Stability indicating UPLC method for simultaneous determination of atorvastatin, fenofibrate and their degradation products in tablets

A stability indicating UPLC method was developed and validated for the simultaneous determination of atorvastatin, fenofibrate and their impurities in tablets. The chromatographic separation was performed on acquity UPLCtrade mark BEH C18 column (1.7mum, 2.1mmx100mm) using gradient elution of acetonitrile and ammonium acetate buffer (pH 4.7; 0.01M) at flow rate of 0.5ml/min. UV detection was performed at 247nm. Total run time was 3min within which main compounds and six other known and major unknown impurities were separated. Stability indicating capability was established by forced degradation experiments and separation of known degradation products. The method was validated for accuracy, repeatability, reproducibility and robustness. Linearity, LOD and LOQ was established for atorvastatin, fenofibrate and their known impurities.     

High performance liquid chromatographic determination of etofibrate and its hydrolysis products

High performance liquid chromatographic (HPLC) method is presented for the determination of etofibrate (EF) and its hydrolysis products. The method was based on HPLC separation of EF from its hydrolysis products using cyanopropyl column at ambient temperature with mobile phase consisting of acetonitrile-10 mM potassium dihydrogen phosphate, pH was adjusted to 4.1 using phosphoric acid (50:50, v/v). Quantitation was achieved with UV detection at 221 nm based on peak area. The flow rate was 1.5 ml min(-1). The proposed method was used to investigate the kinetics of acidic hydrolysis process of EF at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The kinetics of alkaline hydrolysis process of EF using 0.01 M sodium hydroxide at different temperatures cannot be studied as the drug is rapidly hydrolyzed in alkaline medium. The pH-rate profile of hydrolysis of EF in Britton-Robinson buffer solutions within the pH range 2-10 were studied.     

High performance liquid chromatographic determination of oxeladin citrate and oxybutynin hydrochloride and their degradation products

Two high performance liquid chromatographic (HPLC) methods are presented for the determination of oxeladin citrate (OL) and oxybutynin hydrochloride (OB) and their degradation products. The first method was based on HPLC separation of OL from its degradation product using a Nucleosil C(18) column with a mobile phase consisting of acetonitrile -0.1% phosphoric acid (60:40 v/v). The second method was based on HPLC separation of OB from its degradation product using a VP-ODS C(18) column with a mobile phase consisting of acetonitrile/0.01 M potassium dihydrogen phosphate/diethylamine (60:40:0.2). Quantitation was achieved with UV detection at 220 nm based on peak area. The two HPLC methods were applied for the determination of OL or OB, their degradation products, methylparaben and propylparaben in pharmaceutical preparations. The proposed methods were used to investigate the kinetics of acidic and alkaline degradation processes of OL and OB at different temperatures and the apparent pseudofirst-order rate constant, half-life and activation energy were calculated. The pH-rate profiles of degradation of OL and OB in Britton-Robinson buffer solutions within the pH range 2-12 were studied.     

A stability indicating HPLC method for the determination of clobazam and its basic degradation product characterization

Background

Clobazam is used for the treatment of different types of seizure and epilepsy. The present research is undertaken to study the systematic forced degradation of clobazam and to identify its main degradation product under basic conditions.

Methods

The degradation of clobazam was studied under different conditions. Clobazam and its degradation products were separated using a Nova-Pak C18 column and a mixture of KH₂PO₄ 50 mM (pH 8.5) and acetonitrile (50:50, v/v) as the mobile phase with UV detection at 230 nm.

Results

The within-day and between-day precision values in the calibration range of 0.1-20 μg/ml were within 0.5-1.5%. Clobazam was relatively stable in solid from under exposure to visible and UV light and also heat. The clobazam aqueous solution of clobazam was more labile under exposure to visible and UV light. The bulk drug was significantly degraded under exposure to 2 M HCl, 0.1 M NaOH or 3% H₂O₂. Using the tablet powder, higher degradation rates were observed under different stress conditions. The main degradation product of clobazam under basic condition was subsequently characterized.

Conclusion

The developed method could be used for the determination of clobazam in the presence of its degradation products with acceptable precision and accuracy. The applicability of the proposed method was evaluated in commercial dosage forms analysis.     

Stability‐indicating methods for the determination of famciclovir in the presence of its alkaline‐induced degradation product

Five sensitive, selective and precise stability‐indicating methods are presented for the determination of famciclovir (FCV) in the presence of its alkaline‐induced degradation product. Method A utilizes the first derivative spectrophotometry at 321 nm. Method B depends on using the first derivative of the ratio spectrophotometry (DD¹) by measurement of the amplitude at 256 nm. Method C is based on the reaction of FCV with hydroxylamine to form hydroxamic acid, causing the hydroxamic acid to react with triferric ion to form ferric hydroxamate that is measured at 503 nm. Method D is based on the separation of FCV from its degradation product followed by densitometric measurement of the bands at 304 nm. The separation was carried out on silica gel 60 F₂₅₄, using chloroform: methanol (70:30, v/v) as a mobile phase. Method E is based on a high performance liquid chromatographic (HPLC) separation of FCV from its degradation product using an ODS column with a mobile phase consisting of methanol–50 mM dipotassium hydrogen phosphate (25:75, v/v, pH 3.0)with UV detection at 304 nm. Regression analysis showed good correlation in the concentration ranges 16–72 µg/ml, 40–240 µg/ml, 40–240 µg/ml, 0.75–5.25 µg/band and 20–240 µg/ml with percentage recoveries of 99.65 ± 0.85, 100.27 ± 0.91, 99.72 ± 0.84, 100.65 ± 1.52 and 99.88 ± 0.50 for methods A, B, C, D and E, respectively. These methods are suitable as stability‐indicating methods for the determination of FCV in the presence of its degradation product either in bulk powder or in pharmaceutical formulation. Statistical analysis of the results has been carried out revealing high accuracy and good precision. Copyright © 2010 John Wiley & Sons, Ltd.     

Stability-indicating spectrophotometric and spectrodensitometric methods for the determination of diacerein in the presence of its degradation product

Three sensitive, selective, and precise stability-indicating methods for the determination of the novel osteoarthritis drug, diacerein (DIA) in the presence of its alkaline degradation product (active metabolite, rhein) and in pharmaceutical formulation were developed and validated. The first method is a first derivative (D(1) ) spectrophotometric one, which allows the determination of DIA in the presence of its degradate at 322 nm (corresponding to zero crossing of the degradate) over a concentration range of 4-40 μg/mL with mean percentage recovery 100.21 ± 0.833. The second method is the first derivative of the ratio spectra (DD(1) ) by measuring the peak amplitude at 352 nm over the same concentration range as (D(1) ) spectrophotometric method, with mean percentage recovery 100.09 ± 0.912. The third method is a TLC-densitometric one, where DIA was separated from its degradate on silica gel plates using ethyl acetate:methanol:chloroform (8:1.5:0.5 v:v:v) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of DIA at 340 nm over a concentration range of 1-10 μg/spot, with mean percentage recovery 100.24 ± 1.412. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of DIA in pharmaceutical dosage forms without interference from other dosage form additives and the results were statistically compared with reference method.     

Development and validation of a stability-indicating HPLC-UV method for the determination of alizapride and its degradation products

A stability-indicating high-performance liquid chromatography procedure has been developed for the determination of alizapride (AL) and its main degradation products alizapride carboxylic acid (AL-CA) and alizapride N-oxide (AL-NO2) in drug substance and product. The method was developed based on forced degradation data obtained by HPLC–MS analysis. Indeed AL underwent chemical degradation by acid/base catalyzed hydrolysis and oxidation the main degradation products being AL-CA and AL-NO2 respectively. The separation and quantisation were achieved on a 150-mm reverse phase column with a hydrophilic linkage between silica particles and hydrophobic alkyl chains. The mobile phase was constituted (flow rate 1.5 mL min⁻¹) of eluant A: aqueous acetate buffer (pH 4.0; 20 mM) and eluant B: CH₃OH using a gradient elution and detection of analytes at 225 nm. The method showed good linearity for the AL, AL-CA, AL-NO2 mixture in the 25–75, 1–15 and 1–15 μg mL⁻¹ ranges respectively, being all the square of the correlation coefficients greater than 0.999. The precision, determined in terms of intra-day and inter-day precisions and expressed as RSDs were 0.8, 1.3 and 2.1% and 1.0, 1.7, 4.8% for AL, AL-CA and AL-NO2 respectively. The method demonstrated also to be accurate; indeed the average recoveries, at 100% and 0.2% of the target assay concentration, were 100.5, 98.6, and 96.8% for AL, AL-CA and AL-NO2 respectively. The robustness was also evaluated by variations of mobile phase composition and pH. Finally, the applicability of the method was evaluated in commercial dosage form analysis as well as in stability studies.     

Stability-indicating spectrophotometric methods for determination of tazarotene in the presence of its alkaline degradation product by derivative spectrophotometric techniques

The stability of tazarotene (TZ) was investigated and two stability‐indicating methods—namely, first derivative and a derivative ratio spectrophotometric method—were used to determine tazarotene in the presence of its alkaline degradation product (HD) using methanol as a solvent. A linear relationship was obtained in the range 1–10 µg ml⁻¹ for both methods. By applying the proposed methods, it was possible to determine tazarotene in its pure powdered from with accuracy 99.35 ± 1.410 (n = 10) for the first derivative method and 99.45 ± 1.053 (n = 10) for the derivative ratio method. First derivative and derivative ratio methods were used for the analysis of laboratory‐prepared mixtures containing different ratios of tazarotene and its degradation product and they were valid in the presence of up to 70% and 80% degradation product, respectively. The proposed methods were validated and found to be suitable as stability‐indicating assay methods for tazarotene in pharmaceutical formulations. Copyright © 2010 John Wiley & Sons, Ltd.     

High performance thin layer chromatographic determination of nifedipine from bulk drug and from pharmaceuticals

A stability indicating high performance thin layer chromatographic (HPTLC) method for quantification of nifedipine, as bulk drug and from solid oral dosage forms has been developed. The extraction solvent was methanol and the mobile phase was chloroform:ethyl acetate:cyclohexane (19:2:2, v/v/v). The calibration curve of nifedipine in methanol was linear in the concentration range of 180-720 ng. The mean values of correlation coefficient, slope and intercept were 0.995 +/- 1.02, 1.467 +/- 0.56 and 184.16 +/- 2.15. The limit of detection for nifedipine was 20 ng and limit of quantification was 40 ng. No interference was found from photodecomposition products. The percent recovery of nifedipine using the described procedure was 99.08 +/- 1.51. The coefficient of variation for within day and between day analysis was 0.60 and 0.84% for 480 ng and 0.47 and 0.25% for 720 ng nifedipine concentration. The method was utilized to monitor concentration of nifedipine from sustained release marketed solid oral dosage forms as also from the developed sustained release liquid filled and multi unit hard gelatin capsules.     

High-performance liquid chromatographic determination of dyclonine hydrochloride in the presence of its degradation products

A stability-indicating reversed-phase high-performance liquid chromatographic method for the determination of the topical anaesthetic dicyclonine hydrochloride in various oral spray and gel formulations is described.     

Liquid chromatographic analysis of physostigmine salicylate and its degradation products

A simple stability-indicating HPLC assay has been developed for physostigmine salicylate, capable of following its degradation. A 250×5 mm i.d. column packed with 10 μm Bondapak C₁₈ was used, with a mobile phase of acetonitrile–ammonium acetate (pH 6.0; 0.1 M) (50:50, v/v) and flow rate 1.2 ml min⁻¹. All peaks are eluted in <10 min and the method has good precision. The optimum wavelength for detection of degradation products is 305 nm. Application of the assay for a commercial preparation of physostigmine salicylate for injection is presented.     

Identification, isolation and characterization of potential degradation product in risperidone tablets

One unknown impurity (degradation product) present at a level below 0.1% in the initial samples increased to a level of 0.5% in 6M/40 degrees C/75% RH stability samples of risperidone tablets was detected by gradient reverse-phase high-performance liquid chromatography (HPLC). This impurity was isolated using reverse-phase preparative liquid chromatography. Based on the spectral data the structure of this impurity is characterized as 3-[2-[4-[6-fluoro-1,3-benzoxazol-2-yl]piperidin-1-yl]ethyl]-2-methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a] pyrimidin-4-one. Structural elucidation of this impurity by spectral data ((1)H NMR, (13)C NMR, DEPT, MS and IR), formation and mechanism has been discussed in detail.     

Spectrophotometric and liquid chromatographic determination of trimebutine maleate in the presence of its degradation products

Three methods are presented for the determination of trimebutine maleate (TM) in the presence of its degradation products. The first method was based on a high performance liquid chromatographic (HPLC) separation of TM from its degradation products using an ODS column at ambient temperature with a mobile phase consisting of acetonitrile-5 mM heptane sulfonic acid disodium salt (45:55, v/v, pH 4) with UV detection at 215 nm. The second method depends on using first derivative spectrophotometry (1D) by measurement of the amplitude at 252.2 nm. The third method depends on using first derivative of the ratio spectrophotometry (1DD) by measurement of the amplitude at 282.4 nm where a normalized spectrum of 3,4,5-trimethoxy benzoic acid is used as divisor. The proposed HPLC and 1D methods were used to investigate the kinetics of acidic and alkaline degradation processes. The pH-rate profile of degradation of TM in Britton-Robinson buffer solutions within the pH range 2-11.9 was studied.     

用高效液相色谱法测定儿童氨苄青霉素的药动学参数

本文报道用高效液相色谱法研究儿童时期氨苄青霉素的药物动力学。本法以β-羟乙基茶碱为内标物,C_(18)反相色谱柱,0.1mol/L 磷酸二氢钾/乙腈(92/8)作流动相,214nm 检测,方法学考查表明该方法灵敏度、精密度高,特异性强,可用于药动学研究和治疗药物监测。8名儿童静滴氨苄青霉素100mg/kg,药物动力学符合二室开放式模型。其消除半衰期t_(1/2)β1.07h。     

Validated stability-indicating methods for determination of cilostazol in the presence of its degradation products according to the ICH guidelines

Sensitive and selective stability-indicating assay methods (SIAMs) are suggested for the determination of cilostazol (CIL) in the presence of its acid, alkaline and oxidative degradation products. Developing SIAMs is necessary to carry out any stability study. Stress testing of CIL was performed according to the International Conference on Harmonization (ICH) guidelines in order to validate the stability-indicating power of the analytical procedures. Stress testing showed that CIL underwent acid, alkaline and oxidative degradation; on the other hand, it showed stability towards photo- and thermal degradation. Two chromatographic SIAMs were developed, namely HPLC and HPTLC methods. The concentration range and the mean percentage recovery were 1.0-31.0 microg/ml and 99.96+/-0.46 and 0.6-14.0 microg/spot and 99.88+/-1.10 for HPLC and HPTLC methods, respectively. In addition, derivative spectrophotometric methods were developed in order to determine CIL in the presence of its acid degradation product; these were performed by using the third derivative spectra (3D) and the first derivative of the ratio spectra (1DD) methods. The linearity range and the mean percentage recovery were 2.0-34.0 microg/ml and 100.27+/-1.20 for the (3D) method, while they were 2.0-30.0 microg/ml and 99.94+/-1.18 for the (1DD) method. Also, two chemometric-assisted spectrophotometric methods, based on using partial least squares (PLS) and concentration residual augmented classical least squares method (CRACLS), for the determination of CIL were developed. Both methods were applied on zero order spectra of the mixtures of CIL and its acid degradation product, the mean percentage recovery was 100.03+/-1.09 and 99.91+/-1.27 for PLS and CRACLS, respectively. All methods were validated according to the International Conference on Harmonization (ICH) guidelines and applied on bulk powder and pharmaceutical formulations.     

Rapid liquid chromatographic method for the determination of roflumilast in the presence of degradation products

A forced degradation study on roflumilast drug substance was conducted under the conditions of hydrolysis, oxidation, thermal and photolysis. The method was developed and optimized by analyzing forcefully degraded samples. The best separation was achieved on a Zorbax SB C18 1.8 μm column with 0.005 M ammonium formate buffer pH 3.5 and acetonitrile as mobile phase in a 13 min run time. The proposed method was able to resolve all the possible degradation products formed during stress study. The drug was stable to neutral, thermal and photolytic conditions but unstable to acidic, alkaline and oxidative conditions at 80° for 24 h. The degradation products resulting from stress study did not interfere in assay and related substances of roflumilast and thus the method can be regarded as stability indicating. An alternate method was also developed on a conventional 250×4.6 mm, 5 μm column wherein runtime was 38 min. Thus rapid resolution high throughput column was able to reduce the run time from 38 min to 13 min.     

Spectrophotometric and chromatographic determination of rabeprazole in presence of its degradation products

Three methods were presented for the determination of rabeprazole (RA) in presence of its degradation products. The first method was based on high performance liquid chromatographic (HPLC) separation of RA from its degradation products on a reversed phase, ODS column using a mobile phase of methanol-water (70:30, v/v) and UV detection at 284 nm. The second method was based on HPTLC separation followed by densitometric measurement of the spots at 284 nm. The separation was carried out on Merck HPTLC sheets of silica gel 60 F 254, using acetone-toluene-methanol (9:9:0.6 v/v) as mobile phase. The third method depends on first derivative of the ratio spectra (1DD) by measurement of the amplitudes at 310.2 nm. Moreover, the proposed HPLC method was utilized to investigate the kinetics of the oxidative and photo degradation processes. The pH-rate profile of degradation of RA in Britton-Robinson buffer solutions within the pH range 3-11 was studied. In addition, the activation energy of RA degradation was calculated in Britton-Robinson buffer solution pH 7.     

高效液相色谱法测定人血清中伊曲康唑浓度

目的：建立了ＨＰＬＣ法测定血清样品中伊曲康唑的定量分析方法。方法：色谱条件：以ＺＯＲＢＡＸＴＭＣ１８（５μｍ,４．６×１５０ｍｍ）为色谱柱;乙腈水（６７．５∶３２．５）为流动相,检测波长２６３ｎｍ;用正庚烷∶异戊醇（９８．５∶１．５）作为提取剂。结果：三种浓度４０,８０,３００ｎｇ·ｍｌ－１回收率分别为１０５．０５％,１００．５７％,９７．９１％（ｎ＝６）;日内、日间ＲＳＤ分别为３．８３％,４．０５％,３．０９％及６．００％,４．９０％,４．７２％（ｎ＝６）。血清中药物的最低检测浓度为５ｎｇ·ｍｌ－１,在５～６００ｎｇ·ｍｌ－１血药浓度范围内线性关系良好,ｒ＝０．９９９５。结论：方法灵敏、准确、结果满意     

Evaluation of the pharmaceutical quality of docetaxel injection using new stability indicating chromatographic methods for assay and impurities

New stability indicating chromatographic methods have been developed for estimation of Assay and Impurities of Docetaxel in Docetaxel injection for evaluation of pharmaceutical quality. With this method, the process related impurities and degradants are well separated from the peaks due to placebo. The relative retention times and relative response factors of the known impurities have been established. The LOQ of the known impurities and docetaxel are found to be less than 0.2 μg /ml and the recovery falls in the range of 90–110%. Peak purities demonstrated the stability indicating nature of the methods. The methods developed in the present study overcome the lacunae of the existing published methodologies in evaluation of the quality of Docetaxel injection. In essence, the present study provides an improved methodology for evaluation of the pharmaceutical quality of Docetaxel injection.