Determination of enantiomeric compositions of pharmaceutical products by near-infrared spectrometry

Propranolol

Propranolol is a noncardioselective β-blocker. It is reported to have membrane-stabilizing properties, but it does not own intrinsic sympathomimetic activity. Propranolol hydrochloride is used to control hypertension, pheochromocytoma, myocardial infarction, cardiac arrhythmias, angina pectoris, and hypertrophic cardiomyopathy. It is also used to control symptoms of sympathetic overactivity in the management of hyperthyroidism, anxiety disorders, and tremor. Other indications cover the prophylaxis of migraine and of upper gastrointestinal bleeding in patients with portal hypertension. This study provides a detailed, comprehensive profile of propranolol, including formulas, elemental analysis, and the appearance of the drug. In addition, the synthesis of the drug is described. The chapter covers the physicochemical properties, including X-ray powder diffraction, pK, solubility, melting point, and procedures of analysis (spectroscopic, electrochemical, and chromatographic). In-depth pharmacology is also presented (pharmacological actions, therapeutic dosing, uses, Interactions, and adverse effects and precautions). More than 60 references are given as a proof of the abovementioned studies.

Qualitative analysis of chiral alanine by UV-visible-shortwave near infrared diffuse reflectance spectroscopy combined with chemometrics

UV-vis-SWNIR DRS is firstly and successfully used to discriminate the chirality of compounds in powder with a good accuracy.

Evaluation of ecotoxicological effects of drugs on Daphnia magna using different enzymatic biomarkers

The increasing occurrence of pharmaceutical drugs in the aquatic environment is cause of concern, due to the possibility of toxic phenomena in non-target species, including oxidative stress and neurotoxicity. The present study aimed to assess the acute effect of four widely used therapeutic agents: acetaminophen (analgesic), chlorpromazine (antipsychotic), diclofenac (anti-inflammatory) and propranolol (antihypertensive), in the cladoceran species Daphnia magna. Considering the involvement of the mentioned compounds in the impairment of cholinesterasic activity and modifications in cellular redox systems, the purpose of this study was to analyze their effects on biomarkers of neuronal regulation, such as total cholinesterases (ChEs), and enzymatic oxidative stress defense, including as catalase (CAT), glutathione-S-transferases (GSTs), and total and selenium-dependent glutathione-peroxidase (total GPx; Se-GPx) activities. Exposure to acetaminophen caused a significant inhibition of AChE and Se-GPx activities in D. magna relative to the control. Among the biomarkers of oxidative stress, only the activity of CAT was significantly altered in concentration of 0.001mg L(-1) of chlorpromazine, which was not always consistent with the literature. Diclofenac caused a significant inhibition of AChE and Se-dependent GPx, and also in total GPx activities. Propranolol was responsible for a significant decrease in the activity of the latter two enzymes, and also a slight increase of GSTs activity. The results indicated that the exposure to all the tested compounds induced alterations on the cellular redox status in the studied species. In addition, acetaminophen and diclofenac were shown to have the capability of interfering with D. magna neurotransmission, through the inhibition of ChEs. Our data enlighten the need for more research on the ecological consequences of pharmaceuticals in non-target organisms.

Dispersive liquid–liquid microextraction of propranolol enantiomers from human plasma based on the solidification of a floating organic droplet

Background: A dispersive liquid–liquid microextraction based on the solidification of a floating organic droplet was developed and validated for the extraction of propranolol enantiomers from human plasma. The studied enantiomers were extracted from diluted and alkalized plasma samples using 1-undecanol as the extracting solvent. HPLC–fluorescence detection analyses were carried out on a chiral column, using n-hexane–ethanol (80:20, v/v) plus 0.2% triethylamine as the mobile phase, at a flow rate of 0.8 ml/min. The significant factors in the microextraction procedure, including extracting and disperser solvents volume, solution pH and salt contents were optimized by using a central composite design and the response surface methodology. Results: Under optimized conditions, the mean recoveries were approximately 14% with linear responses over the 0.5–100 ng/ml concentration range for both enantiomers. The LOQ was 0.5 ng/ml (S/N = 10). Intra-day (n = 5) and inter-day (n = 3) assay precision (1 and 50 ng/ml) showed RSD lower than 8 and 9.5% for studied enantiomers, respectively. Finally, the method was successfully used for the determination of propranolol enantiomers in plasma samples obtained after single drug administration of racemic propranolol tablet to three healthy volunteers. The plasmatic concentrations of (-)-(S)-PROP were higher than those of (+)-(R)-PROP in all times after oral administration of the racemic drug. Conclusion: The obtained results proved that the proposed method is a powerful technique for sample preparation, providing suitable recoveries, efficient cleanup, high selectivity and sensitivity and low consumption of organic solvent for determination of the studied enantiomers in plasma samples after oral administration of the racemic drug to volunteers.

Sucrose as chiral selector for determining enantiomeric composition of metalaxyl by UV-vis spectroscopy and PLS regression

This study revealed that it was possible to determine the enantiomeric composition of with multivariate regression models of spectral data obtained by ordinary UV-vis spectrophotometry of enantiomeric guest-host complexes. The total 60samples involving three concentration levels of metalaxyl as low, medium and high were prepared for spectral collecting. Four methods of modeling were subsequently proposed and compared including two common ways and two compensating ways for variations in total analyte concentration. Firstly, without normalization robust modeling was failed to achieve while employing the medium concentration levels as calibration and the other two levels as a validation. The same case occurred when full-cross validation was conducted. Besides, two enhanced methods were developed to account for the systematic variation. One of which normalized the spectra with respect to the total concentration of enantiomeric, along with spectral data, as a variable in the statistical analysis. The other one ignored variations in total concentration, relying on the specific band normalization to sort out any variations due to total concentration differences. The results clearly demonstrated that the spectra according to concentration provided the acceptable predictive ability in determining enantiomeric composition.

Fluorescence determination of enantiomeric composition of pharmaceuticals via use of ionic liquid that serves as both solvent and chiral selector

A new method has been developed for the sensitive and accurate determination of enantiomeric compositions of a variety of drugs, including propranolol, naproxen, and warfarin. The method is based on the use of the fluorescence technique to measure diastereomeric interactions between both enantiomeric forms of a drug with an optically active room temperature ionic liquid (RTIL) followed by partial least squares analysis of the data. The chiral RTIL used in this study, S-[(3-chloro-2-hydroxypropyl) trimethylammonium] [bis((trifluoromethyl)sulfonyl)amide] (S-[CHTA](+) [Tf(2)N](-)), is a novel chiral RTIL that has been synthesized successfully recently in our laboratory in optically pure form using a simple one-step reaction with commercially available reagents. The high solubility power and strong enantiomeric recognition ability make it possible to use this chiral RTIL to solubilize a drug and to induce diastereomeric interactions for the determination of enantiomeric purity, that is, to use it as both solvent and chiral selector. Enantiomeric compositions of a variety of pharmaceutical products with different shapes, sizes, and functional groups can be determined sensitively (microgram concentration) and accurately (enantiomeric excess as low as 0.30% and enantiomeric impurity as low as 0.08%) by use of this method.

The Use of Poly(Sodium N-Undecanoyl-l-Leucylvalinate), Poly(Sodium N-Undecanoyl-l-Leucinate) and Poly(Sodium N-Undecanoyl-l-Valinate) Surfactants as Chiral Selectors for Determination of Enantiomeric Composition of Samples by Multivariate Regression Modeling of Fluorescence Spectral Data

Steady-state fluorescence spectroscopy was employed to investigate the use of chiral polymeric surfactants as chiral selectors in chiral analysis by multivariate regression modeling of spectral data. Partial-least-squares regression modeling (PLS-1) was used to correlate changes in the fluorescence spectral data of 1,1'-bi-2-naphthol (BOH), 1,1'-binaphthyl-2,2'-diamine (BNA), or 2,2,2-trifluoroanthrylethanol (TFA) in the presence of poly(sodium N-undecanoyl-L-leucylvalinate), poly(sodium N-undecanoyl-L-leucinate) or poly(sodium N-undecanoyl-L-valinate) as the enantiomeric composition of the chiral analytes was varied. The regression models produced from the spectral data were validated by determining the enantiomeric composition of independently prepared test solutions. The ability of the model to correctly predict the enantiomeric composition of future samples was evaluated using the root-mean-square percent-relative error (RMS%RE) of prediction. In terms of RMS%RE, the ability of the model to accurately predict the enantiomeric composition of future samples was dependent on the chiral analyte, the polymeric surfactant used, and the surfactant medium, and ranged between 1.57 and 6.10%. Chiral analyte concentrations as low as 5 x 10(-6) M were found to give regression models with good predictability.

Solid-phase microextraction coupled with capillary electrophoresis for the determination of propranolol enantiomers in urine using a sol–gel derived calix[4]arene fiber

A new type of diglycidyloxy-calix[4]arene coated fiber made by sol-gel method was initially prepared for capillary electrophoresis (CE) sample pretreatment. By using headspace solid-phase microextraction (SPME) combined with a novel back-extraction facility coupled off-line to capillary zone electrophoresis (CZE), the simultaneous determination of propranolol enantiomers in human urine was achieved. The clean up effect and preconcentration effect were realized for the first time without derivatization during the SPME process in terms of these strong polarity and thermal stable compounds. Ultrasonic back-extraction and field amplified sample injection (FASI) technologies were employed. Extraction and back-extraction parameters were optimized. Preconcentration of the sample by calix[4]arene fiber based SPME and FASI increased the sensitivity, yielding a limit of detection (LOD) of 0.01microg/ml by CZE-diode array detection (DAD). Method repeatability (RSD<6.5%) and fiber reusability (>150 extraction procedures) were observed over a linear range (0.05-10microg/ml) in urine samples. Based on the superior thermal stability, high alkali- and solvent-resistant ability, marvelous repeatability and long lifetime of the novel fiber, this SPME-FASI-CZE procedure could meet the demand of minimum required performance limit (MRPL) set by the World Anti-doping Agency (WADA) for the detection of propranolol in urine samples.

Near-infrared spectrophotometric determination of compositions of fullerene samples

A novel method has been developed for the sensitive and accurate determination of compositions of fullerene samples. The method is based on the synergistic use of spectrophotometric measurements and partial least square method. The method is not only simple, inexpensive and fast but also is non-destructive. Compositions of various fullerene samples including fullerite which is the precursor to C(60) and C(70), can be directly and non-destructively determined by this method without any time-consuming separation step as in the HPLC method or destruction as in the MS method.