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At least 883 records · Page 49Linked to original sources
PubMed2001

Voltammetric determination of nilvadipine in dosage forms and spiked human urine.

The voltammetric behaviour of nilvadipine was studied adopting direct-current, differential-pulse and alternating current polarography. Nilvadipine-being nitroderivative-exhibited well-defined cathodic waves over the whole pH range in Britton-Robinson buffers. At pH 5, the diffusion-current constant, (Id) was 4.78. The current-concentration plots are rectilinear over the range 1.5-20 and 0.2-10 microg/ml using the direct current and differential pulse-polarographic techniques with minimum detectability of 0.05 microg/ml (1.3 x 10(-7) M) using the latter technique. The proposed method was applied to commercial capsules containing the drug. The percentage recoveries were in agreement with those obtained by a reference method. Furthermore, the method was applied to spiked human urine, the percentage recovery was 95.54+/-2.137.

Antihypertensive Agents↗
PubMed2002

Simultaneous dissolution profiles of two drugs, sulfadiazine-trimethoprim and amitriptyline-perphenazine, in solid oral dosage forms by a FIA manifold provided with a single spectrophotometric detector.

The simultaneous determination of two dissolution profiles wih the aid of a flow injection analysis assembly has been applied to: (a) sulfadiazine-trimethoprim in tablets and (b) amitriptyline-perphenazine in sugar coated pills. The selected combinations are drugs which have overlapping UV-vis spectra. The officially proposed procedure from the pharmacopoeias has been adapted for the FIA methodology and derivative spectrophotometry and zero crossing. Preliminary experiments on the suitability of the simultaneous determination of both drugs were performed. The empirical profiles were adjusted by regression analysis using different approaches. The 3-parameter plot method was finally selected as the most suitable for the sulfadiazine-trimethoprim and the 4-parameter equation plot for amitriptyline-perphenazine.

Administration, Oral↗
PubMed1992

Interaction between polyethylene films and bromhexine HCl in solid dosage form. V. Effect of packaging materials on the sorption of bromhexine HCl.

A prevention method of the sorption of bromhexine HCl to plastic materials used in packaging was investigated. Four kinds of plastic packaging materials were used: Polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP) and polyacrylonitrile (PAN). Three polyethylenes having different densities were used. No effect of PE density on the sorption of bromhexine HCl from granules was observed. The effects of different kinds of plastics on the sorption of bromhexine HCl from solution and granules were studied. The sorption of bromhexine HCl to PAN, which had a high relative dielectric constant, was the most depressed among the four plastics. The sorption of meclizine HCl to PAN from the solution was also lowest, the same as bromhexine HCl.

Acrylic Resins↗
PubMedDate not supplied

Escin in pharmaceutical oral dosage forms: quantitative densitometric HPTLC determination.

A practical and reliable method for the quantitative determination of escin in pharmaceuticals was developed. The TLC-densitometric determination was performed without using spray or dipping reagents in order to provide a more rapid and simple analytical procedure. Chromatographic separations were obtained on analytical HPTLC silica gel plates and the elution was made with 3.5:4.5:2 PropOH-ethyl acetate-water (v/v/v). Densitometric analysis was performed directly at 212 nm, corresponding to lambda max of escin obtained by in situ-scanning. A second degree polynomial regression relationship was found between the peak areas and the amounts of the escin standard deposited in the range 1.15-6.90 micrograms. The method is specific, accurate and reliable and was applied successfully to the quantitative determination of escin in commercial samples.

Administration, Oral↗
PubMed2005

Equivalence studies for complex active ingredients and dosage forms.

This article examines the United States Pharmacopeia (USP) and its role in assessing the equivalence and inequivalence of biological and biotechnological drug substances and products-a role USP has played since its founding in 1820. A public monograph in the United States Pharmacopeia-National Formulary helps practitioners and other interested parties understand how an article's strength, quality, and purity should be controlled. Such a monograph is a standard to which all manufactured ingredients and products should conform, and it is a starting point for subsequent-entry manufacturers, recognizing that substantial additional one-time characterization studies may be needed to document equivalence. Review of these studies is the province of the regulatory agency, but compendial tests can provide clarity and guidance in the process.

Biotechnology↗
PubMed1995

New oral dosage form for elderly patients. II. Release behavior of benfotiamine from silk fibroin gel.

Silk fibroin gel (SFG) containing benfotiamine (BTMP) was prepared. The release behavior of BTMP from SFG was studied as a function of silk fibroin (SF) content and glycerol content, and the influence of the existence of beta-cyclodextrin (beta-CD) on the physicochemical properties of SFG were investigated. The release rate of BTMP from SFG was retarded by an increase in SF concentration. The addition of beta-CD affected both the release properties and rheological properties of the SFG. It was found from the results of the "paddle-bead method" that the release profiles of BTMP from SFG were inversely proportional to the SFG firmness.

Adjuvants, Immunologic↗
PubMed1988

Determination of fat-soluble vitamins in a pharmaceutical dosage form by solid-phase extraction and reversed-phase liquid chromatography.

A rapid and precise method for the determination of fat-soluble vitamins from a water-based multivitamin mixture was developed utilizing solid-phase extraction and reversed-phase high-performance liquid chromatography (HPLC). Cholecalciferol, alpha-tocopherol acetate, and retinol palmitate were extracted in a single stage from the matrix using Bond Elut C18 columns. The vitamins were then chromatographed on a Hypersil 5-microns C18 column, using a water:methanol gradient, and quantified simultaneously using individual UV absorption maxima. The recovery of added analytes varied from 92.6 to 100.6%. The assay coefficient of variation was 1.7-2.7%. The sample preparation method and HPLC assay described here are practical for pharmaceutical quality control purposes.

Cholecalciferol↗
PubMed2000

Amoxycillin release from a floating dosage form based on alginates.

Floating alginate beads have been prepared from alginate solutions containing either dissolved or suspended amoxycillin. The beads were produced by the dropwise addition of the alginate into calcium chloride solution, followed by removal of the gel beads and freeze drying. Drug release studies showed that beads prepared with the drug in solution provided some sustained release characteristics and that these could be improved by the addition of amylose. In all cases, the drug release was consistent with release of a dissolved solute from a granular or porous matrix. The beads retained their buoyancy when amylose and amoxycillin were incorporated, exhibiting resultant weight values greater than zero after 20 h. Preparation of the beads from alginate solutions containing the drug in suspension allowed higher drug loadings, at the expense of faster release and lower buoyancy.

Alginates↗
PubMed2004

Toward the development of an injectable dosage form of propofol: preparation and evaluation of propofol-sulfobutyl ether 7-beta-cyclodextrin complex.

The objectives of the present study were to undertake activities toward the development of an aqueous-based formulation of propofol (2,6-diisopropyl phenol), using sulfobutylether 7-beta-cyclodextrin (SBECD). Preformulation studies, including high performance liquid chromatography (HPLC) method development and phase-solubility evaluation in the presence of SBECD were conducted. It was determined that equilibrium solubility has been reached by 4-day and 7-day phase-solubility analysis at 30 degrees C and 37 degrees C. The apparent binding constants and various thermodynamic parameters were calculated from this data. These results suggest that "nonclassical hydrophobic effects" are the driving forces for inclusion complex formation. Compounding and lyophilization of the formulation with 20% SBECD yielded a product with propofol concentration of 10 mg/mL. The formulation properties were probed by using techniques that included modulated differential scanning calorimetry (MDSC) and Karl Fischer analysis. MDSC showed that propofol, SBECD, and the Propofol-SBECD complex displayed thermal properties at widely varying temperatures, suggesting the formation of a new solid form. The active pharmaceutical ingredient in the liquid formulation and lyophilized product was determined by the newly developed and qualified HPLC method. Short-term stability studies of the liquid formulation showed that they were stable for a month at 4 degrees C. Short-term stability studies of the freeze-dried cakes showed that the product was stable for over a month at 4 degrees C, 37 degrees C, and 50 degrees C. Based on these preliminary results, we believe that an aqueous based injectable formulation of propofol with sulfobutylether 7-beta-cyclodextrin can be successfully developed.

Algorithms↗
PubMed2005

Spectrophotometric determination of tranexamic acid in pharmaceutical bulk and dosage forms.

In this study, a simple, fast, accurate and sensitive spectrophotometric method has been developed for the determination of tranexamic acid in bulk and pharmaceutical preparations. The method is based on the reaction of ninhydrin with the primary amino group of tranexamic acid in the basic medium at pH 8.0. The reaction produces a bluish-purple color which absorbs maximally at 565 nm. Beer's law was obeyed in the range of 3-40 microg ml(-1) with molar absorptivity of 5.093 x 10(3) L mol(-1) cm(-1). The effects of various factors such as temperature, heating time, concentration of reagent, color stability and interferences were investigated to optimize the procedure. The results have been validated analytically and statistically. The proposed method has been applied for the determination of tranexamic acid in bulk and pharmaceutical preparations with good results.

Dosage Forms↗
PubMed2006

HPLC resolution of thioridazine enantiomers from pharmaceutical dosage form using cyclodextrin-based chiral stationary phase.

Resolution of racemic thioridazine obtained from Thioril tablets (Cipla Ltd., Goa, India) into its enantiomers has been achieved by HPLC using a beta-cyclodextrin (CD)-bonded stationary phase. Thioridazine was isolated from commercial formulations and was purified using preparative TLC. The purity was ascertained by RP-HPLC. For the resolution of rac-thioridazine using cyclodextrin based CSP and mobile phase of 0.05 M phosphate buffer (pH 6.5)-acetonitrile (50:50) was found to be successful. The optimum conditions of resolution were established by systematically studying the effect of organic modifier, concentration of buffer, pH and flow rate of mobile phase. The detection limit was found to be 10 microg (5 microg of each enantiomer). The enantiomeric purity of each of the resolved isomers was verified by optical rotation.

Buffers↗
PubMed2006

Pharmacokinetics of desmopressin administrated as an oral lyophilisate dosage form in children with primary nocturnal enuresis and healthy adults.

The population pharmacokinetics of desmopressin in children with nocturnal enuresis and in healthy adults were compared using a 1-compartment model with first-order absorption and first-order elimination. In addition, the model consisted of a number of transit compartments before absorption to describe a lag-time. The model gave an adequate description of adult as well as children data and provided a statistically significant better fit to data than a standard lag-time model. The main difference in the pharmacokinetics between children and adults was the absorption delay. The pharmacokinetic difference was minor and presumably of no clinical relevance.

Administration, Sublingual↗
PubMed1998

Studies on development of dosage forms for pediatric use (V) oral mucosal irritation study of gummi drugs in hamster cheek pouch.

In the present study we investigated irritation of the oral mucosa and the safety of gummi drugs containing acetaminophen (AAP). The oral mucosae of hamsters were macroscopically examined for any evidence of irritation after gummi drugs were inserted into the cheek pouch and left there for 1 h. The cheek pouch tissue was also macroscopically and microscopically examined 24 h after gummi drugs were withdrawn from the cheek pouch. As a result, no evidence of irritation was found macroscopically 1 h after insertion, or macroscopically and microscopically 24 h after the withdrawal of the gummi drugs or placebos as compared with negative controls (saline). Considering these results, the gummi drugs administered in the present study produced no irritation to the oral mucosa.

Acetaminophen↗
PubMedDate not supplied

Quantitative analysis of phenobarbital in dosage form by thin-layer chromatography combined with densitometry.

In this paper, a high-performance thin-layer chromatography (HPTLC) method combined with densitometry has been described. Chromatography was performed on silica gel Si 60F254 plates using dichloromethane-ethyl acetate-formic acid (9.5 +/- 0.5 +/- 0.1, v/v) mobile phase. This method has been successfully applied for the determination of phenobarbital in pharmaceuticals. Obtained results were comparable with traditionally used column high-performance liquid chromatography (HPLC) methods. For the proposed procedure, linearity (r > 0.999), sensitivity (limit of detection 0.4 microg/spot), recovery (97.8-102.1%), and repeatability were found to be satisfactory. The HPTLC-densitometry method has many advantages, such as simplicity, reasonable sensitivity, rapidity, and low cost, and it can be successfully used in routine quality control of multidrug preparations containing barbiturates.

Acetates↗
PubMed2004

Evaluation of honey locust (Gleditsia triacanthos Linn.) gum as sustaining material in tablet dosage forms.

In this study, honey locust gum (HLG) obtained from Gleditsia triacanthos (honey locust) beans was investigated as a hydrophilic matrix material in the tablets prepared at different concentrations (5% and 10%) by wet granulation method. Theophylline was chosen as a model drug. The matrix tablets containing hydroxyethylcellulose and hydroxypropyl methylcellulose as sustaining polymers at the same concentrations were prepared and a commercial sustained release (CSR) tablet containing 200 mg theophylline was examined for comparison of HLG performance. Physical analysis on CSR tablet, matrix tablets and their granules before compression were performed. According to the results obtained from dissolution studies in distilled water, pH 1.2 HCl buffer and pH 7.2 phosphate buffer, no significant difference was found between CSR tablet and the matrix tablet containing 10% HLG in each medium (P > 0.05) and these tablets showed zero-order kinetic model in all the mediums.

Animals↗
PubMed2004

Amlodipine besylate-excipients interaction in solid dosage form.

This article studies the compatibility of amlodipine besylate in its solid formulations with various drug excipients. The various factors affecting amlodipine besylate stability were studied using high-performance liquid chromatography (HPLC). It has been found that binary 1:1 mixtures of amlodipine besylate and an excipient are stable at 65 degrees C and 40 degrees C/75% RH. Further investigations were conducted to study the stability of amlodipine besylate in multicomponent mixtures, including mixtures with actual formulations. The study reveals that mixtures of lactose, magnesium stearate, and water induce some instability on amlodipine besylate. The major degradation product confirmed by HPLC-mass spectrometry is amlodipine besylate glycosyl. This is in conformity with the well-known Maillard reaction between primary amines and lactose. Thus, lactose-free amlodipine formulations are recommended from the safety, quality, efficacy, and process cost points of view.

Amlodipine↗
PubMed1999

The relevance of the amorphous state to pharmaceutical dosage forms: glassy drugs and freeze dried systems.

Many pharmaceuticals, either by accident or design, may exist in a total or partially amorphous state. Consequently, it is essential to have an understanding of the physico-chemical principles underpinning the behaviour of such systems. In this discussion, the nature of the glassy state will be described, with particular emphasis on the molecular processes associated with glass transitional behaviour and the use of thermal methods for characterising the glass transition temperature, Tg. The practicalities of such measurements, the significance of the accompanying relaxation endotherm and plasticization effects are considered. The advantages and difficulties associated with the use of amorphous drugs will be outlined, with discussion given regarding the problems associated with physical and chemical stability. Finally, the principles of freeze drying will be described, including discussion of the relevance of glass transitional behaviour to product stability.

Calorimetry, Differential Scanning↗
PubMed2005

Electrochemical study of natamycin--analytical application to pharmaceutical dosage forms by differential pulse voltammetry.

The electrochemical oxidation and determination of natamycin has been carried out at a carbon paste electrode in aqueous solutions in the pH range of 2.5-10.30 by cyclic and differential pulse voltammetry. Best results were obtained with the differential pulse voltammetric technique in 0.5 M sulfuric acid at pH 1.82. The diffusion controlled nature of the waves was established. A differential pulse voltammetric technique for the determination of natamycin 0.5 M sulfuric acid which allows quantitation over the range of 2 x 10(-6)-8 x 10(-5) M range method is proposed. Limit of detection and limit of quantitatification were 1.5 x 10(-6) and 5 x 10(-6) M, respectively. Based on this study a simple, rapid, selective and sensitive voltammetric method was developed for the determination of natamycin in capsules. In order to validate the proposed method, UV spectroscopy was applied.

Antifungal Agents↗