica Stapf (ES). Therefore, the present study was designed to assess the antiobesity effects of GBJ and to compare the effects of GBJ and ES on obesity. GBJ administration remarkably reduced the body weight, Body mass index (BMI), and body fat percentage compared to the ES administration in human subjects. GBJ-treated mice had lower white adipose tissue (WAT) amounts than ES-treated mice. GBJ and ES administration enhanced adenosine monophosphate-activated protein kinase (AMPK) expression in 3T3-L1 adipocytes, epididymal WAT and liver of HFD-induced obese mice. Moreover, GBJ and ES reduced food intake by suppressing the mRNA levels of orexigenic peptides, agouti-related protein (AgRP) and neuropeptide-Y (NPY), as well as AMPK in the brain of HFD-induced obese mice. Furthermore, GBJ-treated mice had dramatically lower expression of macrophage marker F4/80 in epididymal WAT than those of ES-treated mice. Based on these results, we suggest the use of GBJ as a natural drug to control weight gain.

Quality Evaluation and Characterization of Fractions with Biological Activity from Ephedra Herb Extract and Ephedrine Alkaloids-Free Ephedra Herb Extract.

Previously, we reported that the c-Met inhibitory effect of Ephedra Herb extract (EHE) is derived from ingredients besides ephedrine alkaloids. Moreover, analgesic and anti-influenza activities of EHE and ephedrine alkaloids-free Ephedra Herb extract (EFE) have been reported recently. In this study, we examined the fractions containing c-Met kinase inhibitory activity from EHE and the fractions with analgesic and anti-influenza activities from EFE, and elucidated the structural characteristics of the active fractions. Significant c-Met kinase activity was observed in 30, 40, and 50% methanol (MeOH) eluate fractions obtained from water extract of EHE using Diaion HP-20 column chromatography. Similarly, 20 and 40% MeOH, and MeOH eluate fractions obtained from water extract of EFE were found to display analgesic and anti-influenza activities. Reversed phase-HPLC analysis of the active fractions commonly showed broad peaks characteristic of high-molecular mass condensed tannin. The active fractions were analyzed using 13C-NMR and decomposition reactions; the deduced structures of active components were high-molecular mass condensed tannins, which were mainly procyanidin B-type and partly procyanidin A-type, including pyrogallol- and catechol-type flavan 3-ols as extension and terminal units. HPLC and gel permeation chromatography (GPC) analyses estimated that the ratio of pyrogallol- and catechol-type was approximately 9 : 2, and the weight-average molecular weight based on the polystyrene standard was >45000. Furthermore, GPC-based analysis was proposed as the quality evaluation method for high-molecular mass condensed tannin in EHE and EFE.

Simultaneous identification of the three active constituents in Lung-Ventilating-Regulating Oral Liquid by RP-HPLC.

The study aimed to develop a HPLC method for ephedrine, hesperidin, and baicalin in Lung-Ventilating-Regulating Oral Liquid. The three active constituents were identified in an Agilent TC-C18 (2) chromatographic column (250mm × 4.6mm, 5µm), with 0.2% phosphoric acid solution - methyl cyanides as mobile phase, which was performed at a gradient elution column temperature of 25oC and a flow rate of 0.8 mL•min-1. Then the eluate was detected at detection wavelengths of 207 nm (for ephedrine) and 278 nm (for hesperidin and baicalin). Under the chromatographic conditions, ephedrine, hesperidin, and baicalin were well separated, which showed good linear relationships at 0.158-2.370, 0.164-4.100 and 0.160-4.000µg, respectively. The coefficients of recovery of these three kinds of samples showed 100.2%, 98.7% and 97.8%, respectively. The developed method is convenient, accurate and well repeatable, and consequently can be applied for the quality control of Lung-Ventilating-Regulating Oral Liquid.

[Enhanced separation behavior of ephedrine in organic solution by nanofiltration mass transfer model].

Based on the nanofiltration mass transfer model, the enhanced separation behavior of ephedrine in organic solution was studied. In the experiment, the sensitive region of ethanol concentration and pH on the rejection of ephedrine was screened out by Box-Behnken central composite experiment design. Furthermore, to analyze the separation regularity of ephedrine and organic solution, the correlation between mass transfer coefficient and concentration of organic solvent was fitted with the changed organic solution by nanofiltration mass transfer mathematical model. Experiments showed the enhanced separation behavior, the decrease in the mass transfer coefficient while the increase in ethanol concentration from 20% to 40%, MWCO at 450 and pH 6.0. Under the same conditions, the enhanced separation behavior was appeared as the solvent changed into methanol and acetonitrile, the enhanced effect was positively correlated with the concentration of the three common organic solvents, and the effect order was acetonitrile>ethanol>methanol. This study took ephedrine as an example, and explored the mechanism of nanofiltration separation in the environment of organic solution, so as to provide references for nanofiltration separation for heat-sensitive traditional Chinese medicine of alkaloid.

Simultaneous UPLC-MS/MS determination of four components of Socheongryong-tang tablet in human plasma: Application to pharmacokinetic study.

The purpose of this study was to develop a method for simultaneous analysis of schizandrin, ephedrine, paeoniflorin, and cinnamic acid as constituents of Socheongryong-tang tablet in human plasma using UPLC-MS/MS. These four components were separated using water containing 0.01% formic acid and methanol as a mobile phase by gradient elution at a flow rate of 0.3 mL/min with a HALO-C18 column (2.1 mm × 100 mm, 2.7 µm particle size). Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique operated in multiple reaction monitoring mode. Mass transitions were m/z 432.9 → 384.1 for schizandrin, 165.8 → 148.1 for ephedrine, 525.0 → 449.2 for paeoniflorin, 146.8 → 102.9 for cinnamic acid, and 340.0 → 324.0 for papaverine as internal standard. Liquid-liquid extraction and protein precipitation with ethyl acetate-methanol (1:2, v/v) were used to obtain these four components. Chromatograms showed high resolution, sensitivity, and selectivity without interference by plasma constituents. Calibration curves of schizandrin, ephedrine, paeoniflorin, and cinnamic acid in human plasma ranged from 0.02 to 8 ng/mL, 0.5 to 200 ng/mL, 0.2 to 80 ng/mL, and 1 to 400 ng/mL, respectively. Calibration curves of each analyte displayed excellent linearity, with correlation coefficients > 0.99. For all four components, both intra- and inter-day precisions (CV%) were <5.99%. The accuracy was 99.35-103.30% for schizandrin, 98.48-104.38% for ephedrine, 97.06-103.34% for paeoniflorin, and 99.97-104.36% for cinnamic acid. This analytical method developed in this study satisfied the criteria of international guidance. It could be successfully applied to pharmacokinetic studies of schizandrin, ephedrine, paeoniflorin, and cinnamic acid after oral administration of Socheongryong-tang tablet to humans.

Ephedrine Alkaloids-Free Ephedra Herb Extract, EFE, Has No Adverse Effects Such as Excitation, Insomnia, and Arrhythmias.

Ephedrine alkaloids-free Ephedra Herb extract (EFE) has been developed to eliminate the adverse effects caused by ephedrine alkaloid-induced sympathetic hyperactivation. Previously, we reported that EFE possesses analgesic, anti-influenza, and cancer metastatic inhibitory effects at comparable levels to that of Ephedra Herb extract (EHE). However, it has not yet been demonstrated that EFE is free from the known side effects of EHE, such as excitation, insomnia, and arrhythmias. In this study, the incidence of these adverse effects was compared between mice administered EHE and those administered EFE. Increased locomotor activity in an open-field test, reduced immobility times in a forced swim test, and reduced sleep times in a pentobarbital-induced sleep test were observed in EHE-treated mice, when compared to the corresponding values in vehicle-treated mice. In contrast, EFE had no obvious effects in these tests. In electrocardiograms, atrial fibrillation (i.e., irregular heart rhythm, absence of P waves, and appearance of f waves) was observed in the EHE-treated mice. It was suggested that this atrial fibrillation was induced by stimulation of adrenaline ß1 receptors, but not by hypokalemia. However, EFE did not affect cardiac electrophysiology. These results suggest that the abovementioned side effects are caused by ephedrine alkaloids in EHE, and that EFE is free from these adverse effects, such as excitation, insomnia, and arrhythmias. Thus, EFE is a promising new botanical drug with few adverse effects.

Two flavone C-glycosides as quality control markers for the manufacturing process of ephedrine alkaloids-free Ephedra Herb extract (EFE) as a crude drug preparation.

As part of our continuing study of ephedrine alkaloids-free Ephedra Herb extract (EFE) in pursuit of its approval as a crude drug preparation, we identified two quantitative markers for the quality control of the manufacturing process of EFE and sought to establish cost-effective and simple methods for quantitative analyses. We analysed Ephedra Herb extracts grown in different habitats and collection years by liquid chromatography/high-resolution mass spectrometry (LC/HRMS) and detected two notable peaks common to each extract. These peaks were identified as vicenin-2 (1) and isovitexin 2″-O-rhamnoside (2). Quantitative analyses using the isocratic condition of LC/MS showed that the content percentages of 1 and 2 in EFE were 0.140-0.146% and 0.350-0.411%, respectively. We concluded that 1 and 2 were adequate quality control markers for quantitative analysis of EFE. Furthermore, we quantitatively analysed apigenin (3), an aglycon common to 1 and 2, and found that the conversion factors of 1 to 3 and 2 to 3 were 1.3 and 1.5, respectively. Therefore, we concluded that 3 was a secondary standard for quantifying the contents of 1 and 2 in EFE. A series of results obtained from this study will be valuable for the quality control of EFE.

Ephedra alkaloid contents of Chinese herbal formulae sold in Taiwan.

Consumption of Ephedra alkaloids is prohibited in-competition by the World Anti-Doping Agency (WADA). In Taiwan, colds are often treated with Chinese herbal formulae containing Herba Ephedrae. We screened products sold in Taiwan and preliminarily assessed their relationships with WADA threshold violations. Fifty-six concentrated powder products, including 19 Chinese herbal formulae that contained Herba Ephedrae, were collected. The content of Ephedra alkaloids, namely ephedrine (E), methylephedrine (ME), norpseudoephedrine (NPE; cathine), pseudoephedrine (PE), and norephedrine (NE; phenylpropanolamine), was determined using a validated high-performance liquid chromatography method. The results revealed that the phenotypic indicators of the collected products, E/PE and E/total ratios, were 1.52-4.70 and 0.49-0.72, respectively, indicating that the Herba Ephedrae species in these products was probably E. sinica or E. equisetina, but not E. intermedia. The contents of E, ME, NPE, PE, and NE and the total alkaloid contents in the daily doses of the products were 0.45-34.97, 0.05-4.87, 0.04-3.61, 0.15-12.09, and 0.01-2.00 mg and 0.68-53.64 mg, respectively. The alkaloid contents followed a relatively consistent order (E > PE > ME ≈ NPE > NE), even for products from different manufacturers. We calculated that single doses of 50.0% and 3.6% of the products would result in the WADA thresholds of E and NPE being exceeded, respectively. Our data provide critical information for athletes and medical personnel, who should be wary of using complex Chinese herbal formulae in addition to over-the-counter products.

Carbon and Nitrogen Stable Isotope Analyses of Ephedra Plant and Ephedrine Samples and Their Application For Methamphetamine Profiling.

In this study, stable isotope ratio analysis was used to track the precursor information of methamphetamine. The δ13 C and δ15 N values of 30 nature ephedra plants, 12 synthetic ephedrine/pseudoephedrine (ephedrine), 14 natural ephedrine, and 987 seized methamphetamine samples were measured and compared. Due to different weather and earth conditions, the δ13 C and δ15 N values of ephedra plants grown in the east and the west of Inner Mongolia showed great difference. The δ15 N values of ephedra plants were consistent with related ephedrine extracted from them. Moreover, the criteria to infer the synthetic origin of ephedrine were set up after the analysis of natural and synthetic ephedrine samples. Finally, the precursor origins of 949 seized methamphetamine samples synthesized by Emde and Nagai method were tentatively inferred. Influenced by different preprecursors, the δ13 C values of seized methamphetamine samples that synthesized from P2P also showed great difference, and this result is consistent with the reported data.

1H and 31P benchtop NMR of liquids and solids used in and/or produced during the manufacture of methamphetamine by the HI reduction of pseudoephedrine/ephedrine.

In this study, the use of benchtop NMR spectroscopy in the analysis of solids and liquids used and/or produced during the HI reduction of pseudoephedrine was evaluated. The study focused on identifying organic precursors and phosphorus containing compounds used in and/or produced during the manufacturing process. Samples taken from clandestine laboratories, where this synthesis process was suspected of occurring, were also analysed and evaluated. Benchtop NMR was able to distinguish between ephedrine, pseudoephedrine and methamphetamine as the free base and hydrochloride salt. This technique was also effective at identifying and distinguishing between phosphorus containing compounds used and/or produced during the manufacture of methamphetamine. Benchtop NMR was also determined to be effective at analysing samples from suspected clandestine laboratories.

Distribution Analysis via Mass Spectrometry Imaging of Ephedrine in the Lungs of Rats Orally Administered the Japanese Kampo Medicine Maoto.

Maoto, a traditional Japanese Kampo medicine, has been used to treat various respiratory diseases, including respiratory infections and influenza. Ephedrine (EPD), the main ingredient in maoto, is also clinically used to treat respiratory diseases. However, the pharmacokinetics and distribution of EPD in the lungs after the administration of maoto have not been demonstrated. This study aimed to determine the concentrations, distribution, and pharmacokinetics of EPD and its precursor methylephedrine (MEPD) in the lungs of rats orally administered maoto (1 and 4 g/kg). We used liquid chromatography-electrospray ionization-tandem mass spectrometry to measure the ingredient concentrations. Both ingredients were detected in maoto-treated lung homogenates. Next, we examined the distribution of both ingredients in lung sections by using matrix-assisted laser desorption/ionization-mass spectrometry imaging, a powerful tool for the visualization of the distribution of biological molecules. The mass spectrometry imaging analysis detected only EPD and provided the first visual demonstration that EPD is distributed in the alveoli, bronchi, and bronchioles in the lungs of rats orally administered maoto (4 g/kg, three times at 2-h intervals). These results suggest that the pharmacological efficacy of maoto for the amelioration of respiratory symptoms is related to the distribution of EPD in the lung.

Ephedrine alkaloids-free Ephedra Herb extract: a safer alternative to ephedra with comparable analgesic, anticancer, and anti-influenza activities.

It is generally accepted that the primary pharmacological activities and adverse effects of Ephedra Herb are caused by ephedrine alkaloids. Interestingly, our research shows that Ephedra Herb also has ephedrine alkaloid-independent pharmacological actions, such as c-MET inhibitory activity. This study describes the preparation of an ephedrine alkaloids-free Ephedra Herb extract (EFE) by ion-exchange column chromatography, as well as in vitro and in vivo evaluation of its pharmacological actions and toxicity. We confirmed that EFE suppressed hepatocyte growth factor (HGF)-induced cancer cell motility by preventing both HGF-induced phosphorylation of c-Met and its tyrosine kinase activity. We also investigated the analgesic effect of EFE. Although the analgesic effect of Ephedra Herb has traditionally been attributed to pseudoephedrine, oral administration of EFE reduced formalin-induced pain in a dose-dependent manner in mice. Furthermore, we confirmed the anti-influenza virus activity of EFE by showing inhibition of MDCK cell infection in a concentration-dependent manner. All assessments of toxicity, even after repeated oral administration, suggest that EFE would be a safer alternative to Ephedra Herb. The findings described here suggest that EFE has c-Met inhibitory action, analgesic effect, and anti-influenza activity, and that it is safer than Ephedra Herb extract itself. Therefore, EFE could be a useful pharmacological agent.

Efficiently prepared ephedrine alkaloids-free Ephedra Herb extract: a putative marker and antiproliferative effects.

Ephedrine alkaloids (EAs) have been considered the main pharmacologically active substances in Ephedra Herb (, Mao; EH) since they were first identified by Prof. N. Nagai, and are known to induce palpitation, hypertension, insomnia, and dysuria as side effects. Therefore, the administration of drugs containing EH to patients with cardiovascular-related diseases is severely contraindicated. While our previous studies suggest that some of the effects of EH may not be due to EAs, considering their side effects would be expedient to develop a new EAs-free EH extract (EFE). Here, we established a preparation method for EFE and revealed its chemical composition, including the content of herbacetin, a flavonoid aglycon present in EH and a potential putative marker for EFE quality control. In addition, we showed the antiproliferative effects of EFE against the H1975 non-small cell lung cancer (NSCLC) cell line. EFE was prepared from EH extract using the ion exchange resin SK-1B. LC/Orbitrap MS analysis revealed the removal of EAs, 6-methoxykynurenic acid, and 6-hydroxykynurenic acid from the original extract. Quantitative analysis of herbacetin using LC/MS in acid-hydrolyzed EFE showed that its content was 0.104 %. Although several alkaloidal constituents were removed from EH extract, the antiproliferative effect of EFE against H1975 cells was comparable to that of EH extract. These results indicate that EFE retained the anticancer effect of EH and demonstrated its potential for future development as a new herbal medicine with reduced side effects.

GC-MS based metabolomics study of stems and roots of Ephedra sinica.

Therapeutic effects of herbal medicines differ greatly due to the use of different anatomical parts or processing methods in traditional Chinese medicine, and Ephedra sinica (ES) is just a case in point. To better understand different traditional uses of the stems (known as Mahuang, MH) and roots (known as Mahuanggen, MHG) of ES, their therapeutic material basis should be investigated. In this study, ephedrine alkaloids were profiled simultaneously with primary metabolites using GC-MS based metabolomics. Ephedrine (E) has been reported to be the major bioactive constituent in MH for the treatment of asthma. The results showed that compared with MH, MHG contained much lower levels of five ephedrine alkaloids, which may well explain that MHG has not been used as an antiasthmatic. Additionally, these pharmacologically important ephedrine alkaloids exhibited strong positive correlation with five primary metabolites. In conclusion, this study facilitates better understanding of different traditional uses of MH and MHG.

Multi-ingredient, caffeine-containing dietary supplements: history, safety, and efficacy.

PURPOSE: Our objective was to review the history, safety, and efficacy of caffeine-containing dietary supplements in the United States and Canada. METHODS: PubMed and Web of Science databases (1980-2014) were searched for articles related to the pharmacology, toxicology, and efficacy of caffeine-containing dietary supplements with an emphasis on Ephedra-containing supplements, Ephedra-free supplements, and energy drinks or shots. FINDINGS: Among the first and most successful dietary supplements to be marketed in the United States were those containing Ephedra­combinations of ephedrine alkaloids, caffeine, and other phytochemicals. A decade after their inception, serious tolerability concerns prompted removal of Ephedra supplements from the US and Canadian markets. Ephedra-free products, however, quickly filled this void. Ephedra-free supplements typically contain multiple caffeine sources in conjunction with other botanical extracts whose purposes can often be puzzling and their pharmacologic properties difficult to predict. Ingestion of these products in the form of tablets, capsules, or other solid dosage forms as weight loss aids, exercise performance enhancers, or energy boosters have once again brought their tolerability and efficacy into question. In addition to Ephedra-free solid dosage forms, caffeine-containing energy drinks have gained a foothold in the world market along with concerns about their tolerability. IMPLICATIONS: This review addresses some of the pharmacologic and pharmaceutical issues that distinguish caffeine-containing dietary supplement formulations from traditional caffeine-containing beverages. Such distinctions may account for the increasing tolerability concerns affiliated with these products.

Determination of ephedrine and pseudoephedrine by field-amplified sample injection capillary electrophoresis.

A simple and rapid capillary electrophoresis method was developed for the separation and determination of ephedrine (E) and pseudoephedrine (PE) in a buffer solution containing 80 mM of NaH2PO4 (pH 3.0), 15 mM of ß-cyclodextrin and 0.3% of hydroxypropyl methylcellulose. The field-amplified sample injection (FASI) technique was applied to the online concentration of the alkaloids. With FASI in the presence of a low conductivity solvent plug (water), an approximately 1,000-fold improvement in sensitivity was achieved without any loss of separation efficiency when compared to conventional sample injection. Under these optimized conditions, a baseline separation of the two analytes was achieved within 16 min and the detection limits for E and PE were 0.7 and 0.6 µg/L, respectively. Without expensive instruments or labeling of the compounds, the limits of detection for E and PE obtained by the proposed method are comparable with (or even lower than) those obtained by capillary electrophoresis laser-induced fluorescence, liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry. The method was validated in terms of precision, linearity and accuracy, and successfully applied for the determination of the two alkaloids in Ephedra herbs.