Pharmacopoeia Method Research Articles

Rapid inexpensive assay method for verapamil by spectrophotometric sequential injection analysis

Sequential injection analysis (SIA) technique with a miniaturized fibre optic spectrophotometry was exploited to optimize and validate a new method for the assay of verapamil in pharmaceutical formulations. The reduction of acidified permanganate by verapamil was spectrophotometrically detected at 546 nm. The 2(3) full-factorial design was adopted for screening the effect of conditions controlling the proposed method, and accordingly for the purpose of optimization. The remarkable advantages of the method are high rapidity (sample frequency was 10.6 samples/h), saving in reagents and sample (total consumed volume was 190 µl) and better safety for the environment (total waste production volume was 2140 µl). Additionally, the method was selective in the presence of excipients usually found in tablet and injection formulations. The average of recovery in synthetic samples as well as dosage forms was 98.8-103.0%. The obtained results were realized by the British Pharmacopoeia method and comparable results were obtained.

¿Quién debe aplicar las inyecciones intravítreas?

Ganciclovir is synthetic nucleoside analog of guanine closely related to acyclovir but has greater activity against cytomegalovirus. This comprehensive profile on ganciclovir starts with a description of the drug: nomenclature, formulae, chemical structure, elemental composition, and appearance. The uses and application of the drug are explained. The methods that were used for the preparation of ganciclovir are described and their respective schemes are outlined. The methods which were used for the physical characterization of the dug are: ionization constant, solubility, X-ray powder diffraction pattern, crystal structure, melting point, and differential scanning calorimetry. The chapter contains the spectra of the drug: ultraviolet spectrum, vibrational spectrum, nuclear magnetic resonance spectra, and the mass spectrum. The compendial methods of analysis of ganciclovir include the United States Pharmacopeia methods. Other methods of analysis that were reported in the literature include: high-performance liquid chromatography alone or with mass spectrometry, electrophoresis, spectrophotometry, voltammetry, chemiluminescence, and radioimmunoassay. Biological investigation on the drug includes: pharmacokinetics, metabolism, bioavailability, and biological analysis. Reviews on the methods used for preparation or for analysis of the drug are provided. The stability of the drug in various media and storage conditions is reported. More than 240 references are listed at the end of the chapter.

Significant fluorescence enhancement by supramolecular complex formation between berberine chloride and cucurbit( n = 7)uril and its analytical application

The supramolecular interaction of cucurbit( n = 7)uril (Q[7]) with berberine chloride (BER) has been studied in aqueous solution at pH 2.0 and room temperature by spectro-fluorimetry. The association constant of the complex was 2.07 × 10 6 L mol −1 calculated by using a nonlinear least squares method. 1H NMR spectra confirmed that a 1:1 stable complex is formed between Q[7] and BER. This work proposes a possible interaction mode, in which the guest BER is incorporated inside the hydrophobic cavity of the host Q[7] via the isoquinoline ring part of the guest molecule. Based on a significant enhancement of the fluorescence intensity of this supramolecular complex, a spectrofluorimetric method with high sensitivity and selectivity has been developed for the determination of BER in aqueous solution in the presence of Q[7]. The linear range of the method was from 7.43 to 11.2 × 10 3 ng mL −1with the detection limit 4.2 ng mL −1. There was no interference from the compounds normally used in tablets, serum or urine constituents. The proposed method was applied to the determination of BER in tablets, serum and urine samples with satisfactory results and good consistency with those obtained by the pharmacopoeia method. This shows that it has promising potential for therapeutic drug monitoring and pharmokinetics and for clinical application.

Mass spectrometric characterization of gentamicin components separated by the new European Pharmacopoeia method

Liquid chromatography combined with pulsed electrochemical detection (LC–PED) is the method of choice in the European Pharmacopoeia for the determination of gentamicin and its related substances. A recently approved improved LC–PED method, with a reversed-phase C 18 column and a mobile phase consisting of trifluoroacetic acid (TFA), pentafluoropropionic acid (PFPA), sodium hydroxide and acetonitrile, showed better separation and more sensitive detection of the gentamicin components than the previous method using a polymer column. More unknown peaks can be separated from the main components and from each other. As the LC–PED method cannot be directly coupled to a mass spectrometer (MS), the unknown substances were collected after the LC column, desalted and analyzed by MS. The structures of the unknown compounds were deduced based on comparison of their fragmentation patterns with those of reference substances investigated by MS n experiments using an electrospray ion trap mass spectrometer. A comparison was also made with an already previously published LC–MS method using a volatile mobile phase.

Septonex–tetraphenylborate screen-printed ion selective electrode for the potentiometric determination of Septonex in pharmaceutical preparations

A screen-printed electrode (SPE) was fabricated for the determination of 1-(ethoxycarbonyl)pentadecyltrimethylammonium bromide (Septonex) based on the use of Septonex-tetraphenylborate as the electroactive substance, and o-nitrophenyloctylether (o-NPOE) as the plasticizing agent. The electrode passes a near-Nernstian cationic slope of 59.33 ± 0.85 mV from activity between pH values of 2 to 9 with a lower detection limit of 9×10(-7) M and response time of about 5 s and exhibits an adequate shelf-life of 6 months. The method was applied for the determination of Septonex in pharmaceutical preparations. A percentage recovery of 99.88% was obtained with RSD=1.24%. The electrode was successfully applied in the determination of Septonex in laboratory-prepared samples by direct potentiometric, calibration curve and standard addition methods. Potentiometric titration of Septonex with sodium tetraphenylborate and phosphotungstic acid as a titrant was monitored with the modified screen-printed electrode as an end-point indicator electrode. Selectivity coefficients for Septonex relative to a number of potential interfering substances were determined. The sensor was highly selective for Septonex over a large number of compounds. Selectivity coefficient data for some common ions show negligible interference; however, cetyltrimethylammonium bromide and iodide ions interfere significantly. The analytical usefulness of the proposed electrode was evaluated by its application in the determination of Septonex in laboratory-prepared pharmaceutical samples with satisfactory results. The results obtained with the fabricated sensor are comparable with those obtained by the British Pharmacopeia method.

Animal Refinement and Reduction: Alternative Approaches for Potency Testing of Diphtheria and Tetanus Vaccines

Evaluation and quality control of diphtheria and tetanus vaccines have traditionally relied on the use of in vivo protection models involving challenge of laboratory animals with toxins. However, for routine lot release, validated serological assays are routinely being used that offer significant advantages in terms of reduction in animal numbers because responses to multiple vaccine components can be measured in a single group. Use of a serological assay also represents a refinement of procedures since the requirement for toxin challenge is removed. The National Institute for Biological Standards and Control (NIBSC, UK) contributed to international validation studies on the use of serology for diphtheria and tetanus potency testing, which led to revisions of the relevant European Pharmacopoeia method chapters. Here we describe the impact of routine use of a serological assay for testing diphtheria and tetanus components of a combined vaccine used for primary immunization of children as part of the UK immunization schedule. Opportunities for further reduction in animal numbers are also discussed.

Fluorimetric Analysis of Aluminum in Diluted Hemodialysis Solutions by Using a Novel Schiff Base

A spectrofluorimetric method has been developed for trace amount of aluminum(III) by using a novel Schiff base, N,N′-bis(salicylidene)-1,4-diaminobuthane (BUTAS), and 4-methyl-2-aminophenol (OAP). Since the aluminum complexes are generally fluorescent, aluminum(III) increases the fluorescence intensity of BUTAS-OAP by formation of Al-BUTAS-OAP complex. The fluorescence of the complex is measured at an excitation wavelength of 410 nm with an emission at 526 nm. Aluminum(III) can be detected within a concentration limit of 0.11–1.62 ppb and the lowest detection limit being 0.07 ppb. The proposed method was applied to diluted hemodialysis solution and spectrofluorimetric data was compared with data of standard pharmacopoeia method.

Development of a new contact lens multipurpose solution: Comparative analysis of microbiological, biological and clinical performance

Purpose Antimicrobial, cytotoxicity and clinical performance of a new soft contact lens multi-purpose solution (COMPLETE ® RevitaLens) based on polyquaternium-1 and alexidine dihydrochloride (NuMPS) was evaluated. Methods Antimicrobial efficacy was assessed according to ISO 14729 for both biocidal and regimen performance against bacteria and fungi. Acanthamoeba efficacy was tested along with ability to retain antimicrobial activity on partial evaporation. In vitro cytotoxicity of NuMPS and OPTI-FREE ® RepleniSH ® MPS (MPS-3) was assessed based on ISO 10993-5 and United States Pharmacopeia (USP) methods. In addition, a 3 month, double-masked, parallel group clinical trial comparing safety and acceptability with respect to MPS-3 was conducted with 4 silicone hydrogel (SiHy) and FDA Group IV lens types. Results NuMPS showed broad antimicrobial efficacy, including Acanthamoeba, giving a 3–4 log 10 reduction in viability after 6 hours contact time. NuMPS also passed ISO 14729 regimens with SiHy and etafilcon lenses for bacteria, fungi and also Acanthamoeba. The cytotoxicity of NuMPS was equivalent or better compared to MPS-3. In the clinical trial, there was no statistically significant between-group difference in corneal staining (p > 0.05). Patients using MPS-3 had more adverse events than patients using NuMPS: 11.8 % (11/93) versus 2.8 % (5/177), respectively, (p < 0.05). There were no differences noted in cleanliness or wearing comfort (p > 0.05). Conclusion Taken together, the results of these studies indicate that the NuMPS is a novel and effective soft contact lens care solution.

Development of a biomimetic chitosan film-coated gold electrode for determination of dopamine in the presence of ascorbic acid and uric acid

A gold electrode surface was modified using a dinuclear copper complex [Cu II 2 (Ldtb)(μ-OCH 3)](BPh 4) and then coated with a chitosan film. This biomimetic polymer film-coated electrode was employed to eliminate the interference from ascorbic acid and uric acid in the sensitive and selective determination of dopamine. The optimized conditions obtained for the biomimetic electrode were 0.1 M phosphate buffer solution (pH 8.0), complex concentration of 2.0 × 10 −4 M, 0.1% of chitosan and 0.25% of glyoxal. Under the optimum conditions, the calibration curve was linear in the concentration range of 4.99 × 10 −7 to 1.92 × 10 −5 M, and detection and quantification limits were 3.57 × 10 −7 M and 1.07 × 10 −6 M, respectively. The recovery study gave values of 95.2–102.6%. The lifetime of this biomimetic sensor showed apparent loss of activity after 70 determinations. The results obtained with the modified electrode for dopamine quantification in the injection solution matrix were in good agreement with those of the pharmacopoeia method.

Evaluation of a simple and low cost potentiometric biosensor for pharmaceutical and in vivo adrenaline determination

In this work the polyphenol oxidase (PPO) was the main component of a biosensor for adrenaline determination. The activity of this enzyme was measured in several vegetables. Banana ( Musa sp.) extracts presented better results with 974 UA (units of activity). The biosensor was constructed with a polyethylene tube (0.8 mm i.d.) filled with: carbon paste containing 50 UA of the PPO in phosphate buffer (pH = 7.00) solution and vaseline as agglutinant. When the biosensor was applied in medicine samples it provided a linear range from 8.00 × 10 −9 to 8.00 × 10 −4 mol L −1; the results obtained with the proposed method and the Brazilian Pharmacopoeia method were in agreement ( t-test). When it was applied in blood samples, the matrix-matching calibration was used, and the linear range was from 8.00 × 10 −7 to 8.00 × 10 −3 mol L −1. In vivo studies were also done. The obtained results for those electrodes, which were inserted in the jugular vein of Wistar rats, were very promising.

Simultaneous voltammetric determination of levodopa, carbidopa and benserazide in pharmaceuticals using multivariate calibration

An analytical methodology based on differential pulse voltammetry (DPV) on a glassy carbon electrode and the partial least-squares (PLS-1) algorithm for the simultaneous determination of levodopa, carbidopa and benserazide in pharmaceutical formulations was developed and validated. Some sources of bi-linearity deviation for electrochemical data are discussed and analyzed. The multivariate model was developed as a ternary calibration model and it was built and validated with an independent set of drug mixtures in presence of excipients, according with manufacturer specifications. The proposed method was applied to both the assay and the uniformity content of two commercial formulations containing mixtures of levodopa–carbidopa (10:1) and levodopa–benserazide (4:1). The results were satisfactory and statistically comparable to those obtained by applying the reference Pharmacopoeia method based on high performance liquid chromatography. In conclusion, the methodology proposed based on DPV data processed with the PLS-1 algorithm was able to quantify simultaneously levodopa, carbidopa and benserazide in its pharmaceuticals formulations using a ternary calibration model for these drugs in presence of excipients. Furthermore, the model appears to be successful even in the presence of slight potential shifts in the processed data, which have been taken into account by the flexible chemometric PLS-1 approach.

Kinetic approach for the enzymatic determination of levodopa and carbidopa assisted by multivariate curve resolution-alternating least squares

A combination of kinetic spectroscopic monitoring and multivariate curve resolution-alternating least squares (MCR-ALS) was proposed for the enzymatic determination of levodopa (LVD) and carbidopa (CBD) in pharmaceuticals. The enzymatic reaction process was carried out in a reverse stopped-flow injection system and monitored by UV–vis spectroscopy. The spectra (292–600 nm) were recorded throughout the reaction and were analyzed by multivariate curve resolution-alternating least squares. A small calibration matrix containing nine mixtures was used in the model construction. Additionally, to evaluate the prediction ability of the model, a set with six validation mixtures was used. The lack of fit obtained was 4.3%, the explained variance 99.8% and the overall prediction error 5.5%. Tablets of commercial samples were analyzed and the results were validated by pharmacopeia method (high performance liquid chromatography). No significant differences were found ( α = 0.05) between the reference values and the ones obtained with the proposed method. It is important to note that a unique chemometric model made it possible to determine both analytes simultaneously.

Spectrophotometric Determination of Nitrazepam in Pharmaceutical Tablets Using Flow Injection Analysis

Nitrazepam (NZP) was determined spectrophotometrically in the pure form and in the pharmaceutical tablets using flow injection analysis (FIA). The method was based on oxidative coupling organic reaction of reduced NZP with promethazine hydrochloride in the presence of sodium periodate to give a green solution having an absorbance maximum at 613 nm. The various chemical and physical variables were optimized. The calibration graph of NZP is linear from 1 to 50 μg mL-1 with detection limit (S/N = 3) was 0.9284 μg mL-1. The method was successfully applied to the analysis of NZP in pharmaceutical tablets. The results obtained by applying the proposed FIA method were in good agreement with those obtained by British Pharmacopoeia method at the 95% confidence.

An interlaboratory study on the suitability of a gradient LC-UV method as a compendial method for the determination of erythromycin and its related substances

A liquid chromatographic (LC) method for the analysis of erythromycin and related substances has been adapted from an isocratic method developed by Chepkwony et al. (2001) [1]. The suitability of the method for general application as a compendial (pharmacopoeia) method has been assessed by means of an interlaboratory (collaborative) study. The method involves LC separation on a XTerra C18 column kept at 65 °C and UV detection at 210 nm. Five laboratories, located in Europe and the United States (US), participated in the study. Four erythromycin samples were tested. The main components (erythromycin A (EA), erythromycin B (EB), erythromycin C (EC)) and the impurities were determined. The analysis of variance was carried out on the results of the five laboratories to evaluate the between-laboratory consistencies and the laboratory-sample interaction. The estimates for the repeatability and reproducibility of the method, expressed as relative standard deviation (RSD) of the result of the determination of EA, were calculated to be 0.8% and 1.4% respectively. It is concluded that the method examined is a good replacement for the methods currently described in the European Pharmacopoeia (Ph. Eur.) and the United States Pharmacopoeia (USP), especially for its enhanced selectivity.

Spectrophotometric determination of metoclopramide hydrochloride in pharmaceutical tablets, by diazotization-coupling method with 1-naphthol as the coupling agent

Simple, rapid and sensitive spectrophotometric method was proposed for the analysis of metoclopramide hydrochloride (MPH) in pure form as well as in pharmaceutical tablets. The method is based on the diazotization reaction of MPH with sodium nitrite in hydrochloric acid medium to form diazonium salt, which is coupled with 1-naphthol in sodium hydroxide medium to form azo dye, showing absorption maxima at 550 nm. Beer’s law is obeyed in the concentration range of 0.4 – 18 µg mL-1 of MPH with detection limit 0.5448 µg mL-1. The molar absorptivity and Sandell’s sensitivity are 3.4969 × 104 L mol-1 cm-1 and 0.0101 µg cm-2, respectively. The method was successfully applied to the determination of MPH in pharmaceutical tablets without any interference from common excipients used as additives in tablets. The results agree favorably with the official British Pharmacopoeia method.

BATCH AND FLOW INJECTION SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF PARACETAMOL IN PHARMACEUTICAL PREPARATIONS VIA OXIDATIVE COUPLING WITH 4-AMINOANTIPYRINE

A simple, rapid and sensitive batch and flow injection spectrophotometric methods have been developed for the determination of paracetamol in pure form and pharmaceutical preparations. The proposed methods are based on the oxidative coupling reaction of paracetamol with 4-aminoantipyrine in presence of ammonium persulfate in alkaline medium to produce an orangereddish product that having absorptivity maximum at 461 nm. The optimum reaction conditions and other analytical parameters have been evaluated. Linearity was observed from 2-16 and 100-700 g mL -1 paracetamol by batch and flow injection procedures, respectively. Statistical analysis of the results and comparison with results by the British Pharmacopoeia method are also reported.

Glucoraphanin hydrolysis by microbiota in the rat cecum results in sulforaphane absorption

In the absence of the plant enzyme myrosinase, such as in cooked broccoli, glucoraphanin is considered to be hydrolyzed by bacteria in the lower gut to produce the bioactive isothiocyanate sulforaphane. Simulated digestion using US Pharmacopeia methods caused no loss of glucoraphanin, confirming that glucoraphanin is not destroyed by digestive enzymes during passage through the digestive tract and is able to reach the rat cecum intact. Introduction of glucoraphanin (150 μmol/kg BW) directly into the cecum resulted in appearance of isothiocyanates in the mesenteric plasma by 120 min. In contrast, introduction of sulforaphane (150 μmol/kg BW) directly into the cecum resulted in the appearance of isothiocyanates in the mesenteric plasma within 15 min. Plasma levels remained constant for over an hour. Anaerobic incubation ex vivo of cecal microbiota from male F344 rats with glucoraphanin resulted in very low levels of the hydrolytic metabolite erucin nitrile, showing that hydrolysis of glucosinolates is carried out by cecal microbiota, but metabolism ex vivo by microbiota did not reflect not reflect metabolism in situ. These data are the first to report direct evidence of hydrolysis of glucoraphanin to sulforaphane in the cecum of rats and to show that sulforaphane is able to cross the cecal enterocyte for systemic absorption.

An HPLC method for the determination of digoxin in dissolution samples

An HPLC method for digoxin quantification in dissolution samples obtained as per the official British Pharmacopeia (BP) method is presented in this paper. The chromatography was performed at 20 ?C on a Symmetry C18; 3.5 ?m, 75 x 4.6 mm column with water - acetonitrile (72 : 28, v/v), as the mobile phase and UV detection at 220 nm. The method was found to be selective, linear, accurate and precise in the specified ranges. The LOD and LOQ were 0.015 ?g mL-1 and 0.050 ?g mL-1, respectively. Robustness testing was conducted to evaluate the impact of minor changes in the chromatographic parameters (i.e., acetonitrile fraction, flow rate of the mobile phase, column temperature and column length) on the characteristics of the digoxin peak. A. full factorial design (24) was used to investigate the influence of the four variables The presented HPLC method was applied in quality and stability testing of Digoxin tablets 0.25 mg.

Desenvolvimento de um método reflectométrico ambientalmente mais amigável para a determinação de metoclopramida em formulações farmacêuticas

A simple and more environmentally friendly method by combined spot test-diffuse reflectance spectroscopy for determining metoclopramide in pharmaceutical formulations is described. The method is based on the reaction between metoclopramide and p-dimethylaminocinnamaldehyde, in the presence of HCl, producing a colored compound (λmax = 580 nm) on the filter paper. The linear range was from 5.65 x 10-4-6.21x10-3 mol L-1 (r = 0.999). The limit of detection was 1.27 x 10-4 mol L-1. The proposed reflectometric method was applied successfully to the determination of metoclopramide in pharmaceuticals and it was favorably compared with the Brazilian or British Pharmacopoeia methods at 95% confidence level.

Determinação espectrométrica dos flavonóides das folhas de Maytenus (Celastraceae) e de Passiflora (Passifloraceae) e comparação com método CLAE-UV

Este trabalho apresenta uma modificação dos procedimentos descritos nas Farmacopéias Francesa e Européia para a análise de flavonoides de Passiflora incarnata L., Passifloraceae, por espectrometria UV-Visível e propõe a sua aplicação na determinação dos flavonoides totais das folhas da espinheira-santa (Maytenus aquifolium Mart. e Maytenus ilicifolia (Schrad.) Planch., Celastraceae) e do maracujá (Passiflora edulis Sims. e Passiflora alata Curtis, Passifloraceae). Os resultados obtidos por espectrometria no UV-Visível foram comparados aos obtidos por cromatografia líquida de alta eficiência (CLAE-UV), encontrando-se resultados estatisticamente similares entre os métodos espectrométrico modificado da Farmacopéia Francesa e CLAE-UV.