Chemical Characterization and Potential Mechanism of the Anti-Asthmatic Activity of a Subfraction from Schisandra chinensis Fruit Extract.

Schisandra chinensis fruit is a widely edible and medicinal resource, whose extract had a good inhibitory effect on airway inflammation in asthmatic mice. However, the main active components remain unknown. In this work, we found that PET2, a subfraction of its ethanolic extract petroleum ether, displayed significant anti-inflammatory effects in interleukin (IL)-4/tumor necrosis factor (TNF)-α-stimulated BEAS-2B cells. Meanwhile, in the ovalbumin (OVA)-induced allergic asthma mice model, PET2 (200 and 400 mg/kg) had significant effects on attenuating airway inflammatory cell infiltration and reducing serum Th2-related cytokines. Further studies led to the isolation and identification of 14 compounds, guided by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS)-based rapid characterization of chemical constituents. Combining network pharmacology analysis and in vitro experiments, we found that six compounds from PET2 had good anti-inflammatory properties. The potential mechanism may be involved in Fc epsilon RI, T cell receptor, and Jak-STAT signaling pathways. This study clarified the anti-inflammatory properties of the main active fraction and active compounds of S. chinensis fruit and provided a theoretical basis for its anti-asthma scientific utilization.

A Review of Different Analytical Techniques for Fexofenadine Hydrochloride and Montelukast Sodium in Different Matrices.

Fexofenadine hydrochloride is an antihistamine agent used for the treatment of allergic disorders like rhinitis. It is a second generation antihistamine. Montelukast sodium is an anti-asthmatic agent and leukotriene receptor antagonist used in the treatment of respiratory disorders. This article exemplifies the reported analytical methods like electrometric methods, ultraviolet spectroscopy, mass spectroscopy, thin layer chromatography, high performance liquid chromatography, high performance thin layer chromatography and tandem spectroscopy for determination of fexofenadine HCl and montelukast sodium in dosage form and in biological matrices. This review covers almost all the analytical methods for fexofenadine hydrochloride and montelukast sodium form 1968-2018 years. Complete analytical validation parameters reported are discussed in this review for both analytes. Among various analytical methods, HPLC and UV-visible spectrophotometry were found to be the most extensively used methods by the researchers.

Aqueous extracts from Uncaria tomentosa (Willd. ex Schult.) DC. reduce bronchial hyperresponsiveness and inflammation in a murine model of asthma.

ETHNOPHARMACOLOGICAL RELEVANCE: Uncaria tomentosa (Willd. Ex Schult) DC is used by indigenous tribes in the Amazonian region of Central and South America to treat inflammation, allergies and asthma. The therapeutic properties of U. tomentosa have been attributed to the presence of tetracyclic and pentacyclic oxindole alkaloids and to phenolic acids. AIMS OF THE STUDY: To characterize aqueous bark extracts (ABE) and aqueous leaf extracts (ALE) of U. tomentosa and to compare their anti-inflammatory effects. MATERIALS AND METHODS: Constituents of the extracts were identified by ultra performance liquid chromatography-mass spectrometry. Anti-inflammatory activities were assessed in vitro by exposing lipopolysaccharide-stimulated macrophage cells (RAW264.7-Luc) to ABE, ALE and standard mitraphylline. In vivo assays were performed using a murine model of ovalbumin (OVA)-induced asthma. OVA-sensitized animals were treated with ABE or ALE while controls received dexamethasone or saline solution. Bronchial hyperresponsiveness, production of Th1 and Th2 cytokines, total and differential counts of inflammatory cells in the bronchoalveolar lavage (BAL) and lung tissue were determined. RESULTS: Mitraphylline, isomitraphylline, chlorogenic acid and quinic acid were detected in both extracts, while isorhyncophylline and rutin were detected only in ALE. ABE, ALE and mitraphylline inhibited the transcription of nuclear factor kappa-B in cell cultures, ALE and mitraphylline reduced the production of interleukin (IL)-6, and mitraphylline reduced production of tumor necrosis factor-alpha. Treatment with ABE and ALE at 50 and 200 mg kg-1, respectively, reduced respiratory elastance and tissue damping and elastance. ABE and ALE reduced the number of eosinophils in BAL, while ALE at 200 mg kg-1 reduced the levels of IL-4 and IL-5 in the lung homogenate. Peribronchial inflammation was significantly reduced by treatment with ABE and ALE at 50 and 100 mg kg-1 respectively. CONCLUSION: The results clarify for the first time the anti-inflammatory activity of U. tomentosa in a murine model of asthma. Although ABE and ALE exhibited distinct chemical compositions, both extracts inhibited the production of pro-inflammatory cytokines in vitro. In vivo assays revealed that ABE was more effective in treating asthmatic inflammation while ALE was more successful in controlling respiratory mechanics. Both extracts may have promising applications in the phytotherapy of allergic asthma.

Transfer of Montelukast into Human Milk During Lactation.

AIM: The aim of this study was to determine levels of montelukast in human milk and to develop a simple, sensitive analytical method using mass spectrometry. METHODS: Milk samples were collected from seven breastfeeding mothers, age 26-35 years, at 0, 1, 2, 4, 8, and 12 hours after oral ingestion of 10 mg montelukast. The samples were analyzed using a new Liquid Chromatography-Tandem Mass Spectrometry method. Area under the milk concentration time curve from zero to the time of the last sample (12 hours) was estimated by the linear trapezoidal rule. RESULTS: Average montelukast levels (Cavg) in milk were 5.3 ng/mL, and the relative infant dose was 0.68% of the maternal dose. The maximum concentration (Cmax) observed at 4 hours (Tmax) was 9.7 ng/mL. CONCLUSION: The exposure to the infant seems to be very low, far below therapeutic ranges in an infant. Our data suggest that montelukast is probably safe to use in a breastfeeding mother.

Establishment of a standard reference material (SRM) herbal DNA barcode library of Vitex negundo L. (lagundi) for quality control measures.

The majority of the population in the Philippines relies on herbal products as their primary source for their healthcare needs. After the recognition of Vitex negundo L. (lagundi) as an important and effective alternative medicine for cough, sore throat, asthma and fever by the Philippine Department of Health (DOH), there was an increase in the production of lagundi-based herbal products in the form of teas, capsules and syrups. The efficiency of these products is greatly reliant on the use of authentic plant material, and to this day no standard protocol has been established to authenticate plant materials. DNA barcoding offers a quick and reliable species authentication tool, but its application to plant material has been less successful due to (1) lack of a standard DNA barcoding loci in plants and (2) poor DNA yield from powderised plant products. This study reports the successful application of DNA barcoding in the authentication of five V. negundo herbal products sold in the Philippines. Also, the first standard reference material (SRM) herbal library for the recognition of authentic V. negundo samples was established using 42 gene accessions of ITS, psbA-trnH and matK barcoding loci. Authentication of the herbal products utilised the SRM following the BLASTn and maximum-likelihood (ML) tree construction criterion. Barcode sequences were retrieved for ITS and psbA-trnH of all products tested and the results of the study revealed that only one out of five herbal products satisfied both BLASTn and ML criterion and was considered to contain authentic V. negundo. The results prompt the urgent need to utilise DNA barcoding in authenticating herbal products available in the Philippine market. Authentication of these products will secure consumer health by preventing the negative effects of adulteration, substitution and contamination.

Impact of Ternary Solvent System in Stability-Indicating Assay Method of Bambuterol: Design of Experiments Approach.

High-performance liquid chromatography method for anti-asthmatic ß2-agonist drug bambuterol, its process-related impurities and its major degradation products was developed and validated using quality by design concept. A 3(3) full factorial design was employed to study the effect of three independent factors, namely, ratio of organic modifiers in mobile phase, pH of the buffer and flow rate of the mobile phase. The responses considered were retention time of the last peak and resolution of poorly separated peaks (drug and PR-4 and drug and DP-3). The optimum conditions for separation were determined with the aid of design of experiments. The optimized ternary solvent composition was a mixture of 10 mM ammonium acetate buffer (pH 6.0), methanol and acetonitrile in the ratio of 90:5: 5 (v/v/v) in solvent reservoir A and 10:45:45 (v/v/v) in solvent reservoir B. The separation of the analytes was achieved by using a gradient method. The predictability criteria of the optimized method demonstrated good correlation between observed and predicted response. The method was validated for specificity, linearity, accuracy, precision and robustness in compliance with the International Conference on Harmonization guidelines Q2R1.

Determination of the impurities in drug products containing montelukast and in silico/in vitro genotoxicological assessments of sulfoxide impurity.

Impurities affecting safety, efficacy, and quality of pharmaceuticals are of increasing concern for regulatory agencies and pharmaceutical industries, since genotoxic impurities are understood to play important role in carcinogenesis. The study aimed to analyse impurities of montelukast chronically used in asthma theraphy and perform genotoxicological assessment considering regulatory approaches. Impurities (sulfoxide, cis-isomer, Michael adducts-I&II, methylketone, methylstyrene) were quantified using RP-HPLC analysis on commercial products available in Turkish market. For sulfoxide impurity, having no toxicity data and found to be above the qualification limit, in silico mutagenicity prediction analysis, miniaturized bacterial gene mutation test, mitotic index determination and in vitro chromosomal aberration test w/wo metabolic activation system were conducted. In the analysis of different batches of 20 commercial drug products from 11 companies, only sulfoxide impurity exceeded qualification limit in pediatric tablets from 2 companies and in adult tablets from 7 companies. Leadscope and ToxTree programs predicted sulfoxide impurity as nonmutagenic. It was also found to be nonmutagenic in Ames MPF Penta I assay. Sulfoxide impurity was dose-dependent cytotoxic in human peripheral lymphocytes, however, it was found to be nongenotoxic. It was concluded that sulfoxide impurity should be considered as nonmutagenic and can be classified as ordinary impurity according to guidelines.

Simultaneous quantitative determinations of fluticasone propionate and salmeterol xinafote in diskus inhalers.

In the present study, two new methods were developed for the quantitative determination of active components of Seretide(®), commercially available pharmaceutical preparation in the diskus form. One of these methods was based on derivative spectrophotometry and used a zero-crossing technique. The determinations of fluticasone propionate and salmeterol xinafoate were performed by first order derivatisation at 216.5 nm and second order derivatisation at 250 nm, respectively. The concentration ranges were 5.0-32.5 µg/mL for fluticasone propionate and 2-12 µg/mL for salmeterol xinafoate. The second method developed also included high performance liquid chromatography. In this method, a methanol-water mobile phase mixture (95:5, v/v) and a C18 chromasil column as a stationary phase were used. The wavelength of the diode array UV detector was 260 nm; the flow rate was 1 mL/min. The concentration ranges were 2-16 µg/mL for fluticasone propionate and 1-8 µg/mL for salmeterol xinafoate. The results for both methods from diskus are in the pharmacopea limits. For the statistical determination of these results, these two methods were compared with t-test for the means and with F-test for the standard deviations.

Novel spectroscopic methods for determination of Cromolyn sodium and Oxymetazoline hydrochloride in binary mixture.

New accurate, sensitive and selective spectrophotometric and spectrofluorimetric methods were developed and subsequently validated for determination of Cromolyn sodium (CS) and Oxymetazoline HCl (OXY) in binary mixture. These methods include 'H-point standard addition method (HPSAM) and area under the curve (AUC)' spectrophotometric method and first derivative synchronous fluorescence spectroscopic (FDSFS) method. For spectrophotometric methods, absorbances were recorded at 241.5nm and 274.9nm for HPSAM and the wavelength was selected in ranges 232.0-254.0nm and 216.0-229.0nm for AUC method, where the concentration was obtained by applying Cramer's rule. For FDSFS method, the first-derivative synchronous fluorescence signal was measured at 290.0nm, using Δλ=145.0nm. The suggested methods were validated according to International Conference of Harmonization (ICH) guidelines and the results revealed that they were precise and reproducible. All the obtained results were statistically compared with those of the reported method and there was no significant difference.

Determination of the enantiomeric purity of the antiasthmatic drug montelukast by means of 1H NMR spectroscopy.

In order to define an enantioselective nuclear magnetic resonance (NMR) method for the antiasthmatic drug montelukast, a series of nine easily available products were evaluated as NMR chiral solvating agents (CSAs): D-dibenzoyltartaric acid, D-ditoluoyltartaric acid, (+)-camphorsulfonic acid, (S)-BINOL, (S)-3,3'-diphenyl-2,2'-binaphthyl-1,1'-diol, (R)-3,3''-di-9-anthracenyl-1,1''-bi-2-naphthol, (R)-3,3''-di-9-phenanthrenyl-1,1''-bi-2-naphthol, Pirkle's alcohol, and (-)-cinchonidine. It was proved that most of the studied agents constitute diastereomeric complexes with both drug enantiomers in CD2 Cl2 or CDCl3 solutions, thus permitting the direct (1)H NMR detection of the unwanted S-enantiomer, even at levels of 0.75%. (-)-Cinchonidine was found to be the more convenient CSA in terms of NMR enantiodiscrimination power and ease of experimental requirements. The final method was validated and applied to the fast monitoring of the optical purity of montelukast "in-process" samples, circumventing the need for tedious and slower analytical procedures like enantioselective chromatography or capillary electrophoresis. In addition, a method for the enantiopurity control of the commercial drug (montelukast sodium salt) was also established using (S)-BINOL as NMR CSA.

Quantitive analysis of gleditsia saponins in the fruits of Gleditsia sinensis Lam. by high performance liquid chromatography.

A high performance liquid chromatography method was developed for simultaneous quantification of 29 ingredients occurring as a very complex mixture in the gleditsia fruits. The analysis was performed on an ODS-2 Hypersil column (250 mm × 4.6 mm, 5 µm) with a binary gradient mobile phase of water and acetonitrile both containing 0.1% acetic acid. The method was validated in terms of linearity, sensitivity, stability, precision, and accuracy. It was found that this method had linearity with R² at 0.99889-0.99997 in the test range of 1.0-24.0 µg. The limit of detection (LOD) and limit of quantification (LOQ) for 16 tested reference saponins were 0.24-0.39 µg and 1.0-1.2 µg, respectively. The relative standard deviations (RSDs %) for intra-day and inter-day repeatability were not more than 3.11% and 4.02%, respectively. The analyzed samples were stable for at least 48 h. The spike recoveries for eight analyzed saponins were 99.68-102.17%. The established HPLC analytic method was successfully used to determine the concentrations of 29 compounds including 19 gleditsia saponins and ten unidentified ingredients in eight commercial gleditsia fruits from different sources. The results from this study suggested that this newly developed HPLC method could be used for qualitative and quantitative analysis of the saponins in the gleditsia fruits and the gleditsia extracts that used for animal study and other purpose.

Ursolic acid, a potential PPARγ agonist, suppresses ovalbumin-induced airway inflammation and Penh by down-regulating IL-5, IL-13, and IL-17 in a mouse model of allergic asthma.

Allergic asthma is a chronic airway disorder characterized by airway hyperresponsiveness to allergens, chronic airway inflammation, airway edema, increased mucus secretion, excess production of Th2 cytokines, and eosinophil accumulation in the lungs. Ursolic acid is known for its pharmacological effects, such as its anti-tumor, anti-inflammatory and antimicrobial activities. To investigate the anti-asthmatic effects and mechanism of ursolic acid, we studied the development of pulmonary eosinophilic inflammation and enhanced pause (Penh) in a mouse model of allergic asthma. In this study, BALB/c mice were systemically sensitized to ovalbumin followed by intratracheal, intraperitoneal, and aerosol allergen challenges. We investigated the effect of ursolic acid and Cyclosporin A (CsA) on Penh, pulmonary eosinophilic infiltration, various immune cell phenotypes, Th2 cytokines, IL-17 production, and ovalbumin specific IgE production in a mouse model of asthma. In BALB/c mice, ursolic acid had suppressed eosinophil infiltration, allergic airway inflammation, and Penh, which occurred by suppressing the production of IL-5, IL-13, IL-17, and ovalbumin-specific IgE by blocking the GATA-3 and STAT6 pathways. Our data suggest the therapeutic mechanism of ursolic acid in asthma is based on reductions of Th2 cytokines (IL-5 and IL-13), ovalbumin-specific IgE production, and eosinophil infiltration via the Th2-GATA-3, STAT6, and IL-17-NF-κB pathways.

Analysis of fluticasone propionate in induced sputum by mass spectrometry.

Although evaluation of induced sputum has shown promise as a marker of eosinophilic airway inflammation in asthmatic subjects, most studies, to date, do not adequately address the potential effect that inhaled corticosteroids may have on sputum eosinophilia. This study was designed to prospectively evaluate analysis of fluticasone propionate (FP) in whole sputum by mass spectrometry as a tool to determine recent administration of inhaled FP. Induced sputum of nonsmoking asthmatic subjects was prospectively analyzed 16-24 hours after witnessed administration of orally inhaled FP. FP was extracted from whole sputum via an acetonitrile protein precipitation followed by methylene chloride liquid extraction of the supernatant (AB 4000; AB Sciex). A portion of the reconstituted sample was analyzed by liquid chromatography tandem mass spectrometry using a triple quad tandem mass spectrometer. Results were compared with those from nonsmoking asthmatic subjects not receiving inhaled FP. Twenty-two asthmatic subjects on FP and 9 asthmatic subjects without FP underwent sputum induction 16-24 hours following witnessed administration of FP. Sufficient sputum for analysis was obtained from 30 of 31 subjects. FP was detected in 22 of 22 asthmatic subjects receiving FP (range, 29-133,000 pg/mL) and was undetectable in 8 of 8 subjects not receiving FP. The sensitivity and specificity of tandem mass spectrometry's ability to detect FP in sputum was 100% and 100%, respectively. Analysis of FP in induced sputum is a reliable method to verify recent administration of inhaled FP. Induced asthmatic sputum from one induction may be used to concomitantly assess sputum eosinophilia as well as recent administration of FP.

Validated stability-indicating derivative and derivative ratio methods for the determination of some drugs used to alleviate respiratory tract disorders and their degradation products.

Derivative and derivative ratio methods are presented for the determination of butamirate citrate, formoterol fumarate, montelukast sodium, and sodium cromoglycate. Using the second derivative ultraviolet (UV) spectrophotometry, butamirate citrate and formoterol fumarate were determined by measuring the peak amplitude at 260.4 and 261.8 nm, respectively, without any interference of their degradation products. Butamirate citrate degradation product, 2-phenyl butyric acid, was determined by the measurement of its second derivative amplitude at 246.7 nm where butamirate citrate displays zero crossing. Formoterol fumarate degradation product, desformyl derivative, could be evaluated through the use of the first derivative at peak amplitude of 264.8 nm where interference of formoterol fumarate is negligible. In the first mode, the zero-crossing technique was applied at 305 nm for the determination of montelukast sodium in the presence of its photodegradation product, cis-isomer. The derivative of ratio spectra of montelukast sodium and its cis- isomer were used to determine both isomers using the first derivative of the ratio spectra by measuring the amplitudes of the trough at 305 nm and the peak at 308 nm, respectively. The later technique was also used for the determination of a ternary mixture of sodium cromoglycate and its two degradation products using zero-crossing method. In the derivative ratio spectra of the ternary mixture, trough depths were measured at 271.6, 302.8 and 302.2 nm, using the second, the first, and the second mode to evaluate sodium cromoglycate, degradation product (1) and degradation product (2), respectively. All the methods were applied successfully to the pharmaceutical preparation and were validated according to ICH guidelines.

Chemical mapping of tulobuterol in transdermal tapes using microscopic laser Raman spectroscopy.

Microscopic Laser Raman Spectroscopy and Mapping (MLRSM) technique was used to investigate the distribution of tulobuterol (TBR) crystals in transdermal tapes. TBR is one of suitable compounds for the transdermal pharmaceuticals because it has high permeability into skin. In case of TBR transdermal tapes, some commercial products also contain TBR crystals in order to control a release rate from a matrix. Therefore, the presence of TBR crystals in the matrix is a critical factor for quality assurance of this type of TDDS tapes. The model tapes prepared here employed two kinds of matrices, i.e., rubber or acrylic, which are generally used for transdermal pharmaceuticals. TBR crystals in the matrix were observed by MLRSM. Accurate observation of the distribution of TBR in the tapes was achieved by creating a Raman chemical map based on detecting unique TBR peak in each pixel. Moreover, differences in the growth of TBR crystals in the two kinds of matrices were detected by microscopic observation. MLRSM also enabled the detection of TBR crystals in commercial products. The present findings suggest that Raman micro-spectroscopic analysis would be very useful for verifying and/or assessing the quality of transdermal pharmaceuticals in development, as well as for manufacturing process control.

Identification, characterization and synthesis of impurities of zafirlukast.

Zafirlukast is a drug in the treatment of pulmonary disorders such as asthma. During the process development of zafirlukast, five unknown impurities were detected at levels of below 0.10% (ranging from 0.05 to 0.15%) in reverse phase gradient high performance liquid chromatography (HPLC) method. The molecular weights were determined by LC-MS analysis. These impurities were isolated from crude samples of zafirlukast using gradient reverse phase preparative HPLC and were subsequently synthesized. Based on the spectral data, the structures of these impurities were characterized as 3-methoxy-4-(5-methoxycarbonylamino-1-methyl-1H-indol-3-ylmethyl)-benzoic acid (Impurity 1), {3-[2-methoxy-4-(toluene-2-sulfonylaminocarbonyl)-benzyl]-1-methyl-1H-indol-5-yl}-carbamic acid methyl ester (Impurity 2), {3-[2-methoxy-4-(toluene-3-sulfonylaminocarbonyl)-benzyl]-1-methyl-1H-indol-5-yl}-acetic acid cyclopentyl ester (Impurity 3), {3-[2-methoxy-4-(toluene-4-sulfonylaminocarbonyl)-benzyl]-1-methyl-1H-indol-5-yl}-acetic acid cyclopentyl ester (Impurity 4), and 4-(5-cyclopentyloxy carbonylamino-1-methyl-1H-indol-3-yl methyl)-3-methoxy-benzoic acid methyl ester (Impurity 5). The separation of the impurities by reverse phase HPLC, the confirmation of their structures by IR, MS and NMR spectral data, the mechanism of their formation and their syntheses are discussed in detail.

Kinetic analysis of effects of mouth washing on removal of drug residues following inhalation of fluticasone propionate dry powder.

Fluticasone propionate dry powder inhaler (FP-DPI) is widely used for the treatment of asthma. However, local adverse effects such as oropharyngeal candidiasis are often seen and mouth washing after inhaling is recommended. In our previous study, we reported a nonlinear relationship between the amount of drug residue and number of times mouth washing was employed. Thus, we developed a compartment model, in which the inhaled drugs were distributed in both easy and difficult to remove areas. Using this model, we analyzed drug removal efficiency in each area with different mouth washing procedures. Three methods of mouth washing were studied; gargling and rinsing in combination, rinsing alone, and gargling alone, following administration of FP-DPI by sprinkling or inhaling. The amounts of drugs recovered from areas considered to be easy to remove (X(1)) and difficult to remove (X(2)) were determined using a nonlinear least-squares program, while the removal efficiency of each of the 3 methods was also calculated. The ratios of X(1) after sprinkling and inhalation were 63.9% and 21.8%, respectively, while those of X(2) were 6.0% and 12.4%, respectively. The numbers of mouth washings required to remove half doses from easy and difficult to remove areas were 0.2 and 1.4 times, respectively, with a combination of gargling and rinsing following inhalation of FP-DPI, while those were 0.3 and 3.6 times, respectively, with rinsing alone, and 0.4 and 5.8 times, respectively, with gargling only, thus demonstrating significant differences among the mouth washing methods for efficiency in the difficult to remove area. The present results show that the employed methods of mouth washing had a significant influence on the removal of drug residues following inhalation of FP-DPI, with gargling and rinsing in combination considered to be the most effective.

Recent studies of the electrospray ionisation behaviour of selected drugs and their application in capillary electrophoresis-mass spectrometry and liquid chromatography-mass spectrometry.

This review is concerned with recent studies of electrospray ionisation-mass spectrometry (ESI-MS) of selected small molecular mass drugs and their application in qualitative and quantitative analytical methods using the techniques liquid chromatography mass spectrometry (LC-ESI-MS) and capillary electrophoresis mass spectrometry (CE-ESI-MS). The publications reviewed are taken from the Web of Knowledge database for the year 2006. The drugs have molecular mass less than 1000 Da and are chosen according to selected drug classifications in which they give ESI signals primarily as [M+H]+ ions. The drug classifications are antibiotics/antibacterials, steroids, anti-tumour drugs, erectile dysfunction agents, anti-epileptic drugs, antiasthmatic drugs, psychoactive drugs and miscellaneous drugs. Details are given on the fragmentations, where available, that these ionic species exhibit in-source and in ion trap, triple quadrupole and time-of-flight mass spectrometers. Analytical methods for the detection and determination of these small molecular mass drug molecules are also discussed, where appropriate, under the particular drug classifications. Analytical information on, for example, sample concentration techniques, separation conditions, recoveries from biological media and limits of detection/quantitation (LODs and LOQs) are provided.

Simultaneous estimation of Montelukast sodium and Bambuterol hydrochloride in tablets by spectrophotometry.

Two simple, rapid, accurate and precise methods have been developed for simultaneous estimation of Montelukast sodium and Bambuterol hydrochloride from tablet dosage form. In the first method, the first derivative spectrum was determined. Montelukast sodium showed zero crossing point at 209.5 nm and Bambuterol hydrochloride showed zero crossing point at 238.5 nm. The dA/dlambda was measured at 209.5 nm for Bambuterol hydrochloride and 238.5 nm for Montelukast sodium and calibration curves were plotted as dA/dlambda versus concentration respectively. Quantitative determination of Montelukast sodium and Bambuterol hydrochloride in tablets was carried out using calibration curve by interpolation method. In the second method, Multicomponent mode of analysis was used and the measurement of absorbances at two wavelengths, 283.6 nm (lambda-max of MKST) and 211.8 nm (working wavelength selected for BHC) in 95% methanol, was carried out. These methods were validated statistically as per ICH guidelines. The recovery studies confirm the accuracy of the proposed method.