Simple Eco-Friendly RP-LC Method for the Synchronous Separation of Six Widely Used Drugs in the Treatment of Cerebrovascular and Vestibular Disorders: Application for Analysis in Their Single and Combined Drug Products.

BACKGROUND: Reverse phase liquid chromatography (RP-LC) is considered the most extensively used chromatographic technique in drug separation and quantification, yet its routine use shows increasing environmental challenges about energy consumption, solvent used, and waste engendered. From this perception, efforts for greening the developed RP-LC methods are focused on using green solvents and reducing the amount of solvent used and waste produced. OBJECTIVE: The target of this work is to develop an eco-friendly RP-LC method for the synchronous separation of six widely used drugs in the treatment of cerebrovascular and vestibular disorders, namely neurotropic piracetam, antihistamines dimenhydrinate, cinnarizine, and fluranizine, and vasodilators vincamine and vinpocetine. METHOD: Separation and quantification are accomplished at ambient temperature by isocratic elution mode using acetonitrile-0.2% triethylamine (85:15 by volume) as a mobile phase at a flow rate of 1.5 mL/min on a Hypersil C18 column. UV detection and quantification are carried out at 225 nm. RESULTS: The method is fully validated per ICH guidelines, where all analytical parameters are within the acceptable range (r > 0.9999), accuracy (≥99.55%), and precision (0.02-0.97%). CONCLUSIONS: The method is applied for the routine analysis of the cited drugs in their single and combined drug products, and it is considered excellent in terms of greenness with respect to Eco-Scale assessment. HIGHLIGHTS: As the routine use of the RP-LC technique shows increasing environmental challenges, efforts for greening are attempted focusing on the use of green solvents and reducing the amount of solvent used and waste produced. A simple eco-friendly RP-LC method for the synchronous separation of six widely used drugs in the treatment of cerebrovascular and vestibular disorders is developed. The method is fully validated per ICH guidelines, where all analytical parameters are within the acceptable range. The method is applied for the routine analysis of the cited drugs in their single and combined drug products.

Application of ICH Guidelines for Studying the Degradation Behavior of Rocuronium Bromide Coupled with Stability-Indicating RP-LC Method.

Non-depolarizing neuromuscular blocking agent Rocuronium bromide was quantified in drug substance and drug product using reversed-phase liquid chromatographic method. Forced degradation studies were conducted for Rocuronium bromide in drug substance under acidic (2MHCl), basic (2MNaOH), oxidative (3% H2O2), thermal (135°C) and photolytic (254 nm) stress conditions. An Agilent H12 C18 column was used for separation using diammonium hydrogen phosphate buffer (pH 8; 0.04M)- acetonitrile (50:50; v/v) as mobile phase at flow rate of 1 mL/min. The quantification was done using UV detection at 210 nm. The limit of quantification and detection was 11.1 and 3.66 µg/mL, respectively, and the recovery percentage was 99% in drug substance and drug product. ICH guidelines were adopted for method validation. The proposed LC method monitored the degradation profile for Rocuronium bromide under various stress conditions and provided a specific LC method for its routine analysis. Besides, the MS data were used to identify all Rocuronium bromide degradation products and the possible degradation pathway was designated.

Versatile TLC-Densitometric Methods for the Synchronous Estimation of Cinnarizine and Acefylline Heptaminol in The Presence of Potential Impurity and Their Reported Degradation Products.

From evolution, thin-layer chromatography (TLC) attracts attention as a versatile technique for efficient separation and identification of many drug substances and chemicals. Owing to its simplicity and other outstanding advantages, TLC is extensively used by chromatographers in quantification and purity profiling objectives. In the present study two TLC-Densitometric methods are established and validated for the synchronous estimation of Cinnarizine (Cinn) and Acefyline Heptaminol (Acef) in the presence of Cinn/Acef reported degradation products and Thoephylline (Theo) as Acef potential impurity. The proposed methods are based on densitometric measurements of the spots of Cinn and Acef after separation from their degradation products. Separation is attained on silica gel sheet with dichloromethane: methanol: formic acid as a developing system in ratio: (15, 1, 0.5, by volume) and (15, 0.75, 0.4, by volume) for Cinn (method 1) and Acef (method 2) degradation, consecutively. Quantification is done at 254 nm over concentration ranges of 0.2-1.8 and 2-18 µg/spot for Cinn and Acef; respectively, with mean percentage recoveries of 99.18 ± 0.60/99.84 ± 0.53 and 99.19 ± 0.93/99.66 ± 0.58 for method 1 and method 2; consecutively. The two methods are fully validated and proven to be selective, robust and retained their accuracy in up to 50% of Cinn/Acef reported degradation products and Theo. Moreover, the two methods are applied to a coformulated drug product comprising Cinn and Acef showing satisfactory results. Comparison of the obtained results by the proposed methods with that of the reference ones statistically shows no significant differences.

Synchronous LC-MS/MS determination of pantoprazole and amitriptyline in rabbit plasma: application to comparative in vivo pharmacokinetic study of novel formulated effervescent granules with its marketed tablet dosage form.

In the present study the bioavailability and pharmacokinetics properties of pantoprazole (proton pump inhibitor)/amitriptyline (tricyclic antidepressant) in novel formulated effervescent granules was estimated in rabbit plasma using a validated, selective and rapid LC-MS/MS method. Separation and detection of pantoprazole, amitriptyline and internal standards namely omeprazole and dothiepin, respectively, were achieved at ambient column temperature on C18. Acetonitrile: 4mM ammonium acetate solution (comprising 0.05 % formic acid) (40:60, v/v) was used as mobile phase and the flow rate of 0.6 mLmin-1 was applied. Liquid-liquid extraction technique with diethyl ether: dichloromethane (70:30, v/v) was used to extract the cited drugs from rabbit plasma. Multiple reactions monitoring (MRM) in the positive ionization mode was carried out for quantification. The method was validated over linear concentration range of 0.01-4µgmL-1 and 0.001-0.1 µgmL-1 for Pan and Ami respectively, with regression coefficient (r2) ≥ 0.9961. The intra- and inter-run precisions (%CV) were ≤4.03. The extraction recoveries were in the range of 95.92%-100.24 %. Pan and Ami were stable during three freeze-thaw cycle and post-preparative stability. The work also aimed to formulate immediate release novel effervescent granules by melt granulation technique. Nine formulae were assessed by validated dissolution test for their micrometric properties and dissolution profile. Experimental design was applied to select formula that fulfilled the desired criteria of optimum release of pantoprazole and amitriptyline with optimum micrometric properties for the study. A single period randomized open-label parallel design was applied on Chancellor's rabbit. The selected formula showed superior pharmacokinetic parameters for pantoprazole and amitriptyline than that of marketed products.

Stability indicating liquid chromatography method for the analysis of Vecuronium bromide: study of the degradation profile.

Neuromuscular blocker agent namely; Vecuronium bromide (VEC) was quantified through developing a simple reversed phase liquid chromatographic (RP-LC) method, in drug substance and in drug product. The proposed method could quantify VEC in the presence of its degradation products produced from exposing VEC to different stress conditions as recommended by the International Conference on harmonization (ICH) guidelines. Acidic (2M HCl), basic (2MNaOH) hydrolysis, oxidation (3% H2O2), photolysis (UV light at 254nm), and thermal (135 °C) degradation were estimated by exposing the drug substances to different stress conditions. The separation of the drug from its degradation products was successfully conducted on Tracer Extrasil CN (150 × 4.6mm; 5µm) column using O-phosphoric acid (pH6; 0.05M)-acetonitrile (50:50v/v) as mobile phase. The detection and quantification was done with UV detection at210nm.The validation data were found to be acceptable over a concentration range10-120 µg/ml. The limit of quantification (LOQ) and detection (LOD) were 8.10 and 2.67 µg/ml, respectively. The proposed method met all criteria for validation in accordance with the International Conference on harmonization (ICH) guidelines. The presented work monitored the degradation profile for VEC under various stress conditions and provided a simple LC method for its routine analysis. The structures of the forced degradation products had been described in details using the MS data and the possible degradation pathways were outlined. Besides, the results obtained from the developed method compared statistically with that of the official method indicting high accuracy and precision.

HPTLC Method for Determination of R, R-Glycopyrronium Bromide and its Related Impurities.

An innovative high-performance thin layer chromatographic (HPTLC) method was designed, optimized and validated for the quantification of R, R-glycopyrronium bromide (GLY) and its related impurities in drug substance and drug product. Separation was performed on HPTLC plates pre-coated with silica gel 60 F254 by dichloromethane:methanol:formic acid (10:0.5:0.5, v/v/v) as a developing system. GLY and its related impurities namely, glycopyrronium impurity G and glycopyrronium impurity J, were separated giving compact well-resolved spots with significant retardation factor (Rf) values of 0.17 ± 0.02, 0.34 ± 0.02 and 0.69 ± 0.02, respectively. Quantification was done at 220 nm in the ranges of 0.3-10 and 0.2-4.0 µg/spot with limits of detection and quantification of 0.1, 0.3 and 0.05, 0.2 µg/spot for GLY and its related impurities, respectively. Good accuracy was obtained with mean percentage recovery of 99.48 ± 1.36, 100.04 ± 1.32 and 99.61 ± 0.80 and R2 ≥ 0.9968 for GLY and its impurities, consecutively. Validation parameters were presented according to the International Conference on Harmonization. The method was used to investigate impurity profile of GLY in drug substance and drug product and could be applied in routine analysis of the drug. Comparison between the developed method and the reported method revealed no statistical difference.

Screen printed potentiometric sensor for therapeutic monitoring of rocuronium at the point of care.

Rocuronium bromide (ROC) is currently regarded as the 'gold-standard' in emergency medicine and anesthesia. Globally, millions of human beings are daily administered ROC at emergency settings where it is favored among all the neuromuscular blockers, particularly succinylcholine, for both its fast onset of action and short duration. However, it has been reported that 45% of patients in the post-anesthesia care unit are susceptible to residual postoperative paralysis, undesired ventilator effects and incomplete recovery after ROC administration. From an analytical chemistry perspective, direct determination of ROC is a difficult approach due to the complexity in isolation from biological specimens as well as the lack of a sensitive detection techniques and detectable chromophore. This contribution describes the development of a calix[6]arene-based screen-printed electrode (SPE) that is capable of ROC detection in biological samples at the point of care. This fabricated SPE (sensor 1) exhibited superior performance characteristics (slope, LOD and life time) with respect to an ionophore-free liquid-contact electrode, LCE, (sensor 2). The proposed SPE showed a linear response over a concentration from 1 µM to 10 mM, with a Nernstian slope of 57.9 mV/decade and a detection limit of 0.39 µM. Moreover, this sensor showed a considerable selectivity towards ROC in presence of the anticipated interfering ions. To investigate the ability of the SPE to detect ROC in real biological specimens, ROC has been spiked at a concentration comparable to its anticipated level in human plasma (Cmax~ 40 µM) and the proposed SPE displayed an excellent platform for therapeutic drug monitoring (TDM) of ROC with respect to UV-spectrophotometry and LC/MS. Finally, the developed SPE was used for the determination of ROC in its commercial pharmaceutical formulation.

Development and Validation of RP-LC Method for the Determination of Cinnarizine/Piracetam and Cinnarizine/Heptaminol Acefyllinate in Presence of Cinnarizine Reported Degradation Products.

Specific stability indicating reverse-phase liquid chromatography (RP-LC) assay method (SIAM) was developed for the determination of cinnarizine (Cinn)/piracetam (Pira) and cinnarizine (Cinn)/heptaminol acefyllinate (Hept) in the presence of the reported degradation products of Cinn. A C18 column and gradient mobile phase was applied for good resolution of all peaks. The detection was achieved at 210 nm and 254 nm for Cinn/Pira and Cinn/Hept, respectively. The responses were linear over concentration ranges of 20-200, 20-1000 and 25-1000 µgmL(-1) for Cinn, Pira, and Hept respectively. The proposed method was validated for linearity, accuracy, repeatability, intermediate precision, and robustness via statistical analysis of the data. The method was shown to be precise, accurate, reproducible, sensitive, and selective for the analysis of Cinn/Pira and Cinn/Hept in laboratory prepared mixtures and in pharmaceutical formulations.

High performance liquid chromatographic and thin layer densitometric methods for the determination of risperidone in the presence of its degradation products in bulk powder and in tablets.

Two reproducible stability indicating methods were developed for the determination of risperidone (RISP) in presence of its degradation products in pure form and in tablets. The first method was based on reversed phase high performance liquid chromatography (HPLC), on Lichrosorb RP C 18 column (250 mm i.d., 4 mm, 10 microm), using methanol:0.05 M potassium dihydrogen phosphate pH 7 (65:35 (v/v)) as the mobile phase at a flow rate of 1 ml min(-1) at ambient temperature. Quantification was achieved with UV detection at 280 nm over a concentration range of 25-500 microg ml(-1) with mean percentage recovery of 99.87 +/- 1.049. The method retained its accuracy in the presence of up to 90% of RISP degradation products. The second method was based on TLC separation of RISP from its degradation products followed by densitometric measurement of the intact drug spot at 280 nm. The separation was carried out on aluminum sheet of silica gel 60F254 using acetonitrile:methanol:propanol:triethanolamine (8.5:1.2:0.6:0.2 (v/v/v/v)), as the mobile phase, over a concentration range of 2-10 microg per spot and mean percentage recovery of 100.1 +/- 1.18. The two methods were simple, precise, sensitive and could be successfully applied for the determination of pure, laboratory prepared mixtures and tablets. The results obtained were compared with the manufacturer's method.

Stability indicating reversed-phase high-performance liquid chromatographic and thin layer densitometric methods for the determination of ziprasidone in bulk powder and in pharmaceutical formulations.

Two sensitive and reproducible methods were developed and validated for the determination of ziprasidone (ZIP) in the presence of its degradation products in pure form and in pharmaceutical formulations. The fi rst method was based on reversed-phase high-performance liquid chromatography (HPLC), on a Lichrosorb RP C(18) column using water:acetonitrile:phosphoric acid (76:24:0.5 v/v/v) as the mobile phase at a fl ow rate of 1.5 mL min(-1) at ambient temperature. Quantification was achieved with UV detection at 229 nm over a concentration range of 10-500 micro g mL(-1) with mean percentage recovery of 99.71 +/- 0.55. The method retained its accuracy in presence of up to 90% of ZIP degradation products. The second method was based on TLC separation of ZIP from its degradation products followed by densitometric measurement of the intact drug spot at 247 nm. The separation was carried out on aluminium sheet of silica gel 60 F(254) using choloroform:methanol:glacial acetic acid (75:5:4.5 v/v/v) as the mobile phase, over a concentration range of 1-10 micro g per spot and mean percentage recovery of 99.26 +/- 0.39. Both methods were applied successfully to laboratory prepared mixtures and pharmaceutical capsules.