Separation and Characterization of Novel Degradation and Process Related Impurities of Bedaquiline Bulk Drug.

Bedaquiline (BDQ) is a new drug approved by United States Food and Drug Administration (USFDA) in 2012 for the treatment of drug-resistant tuberculosis, which has become a major threat globally. The manuscript presents the development of three liquid chromatography (LC) based analytical methods. The first is a stability indicating RP-HPLC (reverse phase-high performance liquid chromatography) method to analyze the BDQ in presence of its degradation products. Another UPLC/ESI-MS (ultra-performance liquid chromatography/electron spray ionization-mass spectrometry) method was developed for the identification of different degradation based and process related impurities and the third, preparative HPLC method was developed for the isolation of major degradation products. Eleven degradation products and one process related impurity were identified using UPLC/ESI-MS whereas preparative HPLC was used to isolate two degradation products and their chemical structure was elucidated using nuclear magnetic resonance, mass and infra-red spectral data.

Investigation of in vitro permeability and in vivo pharmacokinetic behavior of bare and functionalized MCM-41 and MCM-48 mesoporous silica nanoparticles: a burst and controlled drug release system for raloxifene.

In the present work, MCM-41 and MCM-48 type of nanoparticles were successfully engineered. Effect of nanosize and amine functionalization on drug release, in vitro intestinal absorption and in vivo pharmacokinetic behavior was investigated in a comprehensive manner. The tailor-made bare and surface decorated MCM-41 and MCM-48 were synthesized and evaluated for their mesoporous skeleton, pore size, particle size, surface area, zeta potential, etc. by nitrogen sorption, DLS, TEM, etc. Incorporation of raloxifene (RLF) was affirmed using optimized immersion-solvent evaporation technique and its success confirmed by DSC, IR, and XRD analysis. TGA analysis revealed higher %grafting of amine groups on the exterior and larger RLF encapsulation into mesoporous derivate. The detailed in vitro release study revealed SGF to be the most compatible media for RLF showing an initial burst release from pristine nanoparticles and a delayed release from surface coated nanoparticles. Furthermore, release kinetics model data demonstrated Weibull and Higuchi as the best fit models for bare and amine-functionalized nanoparticles respectively. Moreover, an in vitro permeability study on Caco-2 cell line revealed higher absorption by engineered nanoparticle as compared to pure RLF and its marketed formulation. The supremacy in the in vivo pharmacokinetic parameters of RLF-41 and RLF-48 was demonstrated with 3.33 and 3.50 times enhancement in the bioavailability of RLF with respect to RLF suspension. To sum up, the results obtained were superior and promising for synthesized nanoparticles and more precisely for MCM-48 amongst them.

Facile development, characterization, and evaluation of novel bicalutamide loaded pH-sensitive mesoporous silica nanoparticles for enhanced prostate cancer therapy.

It is a challenge to deliver therapeutics exclusively to cancer cells, while sparing the normal cells. However, pH-sensitive delivery systems have proved to be highly efficient in fulfilling this task due to their ability to provide on-demand and selective release of drug at acidic tumor sites. As a proof of concept, here pH responsive drug delivery system based on mesoporous core shell nanoparticles (NPs) surrounded with poly acrylic acid (PAA) layers were prepared employing a facile synthesis strategy. Bicalutamide (BIC) was encased into surface functionalized MCM-41 nanoparticles via electrostatic interactions. The synthesized NPs were characterized by nitrogen adsorption and desorption isotherms, SEM-EDS, TEM, LXRD, and WXRD. In vitro release studies demonstrated that BIC-MSN-PAA NPs exhibited a higher release in the acidic media which varied inversely with the increase in pH. Further, the results of cell cytotoxicity assay were evident that BICMSNs exhibited more potent killing of both PC-3 and LNCaP cells than free BIC. PAA-MSNs also exhibited an enhanced cellular uptake and prolonged circulation time in vivo. The results are suggestive of the fact that PAA functionalized MSNs can serve as an effective pH-responsive template and hold a great potential ahead in controlled release and effective cancer treatment.

Advances in the Development of Novel Factor Xa Inhibitors: A Patent Review.

Development of new anticoagulants has been in constant demand throughout the world due to increasing rate of morbidity and mortality caused by thrombotic diseases. Factor Xa (FXa), one of the enzymes and validated target for anticoagulation, regulates the production of thrombin in the coagulation cascade. The importance of oral FXa inhibitors like rivaroxaban, apixaban and edoxaban in thromboembolic conditions is well supported by increasing number of patents and research publications during the recent years. Direct FXa inhibitors as antithrombotic agents offer selective, efficacious and orally active therapy with respect to the other traditional anticoagulants. Newly developed patented molecules are mainly structural bioisosteres of existing drugs and have exhibited better efficacy and safety profile. Development of antidotes for oral direct FXa inhibitors is in pipeline and their expected approval for therapeutic purposes will be further beneficial to anticoagulation therapy. This review is mainly focused on industrial and academic patents on the discovery of direct FXa inhibitors. The review covers patented compounds from December 2011 till date, describing various structural modifications along with biological activity data and advances in the process and formulation technologies of the reported FXa inhibitors.

Tailor-made pH-sensitive polyacrylic acid functionalized mesoporous silica nanoparticles for efficient and controlled delivery of anti-cancer drug Etoposide.

A multifaceted therapeutic platform has been proposed for controlled delivery of Etoposide (ETS) leading to a synergistic advantage of maximum therapeutic efficacy and diminished toxicity. A state of the art pH responsive nanoparticles (NPs) MSNs-PAA consisting of mesoporous silica nanoparticles core and polymeric shell layers, were developed for controlled release of model anti-cancer drug ETS. Graft onto strategy was employed and amination served as an interim step, laying a vital foundation for functionalization of the MSN core with hydrophilic and pH responsive polyacrylic acid (PAA). MCM-41-PAA were investigated as carriers for loading and regulated release of ETS at different pH for the first time. The PAA-MSNs contained 20.19% grafted PAA as exhibited by thermogravimetric analysis (TGA), which enormously improved the solubility of ETS in aqueous media. The synthesized PAA-MSNs were characterized by various techniques viz, SEM-EDS, TEM, BET, FT-IR and powder XRD. ETS was effectively loaded into the channels of PAA-MSN via electrostatic interactions. The cumulative release was much rapid at extracellular tumor (6.8) and endosomal pH (5.5) than that of blood pH (7.4). Hemolysis study was done for the prepared NPs. MTT assay results showed that the drug-loaded ETS-MCM-41-PAA NPs were more cytotoxic to both prostate cancer cells namely PC-3 and LNCaP than free ETS, which was attributed to their slow and sustained release behavior. The above results confirmed that PAA-MSN hold a great potential as pH responsive carriers with promising future in the field of cancer therapy.

Facile Synthesis of Chitosan Capped Mesoporous Silica Nanoparticles: A pH Responsive Smart Delivery Platform for Raloxifene Hydrochloride.

An encapsulation of model drug raloxifene hydrochloride (RAL) inside the chitosan decorated pH responsive mesoporous system has a greater potential for accumulating in the tumor cells. The present study involves synthesis of surface modified mesoporous silica nanoparticles (MSN) with the aim of achieving pH sensitive drug delivery system. A silanol skeleton of MSN has been productively modified to amine intermediate which served as a firm platform to adapt chitosan grafted assembly and systematically evaluated. RAL incorporation inside the featured mesopores was performed employing novel immersion solvent evaporation methodology and evaluated further. The pH responsive behavior of formulated nano framework was studied at three different pH of a phosphate buffer saline individually. The in vitro cell viability assay on MCF-7 breast carcinoma cells was performed in time and concentration dependent manner. Finally, the hemolysis assay of designed nanoparticle was accomplished to envisage the hemocompatibility. The outcome of characterization details unveiled a perfect 2D hexagonal spherical structure gifted with higher surface area and optimum pore size for designed nanoparticles. The higher percentage grafting of amine and chitosan residue, i.e., 4.01 and 28.51% respectively along with 31.89 and 33.57% RAL loading efficiency made MSNs more attractive and applicable. Eventually, in vitro release study exhibited higher RAL release in acidic media for extended time periods confirming successful formation of pH responsive nanoparticle having controlled release property. Conclusively potential of designed nanosystem to serve efficient anti-cancer remedy was confirmed by superior behaviour of chitosan grafted MSN towards MCF-7 cells with supreme hemocompatibility.

Stress degradation of edaravone: Separation, isolation and characterization of major degradation products.

In the present study the International Conference on Harmonization-prescribed stress degradation was carried out to study the degradation profile of edaravone. To establish a Quality by Design (QbD)-assisted stability-indicating assay, the reaction solutions in which different degradation products were formed were mixed. Plackett Burman and central composite design were used to screen and optimize experimental variables to resolve edaravone and its impurities with good peak symmetry using an RP C18 column. The method was validated according to International Conference on Harmonization guidelines. Seven unknown and two known degradation products were identified and characterized by LC-MS/MS. Two major degradation products formed under thermal degradation were isolated and characterized as 4-(4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl-4-(4,5-dihydro-5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and 3-hydroxy-dihydro-thiazolo[1-(2-methyl-buta-1,3dienyl)-1-phenylhydrazine]5-one. The degradation pathways of degradants were proposed based on m/z values.

Etoposide encased folic acid adorned mesoporous silica nanoparticles as potent nanovehicles for enhanced prostate cancer therapy: synthesis, characterization, cellular uptake and biodistribution.

The present research was motivated by the dire need to design a targeted and safe Nano-vehicle for delivery of Etoposide (ETE), which would be tolerant of normal cells and exclusively toxic to prostate cancer cells. The folic acid functionalized mesoporous silica nanoparticles (MSNs) constructed by using a facile method acting as a unique selective platform for ETE delivery for effective prostate cancer treatment. FA@MSNs possessed good payload and encouraging in vitro release was obtained for ETE caged inside FA-MSNs compared with ETE-MSNs alone. Further, FA@MSNs exhibited an improved blood compatibility compared with pristine silica. The cellular analysis on PC-3 and LNCaP cell lines unveiled an excellent performance of cytotoxicity. Apoptosis assay confirmed a programmed cell death ruling out necrosis. Most importantly enhanced cellular uptake was obtained for FITC#FA@MSNs. In addition, pharmacokinetic and biodistribution studies in healthy mice indicated a favourable longer circulation time and reduced plasma elimination rate for ETE/FA@MSNs than free ETE. Further, histological and cell cytotoxicity results proved that nanocarriers themselves were safe without any noticeable toxicity. The results showed that FA@MSNs were ideal candidates for safe and effective delivery of ETE and hold a substantial potential as drug delivery vehicles for enhanced prostate cancer therapy.

Preparation and physicochemical characterization of ingredients of Indian traditional medicine, Mahamrutyunjaya Rasa.

Background: Mahamrutyunjaya rasa is an ayurvedic formulation used in the treatment of cardiac disorders. It contains the purified roots of Visa (Aconitum ferox), Brihati (Solanum indicum), fruits of Pippali Kana (Piper longum), Marica (Piper nigrum), Gandhaka (Sulfur), Hingula (Cinnabar) and Tankana (Sodium metaborate) as per Bhaishajya Ratnavali. The purification (shodhana) process changes the physiochemical properties of the raw materials which need to be studied and understood. Objective: The present work aims to perform a comprehensive physicochemical characterization of raw materials, intermediates and the final product obtained during purification, using modern analytical techniques. Materials and methods: The standard methods as per traditional text were followed and the physicochemical changes were also investigated by collecting samples at different steps of purification. The samples were analysed using various techniques, viz. Fourier transform infra-red spectroscopic (FTIR), X-ray diffraction (XRD), Differential Scanning Calorimeter (DSC) and High Performance thin Layer chromatography (HPTLC). Results: The FTIR and HPTLC analysis of the alkaloidal extracts of Visa showed loss of an ester group with shift in the peaks from 1720 cm-1 (C[bond, double bond]O stretching of esters) to 1676 cm-1 (C[bond, double bond]O stretching of Ketone) which signifies the conversion of alkaloid Aconitine (LD50 - 0.08 mg/kg) to Benzoylaconine (LD50 - 24 mg/kg) improving its safety. The analysis of gandhaka by XRD and DSC showed that purification brought about transformation of orthorhombic sulphur into monoclinic sulphur and it reverted back to original form with higher purity. The treatments given to gandhaka and hingula with organic compounds made them homologous to the body tissues. Analysis of purified tankana showed that the processing led to loss of water and slight change in the crystal structure with the shift in the endothermic peak from 110.6 °C to 104.2 °C. Conclusion: Thus, the present study provides a scientific backing to the methodologies used by Ayurvedic practitioners. The study also provides physicochemical fingerprints for the standardization as well as characterization of raw materials and forms a technical platform for manufacturers to develop quality control standards.

Nanosuspension of efavirenz for improved oral bioavailability: formulation optimization, in vitro, in situ and in vivo evaluation.

CONTEXT: Nanosuspensions (NSs) of poorly water-soluble drugs are known to increase the oral bioavailability. OBJECTIVES: The purpose of this study was to develop NS of efavirenz (EFV) and to investigate its potential in enhancing the oral bioavailability of EFV. MATERIALS AND METHODS: EFV NS was prepared using the media milling technique. The Box-Behnken design was used for optimization of the factors affecting EFV NS. Sodium lauryl sulfate and PVP K30 were used to stabilize the NS. Freeze-dried NS was completely re-dispersed with double-distilled filtered water. RESULTS: Mean particle size and zeta potential of the optimized NS were found to be 320.4 ± 3.62 nm and -32.8 ± 0.4 mV, respectively. X-ray diffraction and differential scanning calorimetric analysis indicated no phase transitions. Rate and extent of drug dissolution in the dissolution medium for NS was significantly higher compared to marketed formulation. The parallel artificial membrane permeability assay revealed that NS successfully enhanced the permeation of EFV. Results of in situ absorption studies showed a significant difference in absorption parameters such as Ka, t1/2 and uptake percentages between lyophilized NS and marketed formulation of EFV. Oral bioavailability of EFV in rabbits resulting from NS was increased by 2.19-fold compared to the marketed formulation. CONCLUSION: Thus, it can be concluded that NS formulation of EFV can provide improved oral bioavailability due to enhanced solubility, dissolution velocity, permeability and hence absorption.

Preparation and characterization of microemulsion of cilostazol for enhancement of oral bioavailability.

Cilostazol is a promising drug for antiplatelet combination therapy that is very important for treatment for various cardiovascular disorders. However, oral delivery of this drug is greatly impeded by the poor solubility in aqueous solutions. The aim of this study was to develop microemulsion (ME) delivery system capable of improving the drug bioavailability. In this study, Capmul MCM C8 (glycerol monocaprylate) based MEs containing Tween 20(polysorbate 20) and/or Labrafil M 1944(poly oxyglycerides) as surfactant(S) and Transcutol P(diethyl glycol monoethyl ether) as cosurfactant(CoS) were studied as potential delivery systems of cilostazol. A number of such systems were prepared containing different S:CoS ratios(1:1, 2:1 and 3:1) based on phase diagrams. Loading of cilostazol was selected as per solubilization capacity and was characterized for pH, viscosity, conductivity, particle size, zeta potential and % transmittance. The MEs systems were further investigated for chemical stability, diffusion and bioavailability. Cilostazol displayed high solubility in microemulsions with particle size up to 70 nm. It was also stable at ambient temperature up to 6 months without significant change in particle size, zeta potential, and % transmittance. Dilution up to 100 fold with aqueous medium observed a visible cloudiness having a particle size up to 104 nm. The in vitro release, and ex vivo intraduodenal diffusion, and in vivo study indicated the capacity of developed ME to improve the bioavailability (1.43 fold) via oral route administration when compared with commercially available tablets (Pletoz-50).

Optimization of the in vitro oxidative biotransformation of glimepiride as a model substrate for cytochrome p450 using factorial design.

BACKGROUND AND PURPOSE OF THE STUDY: Glimepiride (GLM) was chosen as a model substrate in order to determine the kinetic parameters for in vitro metabolism via human liver micrososmes (HLM). We aimed to optimize the turnover of the substrate by the test system in relation to incubation time and HLM concentration in such a way that it was linearly dependent on time and less than 20% of the substrate was consumed which utilized the lowest amount of the HLM. Further we aimed to report Km and Vmax values for GLM. METHODS: Linearity of enzyme reactions in microsomal incubations was assessed by monitoring the effect of incubation time (from 5 to 60 min) and HLM concentration (from 0.2 to 0.75 mg/ml) on metabolite formation of GLM. The ideal conditions for turnover of GLM were justified using 3x3 factorial design. F value was calculated to confirm the omission of insignificant terms from the full-model to derive a reduced- model polynomial equation. The regression equation was used to develop a contour plot that showed turnover rate within the limits of this design. The optimized reaction velocity data was extrapolated to carry out the kinetic studies in vitro to generate a saturation curve for the determination of Km and Vmax values. RESULTS: The reaction was found to be linear with respect to both incubation time between 24 and 50 min and HLM concentration between 0.3 to 0.65 mg/ml. The Km and Vmax values obtained by nonlinear least squares regression method was found to be 28.9 ± 2.97 µMole and 0.559 ± 0.017 µMole respectively. Lineweaver-Burk plot was also used to estimate Km and Vmax which yield value of 29.411 ± 1.25 µMole and 0.571 ± 0.020 µMole/min/mg protein respectively. MAJOR CONCLUSION: The statistical approach successfully allows for the optimization of reaction time course experiments. The results obtained with linear as well as the nonlinear transformation were found to be in close agreement with each other which shows the best precision for estimates of Km and Vmax.

RP-HPLC method for simultaneous determination of butenafine hydrochloride and betamethasone dipropionate in a cream formulation.

An RP-HPLC method has been developed for the simultaneous determination of butenafine hydrochloride and betamethasone dipropionate on an Inertsil C18 column (250 x 4.6 mm id) using a mobile phase gradient consisting of methanol and water at a flow rate of 1 mL/min. Detection was carried out at 254 nm. Retention times of betamethasone dipropionate and butenafine hydrochloride were 4.82 (+/- 0.80) and 16.18 (+/- 0.17) min, respectively. The method was validated with respect to specificity, linearity, accuracy, precision, ruggedness, and robustness. This method is simple, precise, and sensitive, and applicable for the simultaneous quantification of butenafine hydrochloride and betamethasone dipropionate in a cream formulation.

Biological Evaluation of Polyherbal Ayurvedic Cardiotonic Preparation "Mahamrutyunjaya rasa".

Mahamrutyunjaya rasa (MHR), an Ayurvedic formulation, used as cardiotonic, contains potentially toxic compounds like aconitine, which are detoxified during preparation using traditional methods. Comparative toxicological evaluation of laboratory prepared formulation (F1) and two marketed formulations (F2 and F3) were performed based on their effects on viability of H9c2 cells and after single oral dose administration in mice. Cardioprotective effect of formulations at 25 and 50 mg/kg doses were studied in isoproterenol- (ISO-) induced myocardial infarcted rats. F1 and F2 did not affect the cell viability, while F3 decreased the cell viability in concentration and time-dependent manner. Rats administered with ISO showed significant increase in the serum levels of glutamate oxaloacetate transaminase, alkaline phosphotase, creatinine kinase isoenzymes, lactate dehydrogenase, and uric acid, while F1 and F2 treatment showed significant reduction in the same. F3 showed further increase in the serum levels of enzymes and uric acid in ISO-challenged rats. High pressure liquid chromatographic analysis of formulations showed higher concentration of aconitine in F3. Study shows that F1 and F2 possess cardioprotective property with higher safety, while formulation F3 cannot be used as cardioprotective due to its cytotoxic effects. Thus, proper quality assessment methods are required during preparation of traditional formulations.

Stability-indicating HPLC method for simultaneous determination of clidinium bromide and chlordiazepoxide in combined dosage forms.

The study describes development and subsequent validation of a stability indicating reverse-phase high-performance liquid chromatography method for the simultaneous estimation of clidinium bromide (CLI) and chlordiazepoxide (CHLOR) from their combination drug product. Chromatographic separations are performed at ambient temperature on a Phenomenex Luna C(18) (250 mm x 4.6 mm, i.d., 5 microm) column using a mobile phase consisting of potassium dihydrogen phosphate buffer (0.05 M, pH 4.0 adjusted with 0.5% orthophosphoric acid)-methanol- acetonitrile (40:40:20, v/v/v). The flow rate is 1.0 mL/min, and the detection wavelength is 220 nm. The method is validated with respect to linearity, precision, accuracy, system suitability, and robustness. The utility of the procedure is verified by its application to marketed formulations that were subjected to accelerated degradation studies. The method distinctly separated the drug and degradation products even in actual samples. The products formed in marketed tablet dosage forms are similar to those formed during stress studies.

Preparation and bioavailability assessment of SMEDDS containing valsartan.

A self-microemulsifying drug delivery system (SMEDDS) has been developed to enhance diffusion rate and oral bioavailability of valsartan. The solubility of valsartan was checked in different oils, surfactants, and cosurfactants and ternary phase diagrams were constructed to evaluate the microemulsion domain. The valsartan SMEDDS was prepared using Capmul MCM (oil), Tween 80 (surfactant), and polyethylene glycol 400 (cosurfactant). The particle size distribution, zeta potential, and polydispersity index were determined and were found to be 12.3 nm, -0.746, and 0.138, respectively. Diffusion rate of valsartan was measured by in vitro dialysis bag method using phosphate buffer pH 6.8 as diffusion media. Developed high-performance liquid chromatography method was used to determine drug content in diffusion media. Oral bioavailability of valsartan SMEDDS was checked by using rabbit model. Results of diffusion rate and oral bioavailability of valsartan SMEDDS were compared with those of pure drug solution and of marketed formulation. Diffusion of valsartan SMEDDS showed maximum drug release when compared to pure drug solution and marketed formulation. The area under curve and time showed significant improvement as the values obtained were 607 ng h/mL and 1 h for SMEDDS in comparison to 445.36 and 1.36 h for market formulation suggesting significant increase (p < 0.01) in oral bioavailability of valsartan SMEDDS.

Stability-indicating reversed-phase liquid chromatographic methods for the determination of aconitine and piperine in a polyherbal formulation.

Simple and rapid stability-indicating HPLC methods were developed for the individual analysis of aconitine (ACN) and piperine (PIN) in Mahamrutynjaya rasa, an herbal dosage form containing Aconitum ferox, Piper nigrum, and Piper longum in combination. Separation of the ACN from its major and minor degradation products was successfully achieved on a reversed-phase C18 column (250 x 4.6 mm id, 5 microm particle size), with isocratic elution using a mixture of acetonitrile-KH2PO4 buffer (10 mM, pH 8 +/- 0.1; 50 + 50, v/v) at flow rate of 0.7 mL/min with UV detection at 227 nm. PIN separation was performed on a reversed-phase C18 column (250 x 4.6 mm id, 5 microm particle size), with isocratic elution in acetonitrile-KH2PO4 buffer (10 mM, pH 7 +/- 0.1; 35 + 65, v/v) at a flow rate of 1 mL/min with UV detection at 343 nm. The methods were validated with respect to linearity, precision, accuracy, specificity, system suitability, and robustness. The responses were linear in the drug concentration range of 10-100 microg/mL for both ACN and PIN. The percent recoveries of both the markers from a mixture of degradation products were in the range between 98-101%. The utility of the procedures was verified by their application to marketed formulations that were subjected to accelerated degradation studies. The methods could distinctly separate the drug and degradation products. The products formed in the marketed tablets were similar to those formed in the laboratory during stress studies.

Enhancement of oral bioavailability of cilostazol by forming its inclusion complexes.

The study was designed to investigate the effect of cyclodextrins (CDs) on the solubility, dissolution rate, and bioavailability of cilostazol by forming inclusion complexes. Natural CDs like beta-CD, gamma-CD, and the hydrophilic beta-CD derivatives, DM-beta-CD and HP-beta-CD, were used to prepare inclusion complexes with cilostazol. Phase solubility study was carried out and the stability constants were calculated assuming a 1:1 stoichiometry. Solid cilostazol complexes were prepared by coprecipitation and kneading methods and compared with physical mixtures of cilostazol and cyclodextrins. Prepared inclusion complexes were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) studies. In vitro dissolution study was performed using phosphate buffer pH 6.4, distilled water, and HCl buffer pH 1.2 as dissolution medium. The optimized inclusion complex was studied for its bioavailability in rabbit and the results were compared with those of pure cilostazol and Pletoz-50. Phase solubility study showed dramatic improvement in the solubility of drug by formation of complexes, which was further increased by pH adjustment. The dissolution rate of cilostazol was markedly augmented by the complexation with DM-beta-CD. DSC and XRD curves showed sharp endothermic peaks indicating the reduction in the microcrystallinity of cilostazol. Selected inclusion complex was also stable at ambient temperature up to 6 months. The in vivo study revealed that DM-beta-CD increased the bioavailability of cilostazol with low variability in the absorption. Among all cilostazol-cyclodextrins complexes, cilostazol-DM-beta-CD inclusion complex (1:3) prepared by coprecipitation method showed 1.53-fold and 4.11-fold increase in absorption along with 2.1-fold and 2.97-fold increase in dissolution rate in comparison with Pletoz-50 and pure cilostazol, respectively.

Simultaneous determination of a ternary mixture of doxylamine succinate, pyridoxine hydrochloride, and folic acid by the ratio spectra-zero-crossing, double divisor-ratio spectra derivative, and column high-performance liquid chromatographic methods.

Three simple, rapid, and accurate methods, i.e., the derivative ratio spectra-zero-crossing method (method I), double divisor-ratio spectra derivative method (method II), and column reversed-phase high-performance liquid chromatographic (RP-HPLC) method (method III) were developed for the simultaneous determination of doxylamine succinate (DOX), pyridoxine hydrochloride (PYR), and folic acid (FA) in their ternary mixtures and in tablets. In methods I and II, the calibration graphs were linear in the range of 2.5-80, 1.0-40, and 1.0-30 microg/mL for DOX, PYR, and FA, respectively. In the HPLC method, the separation of these compounds was performed using mobile phase consisting of 0.05 M phosphate buffer (pH 6.3)-methanol-acetonitrile (50 + 20 + 30, v/v/v), and UV detection was performed at 263 nm. Linearity was observed between the concentrations of the analytes and peak areas [correlation coefficient (r) > or =0.9998] in the concentration range of 1.0-200, 4.0-600, and 4.0-600 microg/mL for DOX, PYR, and FA, respectively. The standard deviation of retention time in method III was 0.011, 0.015, and 0.016 for DOX, PYR, and FA, respectively. The precision studies for all of the methods gave relative standard deviation values of <2%. The results obtained from the methods were statistically compared by means of Student's t-test and the variance ratio F-test. It was concluded that all of the developed methods were equally accurate, sensitive, and precise. These methods could be applied to determine DOX, PYR, and FA in their combined dosage forms.

Development of a stability-indicating high-performance liquid chromatographic method for the simultaneous determination of alprazolam and sertraline in combined dosage forms.

The objective of the current study was to develop a validated stability-indicating high-performance liquid chromatographic method for alprazolam and sertraline in combined dosage forms. The method was validated by subjecting the drugs to forced decomposition under hydrolysis, oxidation, photolysis, and thermal stress conditions prescribed by the International Conference on Harmonization. The drugs were successfully separated from major and minor degradation products on a reversed-phase C18 column by using 75 mM potassium dihydrogen phosphate buffer (pH 4.3)-acetonitrile-methanol (50 + 45 + 5, v/v/v) as the mobile phase with determination at 227 nm. The flow rate was 0.9 mL/min. The method was validated with respect to linearity, precision, accuracy, system suitability, and robustness. The responses were linear over the ranges of 1-80 and 5-200 microg/mL for alprazolam and sertraline, respectively. The recoveries of both drugs from a mixture of degradation products were in the range of 97-101%. The utility of the procedure was verified by its application to marketed formulations that were subjected to accelerated stability studies. The method distinctly separated the drugs and degradation products, even in actual samples. The products formed in marketed tablets were similar to those formed during stress studies.