Determination of Alendronate Sodium by Box-Behnken Statistical Design

Spectrophotometric and LC methods have been developed and validated for the analysis of alendronate sodium in tablet dosage forms. Methods were based on reaction of the primary amino group of alendronate with ninhydrin reagent in methanolic solution of sodium bicarbonate. The condensed product exhibited UV absorption maximum at 569 nm whereas neither the reagents nor the analyte had any UV absorption. A Box-Behnken statistical design was employed to study the effect of independent variables, ninhydrin (X ₁ ), NaHCO₃ (X ₂ ) and drug concentration (X ₃ ) on dependent variable, absorption via spectrophotometer. From the point prediction tool of design software, it was observed that ninhydrin (0.26%) and NaHCO₃ (0.048 mol L^?1) produced maximum absorption. These optimized parameters were then selected for method validation. The methods obeyed Beer’s law over a selected concentration range with good correlation co-efficient (>0.99). The limit of detection and limit of quantification were 4.5 and 13.75 μg mL^?1 by spectroscopy, and 87 and 263 ng mL^?1 by LC, respectively. Accuracy, precision and % recovery were satisfactory for the proposed method. The method was highly feasible and reproducible for determination of alendronate sodium in bulk powder and pharmaceutical dosage form.     

Study on gamma and electron beam sterilization of third generation cephalosporins cefdinir and cefixime in solid state

The effect of gamma radiation from ⁶⁰Co source and 2 MeV e-beam was studied on two thermolabile cephalosporin antibiotics viz cefdinir and cefixime in solid state. The parameters studied to assess radiolytic degradation were loss of chemical and microbiological potency, change in optical rotation, electronic and vibrational absorption characteristics, thermal behavior and color modification. ESR spectroscopic study, HPLC related impurity profile, thermogram and Raman spectrum are applied in deducing the nature of radiolytic impurities and their formation hypotheses. Cefixime is radiation sensitive, whereas cefdinir has acceptable radiation resistance at 25 kGy dose. The nature of radiolytic related impurities and their concentrations indicates that the lactam ring is not highly susceptible to direct radiation attack, which otherwise is considered very sensitive to stress (thermal, chemical and photochemical).     

Determination of Piribedil in Human Serum, Urine and Pharmaceutical Dosage Form by LC-DAD

A rapid, selective and sensitive reversed-phase liquid chromatographic (LC) method was developed for the determination of piribedil in human serum, urine and pharmaceutical dosage form. LC analysis was carried out using reversed-phase isocratic elution with a C₁₈ column and a mobile phase of 0.01 M phosphate buffer-acetonitrile (50:50, v/v). The chromatograms showed good resolution and sensitivity with no interference of human serum and urine. Piribedil concentrations were determined using diode array detection at 240 nm. Sildenafil citrate was used as internal standard. The limit of quantification (LOQ) and limit of detection (LOD) concentrations were 107.2 and 321.6 pg mL^?1, 96.6 and 290.4 pg mL^?1, 161.7 and 53.9 pg mL^?1 for urine, serum and pharmaceutical dosage forms, respectively. The method was validated for its linearity, precision and accuracy and applied to the tablets, urine and human serum. In addition, the results were compared to those obtained from UV-spectrophotometry.     

Development of a Stability-Indicating RP-LC Method for Determination of Betamethasone Dipropionate and Estimation of Its Related Compounds in a Dermatological Pharmaceutical Product

A new stability-indicating reversed-phase LC method has been developed and validated for the assay and identification of betamethasone dipropionate and its related compounds in a dermatological pharmaceutical drug product, namely Diprolene Ointment. Separation of all the peaks of interest was achieved on a Symmetry Shield RP18 (100 mm × 4.6 mm, 3.5 µm) column using a gradient elution at a flow rate of 1.5 mL min^?1 with mobile phase A (10 mM monobasic sodium phosphate at pH 2.5) and mobile phase B (acetonitrile) and UV detection at 250 nm. The limit of detection (LOD) and limit of quantitation (LOQ) of this method was 0.00004  and 0.0001 mg mL^?1, respectively. The method was successfully validated in accordance with ICH guidelines and was accurate, linear, precise, reproducible, specific, and robust. A simple, reproducible and accurate single step sample extraction procedure using tetrahydrofuran, water, and methanol (40:30:30, v/v/v) was developed to extract betamethasone dipropionate and its related compounds from the ointment. The sample extraction procedure and the LC conditions presented in this report can be used for routine analysis of Diprolene Ointment in quality control laboratories. This method may also be applied to other dermatological pharmaceutical drug products “as-is” or with minor modification.     

Determination of cefdinir levels in rat plasma and urine by high‐performance liquid chromatography–tandem mass spectrometry: application to pharmacokinetics after oral and intravenous administration of cefdinir

A selective and sensitive liquid chromatography tandem mass spectrometry method (LC‐MS/MS) was developed and validated for the determination of cefdinir in rat plasma and urine. Following a simple protein precipitation using methanol, chromatographic separation was achieved with a run time of 10 min using a Synergi 4 µ polar‐RP 80A column (150 × 2.0 mm, 4 µm) with a mobile phase consisting of 0.1% formic acid in water and methanol (65:35, v/v) at a flow rate of 0.2 mL/min. The protonated precursor and product ion transitions for cefdinir (m/z 396.1 → 227.2) and cefadroxil, an internal standard (m/z 364.2 → 208.0) were monitored in the multiple reaction monitoring in positive ion mode. The calibration curves for plasma and urine were linear over the concentration range 10–10,000 ng/mL. The lower limit of quantification was 10 ng/mL. All accuracy values were between 95.1 and 113.0% and the intra‐ and inter‐day precisions were <13.0% relative standard deviation. The stability under various conditions in rat plasma and urine was also found to be acceptable at three concentrations. The developed method was applied successfully to the pharmacokinetic study of cefdinir after oral and intravenous administration. Copyright © 2013 John Wiley & Sons, Ltd.     

Selective Densitometric Analysis of Cephalosporins Using Dragendorff’s Reagent

A simple, selective, precise, and stability-indicating thin-layer chromatographic method has been developed and validated for analysis of the cephalosporins cefpodoxime proxetil, ceftriaxone sodium, ceftazidime pentahydrate, cefotaxime sodium, cefoperazone sodium, cefazolin sodium, and cefixime in the bulk drug and in pharmaceutical formulations. TLC was performed on aluminium sheets precoated with silica gel G 60F₂₅₄ as stationary phase. The mobile phases chosen for development gave compact spots for all the drugs (R _F values 0.43–0.60). The separated compounds were visualized as orange spots by spraying with Dragendorff’s reagent. Linear regression analysis data for the calibration plots revealed good linear relationships between response and amounts of the drugs with correlation coefficients ranging from 0.9977 to 0.9998 and determination coefficients ranging from 0.9954 to 0.9996 over the concentration ranges 5–25 μg per spot for cefpodoxime proxetil, ceftriaxone sodium, and ceftazidime pentahydrate and 10–50 μg per spot for cefotaxime sodium, cefoperazone sodium, cefazolin sodium, and cefixime. The method was validated for precision, recovery, and robustness. Limits of detection and quantitation for the drugs ranged from 0.35 to 2.48 and from 1.07 to 7.50 μg per spot, respectively. The method was successfully applied to analysis of the drugs in their pharmaceutical dosage forms with good precision and accuracy. The method can also be used as a stability-indicating assay.     

Sensitive LC–ESI–MS Method for Determination of Tiopronin in Human Plasma

A sensitive liquid chromatographic–electrospray ionization–mass spectrometric (LC–MS) method has been developed for direct measurement of the concentration of tiopronin in human plasma. Hydrochloric acid solution was used to stabilize the tiopronin and prevent formation of a dimer, or reaction with endogenous thiols. The method involved liquid–liquid extraction of tiopronin from plasma samples with ethyl acetate, simple reversed-phase chromatography, and mass spectrometric detection with nanogram detection limits. Acetaminophen was used as internal standard (IS). The limit of quantification was 5 ng mL^?1 (RSD 4.3%). The method was validated within the linear range 5–500 ng mL^?1. The correlation coefficient for the calibration regression line was 0.9997 or better. Intra-day and inter-day accuracy were better than 15%. The method has been successfully used for a pharmacokinetic study with human subjects. Among the pharmacokinetic data obtained, t _1/2 was 2.37 ± 0.63 h and T _max was 4 h.     

Impact of Targeted Specific Antibiotic Delivery for Gut Microbiota Modulation on High-Fructose-Fed Rats

The objective of present investigation was to study the effect of gut microbiota alteration by oral administration of targeted delivery of pH sensitive cefdinir microspheres to high-fructose-fed (HFD) rats. Rats were fed with a high-fructose diet with or without cefdinir microsphere administration for 30 days. The fecal microbiota community, oral glucose tolerance, the markers of liver injury, plasma and hepatic lipids profile, and histological evaluation were investigated. The levels of blood glucose, liver injury markers, lipid profile in plasma and liver, and fat tissue were significantly increased in high-fructose-fed rats. However, after pH-sensitive cefdinir microsphere administration, the elevation of these parameters was significantly suppressed. Cef EL significantly lowered the increased AST (p?<?0.05) and ALT (p?<?0.001) levels in HFD group. There is a significant lower (p?<?0.01) AUC_glucose level in Cef EL group than HFD group The histological changes in the liver and the small and large intestines were more profound in HFD group as compared to cefdinir-treated HFD and control groups. Feeding of cefdinir microsphere sustained lactobacilli and bifidobacteria and significantly decreased (p?<?0.05) the number of Enterobacteriaceae induced by HFD. Experimental evidences demonstrated that the effectiveness of pH-specific cefdinir microsphere on reducing insulin resistance and development of metabolic changes in high-fructose-fed rats and suggested that it may be a promising therapeutic agent in treating type 2 diabetes. Intestinal-targeted antibiotic delivery needs to be further explored for its therapeutic applications.     

Optimization and Validation of an LC Method for the Determination of Cefdinir in Dosage Form and Human Urine

A simple and reliable liquid chromatographic method has been developed and validated for the determination of cefdinir in human urine and capsule samples. A chromatographic separation was achieved on a C₁₈ column using a mobile phase consisting of potassium dihydrogen phosphate (10 mM, pH 4.5)–acetonitrile (90:10, v/v). Quantitation was achieved with UV detection at 285 nm, based on peak area with linear calibration curve at a concentration range of 0.7–39 µg mL^?1. This method was successfully applied for the establishment of an urinary excretion pattern after oral dose.     

LC Analysis of Isepamicin in Plasma Samples Post-Inhalation with Fluorescence Detection and Its Application to a Pharmacokinetic Study

A simple and novel LC method has been developed for determination of isepamicin (ISP) in rat plasma, an aminoglycoside antibiotic agent. After protein precipitation and clean-up procedure to remove lipophilic contaminants, ISP is derivatized by pre-column with 9-fluorenylmethyl chloroformate for fluorescence detection. Chromatographic separations are achieved using a C18 column and mobile phase consisting of water and acetonitrile (68/32, v/v). Amikacin was used as an internal standard. The calibration curve was linear over a concentration range of 0.625–15 μg mL^?1. The limit of quantification was 0.45 μg mL^?1. The intra- and inter-day variabilities of ISP were both less than 5%. Both derivatives were stable for at least a week at ambient condition. This assay procedure should have useful application in therapeutic drug monitoring of ISP. The limit of detection was 0.10 μg mL^?1. The specificity, assay linearity, low level assay linearity and assay repeatability were also investigated. The established method provides a reliable bioanalytical method to carry out isepamicin pharmacokinetics in rat plasma.     

Quantification of Tacrolimus in Human Skin Samples and Ointment by LC-MS

A sensitive and simple liquid chromatography-mass spectrometry method was developed to determine the immunosuppressant tacrolimus in human skin samples after treatment with the commercially available ointment. Utilizing diffusion cell experiments according to Franz, human skin samples were treated with ointment containing tacrolimus and the extraction procedure of the drug was optimized. The analytical assay was performed using an LC system consisting of a reversed phase C₁₈ column and an isocratic mobile phase, coupled with electrospray ionization mass spectrometry. The detection was performed in the positive selected ion monitoring mode. Mycophenolate mofetil was used as internal standard to control the stability of the electrospray ionization. The calibration curve was linear for tacrolimus over the range of 5–1,000 ng mL^?1 (average correlation coefficient of r ² = 0.9941) with a limit of detection (LOD) of 2 ng mL^?1, with a limit of quantification (LOQ) of 5 ng mL^?1 and with a precision of 8.70%. The analytical assay described in this paper was successfully applied in order to quantify tacrolimus in human skin samples as well as in the commercially available ointment.     

A study of the precision and accuracy of peak quantification in comprehensive two-dimensional liquid chromatography in time

Simulated chromatographic data were used to determine the precision and accuracy in the estimation of peak volumes (i.e., peak sizes) in comprehensive two-dimensional liquid chromatography in time (LC × LC). Peak volumes were determined both by summing the areas in the second dimension chromatograms and by fitting the second dimension areas to a Gaussian peak. The Gaussian method is better at predicting the peak volume than the moments method provided there are at least three second dimension injections above the limit of detection (LOD). However, when only two of the second dimension signals are substantially above baseline, the accuracy and precision of the Gaussian fit method become quite poor because the results from the fitting algorithm become indeterminate. Based on simulations in which the modulation ratio (M_R = 4¹σ/t_s) and sampling phase (?) were varied, we conclude for well-resolved peaks that the optimum precision in peak volumes in 2D separations will be obtained when the M_R is between two and five, such that there are typically four to ten second dimension peaks recorded over the eight σ width of the first dimension peak. This sampling rate is similar to that suggested by the Murphy–Schure–Foley criterion. This provides an RSD of approximately 2% for the signal-to-noise ratio used in the present simulations. The precision of the peak volume of experimental data was also assessed, and RSD values were in the range of 4–5%. We conclude that the poorer precision found in the LC × LC experimental data as compared to LC may be due to experimental imprecision in sampling the effluent from the first dimension column.     

Simultaneous quantification and qualification of synacthen in plasma

Tetracosactide (Synacthen), a synthetic analogue of adrenocorticotropic hormone (ACTH), can be used as a doping agent to increase the secretion of glucocorticoids by adrenal glands. The only published method for anti-doping control of this drug in plasma relies on purification by immunoaffinity chromatography and LC/MS/MS analysis. Its limit of detection is 300 pg/mL, which corresponds to the peak value observed 12 h after 1 mg Synacthen IM administration. We report here a more sensitive method based on preparation of plasma by cation exchange chromatography and solid-phase extraction and analysis by LC/MS/MS with positive-mode electrospray ionization using 7–38 ACTH as internal standard. Identification of Synacthen was performed using two product ions, m/z 671.5 and m/z 223.0, from the parent [M?+?5H]⁵⁺ ion, m/z 587.4. The recovery was estimated at 70%. A linear calibration curve was obtained from 25 to 600 pg/mL (R ²?>?0.99). The lower limit of detection was 8 pg/mL (S/N?>?3). The lower limit of quantification was 15 pg/mL (S/N?>?10; CV%?相似文献   

LC–MS/MS Method for Detection of a Highly Selective KCa3.1 Blocker,TRAM-34, in Rat Plasma

1-[(2-Chlorophenyl)diphenylmethyl]pyrazole (TRAM-34) is a highly selective K_Ca3.1 channel blocker. TRAM-34 was commonly used to study the role of K_Ca3.1 in the pathogenesis of disease in vivo, but there was no validated analytical method. Here, we describe the first validated LC–MS/MS analytical method for TRAM-34. Solid-phase extraction (SPE) was performed to extract TRAM-34 from the rat plasma. Chromatographic separation was achieved on the phenyl column. A triple quadrupole mass spectrometer was operated in positive-mode electrospray ionization. There were two multiple-reaction monitoring (MRM) transitions for TRAM-34: m/z 277.2 → 165.1 (for quantification) and m/z 277.2 → 241.2 (for qualification). Bifonazole was used as an internal standard. The lower limit of quantification (LLOQ) achieved was 1 ng mL^?1 and the run time was 7.5 min. The linear range was from 1 to 1,000 ng mL^?1. The pharmacokinetics profile was acquired for rats following an intraperitoneal injection of TRAM-34, with the following pharmacokinetics parameters found: C _max 17.03 ± 1.34 ng mL^?1; T _max 8.67 ± 3.06 h; and T _1/2 13.45 ± 2.72 h. In addition, a suspected metabolite of TRAM-34 was found using this LC–MS/MS method. Given the results of the detailed validation process and its application to TRAM-34 pharmacokinetics, it is clear that a fast, selective, precise, and reproducible TRAM-34 LC–MS/MS analytical method was successfully established.     

Chiral Separation of Carboprost Isomers by Normal Phase LC Using Amylose Chiral Stationary Phase

LC separation of carboprost diastereomers in bulk drug was developed and validated using normal-phase amylose stationary phase Chiralpak AD-H. The effect of the organic modifiers, namely 2-propanol and ethanol in the mobile phase was optimized in order to obtain the best separation. The retention time of (R)-carboprost and (S)-carboprost were 15.3 and 17.1 min, respectively. Calibration curves were linear over the range of 0.2–1.0%, with the regression coefficient (R ²) of 0.9997. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.07 and 0.2%, respectively. The method was accurate, precise and suitable to use for the purpose of controlling unwanted (R)-isomer in the carboprost active pharmaceutical ingredient. This method can be successfully applied to the analysis of chiral purity of carboprost in pharmaceutical bulk drug samples.     

Identification and quantification of flavonoids and ellagic acid derivatives in therapeutically important Drosera species by LC-DAD, LC-NMR, NMR, and LC-MS

Droserae herba is a drug commonly used for treatment of convulsive or whooping cough since the seventeenth century. Because of the contribution of flavonoids and ellagic acid derivatives to the therapeutic activity of Droserae herba, an LC?CDAD method has been developed for quantification of these analytes in four Drosera species used in medicine (Drosera anglica, D. intermedia, D. madagascariensis, and D. rotundifolia). During elaboration of the method 13 compounds, including three substances not previously described for Drosera species, were detected and unambiguously identified by means of extensive LC?CMS and LC?CNMR experiments and by off-line heteronuclear 2D NMR after targeted isolation. The most prominent component of D. rotundifolia and D. anglica, 2??-O-galloylhyperoside, with myricetin-3-O-??-glucopyranoside and kaempferol-3-O-(2??-O-galloyl)-??-galactopyranoside, were identified for the very first time in this genus. The LC?CDAD method for quantification was thoroughly validated, and enables, for the first time, separation and precise analysis of these analytes in Droserae herba. Simple sample preparation and use of a narrow-bore column guarantee low cost and simplicity of the suggested system, which is excellently suited to quality control of the drug or herbal medicinal products containing this drug.

Determination of amphetamine and methamphetamine in urine by solid phase extraction and ion-pair liquid chromatography-electrospray-tandem mass spectrometry

A method using a solid phase extraction (SPE) and ion-pair liquid chromatography-electrospray-tandem mass spectrometry (LC-ES-MS/MS) was developed for determination of amphetamine (Amp) and methamphetamine (mAmp) in urine samples. A reversed phase C₁₈ column was utilized for LC separation and MS/MS was used for detection. Trifluoroacetic acid was added to the mobile phase as an ion-pairing reagent. MS² was employed for quantitative determination. In addition, d₈-amphetamine and d₈-methamphetamine were used as internal standards. An Oasis HLB SPE cartridge, which has hydrophilic and lipophilic functions, was utilized for sample pre-treatment. Recoveries ranging from 97.3 to 102.1% were measured. Good linear ranges, 5-500 ng/ml, for Amp and mAmp were determined. The detection limit of each analytical compound, based on a signal-to-noise ratio of 3, was approximately 1 ng/ml. The applicability of this newly developed method was examined by analyzing several urine samples from drug users.     

Quantitative TLC Analysis of Steroid Drug Intermediates Formed During Bioconversion of Soysterols

A simple, rapid, and accurate method based on thin-layer chromatography (TLC) combined with image-analysis software has been developed for analysis of steroid drug intermediates formed during bioconversion of soysterols. The results obtained have been compared with those from LC. The method has been used to monitor the accumulation of widely used steroid drug intermediates androst-4-ene-3,17-dione (AD) and androsta-1,4-diene-3,17-dione (ADD), formed during the bioconversion of soysterols by Mycobacterium sp. NRRL B-3805 and Mycobacterium sp. NRRL B-3683. The percentage error between TLC and LC ranged between ?0.79 to +4.50 for AD and ?0.61 to +2.48 for ADD. Maximum conversion of soysterols to AD and ADD by Mycobacterium sp. NRRL B-3805 was 49.83 and 9.36 mol%, respectively, after incubation for 144 h, whereas conversion of soysterols by Mycobacterium sp. NRRL B-3683 after incubation 288 h was 41.90 mol% for AD and 37.79 mol% for ADD.     

Reversed-Phase Liquid Chromatographic Method for Determination of Daclatasvir Dihydrochloride and Study of Its Degradation Behavior

A simple and selective reversed-phase stability-indicating liquid chromatographic method has been developed and validated for the determination of daclatasvir in drug substance and drug product. Daclatasvir was subjected to acidic, alkaline, oxidative, thermal and photo-degradation study. The LC method was based on isocratic elution of daclatasvir and its degradation products on a reversed-phase C₁₈ Hypersil column using a mobile phase consisting of phosphate buffer (10 mM, 1 mL triethylamine L^?1): acetonitrile (60:40 v/v) at a flow rate of 2 mL min^?1. Quantitation was achieved with UV detection at 312 nm. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 0.75–120 μg mL^?1, with regression coefficient value of 0.9999, and with limit of detection and quantitation of 0.148 and 0.447 μg mL^?1, respectively. Peak purity was checked for principle drug and its alkali induced degradation product, and the pathway of alkaline hydrolysis of daclatasvir was suggested by LC/MS.     

Simultaneous Determination of Tamsulosin and Dutasteride in Human Plasma by LC–MS–MS

A sensitive and selective liquid chromatographic tandem mass spectrometric (LC–MS–MS) method was developed for simultaneous identification and quantification of tamsulosin and dutasteride in human plasma, which was well applied to clinical study. The method was based on liquid–liquid extraction, followed by an LC procedure with a Gemini C-18, 50 mm × 2.0 mm (3 μm) column and using methanol:ammonium formate (97:3, v/v) as the mobile phase. Protonated ions formed by a turbo ionspray in positive mode were used to detect analytes and internal standard. MS–MS detection was by monitoring the fragmentation of 409.1 → 228.1 (m/z) for tamsulosin, 529.3 → 461.3 (m/z) for dutasteride and 373.2 → 305.3 (m/z) for finasteride (IS) on a triple quadrupole mass spectrometer. The lower limit of quantification for both tamsulosin and dutasteride was 1 ng mL^?1. The proposed method enables the unambiguous identification and quantification of tamsulosin and dutasteride for clinical drug monitoring.