Analysis Of Pharmaceutical Formulations Research Articles

Hydrophilic Interaction Liquid Chromatography for the Analysis of Pharmaceutical Formulations

Abstract: For a long time, Reversed-Phase Liquid Chromatography (RPLC) was the most dominant technique for the analysis of pharmaceutical compounds, but with poor efficiency in the separation of small polar molecules. From the efforts to solve the problem of insufficient retention of these molecules, during the last decades, a mode of liquid chromatography named Hydrophilic Interaction Liquid Chromatography (HILIC) has experienced vast expansion. It is based on the use of a highly hydrophilic stationary phase along with an aqueous mobile phase with high organic modifier content. In this review, the characteristics of stationary and mobile phases used in HILIC are described, and corresponding separation mechanisms are discussed. An overview of recently published papers dealing with the application of HILIC in analyzing pharmaceuticals in biological and non-biological samples is provided. Besides, the application of HILIC systems in the determination of the physicochemical properties of compounds is described.

Synchronous spectrofluorimetry and chemometric modeling: A synergistic approach for analyzing simeprevir and daclatasvir, with application to pharmacokinetics evaluation

Simeprevir and daclatasvir represent a cornerstone in the management of Hepatitis C Virus infection, a global health concern that affects millions of people worldwide. In this study, we propose a synergistic approach combining synchronous spectrofluorimetry and chemometric modeling i.e. Partial Least Squares (PLS-1) for the analysis of simeprevir and daclatasvir in different matrices. Moreover, the study employs firefly algorithms to further optimize the chemometric models via selecting the most informative features thus improving the accuracy and robustness of the calibration models. The firefly algorithm was able to reduce the number of selected wavelengths to 47–44% for simeprevir and daclatasvir, respectively offering a fast and sensitive technique for the determination of simeprevir and daclatasvir. Validation results underscore the models' effectiveness, as evidenced by recovery rates close to 100% with relative root mean square error of prediction (RRMSEP) of 2.253 and 2.1381 for simeprevir and daclatasvir, respectively. Moreover, the proposed models have been applied to determine the pharmacokinetics of simeprevir and daclatasvir, providing valuable insights into their distribution and elimination patterns. Overall, the study demonstrates the effectiveness of synchronous spectrofluorimetry coupled with multivariate calibration optimized by firefly algorithms in accurately determining and quantifying simeprevir and daclatasvir in HCV antiviral treatment, offering potential applications in pharmaceutical formulation analysis and pharmacokinetic studies for these drugs.

A non-extraction sequential injection method for determination of loratadine using formation of its ion-association complex with bromocresol purple in acetonitrile

The formation of an ion-association complex (IA) between sulfonephthalein dye and basic nitrogen-containing compound in an organic solvent medium has been for the first time used to develop an automated SIA method. In highly polar aprotic solvents, the tautomeric equilibrium for such dyes is strongly shifted towards the colorless lactonic form. The addition of a basic nitrogen-containing substance leads to the formation of IA with a highly colored quinonoid form, which is accompanied by an increase in the absorbance of the dye band at approximately 400 nm. Protonation of pyridine nitrogen in loratadine, structure and binding places of IA were shown using quantum-chemical calculations. The very simple, direct and non-extraction spectrophotometric SIA method with high throughput of 43 h−1 was developed based on the formation of IA between loratadine and bromocresol purple in the medium of acetonitrile used both as solvent and carrier. The calibration graph was linear in the concentration range from 1.0 to 20 mg L−1 with correlation coefficient of 0.9992. The developed method was successfully applied to the analysis of pharmaceutical formulations.

Determination of Micro Amounts of Promethazine Hydrochloride in Pure and Pharmaceutical Samples Using UV- Visible Spectrophotometry

This study presents the development of a novel, facile, and overly sensitive spectrophotometric approach for quantifying promethazine hydrochloride (PRO) within its pharmaceutical formulations. The method capitalizes on an oxidative coupling reaction, achieved through the oxidation of the compound in an acidic milieu utilizing ammonium cerium (IV) sulfate dehydrate (Ce+4) solution. This process leads to the creation of a green-colored solution, which, upon conjugation with 5-aminosalicylic acid, exhibits maximum absorption at a wavelength of 598 nm. The methodology investigated several parameters, encompassing oxidation duration, temperature, quantities of oxidizing agent and coupling reagent, and determining the stoichiometric ratio between promethazine hydrochloride and 5-aminosalicylic acid. The established ratio was confirmed to be 1:1. Numerous organic solvents were evaluated, with water emerging as the optimal choice due to its pronounced absorption characteristics at the 598 nm wavelength. The applicability of Beer's law was verified over a concentration range of 2 - 28 μg/mL of promethazine hydrochloride, with a calculated molar absorption coefficient of 1.9606 x 104 L/mol∙cm. The Sandell sensitivity index was determined as 0.0164 μg/cm2, while the relative standard deviation (RSD) ranged from 0.8553- 1.2671%. Notably, recovery percentages were also within the 99.88 – 100.34% range. The efficacy of this technique was effectively demonstrated through its successful application in the analysis of pharmaceutical formulations containing promethazine hydrochloride, employing the standard method as a benchmark.

An on-site and portable electrochemical sensing platform based on spinel zinc ferrite nanoparticles for the quality control of paracetamol in pharmaceutical samples.

In this study, crystalline spinel zinc ferrite nanoparticles (ZnFe2O4 NPs) were successfully prepared and proposed as a high-performance electrode material for the construction of an electrochemical sensing platform for the detection of paracetamol (PCM). By modifying a screen-printed carbon electrode (SPE) with ZnFe2O4 NPs, the electrochemical characteristics of the ZnFe2O4/SPE and the electrochemical oxidation of PCM were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and differential pulse voltammetry (DPV) methods. The calculated electrochemical kinetic parameters from these techniques including electrochemically active surface area (ECSA), peak-to-peak separation (ΔEp), charge transfer resistance (Rct), standard heterogeneous electron-transfer rate constants (k0), electron transfer coefficient (α), catalytic rate constant (kcat), adsorption capacity (Γ), and diffusion coefficient (D) proved that the as-synthesized ZnFe2O4 NPs have rapid electron/mass transfer characteristics, intrinsic electrocatalytic activity, and facilitate the adsorption-diffusion of PCM molecules towards the modified electrode surface. As expected, the ZnFe2O4/SPE offered excellent analytical performance towards sensing of PCM with a detection limit of 0.29 μM, a wide linear range of 0.5-400 μM, and high electrochemical sensitivity of 1.1 μA μM-1 cm-2. Moreover, the proposed ZnFe2O4-based electrochemical nanosensor also exhibited good repeatability, high anti-interference ability, and practical feasibility toward PCM sensing in a pharmaceutical tablet. Based on these observations, the designed electrochemical platform not only provides a high-performance nanosensor for the rapid and highly efficient detection of PCM but also opens a new avenue for routine quality control analysis of pharmaceutical formulations.

Novel analytical method based on chemometric models applied to UV–Vis spectrophotometric data for simultaneous determination of Etoricoxib and Paracetamol in presence of Paracetamol impurities

The multivariate models that are used for spectral data analysis have many beneficial applications, and one of the important applications is the analysis of drugs and their impurities. Three Chemometrically-assisted spectrophotometric models have been proposed and validated. The proposed models are Partial Least Squares (PLS), Artificial Neural Networks (ANN), and Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS). The advanced chemometric models were applied to resolve the significantly overlapping spectra of Etoricoxib (ETO) and Paracetamol (PCM), along with impurities of PCM namely; P-aminophenol (PAP) and P-hydroxy acetophenone (PHA). The proposed models succeeded in simultaneously analyzing the mixture of ETO and PCM along with the impurities of PCM. So, the proposed techniques can be used without requiring a separation step in the analysis of pharmaceutical formulation. Moreover, no significant differences were found when the results of the suggested and published chemometric models were compared statistically with the reported HPLC method.

A Guide to Best Practice in Sensory Analysis of Pharmaceutical Formulations.

It is well established that treatment regime compliance is linked to the acceptability of a pharmaceutical formulation, and hence also to therapeutic outcomes. To that end, acceptability must be assessed during the development of all pharmaceutical products and especially for those intended for paediatric patients. Although acceptability is a multifaceted concept, poor sensory characteristics often contribute to poor patient acceptability. In particular, poor taste is often cited as a major reason for many patients, especially children, to refuse to take their medicine. It is thus important to understand and, as far as possible, optimise the sensory characteristics and, in particular, the taste/flavour/mouthfeel of the formulation throughout the development of the product. Sensory analysis has been widely practiced, providing objective data concerning the sensory aspects of food and cosmetic products. In this paper, we present proposals concerning how the well-established principles of sensory analysis can best be applied to pharmaceutical product development, allowing objective, scientifically valid, sensory data to be obtained safely. We briefly discuss methodologies that may be helpful in reducing the number of samples that may need to be assessed by human volunteers. However, it is only possible to be sure whether or not the sensory characteristics of a pharmaceutical product are non-aversive to potential users by undertaking sensory assessments in human volunteers. Testing is also required during formulation assessment and to ensure that the sensory characteristics remain acceptable throughout the product shelf life. We provide a risk assessment procedure to aid developers to define where studies are low risk, the results of a survey of European regulators on their views concerning such studies, and detailed guidance concerning the types of sensory studies that can be undertaken at each phase of product development, along with guidance about the practicalities of performing such sensory studies. We hope that this guidance will also lead to the development of internationally agreed standards between industry and regulators concerning how these aspects should be measured and assessed throughout the development process and when writing and evaluating regulatory submissions. Finally, we hope that the guidance herein will help formulators as they seek to develop better medicines for all patients and, in particular, paediatric patients.

A new HPLC method for selexipag analysis in pharmaceutical formulation and bulk form

Selexipag is a new non-prostanoid prostacyclin receptor agonist used to treat pulmonary arterial hypertension. Selexipag is a long-acting IP receptor agonist with a shorter half-life than all other licensed drugs targeting the prostacyclin pathway, mostly administered intravenously or by subcutaneous infusion or inhalation. In this study, a new high performance liquid chromatography (HPLC) method was developed to analyze Selexipag in bulk and pharmaceutical formulations. The method used a column with Supelco Ascentis® Express (Sigma Aldrich, USA) model phenyl hexyl functional group (100×4.6 mm, ID, 2.7µm). Chromatographic separation was in isocratic elution mode, and the mobile phase mixture was acetonitrile containing 0.1% formic acid: water containing 0.1% formic acid (60:40, v/v) ratio. The method was linear in the concentration range of 15.7-117.6 µg/mL, and the LOD and LOQ were obtained as 2.4 and 3.1 µg/mL, respectively. Various method parameters have been tested according to the ICH Q2(R1) manual, and it is a method with high accuracy and precision. Therefore, the developed method is suitable for selexipag’s bulk and pharmaceutical formulation analysis.

Development of sugars quantification method using polarimeter couple with UV-Visible quartz cuvette cell

The objective of this study was to develop the method for determination of sugars at low sample volume using UV-Visible quartz cuvette cuvett instead of polarimeter cell. This proposed method could be analysis of sugars with high sample throughput rate and appropriate for analysis of pharmaceutical formulation. This study, the simple determination method by using sample UV-Visible quartz cuvette was developed in order to analyze dextrose, sucrose and lactose. It was found that quartz cuvette was not affected from the sodium light source at wavelength of 589.0 nm and it was possible to adapt for polarimetry technique. The linear calibration curve of dextrose, sucrose and lactose standard solution using polarimeter sample tube were constructed in the concentration ranges of 2.5–15.0 % w/v. Linear regression between the angle of rotation (y) and concentration of each sample (x) were expressed as the equation of y = 1.0941x – 0.1824 (r2= 0.9993), y = 1.3515x –0.1581 (r2= 0.9998) and y= 1.0390x – 0.0162 (r2= 0.9997) for dextrose, sucrose and lactose, respectively. Interestingly, the calibration curve of sugars standard solution using UV-Visible quartz cuvette were shown as y = 0.1050x - 0.1038 (r2= 0.9990), y = 0.1312x – 0.1458 (r2= 0.9989) and y = 0.1072x – 0.0335 (r2= 0.9991) for dextrose, sucrose and lactose, respectively. The detection limits (LOD) of proposed method for determination of dextrose, sucrose and lactose were 0.5, 1.0 and 0.6 % w/v, respectively, while the quantitation limits (LOQ) were 1.6, 3.0 and 1.9 %w/v for anlysis of dextrose, sucrose and lactose, respectively. The interferences study for proposed method from sodium chloride was investigated. It had found that this salt shown none effect for the proposed method. The results acquired the proposed method were compared favorably with those acquired by the reference method at a 95% confidence level with no significant difference (n=10). The developed method had shown accurate, precise, and reproducible. Moreover, this method indicated the possibility of a modified polarimetric method for the quantification of sugars. The method is possible to apply both in simple quality control laboratory and local industrial that involved with pharmaceutical production.

A Different Perspective on the Characterization of a New Degradation Product of Flibanserin with HPLC-DAD-ESI-IT-TOF-MSn and its Pharmaceutical Formulation Analysis with Inter-Laboratory Comparison.

Flibanserin (FLB) was firstly synthesized as an antidepressant drug; however, due to its enhancing effects on sexual activity, it was approved for treatment of hypoactive sexual desire disorder in women in 2015. The aim of this study was to develop a new and fully validated HPLC method for analysis of FLB in pharmaceutical formulations besides its degradation products, and identification of possible formation mechanisms by using HPLC-DAD-ESI-IT-TOF-MSn. The HPLC separation was achieved in an Supelco Ascentis® Express series phenyl hexyl column (100 × 4.6 mm, ID 2.7µm). The mobile phase was acetonitrile-ammonium acetate solution (50:50, v/v, 10 mM, pH 5.4) mixture, which was pumped at the rate of 0.5 mL/min. Chromatography, detection and structural identification was performed by using LCMS-IT-TOF instrument (Shimadzu, Japan). 1-(2-(4-(3-hydroxy-5-(trifluoromethyl)phenyl)piperazine-1-yl)ethyl)-1,3-dihydro-2H-benzo[d]imidazol-2-one is proposed as a novel degradation product, with a mass of 407.1695, and a formula of C20H21F3N4O2 with a margin of error about 0.001 ppm. The developed method is applicable with 98% accuracy within 2.5-50.0 µg/mL range. The LOD and LOQ was about 500 ng/mL and 1.50 µg/mL, respectively. The transferability and variation between laboratories were tested by inter-laboratory comparison and evaluated with one-way analysis of variance. A novel FLB degradation product, which was produced under oxidative forced degradation condition was observed and identified for the first time; in addition, the formation kinetics of the degradation product, besides decomposition of FLB was studied. Furthermore, an inter-laboratory comparison was carried out and application of the proposed method on pseudo Addyi® sample was tested using both instrument configurations. A novel stability indicating assay method was developed and fully validated according to ICH (Q2)R1 for the analysis of FLB in the pharmaceutical preparations. A new degradation product was identified in the oxidative forced degradation condition and characterized using HPLC-DAD-ESI-IT-TOF-MS3. Moreover, the possible mechanism and the formation kinetic of the degradation product were revealed. In addition, the developed method was transferred to another LC-PDA instrument for inter-laboratory comparison. Finally, the current method was applied to pseudo formulation of Addy® in both instruments and ANOVA was applied for evaluation.

Spectrophotometric determination of L-α-glycerylphosphorylcholine in pharmaceutical formulations and industrial equipment cleaning rinse water with the WAKO Phospholipids C assay kit

A simple spectrophotometric method for the determination of L-α-glycerylphosphorylcholine in pharmaceutical formulations and industrial equipment cleaning rinse water using the enzyme glycerophosphocholine phosphodiesterase and the WAKO Phospholipids C assay kit was proposed. The method is based on the enzymatic hydrolysis of α-GPC to choline by glycerophosphocholine phosphodiesterase, the reaction of choline with the components of the assay kit, and the colourimetric determination of the formed product. The calibration graph is linear in the range from 1 to 40 mg/l of α-GPC, the molar attenuation coefficient is 1,110 m2/mol, the limit of detection is 1 mg/l, the limit of quantification is 3.3 mg/l, the method is selective with respect to the common excipients, shows a good accuracy (the relative uncertainty does not exceed 7%) and precision (the relative standard deviation does not exceed 5.5%), does not require lengthy sample preparation and sophisticated laboratory equipment and is suitable for the routine analysis of pharmaceutical formulations and industrial equipment cleaning rinse water.

3D porous nanostructured reduced graphene oxide and nafion composite as an ultrasensitive interface for rapid and nanomolar determination of a flavonoid, galangin

Graphene-based nanostructures are considered ideal modifiers for electrochemical sensors owing to their unique structural, conductive, and catalytic properties. Given this, herein we have developed a three-dimensional reduced porous graphene oxide-nafion nanocomposite film modified glassy carbon electrode (p-rGO/NAF/GCE) for electrochemical determination of a flavonoid, galangin (GAL) for the first time. A simple, almost instantaneous, and environmentally benign “low-temperature solution combustion” method was used for the preparation of p-rGO using glycine as a fuel and green reducing agent simultaneously, followed by compositing it with nafion and coating on GCE to form an electrochemical sensor. The p-rGO/NAF/GCE promoted the mass transfer of GAL to the electrode surface and exhibited excellent electrocatalytic activity towards the oxidation of GAL with a significant enhancement (∼70-fold) in the peak current. The enhanced electrocatalytic activity was attributed to the synergistic contribution from p-rGO and nafion, which provided higher active surface area, porous network structure, feasible cation exchangeability, and strong adsorption capacity. The two anodic peaks exhibited by GAL at p-rGO/NAF/GCE involved an equal number of protons and electrons via diffusion-controlled (peak a1) and adsorption-controlled (peak a2) processes. Linear response over concentration range of 1.99 × 10−8 – 4.5 × 10−5 mol L−1 of GAL was established with the lowest limit of detection value of 1.11 nM by square wave voltammetric (SWV) method. Importantly, the fabricated sensor demonstrated repeatability, high stability, and potential anti-interference properties with practical utility for the analysis of analyte-fortified biological samples and pharmaceutical formulations with good recoveries.

Two New HPLC Methods, Assessed by GAPI, for Simultaneous Determination of Four Antipsychotics in Pharmaceutical Formulations: A Comparative Study

Antipsychotics are widely used to treat various mental disorders. Combination therapies were approved by the FDA to treat manic states. Quetiapine fumarate, aripiprazole, asenapine maleate, and chlorpromazine HCl are frequently used for treatment of these disorders. Green analytical chemistry is primarily concerned with reducing waste generated during sample preparation or analysis. Green solvents, such as ethanol, are being used in HPLC as an alternative to acetonitrile. To this purpose, two new chromatographic methods were developed to determine these four drugs simultaneously in their bulk and pharmaceutical formulations. The greenness of both methods was assessed by the green analytical procedure index (GAPI)—one of them was found to be green ecofriendly, and the other had some environmental hazards (conventional)—and this helps laboratories to choose a method that suits their capabilities. The chromatographic separation for both methods was carried out on a Thermo® C18 column. The total separation times were about 11 min and 9 min for the green and the conventional methods, respectively. Using the Student’s t-test and the F-ratio, there was no significant difference between the results of the two methods. These methods have been validated and successfully applied to the analysis of commercial pharmaceutical formulations. Our study could successfully be used in central quality control laboratories, which need a single analytical method to separate more than one compound with similar pharmacological action.

Design a continuous microfluidic flow cell for turbidimetric-flow injection technology: A new approach for routine analysis of active pharmaceutical formulations

In this study, a new flow injection analysis (FIA) based on a microfluidic flow cell (MFC) with a sample capacity of 40 µL is described. A Tungsten lamp directs light from a typical 2100P Portable Turbidimeter apparatus into a quartz flow cell through a round sidewall aperture of 2.0 mm and emerges through the identical aperture on the opposite side of the flow cell, where a photodiode array (light detector) detects the passing light. When compared to a traditional cuvette (25 mm x 60 mm round) with the same nominal route length, this technique improves sensitivity by around 4.0. This improvement is due to the use of a short, narrow internal diameter microfluid as the flow cell, which reduces physical dispersion. The designed flow cell has been evaluated by developing a turbidimetric method for the detection of promethazine in pure form or pharmaceutical dosages. The developed method is based on forming of a yellowish ion-pair association complex due to the reaction of promethazine and sodium tetraphenylborate (STPB) in an acidic medium. At the flow optimum conditions, the calibration curve (CC) and the LOD for promethazine were obtained 0.5-90 µg mL-1 and 0.35 µg mL-1, respectively (R2 = 0.9955).

Eco-friendly spectrophotometric evaluation of triple-combination therapies in the treatment strategy of patients suffering from hypertension during coronavirus pandemic – Spectralprint recognition study

Recent studies have reported that using certain antihypertensive therapies such as angiotensin II receptor blockers (ARBs) and calcium channel blocker (CCBs) is associated with reduction of fatal outcomes and improving clinical characteristics of patients suffering from hypertension during coronavirus pandemic. Thus, in the current work an effective, innovative and eco-friendly spectrophotometric manner namely, parent spectrum extraction (PSE)was established for evaluation of recommended triple antihypertensive combination therapies incorporate valsartan (VAL) as ARBs, amlodipine besylate as CCBs (AML) and hydrochlorothiazide (HCT)as diuretic into single-pill in challengeable ratio. PSE manner composed of two complementary steps, auxiliary resolution coupled with data analysis resolution(DAR)and it is characterized by resolving the spectral bands of the drugs and extraction of their discrete parent spectra (D0); accordingly, enabling determination of each analyte at its λmax. Auxiliary resolution of AML in triple mixture was applied to decrease complexity of overlapped spectra via constant multiplication (CM) followed by spectrum subtraction (SS) to obtain resolved mixture of VAL and HCT while data analysis resolution (DAR) of this binary mixture was applied via one of three novel methods namely, absorbance extraction (AE), peak-amplitude extraction (PE) and ratio extraction (RE) along with SS method. The proposed methods had analyzed VAL, AML and HCT in the range of 4.0–44.0 µg/mL, 4.0–40.0 µg/mL and 2.0–24.0 µg/mL, respectively with an excellent correlation coefficient (r ≥ 0.9999). Further, the proposed methods in PSR manner were validated as stated by ICH guidelines and it was found that accuracy and precision results are within the acceptable limit. The suggested procedures were effectively utilized for the concurrent quantification of VAL, AML and HCT in synthetic mixtures and tablets. The greenness of the proposed spectrophotometric methods was evaluated by National Environmental Methods Index (NEMI), the Analytical Eco-Scale, the Green Analytical Procedure Index (GAPI) and Analytical greenness metric (AGREE) where the four tools affirmed the eco-friendly nature of the proposed methods. A comparison between the outcomes of the studied methods with the official and reported ones was performed and no statistical difference was arisen between the methods regarding to accuracy and precision.The achieved results along with the simplicity, affordability and low-cost of the proposed methods recommended their appropriateness for the regular quality control examination and analysis of pure materials and pharmaceutical formulations as well as their applicability for the spectralprint recognition of the studied drugs.

DEVELOPMENT AND VALIDATION OF NOVEL STABILITY INDICATING RP-HPLC METHOD FOR QUANTIFICATION OF ALIMEMAZINE IN BULK AND PHARMACEUTICAL DOSAGE FORM

Specific stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method has been developed and validated for the quantification of alimemazine in bulk drug and pharmaceutical dosage forms. Chromatographic separation was done on C 18 column (250 mm X 4.6 mm X 5 µm) using a mobile phase containing a mixture of methanol: 0.02 M potassium dihydrogen orthophosphate buffer in the ratio 75:25 V/V (pH was maintained at 3.0 by using o-phosphoric acid) on isocratic mode at flow rate of 1.0 mL min-1 and detection wavelength of 257 nm. The retention time of alimemazine was found to be 4.528 min with linearity in the concentration range from 10 – 50 µg mL-1. The mean percentage recovery of alimemazine was found to be 99.3 – 100.62 %. The percent relative standard values were less than 2.0 % at all the levels, indicating a satisfactory accuracy and precision of the method. Performed robustness study was found to meet the acceptance criteria. In order to check the selectivity of the proposed method, degradation studies were carried out using hydrolysis (acid and alkali), oxidation, photolytic and thermal degradation conditions. The developed method, after being validated in terms of precision, accuracy, LOD, LOQ and robustness was successively applied to the analysis of pharmaceutical formulation.

Potentiometric quantitation of general local anesthetics with a new highly sensitive membrane sensor.

The detection of local anesthetic drugs is of great importance in the analysis of pharmaceutical, clinical and forensic samples. This paper reports a simple and sensitive potentiometric assay suitable for detecting general local anesthetics (LAs) of two types, namely: amino ester-anesthetics (procaine) and amino amide-anesthetics (lidocaine, articaine). As a detector, a new highly sensitive sensor based on a poly(vinyl chloride)-matrix membrane incorporating ion-pair complexes of protonated procaine with 2-[bis-octadecyl-sulfonic)-closo-decaborate is used. To improve the analytical characteristics of the sensor, the tetradodecylammonium - 2-[bis-octadecyl-sulfonic)-closo-decaborate associate as a lipophilic additive is proposed. The procedures for the synthesis of both electroactive membrane components are described. The dependence of potential response characteristics of the potentiometric system on the membrane composition, local anesthetic properties, and pH of the sample solutions is discussed. The difference in sensitivity and selectivity of the sensor was found to be responsible for the lipophilic property and pKa values of local anesthetic molecules. The developed sensor exhibited a near Nernstian response to cationic forms of procaine and some other anesthetics of higher lipophility, in particular lidocaine and articaine, over a wide linear concentration range. The limit of detection was varied from 2×10-8 to 5×10-7μM, and it is the lowest value among the early published potentiometric analogs. The proposed method was successfully applied to the analysis of pharmaceutical formulations and spiked enzyme-free urine samples containing LAs at low concentration levels (0.5-100μgmL-1). The recovery range (n=5) was 98.0-101.5%, and the relative standard deviation was no more than 5.0%.

Rapid and sensitive simultaneous separation and electrochemical detection of tetracaine hydrochloride and oxymetazoline hydrochloride in pharmaceutical formulations via core-shell reversed-phase liquid chromatography

Tetracaine hydrochloride (TCH) is a nasal anesthetic and oxymetazoline hydrochloride (OZH) is a nasal decongestant. A moderate to acute overdosage of OZH and TCH can lead to mydriasis, nausea, cyanosis, tachycardia, dyspnoea, cardiovascular failure, disorientation, seizures, and even death. Liquid chromatography (LC) has been mainly utilized for the individual determination of either TCH or OZH; however, there is a need for rapid and efficient methods for simultaneous analysis in pharmaceutical formulations and aqueous samples. This study highlights the use of the fast and efficient separation capabilities of core-shell silica particles in liquid chromatography (LC) for the simultaneous determination of TCH and OZH using UV detection and the enhanced selectivity afforded by electrochemical detection at a boron-doped diamond (BDD) electrode. Rapid reversed-phase (RP) separation and detection of OZH and TCH in nasal spray and eye drops was achieved within 45 s using a poroshell 120 EC-C18 column, by adjusting the ratio of organic solvent, mobile phase pH, detection potential and mobile phase flow rate. Sensitivity was compared using ultraviolet (UV) detection at 280 nm, and ECD at + 1.3 V with detection limits of 40 and 70 nM for TCH and OZH, respectively. The developed rapid method was utilized successfully in the analysis of pharmaceutical formulations, where the estimated levels of TCH and OZH in these formulations are in agreement with the specified values outlined by the manufacturers.

Impurity-profiling UPLC methods for quantitative analysis of some antiemetics formulated with pyridoxine.

Cyclizine hydrochloride (CYC) and meclozine hydrochloride (MEC) are antihistaminic drugs generally co-formulated with pyridoxine hydrochloride (PYR) to treat nausea and vomiting in pregnancy. Several analytical techniques have been applied for the determination of CYC or MEC with PYR, but determination of CYC impurity; benzhydrol (BEH) or MEC impurity; or 4-chlorobenzophenone (BEP) has not been paid attention to. Therefore, micellar UPLC method is introduced for analysis of ternary mixtures containing PYR together with both CYC and BEH (mixture I) or MEC and BEP (mixture II). Chromatographic separation was achieved using a Hypersil gold C8 column (50 × 2.1mm, 1.9μm) using 0.01 M sodium dodecyl sulfate modified to pH3.5 using phosphoric acid:acetonitrile (45:55 by volume) for mixture I and 0.1% sodium dodecyl sulfate, 0.1% sodium bicarbonate adjusted to pH2.6 by phosphoric acid:acetonitrile (47:53 by volume) for mixture II as mobile phases. The separated peaks were detected at 230 and 245 nm for mixtures I and II, respectively. The adopted methods were validated in conformance with the International Conference on Harmonization (ICH) recommendations and were properly applied in commercial pharmaceutical formulation analysis. Comprehensive ecological comparison was achieved, confirming a higher ecological value of the presented methods compared to the earlier reported methods.

Selection of essential spectra to improve the multivariate curve resolution of minor compounds in complex pharmaceutical formulations

Multivariate curve resolution unmixing of hyperspectral imaging data can be challenging when low sources of variance are present in complex samples, as for minor (low-concentrated) chemical compounds in pharmaceutical formulations. In this work, it was shown how the reduction of hyperspectral imaging data matrices through the selection of essential spectra can be crucial for the analysis of complex unknown pharmaceutical formulation applying Multivariate Curve Resolution – Alternating Least Squares (MCR-ALS). Results were obtained on simulated datasets and on real FT-IR and Raman hyperspectral images of both genuine and falsified tablets. When simulating the presence of minor compounds, different situations were investigated considering the presence of single pixels of pure composition as well as binary and ternary mixtures. The comparison of the results obtained applying MCR-ALS on the reduced data matrices with those obtained on the full matrices revealed unequivocal: more accurate decomposition could be achieved when only essential spectra were analyzed. Indeed, when analyzing the full dataset, MCR-ALS failed resolving minor compounds even though pure spectra were provided as initial estimation, as shown for Raman hyperspectral imaging data obtained on a medicine sample containing 7 chemical compounds. In contrast, when considering the reduced dataset, all minor contributions (down to 1 pixel over 17,956) were successfully unmixed. The same conclusion could be drawn from the results obtained analysing FT-IR hyperspectral imaging data of a falsified medicine.