Impurities In Pharmaceutical Preparations Research Articles

Simultaneous analysis of carcinogenic N-nitrosamine impurities in metformin tablets using on-line in-tube solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry

Contamination of active pharmaceutical ingredients (APIs) and pharmaceutical preparations with carcinogenic N-nitrosamines has led to recalls of these products and supply shortages to patients. The present study describes the development of a highly sensitive method for simultaneous analysis of seven N-nitrosamines using on-line in-tube solid-phase microextraction (IT-SPME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine their actual contamination in metformin tablets. Using a Carboxen 1006 PLOT capillary as the extraction device for IT-SPME, these compounds were efficiently extracted and concentrated 6‒24-fold by subjecting 40 µL of sample to 25 repeated draw/eject cycles at a rate of 0.2 mL/min. The seven N-nitrosamines were separated within 11 min by gradient elution with 0.1 % formic acid solution and acetonitrile as the mobile phase using a CAPCELL PAK C18 MGII column and detected by multiple reaction monitoring in positive ion mode. The calibration curve showed linearity in the range 0.2‒50 ng/mL and detection limits (S/N = 3) in the range 3‒112 pg/mL. The intra-day and inter-day precisions were less than 5.5 % and 7.0 % (n = 6), respectively, with accuracies ranging from 93‒117 %. Following ultrasonic extraction with water, centrifugation and filtration of the supernatant liquid through a membrane filter, the N-nitrosamine impurities in metformin tablets could be analyzed by IT-SPME/LC‒MS/MS. Their limits of quantification (S/N = 10) were 0.1‒5.1 pg/mg API and recoveries ranged from 87‒102 %. Analysis of eight metformin tablets from eight manufacturers showed that 5.8‒7.5 pg/mg N-nitrosodimethylamine were present in three tablets, with no other N-nitrosamines detected in any of the eight tablets. This method may be useful in testing for N-nitrosamine impurities in pharmaceutical preparations.

Predicting DNA-Reactivity of N-Nitrosamines: A Quantum Chemical Approach.

N-Nitrosamines (NAs) are a class of reactive organic chemicals that humans may be exposed to from environmental sources, food but also impurities in pharmaceutical preparations. Some NAs were identified as DNA-reactive mutagens and many of those have been classified as probable human carcinogens. Beyond high-potency mutagenic carcinogens that need to be strictly controlled, NAs of low potency need to be considered for risk assessment as well. NA impurities and nitrosylated products of active pharmaceutical ingredients (APIs) often arise from production processes or degradation. Most NAs require metabolic activation to ultimately become carcinogens, and their activation can be appropriately described by first-principles computational chemistry approaches. To this end, we treat NA-induced DNA alkylation as a series of subsequent association and dissociation reaction steps that can be calculated stringently by density functional theory (DFT), including α-hydroxylation, proton transfer, hydroxyl elimination, direct SN2/SNAr DNA alkylation, competing hydrolysis and SN1 reactions. Both toxification and detoxification reactions are considered. The activation reactions are modeled by DFT at a high level of theory with an appropriate solvent model to compute Gibbs free energies of the reactions (thermodynamical effects) and activation barriers (kinetic effects). We study congeneric series of aliphatic and cyclic NAs to identify trends. Overall, this work reveals detailed insight into mechanisms of activation for NAs, suggesting that individual steric and electronic factors have directing and rate-determining influence on the formation of carbenium ions as the ultimate pro-mutagens and thus carcinogens. Therefore, an individual risk assessment of NAs is suggested, as exemplified for the complex API-like 4-(N-nitroso-N-methyl)aminoantipyrine which is considered as low-potency NA by in silico prediction.

Metallic Impurities in Pharmaceuticals: An Overview

Backgroun:Metallic impurities are the traces of metals that can be found in finished drug products. Description:These metallic impurities in pharmaceutical preparations can enter from formulation ingredients, catalysts, and process equipment, containers and closures. They are not completely removed from the product by practical manufacturing techniques and should be evaluated relative to safetybased limits. They can affect drug efficacy or produce direct toxic effect on the patient. Methods:In this paper, an attempt has been made to review these metallic impurities including potential sources and analytical procedures to quantify these impurities. ICH guideline on these impurities and measures to control impurities has also been discussed in the paper. Results:The implementation of ICH Q3D guideline with the quality risk assessment approach is an important milestone to harmonize control of elements worldwide. Conclusion:This approach allows manufacturers to provide vital information about the contribution of impurities in the drug product.

TLC—Densitometric Determination of Sulfasalazine and Its Possible Impurities in Pharmaceutical Preparations

A simple, selective, and sensitive thin-layer chromatographic—densitometric method has been developed for the determination of sulfasalazine besides its possible impurities in pharmaceutical preparations. The mobile phase was composed of ethyl acetate—methanol—ammonia 25% 10:7:3 (υ/υ/υ), and the stationary phase was aluminum plates precoated with silica gel 60 F254 that enabled to obtain well resolved peaks of sulfasalazine and its impurities. The developed chromatograms were analyzed densitometrically at λ = 360 nm. RF values and ultraviolet (UV) spectra were used to identify the compounds. The developed method is highly sensitive (limit of detection [LOD] = 17.11 ng spot−1, limit of quantitation [LOQ] = 51.84 ng spot−1), precise (relative standard deviation [RSD] = 1.43%–4.28%), and accurate (RSD = 1.64%–4.27%). The linearity of the method was checked within the range 20–120 ng spot−1. The method was successfully applied for the determination of sulfasalazine in pharmaceutical preparations besides its i...

A Novel Validated Ultra-Performance Liquid Chromatography Method for Separation of Eszopiclone Impurities and its Degradants in Drug Products

A selective, specific, and sensitive ultra-performance LC (UPLC) method was developed for determination of eszopiclone and its degradation products. The chromatographic separation was performed with a Waters ACQUITY UPLC system and BEH C18 column using gradient elution with mobile phases A and B. Mobile phase A was 0.01 M phosphate buffer with 0.2% (w/v) 1-octane sulfonic acid sodium salt as an ion pair reagent, adjusted pH 2.2 with orthophosphoric acid-acetonitrile (85 + 15, v/v). Mobile phase B was pH 2.2 buffer-acetonitrile (20 + 80, v/v). UV detection was performed at 303 nm. Eszopiclone and its impurities were chromatographed with a total run time of 13 min. A calibration study showed that the response for each of the impurities A, B, C, and D was linear between concentrations of 0.02 and 7.2 microg/mL (r2 > or = 0.999). The method was validated over this range for precision, intermediate precision, accuracy, linearity, and specificity. For the precision study, RSD of each impurity was <5% (n = 6). The method was found to be precise, accurate, linear, and specific. The proposed method was successfully used for determination of eszopiclone impurities in pharmaceutical preparations.

A validated ultra high-pressure liquid chromatography method for separation of candesartan cilexetil impurities and its degradents in drug product

Introduction: A selective, specific, and sensitive “Ultra High-Pressure Liquid Chromatography” (UPLC) method was developed for determination of candesartan cilexetil impurities as well asits degradent in tablet formulation. Materials and Methods: The chromatographic separation was performed on Waters Acquity UPLC system and BEH Shield RP18 column using gradient elution of mobile phase A and B. 0.01M phosphate buffer adjusted pH3.0 with Orthophosphoric acid was used as mobile phase A and 95% acetonitrile with 5% Milli Q Water was used as mobile phase B. Ultraviolet (UV) detection was performed at 254nm and 210nm, where (CDS-6), (CDS-5), (CDS-7), (Ethyl Candesartan), (Desethyl CCX), (N-Ethyl), (CCX-1), (1N Ethyl Oxo CCX), (2N Ethyl Oxo CCX), (2N Ethyl) and any unknown impurity were monitored at 254nm wavelength, and two process-related impurities, trityl alcohol and MTE impurity, were estimated at 210nm. Candesartan cilexetil andimpurities were chromatographed with a total run time of 20min. Results: Calibration showed that the response of impurity was a linear function of concentration over the range limit of quantification to 2 μg/mL (r2≥0.999) and the method was validated over this range for precision, intermediate precision, accuracy, linearity, and specificity. For the precision study, percentage relative standard deviation of each impurity was <15% (n=6). Conclusion: The method was found to be precise, accurate, linear, and specific. The proposed method was successfully employed for estimation of candesartan cilexetil impurities in pharmaceutical preparations.

A Validated Stability-Indicating Liquid-Chromatographic Method for Ranitidine Hydrochloride in Liquid Oral Dosage Form

A selective, specific and stability-indicating gradient reverse phase high-performance liquid chromatographic (HPLC) method was developed for the determination of Ranitidine in presence of its impurities, forced degradation products and placebo substances such as saccharide and parabens. Ultraviolet detection was performed at 230 nm. Separate portions of the drug product and ingredients were exposed to stress conditions to induce oxidative, acidic, basic, hydrolytic, thermal and photolytic degradation. Ranitidine was found to degrade significantly at acidic, basic and oxidative stress conditions but was stable at heat and humidity. The developed method was validated as per International Conference on Harmonization (ICH) guidelines. The method was validated over this range for (i) system suitability (ii) specificity, (iii) precision, (iv) limit of detection and limit of quantification, (v) linearity, (vi) accuracy, (vii) robustness. The method was found to be precise, accurate, linear and robust. The proposed method was successfully employed for estimation of Ranitidine impurities in pharmaceutical preparations.

TLC Chromatographic-Densitometric Assay of Ibuprofen and Its Impurities

A simple and sensitive thin-layer chromatographic (TLC)-densitometric method for the quantitative estimation of S(+)-2-[4-isobutylphenyl]propionic acid (ibuprofen) and its impurities in pharmaceutical preparations has been developed. The chromatographic separation was carried out on silica gel 60 F(254) TLC plates using toluene-ethyl acetate-glacial acetic acid (17:13: 1, v/v/v) as the mobile phase. Detection was carried out densitometrically with a UV detector. The developed method has detection and quantitation limits ranging from 0.13 μg per spot to 0.72 μg per spot. For individual constituents the recovery ranged from 96.8% to 99.0%. In addition, the stability of ibuprofen solutions was investigated, including the effect of pH, temperature, and incubation time. The method is rapid, simple, and suitable for routine quality-control analysis of pharmaceuticals containing ibuprofen.

An improved validated ultra high pressure liquid chromatography method for separation of tacrolimus impurities and its tautomers

A selective, specific and sensitive ultra high pressure liquid chromatography (UHPLC) method was developed for determination of tacrolimus degradation products and tautomers in the preparation of pharmaceuticals. The chromatographic separation was performed on Waters ACQUITY UPLC system and BEH C₈ column using gradient elution of mobile phase A (90:10 v/v of 0.1% v/v triflouroacetic acid solution and Acetonitrile) and mobile phase B (90:10 v/v acetonitrile and water) at a flow rate of 0.6 mL min⁻¹. Ultraviolet detection was performed at 210 nm. Tacrolimus, tautomers and impurities were chromatographed with a total run time of 25 min. Calibration showed that the response of impurity was a linear function of concentration over the range 0.3-6 µg mL⁻¹ (r² ≥ 0.999) and the method was validated over this range for precision, intermediate precision, accuracy, linearity and specificity. For precision study, percentage relative standard deviation of each impurity was < 15% (n = 6). The method was found to be precise, accurate, linear and specific. The proposed method was successfully employed for estimation of tacrolimus impurities in pharmaceutical preparations.

Determination of atracurium, cisatracurium and mivacurium with their impurities in pharmaceutical preparations by liquid chromatography with charged aerosol detection

The Corona CAD (charged aerosol detection) is a new type of detector introduced for LC applications that has recently become widely applied in pharmaceutical analysis. The Corona CAD measures a physical property of analyte and responds to almost all non-volatile species, independently of their nature and spectral or physicochemical properties. The LC method with charged aerosol detection was developed for the determination of three isomers of atracurium, cisatracurium and also three isomers of mivacurium with their impurities. The limit of quantitation for laudanosine was 1 microg ml(-1). The elaborate method for the analysis of those active substances and laudanosine proved to be fast, precise, accurate and sensitive. All other impurities were identified using time-of-flight mass spectrometry with electrospray ionization.

Development of a CZE method for the determination of mizolastine and its impurities in pharmaceutical preparations using response surface methodology

A fast and selective CZE method for the determination of mizolastine and related impurities is described. Response surface methodology was applied to study the influence of phosphate/triethanolamine (TEA) buffer concentration, heptakis(2,3,6-tri-O-methyl)-beta-CD (TMbetaCD) concentration, voltage and temperature. The optimum conditions were: 105 mM phosphate/TEA buffer (pH 3.0) containing 10 mM TMbetaCD, temperature 19 degrees C and voltage 30 kV. Validation of the method was performed in drug substance and drug product. Robustness was evaluated using a Plackett-Burman design, including pH among the considered factors. Applying the optimal conditions, the nine peaks were baseline separated in about 10 min. The method was applied to the quality control of mizolastine in controlled-release tablets.

Determination of local anaesthetics and their impurities in pharmaceutical preparations using HPLC method with amperometric detection

A method for the determination of local anaesthetics and their impurities – 2,6-dimethylaniline and o-toluidine – by high-performance liquid chromatographic method with amperometric detection has been developed. The analysis was performed in an isocratic mode on a reversed phase Luna column 5 μm C-18 (100 mm × 4.6 mm). A mobile phase [0.01 mol l −1 Tris buffer of pH 7.9:acetonitrile (45:55)] was selected for the separation and determination of studied anaesthetics and their impurities. Chromatograms were recorded for 500 s by means of an amperometric detector at a potential of +1.0 V of the glassy carbon electrode versus the reference electrode Ag/AgCl. The proposed liquid chromatographic method was successfully applied to the analysis of commercially available pharmaceutical preparations. The limit of the detection for 2,6-dimethylaniline and o-toluidine was 0.8 ng ml −1. The limit of qantitation, considering a signal to noise ratio was 1.5 ng ml −1. The method developed in this study is sensitive and selective and can be applied to routine studies of pharmaceuticals in the form of cream and injection.

Determination of organic impurities in pharmaceutical preparations

Data reported in the literature on methods for the determination of organic impurities in pharmaceutical preparations are systematized; the characteristics and possibilities of the methods are compared.

Determination of organic impurities in pharmaceutical preparations

Determination of organic impurities in pharmaceutical preparations

Determination of organic impurities in pharmaceutical preparations

Determination of organic impurities in pharmaceutical preparations

Quality assessment for tramadol in pharmaceutical preparations with thin layer chromatography and densitometry.

Research studies have been carried out to develop a chromatographic and densitometric method suitable for identification and determination of tramadol and impurities. In addition, the stability of tramadol in solutions was investigated, including an effect of solution pH, temperature and incubation time. In the first instance the conditions for identification and quantitative determination of tramadol and impurities in pharmaceutical preparations were established. The separation was performed on silica gel-coated chromatographic plates (HPTLC) using two mobile phases: (I) chloroform-methanol-glacial acetic acid (9:2:0.1, v/v/v); (II) chloroform-toluene-ethanol (9:8:1, v/v/v). The UV densitometry was carried out at lambda = 270 nm. The developed method is of high sensitivity and low detection and determination limits ranging from 0.044 to 0.35 microg. For individual constituents the recovery ranges from 93.23 to 99.66%. The next step was to evaluate the stability of tramadol and determine a method of decomposition under various experimental conditions. It was found that tramadol decomposes in various ways in acidic and basic environments producing (1RS)-[2-(3-methoxyphenyl)cyclohex-2-enyl]-N,N-dimethylmethanamine (imp. B) and (1RS, 2RS)-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol (imp. cis-T) or imp. cis-T, respectively.

Assay of Ursodeoxycholic Acid and Related Impurities in Pharmaceutical Preparations by HPLC with Evaporative Light Scattering Detector

An HPLC method was developed for assay and purity control of ursodeoxycholic acid, which is separated from all related compounds. Using an evaporative light scattering mass detector (ELSD), equipped with a micronebulizer and a narrow bore column, the bile acids (ursodeoxycholic acid, ursocholic acid, cholic acid, chenodeoxycholic acid, deoxycholic acid and litocholic acid) were efficiently separated on an Hypersil ODS-RP-18 column (100 × 2.1 mm) with methanol-acetonitrile-water (60 : 22: 18), adjusted at pH 4.00 with acetic acid, as mobile phase. Linearity response, accuracy, and precision of the ELSD over the range of sample amounts of interest were established for all compounds. The method demonstrates a suitability of the detector for the assay of ursodeoxycholic and related impurities and was applied for the analysis of ten pharmaceutical preparations.

Analysis of recombinant human growth hormone and its related impurities by capillary electrophoresis

A convenient free solution capillary electrophoretic method is described for the simultaneous quantitation of human growth hormone (hGH) and its related impurities in pharmaceutical preparations. The separation of the cleaved form, the monodeamidated form and two new compounds which may arise from post-translational modifications in Escherichia coli-a succinylated hGH with a blocked amino terminus and a modified hGH having a His to Gln replacement at sequence position 18-is described. The proposed capillary electrophoretic method shows good specificity, linearity and precision. A limit of detection of 0.03% was calculated for the impurities.

Determination of trace amounts of impurities in pharmaceutical preparations by differential-pulse polarography: Part 1. Determination of diisooctyl maleate in the pharmaceutical sodium 1,4-bis(2-ethylhexyl)sulphosuccinate and of maleic acid in fumaric acid

A differential-pulse polarographic procedure is described for the determination of impurities such as diisooctyl maleate and maleic acid in pharmaceutical products. The concentration range for diisooctyl maleate is 1 × 10 −6−30 × 10−6 μg ml−1 and the detection limit is 0.2 μg ml−1; for maleic acid the detection limit is 0.15 μg ml−1. It is possible to determine very low concentrations of maleic acid in the presence of fumaric acid by a preseparation by dissolution in water, in which fumaric acid dissolves to only a small extent.

Determination of trace amounts of impurities in pharmaceutical preparations by differential-pulse polarography: Part 2. Determination of disodium bis(ethanesulphonato) disulphide in sodium 2-mercaptoethanesulphonate

A differential-pulse polarographic procedure is described for the determination of trace amounts of disulphides in sodium 2-mercaptoethanesulphonate and in pharmaceutical products in which the latter compound is a component. Concentrations of the order of 1 mg ml−1 can be determined with a precision of about 3.2%. The lowest concentration of disulphide that could be determined in the mercaptosulphonate and the pharmaceutical product is about 0.1%. No matrix separation is required.