Monolithic matrix tablets of ambroxol hydrochloride were formulated as sustained release tablets employing hydroxypropyl methylcellulose polymer, and the sustained release behaviour of the fabricated tablets was investigated. Sustained release matrix tablets containing 75 mg ambroxol hydrochloride were developed using different drug polymer ratios of hydroxypropyl methylcellulose. Tablets were prepared by direct compression. Formulation was optimized on the basis of acceptable tablet properties and in vitro drug release. The resulting formulation produced robust tablets with optimum hardness, consistent weight uniformity and low friability. All tablets but one exhibited gradual and near-completion sustained release for ambroxol hydrochloride, and 98-101% released at the end of 12 h. The results of dissolution studies indicated that formulation F-V (drug to polymer 1:1.47), the most successful of the study, exhibited drug release pattern very close to theoretical release profile. A decrease in release kinetics of the drug was observed on increasing polymer ratio. Applying exponential equation, all the formulation tablets (except F-V) showed diffusion-dominated drug release. The mechanism of drug release from F-V was diffusion coupled with erosion (anomalous).

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Hybanthus enneaspermus Muell, belonging to family Violaceae, was investigated to evaluate in vitro antibacterial activity of aqueous, ethanolic, petroleum ether and chloroform extracts against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis and Staphylococcus aureus . The major urinary tract infection causing pathogens were tested by disc diffusion assay method, and the minimum inhibitory concentration was evaluated. Ethanol (95%) extract exhibited significant and broader spectrum of inhibition in comparison to aqueous, which showed moderate effect; chloroform and petroleum ether extract showed feeble activity at concentration of 300 mg/disc. An attempt has been made to compare the activity of extracts with standard antibiotics against selected urinary tract pathogens.

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A simple, specific, accurate and precise reverse phase high performance liquid chromatographic method was developed for the simultaneous estimation of bisoprolol fumarate and hydrochlorothiazide in tablet dosage form. A lichrospher 100 C-18, 5 µm column 20 cm × 4.6 mm in isocratic mode, with mobile phase containing water, acetonitrile and tetrahydrofuran in proportion of 80:20:5 v/v/v were used. The flow rate was 1 ml/min, and effluent was monitored at 225 nm. The retention time of bisoprolol fumarate and hydrochlorothiazide were 1.48 ± 0.02 and 4.72 ± 0.03 min respectively, and the resolution factor was 9.0. Linearity values for bisoprolol fumarate and hydrochlorothiazide were in the range of 10-150 µg/ml and 1-90 µg/ml respectively. The limit of detection and limit of quantification for bisoprolol fumarate was found to be 3.5 and 8.5 µg/ml respectively; and for hydrochlorothiazide, 0.4 and 0.9 µg/ml respectively. The proposed method is accurate, precise, specific and rapid for simultaneous estimation of bisoprolol fumarate and hydrochlorothiazide in tablet dosage form.

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Difference spectrophotometric method was developed for the estimation of telmisartan in bulk drug and in pharmaceutical formulations. Telmisartan exists in two different forms in acidic and basic mediums that differ in their UV spectra. Difference spectrum, obtained by keeping telmisartan in 0.01 N NaOH in reference cell and telmisartan in 0.01 N HNO ₃ in sample cell, showed two characteristic peaks at 295 nm and 327 nm with positive and negative absorbance respectively. Difference of absorbance between these two maxima was calculated to find out the amplitude, which was plotted against concentration. The method was found to be linear in the range of 2-12 μg/ml.

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Present work reports extraction of mucilage of Eulophia campestris by multiple maceration technique using water and precipitation by acetone (36% w/w yield). Physicochemical characteristics of mucilage, such as solubility, swelling index, loss on drying, pH and viscosity, were studied and also microbial load was determined. The mucilage was evaluated for its granulating and binding properties in tablets, using paracetamol as a model drug. Mucilage was used in three different concentrations - 6, 8 and 10% w/v. The granules were prepared by wet granulation technique. The prepared granules were evaluated for percentage of fines, average particle size, total porosity, compressibility index and flow properties. The properties were compared with starch, which was used as a standard binder at 10% w/v concentration. The tablets were prepared and evaluated for content uniformity, hardness, friability, disintegration time and in vitro dissolution profiles. The tablets had good physicochemical properties, and the drug release was more than 85% within 3 h. The tablets prepared by using 10% mucilage as binder exhibited more hardness than by using 6 and 8% concentrations. Hence, 6 and 8% concentrations can be considered as ideal concentrations for preparation of tablets.

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The main purpose of this research was to study the mechanism of drug release from solid dispersions of albendazole, giving special emphasis to particle size of the drug in solid dispersions. Solid dispersions were prepared using three different carriers, mixing ratios and methods in an attempt to improve the solubility and dissolution rate of albendazole. The mechanism of enhanced dissolution was investigated by a novel dissolution technique as an adjunct to phase solubility study, wettability test, differential scanning calorimetry, X-ray diffractometry, infrared spectroscopy and scanning electron microscopy. The solubility of albendazole was greater with albendazole-poloxamer 407 system, while polyethylene glycol dispersions showed predominant wettability. Physical mixtures showed enhanced dissolution compared with the pure drug, due to improved wetting and solubilization of drug in the diffusion layer offering carrier-rich microenvironment. Preparation of solid dispersion further improved the dissolution compared to the physical mixture, owing to increased surface area for mass transfer, thermodynamically enhanced dissolution of a higher energy amorphous form from the carrier, in addition to improved wetting and solubilization. All carriers showed comparable degree of drug particle size reduction, whereas mixing ratio and method of preparation substantially affected the particle size. Intermolecular association of drug with the carrier led to inhibition of drug recrystallization.

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Two simple, sensitive, rapid, accurate and economical methods were developed for the estimation of ciprofloxacin and ornidazole in two-component solid dosage form. First method is based on the simultaneous equation, and second method is based on Q-analysis (absorbance ratio method). Ciprofloxacin has absorbance maxima at 271.4 nm, and ornidazole has absorbance maxima at 320 nm in distilled water. The linearity was obtained in the concentration range of 2-10 µg/ml for ciprofloxacin and 2-20 µg/ml for ornidazole. In the first method, the concentrations of the drugs were determined by using simultaneous equations; and in the second method, the concentrations of the drugs were determined by using ratio of absorbances at isoabsorptive point and at the λ_max of one of the drugs. The results of analysis have been validated statistically and by recovery studies.

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Topical microemulsions of nimesulide, a poorly water-soluble nonsteroidal antiinflammatory drug, using olive oil as oil phase and Tween 80/iso-octanol as surfactant/co-surfactant were designed. Various concentrations of surfactant: co-surfactant (2:1, 3:1, 4:1) were used in constructing a pseudoternary phase diagram. Oil-in-water microemulsions with ratio 15/35/50 (o/w/s) was chosen for the present study after evaluating various parameters like centrifugation, viscosity and stability. Using 4:1 ratio of surfactant : co-surfactant, a microemulsion-based gel of nimesulide was prepared with 1% Carbopol 934. In vitro permeation study of the gel was carried out through excised hairless rat skin and compared with a marketed preparation. The drug release after 24 h from the prepared microemulsion gel and marketed formulation was found to be 72% and 81% respectively. No significant difference was observed between the release rates of nimesulide from both formulations despite their differences in alcohol content. Microemulsion-based gel of poorly water-soluble nimesulide was successfully developed with in vitro release rates comparable to that of the marketed gel formulation.

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Soluble inserts of ciprofloxacin hydrochloride using high and low molecular weight polyvinyl alcohol alone and in various combinations were fabricated by a casting technique. The in vitro drug release from the prepared inserts was studied using a continuous flow-through model, developed in our laboratory. The antimicrobial efficacies of the prepared inserts against common ocular pathogens, viz., Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853, were evaluated using a modified in vitro microbiological model. Ciprofloxacin hydrochloride release from the inserts followed matrix diffusion kinetics showing an anomalous release mechanism (erosion-controlled) based on the calculated release exponent (n) values. Drug release increased with an increase in the proportion of high molecular weight polyvinyl alcohol in the inserts. The in vitro microbiological model demonstrated the effectiveness of the inserts against the two microorganisms. Further, the results of the in vitro release studies correlated well with that of the antimicrobial studies.

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Niosomes (nonionic surfactant-based vesicles) containing rifampicin were prepared using various nonionic surfactants of sorbitan ester class and cholesterol in 50:50 percent mol fraction ratio. The drug-entrapped vesicles were characterized for their shape, size, drug entrapment efficiency and in vitro release rate. On the basis of in vitro characterization, the niosomes showing maximum entrapment and minimum release rate were selected for in vivo performance evaluation. Cumulative percent doses of rifampicin recovered in thoracic lymph following intravenous and intraperitoneal administrations of free rifampicin solution and niosome-encapsulated rifampicin were compared. The study revealed that effective compartmentalisation of the drug took place in the lymphatic system following intraperitoneal administration of niosome-encapsulated rifampicin. Thus rifampicin encapsulated in niosomes could successfully be used for treatment of tuberculosis along lymphatic system.

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A reverse phase high performance liquid chromatography method was developed for simultaneous estimation of paracetamol and valdecoxib in tablet formulation. The separation was achieved by Luna C ₁₈ column and methanol: phosphate buffer pH 3.5 (60:40 v/v) as eluent, at a flow rate of 1.0 ml/min. Detection was carried out at 242 nm. Etoricoxib was used as an internal standard. The retention time of PAR and VAL was found to be 3.01 and 8.51 min, respectively. The method was validated for linearity, accuracy and precision. Linearity for paracetamol and valdecoxib were in the range 25-150 µg/ml and 1-6 µg/ml, respectively. The developed method was found to be accurate, precise, and selective for simultaneous estimation of paracetamol and valdecoxib in tablets.

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Two simple, economical, precise and reproducible visible spectrophotometric methods have been developed for the estimation of repaglinide in tablet formulation. The developed methods are based on the formation of chloroform extractable complex of repaglinide with zincon and methylthymol blue in acidic medium. The extracted complex with zincon shows absorbance maxima at 533.0 nm and linearity in the concentration range of 50-250 µg/ml. The extracted complex with methylthymol blue shows absorbance maxima at 427.0 nm and linearity in the concentration range of 100-500 µg/ml. Results of analysis for both the methods were validated statistically and by recovery studies.

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Three simple, rapid and accurate visible spectrophotometric methods have been developed using Orange G dye for the quantitative estimation of citalopram hydrobromide, donepezil hydrochloride and rabeprazole sodium from respective tablet formulations. These developed methods are based on formation of chloroform-extractable coloured complex of drug and dye. The extracted coloured complex shows absorption maxima at 476 nm and linearity in the concentration range of 10-50 μg/ml for citalopram hydrobromide (method I); at 482 nm and linearity in the concentration range of 5-35 μg/ml for donepezil hydrochloride (method II) and at 477.4 nm with linearity in the concentration range of 10-70 μg/ml for rabeprazole sodium (method III). The results of analysis for all three developed methods were validated statistically and by recovery studies.

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Melothria maderaspatana (Linn) Cogn, a plant drug of Siddha medicine, is an annual monoecious tendril climber, belonging to the family Cucurbitaceae, mostly prevalent in South India. It is commonly called Musumusukkai in Tamil. Preliminary phytochemical screening of the plant revealed the presence of phytochemical constituents such as coumarins, flavonoids. Hence an attempt has been made to screen the effect of Melothria maderaspatana in platelet aggregation. Successive extracts of aerial parts of Melothria maderaspatana were used in increasing polarity of solvents (i.e., hexane, chloroform, ethyl acetate and methanol). The antiplatelet activity of different fractions of Melothria maderaspatana was studied using platelet-rich plasma in presence of ADP. Each extract was tested in concentrations of 100 µg/ml, 200 µg/ml, 400 µg/ml and 500 µg/ml for the study. The ethyl acetate extract showed a dose-dependent antiplatelet activity. Hexane and methanol extracts showed antiplatelet activity only at 200 µg/ml and 400 µg/ml concentrations. Chloroform extract showed negligible antiplatelet activity. However, the inhibition of platelet aggregation was only 50% when compared to the standard Aspirin.

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Three extracts of Hibiscus rosasinensis Linn. have been prepared and evaluated for hypotensive activity. Hydroalcoholic extract was found to exhibit prominent activity when compared to the reference standard minoxidil. In an attempt to isolate the active constituents responsible for this activity from hydroalcoholic extract, five new phytoconstituents were isolated and their structures were elucidated from spectral evidence (IR, NMR and Mass). Hypotensive activity of these isolated compounds was also studied.

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Complexation of celecoxib with β-cyclodextrin and hydroxypropyl-β-cyclodextrin in the presence and absence of polyvinylpyrrolidone and the effect of polyvinylpyrrolidone on the solubilizing efficiency of cyclodextrins and on the dissolution rate of celecoxib from the cyclodextrin complexes were investigated. The phase solubility studies indicated the formation of celecoxib-β-cyclodextrin and celecoxib-hydroxypropyl-β-cyclodextrin inclusion complexes at a 1:1 M ratio in solution, both in the presence and absence of polyvinylpyrrolidone. The complexes formed were quite stable. The solubility and dissolution rate of celecoxib were markedly enhanced by complexation with β-cyclodextrin and hydroxypropyl-β-cyclodextrin. Celecoxib-hydroxypropyl-β-cyclodextrin (1:2) inclusion complex gave a 36.57-fold increase in the dissolution rate of celecoxib. Addition of polyvinylpyrrolidone resulted in higher complexation efficiency and markedly enhanced solubilizing efficiency of β-cyclodextrin and hydroxypropyl-β-cyclodextrin. Solid inclusion complexes of cyclodextrins with polyvinylpyrrolidone gave several times higher rates of dissolution than those of celecoxib and its complexes with cyclodextrins alone.

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The present work deals with the development of a simple, accurate and economical method for the simultaneous estimation of valdecoxib and paracetamol in combined tablet dosage form by Vierodt's UV spectrophotometric method. The λ_max values of valdecoxib and paracetamol in 0.1 N NaOH were 244 nm and 257 nm respectively. Both the drugs followed Beer's law in the concentration range of 1-6 µg/ml and 5-30 µg/ml respectively. The A1% 1 cm values for valdecoxib and paracetamol at 244 nm and 257 nm were 520 and 420, 510.8 and 636.8 respectively.

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Transdermal dosage forms, though a costly alternative to the conventional formulations, are becoming popular because of some unique advantages. Controlled zero-order absorption, simple administration mode and the option of easy removal in case of adverse manifestations make them particularly desirable in cardiovascular therapy. Nitroglycerin and isosorbide dinitrate, the two antiischaemic drugs; and clonidine, an antihypertensive molecule, are being extensively used in the transdermal form. Studies that compared these patches with the established dosage forms had shown that though patches were costlier than conventional prescription products, they reduced the occurrence of hospitalization and diagnostic costs. Currently a number of antihypertensive drugs are being developed for transdermal administration. This article reviews the research on cardiovascular patches as well as the marketed products.

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A simple, fast, precise and accurate RP-HPLC method was developed for the simultaneous estimation of valdecoxib and tizanidine hydrochloride in tablet formulations. The separation was achieved by C18 Intersil column and acetonitrile: 0.02 M phosphate buffer (pH 3.5) (60:40 v/v) as mobile phase, at a flow rate of 1.5 ml/min. Detection was carried out at 240 nm. The retention time of valdecoxib and tizanidine hydrochloride was found to be 4.21 and 2.16 min respectively. The validation of the proposed method was also carried out for linearity, accuracy and precision. The linear dynamic range for valdecoxib and tizanidine hydrochloride was 0-100 µg/ml and 0-20 µg/ml respectively. The mean percentage recoveries obtained for valdecoxib and tizanidine hydrochloride were 99.10 and 100.19% respectively. The developed method was found to be accurate, precise, selective and rapid, and it can also be used for routine quality control analysis of these drugs in combination tablets.

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The objective of the present work is to develop a simple and sensitive method for analysis of human insulin injection by using reverse-phase high performance liquid chromatography technique. A reverse-phase high performance liquid chromatography method with UV-detection at room temperature has been developed for the analysis of insulin from formulation. Hypersil BDS C-18 was used as stationary phase, and mobile phase consisted of 60 volume of 1 mmol sodium sulphate and 0.2% triethylamine in water, pH 3.2 adjusted by phosphoric acid, and 40 volume of acetonitrile. The eluent was monitored with a UV detector set at 214 nm with a flow rate of 1 ml/min, and sample size of 20 µl were carried out at room temperature all over the study. The method produced linear response over the concentration range of 10-100 µg/ml, with a mean recovery of 97 ± 0.31% as well as average intra- and inter-day variations of 1.35 and 5.13% respectively. The limits of detection and quantitation of the method were 0.25 and 0.75 µg/ml respectively. Considering the analysis specifications, the system is suitable for direct analysis of routine formulations and stability studies.

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The use of fixed-dose combinations is a widespread clinical practice in the treatment of various cardiovascular disorders. These fixed-dose combinations are valuable only when they have been developed based on sound rational pharmacokinetic and pharmacodynamic criteria, and when claims for their benefits have been supported by evidence-based data and well-designed clinical studies. However, a look at the available fixed-dose combinations reveals that there are combinations which do not meet these basic criteria, and hence their clinical benefit is debatable. In this context, several stakeholders have put forward their views on the rationality of some of the fixed-dose combinations. The situation has become more complicated as there are very limited reports to assess and describe the rationality of fixed-dose combinations on an individual basis. In the present study, a thorough evaluation of 44 fixed-dose combinations used in various cardiovascular disorders using comprehensive criteria has been completed. This evaluation has demonstrated that a large number of fixed-dose combinations are rational, based on the criteria used. Finally, there seems to be enough reason to re-investigate six of them, which did not match the criteria as well as others. These six combinations could be the subject of study by the clinicians and/or pharmaceutical companies to assess their clinical benefit.

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The methanolic extract of a blue-green alga and two green algae have been investigated for in vitro antimicrobial activity against Proteus vulgaris, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, Aspergillus flavus and Rhizopus nigricans using agar cup-plate method. Blue-green alga, namely, Microchaete tenera ; and green algae, namely, Nitella tenuissima and Sphaeroplea annulina , showed significant antibacterial activity against Pseudomonas aeruginosa . Microchaete tenera showed good antimicrobial activity against Proteus vulgaris and Aspergillus niger. Sphaeroplea annulina showed feeble antifungal activity against Aspergillus flavus .

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Simple UV and third derivative spectrophotometric methods in methanol have been developed for the determination of fosinopril sodium in bulk drug and its pharmaceutical formulations. The simple UV spectrum of fosinopril sodium in methanol exhibits absorption maxima (λ_max) at 208 nm, whereas in the third derivative spectrum the maxima occur at 217.4 nm and the minima at 223 nm. Both the methods were found to be simple, economical, accurate, reproducible and can be adopted in routine analysis of fosinopril sodium in bulk drug and in tablet dosage form.

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Three new simple and sensitive spectrophotometric methods in ultraviolet region have been developed for the determination of gatifloxacin in bulk drug, pharmaceutical preparations and biological samples. Gatifloxacin exhibited maximum absorbance at 289 nm (method A) with apparent molar absorptivity of 1.23×10 ⁴ l/mol×cm when dissolved in sodium hydroxide; and maximum absorbance at 292 nm (method B) with apparent molar absorptivity of 1.71×10 ⁴ l/mol×cm when dissolved in hydrochloric acid. Third developed method (method C) was based on the formation of yellow coloured chromogen with ferric chloride and potassium dichromate, which showed maximum absorbance at 352 nm with apparent molar absorptivity of 1.23 × 10 ⁴ l/mol×cm. Beer's law was obeyed in the concentration range of 5-30 µg/ml. Results of analysis of all methods were validated statistically and by recovery studies.

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The human immunodeficiency virus has been shown to be the causative agent for acquired immunodeficiency syndrome (AIDS). The human immunodeficiency virus encodes for unique aspartyl protease that is essential for the production of enzymes and proteins in the final stages of maturation. Protease inhibitors act by preventing the formation of functional proteins from precursor proteins, which are vital for production of mature infectious viral particles. This review summarizes the data documenting the pharmacology and chemistry of non-peptide protease inhibitors that may be used as therapeutic agents against the human immunodeficiency virus infection. These agents are structural mimics of peptides with little or no peptidic character, thus overcoming various pharmacological problems of peptidic protease inhibitors. Structure-based drug designs of potent protease inhibitors, discovered through broad screening, have been developed into various clinical candidates for the treatment of AIDS. Non-peptide protease inhibitors could provide a useful model in the further search for novel compounds with even more pertinent pharmacological and pharmacokinetic profiles.

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An obese animal model having mild glucose intolerance was developed by intravenous administration of sub-optimal dose of alloxan to British Angora rabbits. Mild hypoglycaemic activity of crude extract prepared from leaves of a Nepalese herb Biophytum sensitivum, which was missed by the conventional diabetic animal models, was demonstrable in these animals. Initial fasting hyperglycaemia observed immediately after treatment with alloxan in these animals was followed by reverting of the fasting blood glucose to normal or near normal levels. However, the blood glucose levels rose to higher than normal values following oral glucose load in the 1 h, 2 h and 3 h samples, reflecting glucose intolerance which was stable for up to 4 mo. Hypoglycaemic effect in these animals, designated obese glucose-intolerant (OGI) rabbits, was judged by improvement in glucose tolerance, tested by prevention of blood glucose elevation following oral glucose load. Comparing the corresponding pre-treatment and post-treatment values could even quantitate the hypoglycaemic effect.

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Two new simple and sensitive colorimetric methods were developed for the analysis of cefetamet pivoxil hydrochloride in bulk and in pharmaceutical formulations. In the first proposed method, colour of newly formed complex was measured at 645 nm (λ_max), and the calibration curve was linear in the range of 1-7 μg/ml; while in the second method, intensity of colour was measured at 524 nm (λ_max), and the calibration curve was linear in the range of 2-18 mg/ml. The developed methods were successfully applied to the pharmaceutical formulations.

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Quercetin, a well-known bioflavonoid, is commonly found in human diet. This flavonoid along with Genistein gained much attention during the last few years as a potential anticancer drug. The purpose of this study was to investigate the effect of quercetin on tumour growth in vivo after determining its toxicological profile. The maximum tolerated dose (MTD) of quercetin was found to be 100 mg/kg. Fifty percent of the S-180 ascitic tumour bearing mice, treated with quercetin with a daily intraperitoneal dose (100 mg/kg) for nine consecutive doses, survived for more than 2 mo. Quercetin did not show significant inhibitory effect on the growth of established mammary tumour inoculated in C3H/J mice. However, increase in tumour size was significantly lower when administered in combination with cyclophosphamide compared to remaining groups. Quercetin was found to be protecting the mouse bone marrow from radiation-induced toxicity by creating hypoxic conditions in the marrow. Hypoxic conditions resulted in elevated LDH levels in quercetin-treated group compared to levels in the control group. Haematological parameters did not show significant difference in treated and control groups. Spleen colony assays suggest quercetin to be nontoxic and that it can be administered at 100 mg/kg dose levels in further studies.

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Acquired immunodeficiency syndrome (AIDS) pandemic is one of the biggest challenges of the 21st century. With the development of antiretroviral therapy, the count of human immunodeficiency virus (HIV)-infected people may decrease to a certain extent. Presently available formulations for this disease are found not to be very useful due to poor bioavailability, leading to poor efficacy, various side effects and high cost. In the present investigation, it was proposed to formulate the aqueous injection of saquinavir, which should definitely be more effective, economical, safe and with the least side effects as compared to its existing dosage forms, e.g., hard and soft gelatin capsule. The solubilization of saquinavir (antiHIV drug), practically insoluble in water, by means of physiologically active hydrotropes and cosolvents has been investigated. The results indicate that enhancement in solubility of saquinavir in the presence of hydrotrope at low concentration is due to weak ionic interaction. At higher concentrations (>0.4 M), complexation is found to be the probable mechanism for solubility enhancement by nicotinamide but nature of complex formed is not clear; whereas for ascorbic acid, self-association is the probable mechanism at these concentrations. Using these two approaches, various formulations of saquinavir were developed, and haemolysis study and dilution study of these formulations were carried out. Formulation containing nicotinamide as hydrotrope showed promising results.

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The safe use of medicines depends upon the ability of users to read the information on the medicine label carefully and accurately and being able to act accordingly. The label provides important information on the use of the medicines, which helps the users to make correct use of their medicines. However, legibility is often a problem encountered in the labeling of small packages like eye/ear drops. The consumers as well as health professionals find labels difficult to read because of a number of reasons such as very small letters, poor quality of printing and poor colour contrast. This study aims not only to evaluate the legibility of information on the primary label of the eye drops but also to identify the problem(s) pertaining to its legibility.

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Valdecoxib is a nonsteroidal antiinflammatory drug, and it is listed in class 2 of biopharmaceutic classification of drugs. Valdecoxib is a poorly water-soluble and highly permeable drug. In the present study a new dissolution medium was developed, as there is no official dissolution medium available in the literature. The composition of the dissolution medium was selected on the basis of solubility data at 37°. Solubility data revealed that addition of surfactant may be suitable as dissolution medium. The concentration of 0.6% w/v sodium lauryl sulphate in water could be a suitable dissolution medium. The discriminating power of the selected dissolution medium (0.6% sodium lauryl sulphate in water) relative to the other dissolution mediums was evaluated. The selected dissolution medium was used for the evaluation of valdecoxib tablets.

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A simple spectrophotometric method for determination of famotidine was described. The method was based on bromination of the drug with excess brominating mixture in acidic medium. The yellow colour developed was measured at 350 nm against distilled water blank. Beer's law was obeyed in the range of 40-200 µg/ml.

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A simple, fast, precise multicomponent mode analysis method has been developed for simultaneous estimation of ranitidine and domperidone in tablet formulation. The sampling wavelengths selected for both the drugs were 229 nm, 245 nm, 270 nm, 285 nm, 294 nm on trial-and-error basis using methanol as solvent. The linearity for both the drugs at all the selected wavelengths lies between 3.0 and 50 µg/ml for ranitidine and 0.2 and 3.5 µg/ml for domperidone. The concentrations of both the drugs were evaluated in laboratory mixture and marketed formulation. The recovery study was carried out by standard addition method.

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The development of Vireodt's method for simultaneous estimation of ranitidine and domperidone involves absorbance measurement at 326 nm and 287 nm corresponding to the respective absorption maxima. Both the drugs obey Beer Lambert's law in the range of 3.0-50 µg/ml for ranitidine and 0.2-3.5 µg/ml for domperidone. The tablet formulation (Random, Mankind) was evaluated for the percent content of both the drugs at the selected wavelengths. The method developed was validated to determine its accuracy, precision, specificity and ruggedness. The recovery study was carried out by standard addition method. The average percent recovery was found to be 99.65±0.47 for ranitidine and 100.06±0.18 for domperidone.

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A chemometric model for the simultaneous estimation of phenobarbitone and phenytoin sodium anticonvulsant tablets using the back-propagation neural network calibration has been presented. The use of calibration datasets constructed from the spectral data of pure components is proposed. The calibration sets were designed such that the concentrations were orthogonal and span the possible mixture space fairly evenly. Spectra of phenobarbitone and phenytoin sodium were recorded at several concentrations within their linear range and used to compute the calibration mixture between wavelengths 220 and 260 nm at an interval of 1 nm. The back-propagation neural network model was optimized using three different sets of calibration and monitoring data for the number of hidden sigmoid neurons. The calibration model was thoroughly evaluated at several concentration levels using spectra obtained for 95 synthetic binary mixtures prepared using orthogonal designs. The optimized model showed sufficient robustness even when the calibration sets were constructed from different sets of pure spectra of components. Although the components showed complete spectral overlap, the model could accurately estimate the drugs, with satisfactory precision and accuracy, in tablet dosage with no interference from excipients, as indicated by the recovery study results.

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A reverse phase high performance liquid chromatography method was developed for simultaneous estimation of tizanidine HCl and valdecoxib in tablet formulation. The separation was achieved by Luna C ₁₈ column and acetonitrile: phosphate buffer pH 3.5 (50:50 v/v) as eluent, at a flow rate of 0.5 ml/min. Detection was carried out at 227 nm. Etoricoxib was used as an internal standard. The retention time of tizanidine and valdecoxib was found to be 4.43 and 16.60 min, respectively. The method was validated for linearity, accuracy and precision. Linearity for tizanidine and valdecoxib were in the range 0.4-2.0 µg/ml and 4-20 µg/ml, respectively. The developed method was found to be accurate, precise and selective for simultaneous estimation of tizanidine and valdecoxib in tablets.

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A new plastic membrane ion-selective electrode for determination of metformin hydrochloride has been prepared, after forming the ion pair of metformin hydrochloride with sodium tetraphenylborate. Dioctyl phthalate and sodium tetraphenylborate were used as plasticizer and counter ion respectively. The electrode exhibited a linear potential response in the concentration range 1 × 10 ^-5 M-1 × 10 ^-1 M with slope of 42.0±0.82 mv per decade. The electrode has a rapid response time (45 s), shorter conditioning time (2 h) and a lower limit of detection (1 × 10 ^-5 M). The electrode showed high selectivity for metformin hydrochloride with respect to some common ions, excipients and other drugs present as combined dosage formulations. Stability studies of ion-selective membrane were carried out by differential scanning calorimetry. The electrode can successfully be applied for the analysis of metformin hydrochloride in pure solution, pharmaceutical preparations, biological fluid and in presence of its degraded products.

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