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At least 1,171 records · Page 65Linked to original sources
PubMed1999

Comparison of once and twice daily dosage forms of Pygeum africanum extract in patients with benign prostatic hyperplasia: a randomized, double-blind study, with long-term open label extension.

OBJECTIVES: To compare the efficacy and safety of Pygeum africanum extract, 50 mg twice daily and 100 mg once daily. METHODS: Patients with symptomatic benign prostatic hyperplasia (BPH) entered a 2-month randomized, parallel-group, double-blind, comparative phase (group A, 50 mg twice daily; group B, 100 mg once daily), followed by a 10-month, open phase (100 mg once daily). Main efficacy assessment parameters included International Prostate Symptom Score (IPSS), quality of life (QOL), and maximum urinary flow rate (Qmax). RESULTS: Two hundred nine patients completed the comparative phase in compliance with the protocol; 174 were included in the open phase. Both treatments had similar efficacy. IPSS (baseline 17 in both groups) improved by 38% in group A and 35% in group B. QOL improved by 28% in both groups. Qmax increased by 1.63 mL/s (16%) in group A and 2.02 mL/s (19%) in group B. After 12 months, the IPSS fell from 16 (baseline) to 9 (-46%). Half of the patients had an IPSS below 8. Mean Qmax increased by 1.65 mUs (15%). The safety profile was similar between groups and study phases. CONCLUSIONS: P. africanum extract at 50 mg twice daily and 100 mg once daily proved equally effective and safe at 2 months. Further improvements in efficacy with a satisfactory safety profile were documented after 12 months.

Aged↗
PubMed2000

Solid dosage form preparations from oily medicines and their drug release. Effect Of degree of surface-modification of silica gel on the drug release from phytonadione-loaded silica gels.

A surface-modified silica gel was produced to improve the surface affinity to an oily medicine, phytonadione (VK1). The effect of the degree of surface modification of the silica gel on the drug release behavior from the silica porous matrix was investigated. The silica gels were surface-modified using the silan coupling agent, 3-methacryloxypropyltrimethoxysilane (C7), octadecyltriethoxysilane (C18), or 3,3,3-trifluoropropyltrimethoxysilane (F3). A mixture of VK1 solution and surface-modified silica gel was evaporated under reduced pressure at room temperature, then the resulting powder was dried in vacuo. The degree of surface modification was evaluated based upon elementary analysis. The dissolution profiles of the samples were investigated in Japanese Pharmacopoeia XII, 1st fluid buffer (pH 1.2, 37+/-0.5 degrees C) containing 1.5% sodium lauryl sulfate. The FT-IR spectra of VK1-loaded surface-modified silica gels suggested that the amount of hydrogen-bonded VK1 with the silanol group on the gel surface decreased with increasing hydrophobicity of the silica gel. Since the modified group was rotating on the silica gel surface, and inhibited the adsorption of VK1 to the surface, the attractive molecular interaction between VK1 and the silica gel surface might decrease with increasing length of the modified functional group. However, the characteristics of the affinity of VK1 to the functional groups significantly differed among the groups. The VK1 release from the modified silica gels was initially rapid, slowed markedly after 1 h, and continued for more than 24 h. The amount of VK1 released from the modified surface silica gels by C7, C18 or F3 increased with increasing density of the surface modification group. The mean drug release moment (MDT) decreased with an increase in surface-modified group density.

Adsorption↗
PubMed2001

Modulated insulin delivery from glucose-sensitive hydrogel dosage forms.

Glucose-sensitive hydrogels that undergo sol-gel phase transition were used to develop modulated insulin delivery systems. Glucose-sensitive hydrogels were prepared by mixing glucose-containing polymers and PEGylated concanavalin A (Con A). Glucose was incorporated into the polymer backbone by copolymerization of allyl glucose with comonomers, such as 3-sulfopropylacrylate, potassium salt (SPAK), N-vinyl pyrrolidone (VP), and acrylamide (AM). Con A grafted with five PEG molecules were used to improve the stability of Con A. Three different types of insulin delivery systems were examined: diffusion-controlled reservoir, diffusion-controlled matrix, and erosion-controlled matrix systems. Insulin release through the glucose-sensitive hydrogel membrane and from the glucose-sensitive hydrogel matrix was dependent on the glucose concentration in the receptor chamber. As the glucose concentration was increased from 1 to 4 mg/ml, the release rate increased. The insulin release rate decreased as the glucose concentration was reduced to 1 mg/ml. Modulated insulin release was achieved using the glucose-sensitive membrane and matrix systems. On the other hand, the glucose-sensitive erodible system did not show modulated release as the glucose concentration was changed between 1 and 4 mg/ml.

Glucose↗
PubMed1998

Pharmacodynamic and pharmacokinetic rationales for the development of an oral controlled-release amoxicillin dosage form.

The goal of this investigation was to develop an oral sustained-release formulation for amoxicillin that would maximize the duration of active drug concentration in the extracellular fluid, thus increasing the dosing interval while assuring antimicrobial activity. This rationale is based on the pharmacodynamic properties of the drug which is non- concentration dependent on the one hand, while requiring long exposure of the pathogen to the drug with minimal post-antibiotic effect on the other. Due to pharmacokinetic constraints, including short biological half-life and limited 'absorption window' (confined to the small intestine) with poor colonic absorption, the new matrix tablet formulation, composed of hydrophilic (hydroxypropyl methyl-cellulose) polymer, was designed to release 50% of its contents within the first 3 h and to complete the drug release process over 8 h (under in vitro conditions). The pharmacokinetics of the new formulation was evaluated in 12 healthy volunteers and compared to a conventional gelatin capsule with both formulations containing 500 mg amoxicillin. The plasma concentrations of active amoxicillin and penicilloic acid were determined by an HPLC method with a fluorometric detector. It was found that the area under the concentration-time curve and maximal serum amoxicillin concentrations following the sustained release preparation were lower than the immediate release formulation. However, the time over the required threshold concentrations, i.e. the minimal inhibitory concentration (MIC) as well as the more clinically relevant parameter--four times MIC of the drug against susceptible pathogens, was found to be maintained for significantly longer periods. The results suggest that in order to achieve a twice daily dosing regimen that will provide therapeutic concentrations for the whole 12 h dosing intervals, a larger dose of the new formulation should be given (e.g. 750 mg or even 1 g twice daily). This recommendation is based on the large interindividual differences of the extent of amoxicillin absorption found in this investigation, and is intended to assure that the 'poor' absorbers will also benefit from full antibiotic efficacy. This dosing regimen will lead to increased patient compliance and improved therapeutic outcome.

Administration, Oral↗
PubMed2000

Novel sustained-release dosage forms of proteins using polyglycerol esters of fatty acids.

In order to develop a novel delivery system for proteins based on polyglycerol esters of fatty acids (PGEFs), we studied a model system using interferon-alpha (IFN-alpha) as the test protein. A cylindrical matrix was prepared by a heat extrusion technique using a lyophilized powder of the protein and 11 different types of synthetic PGEFs, which varied in degree of glycerol polymerization (di- and tetra-), chain length of fatty acids (myristate, palmitate and stearate) and degree of fatty acid esterification (mono-, di- and tri-). In an in-vitro release study using an enzyme-linked immunosorbent assay (ELISA) as a detection method, the matrices prepared from a monoglyceride (used for comparison) and from diglycerol esters exhibited a biphasic release pattern with a large initial burst followed by slow release. In contrast, the matrices prepared from tetraglycerol esters showed a steady rate of release without a large initial burst. In an in vivo release study, initial bursts of IFN-alpha release were, also, dramatically reduced when the matrices were prepared from the tetraglycerol esters of palmitate and stearate, and the mean residence time (MRT) of IFN-alpha was prolonged, whereas the matrices prepared from monoglyceride and from diglycerol esters showed large initial bursts of IFN-alpha release. Since the release rates from the matrices prepared from the tetraglycerol esters of palmitate and stearate were governed by Jander's equation modified for a cylindrical matrix, the release from those matrices was concluded to be a diffusion-controlled process. The bioavailability of IFN-alpha after implantation of the matrix formulation prepared using all types of PGEFs, except for tetraglycerol triesters, was almost equivalent to that after injection of IFN-alpha solution; consequently, IFN-alpha in these matrices appears to remain stable during the release period.

Animals↗
PubMed2000

Calcium-level responsive controlled drug delivery from implant dosage forms to treat osteoporosis in an animal model.

The effects of plasma calcium levels on estradiol release from a self-setting apatite bone cement containing 0.5% estradiol and on the bone mineral density (BMD) of ovariectomized rats were investigated. Apatite cement consisting of an equimolar mixture of tetracalcium phosphate, dicalcium phosphate dihydrate and 0.5% beta-estradiol was prepared. The in vitro release profiles from the cements in simulated body fluid containing 0, 5 and 10 mg/100 ml calcium indicated that estradiol release rate decreased with increasing calcium concentration in the dissolution medium. After subcutaneous implantation of the cement, in vivo estradiol release in diseased rats (ovariectomized rats on a low calcium diet) was significantly higher than that in normal rats. The diseased rats maintained a low calcium level during drug release. The bone mass of the recovery model rat was greater after the experiment than before. The results suggested that the severity of osteoporosis in this animals can be reduced by the implantation of this estradiol-loaded apatite cement.

Animals↗
PubMed1998

Physiological considerations in the design of particulate dosage forms for oral vaccine delivery.

The gastrointestinal tract provides a variety of morphological (e.g. epithelial cells, mucus) and physiological (e.g. enzymes, pH, transporters) barriers to the absorption of peptides and proteins. Approaches to overcome these barriers have included the use of particulates which are taken up by specialized mechanisms present in M cells of the gastrointestinal tract. Due to its limited capacity, this approach has found particular application in the delivery of vaccines. In this review, morphological and physiological characteristics of the gastrointestinal tract which influence the design of particulates for oral delivery will be presented. Particulates have been designed to resist luminal factors responsible for limiting absorption and to target a specialized cell population, the M cells, within the gastrointestinal tract employing both physical and biological approaches (e.g. charge, size, hydrophobicity, surface ligands such as lectins). For vaccines, this approach may have 'particular' attraction due to the signal magnification which can be accomplished in the gut associated lymphoid tissue (GALT). Recent studies have demonstrated that epithelial cells can be converted to M cells following exposure to Peyer's patch lymphocytes. Future studies designed to identify the factor(s) responsible for transient conversion of epithelial cells to M cells could provide an approach to enhance efficiency of vaccine delivery.

Journal Article↗
PubMed1987

Comparative efficacy of two dosage forms of oral methoxsalen in psoralens plus ultraviolet A therapy of psoriasis.

Two alternate oral formulations of 8-methoxypsoralen, one liquid and the other crystalline, were evaluated in a double-blind trial for their comparative efficacy in combination with ultraviolet A (UVA) light in the treatment of severe psoriasis. With the liquid formulation a greater proportion of patients achieved a good clinical result within the 20 treatment sessions than patients receiving the crystalline formulation. This difference is even more striking using a more rigorous criterion of clearance. Among all patients who achieved clearance, no significant differences were seen in either the number of treatments required or in the total UVA energy employed between the two groups. The preceding clinical results are discussed in light of published pharmacokinetic data.

Administration, Oral↗
PubMed2002

Optimization of a self-nanoemulsified tablet dosage form of Ubiquinone using response surface methodology: effect of formulation ingredients.

The objectives of the present study were (1) to evaluate the effect of formulation ingredients on the release rate of Ubiquinone from its adsorbing solid compact; and (2) to prepare and evaluate an optimized self-nanoemulsified tablet formulation. A three factor, three-level Box-Behnken design was used for the optimization procedure, with the amounts of copolyvidone (X(1)), maltodextrin (X(2)) and microcrystalline cellulose (X(3)) as the independent variables. The response variable was cumulative percent of Ubiquinone emulsified in 45 min with constraints on weight, flowability index, tensile strength, friability and disintegration time of the dry powdered emulsion and the resultant compact. Based on the experimental design, different Ubiquinone release rates and profiles were obtained. Mathematical equations and response surface plots were used to relate the dependent and independent variables. The regression equation generated for the cumulative percent emulsified in 45 min was Y(6)=64.10-12.32X(1)-4.36X(2)-25.53X(3)+6.99X(1)X(2)+3.97X(1)X(3)+9.70X(2)X(3)-8.98X(1)(2)16.22X(2)(2)+17.10X(3)(2). The optimization model predicted an 85.4% release with X(1), X(2) and X(3) levels of 66.6, 560.1 and 100, respectively. A new formulation was prepared according to these levels. The observed responses were in close agreement with the predicted values of the optimized formulation.

Cellulose↗
PubMed2003

Thermal analysis of the antiretroviral zidovudine (AZT) and evaluation of the compatibility with excipients used in solid dosage forms.

Modern thermal analysis techniques are frequently used because of their ability to provide detailed information about both the physical and the energetic properties of a substance. In the present work, the thermal decomposition of zidovudine (AZT) was studied using differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry (TG/DTG). Thermal analysis was supplemented using elemental analysis (C, H, and N), infrared (IR) spectroscopy, and X-ray powder diffraction to characterize the solid intermediates products. Volatile products of the thermal decomposition of AZT were studied by a system composed of the TG/DTA coupled gas chromatography/mass spectrometry (GC/MS). The physical-chemical properties and compatibilities of several commonly used pharmaceutical excipients with AZT were evaluated using thermal methods. The results showed that the product originated from the first thermal decomposition stage corresponds to the cleavage followed by elimination of the azide group and consequent formation of thymine. The second event corresponds to thermal decomposition of thymine. TG/DTA-GC/MS system identified thymine's decomposition products as furan and 2-furanmethanol like volatile species. Comparison of the thermoanalytical profiles of the mixtures with individual compounds did not give any evidence of interactions.

Antiviral Agents↗
PubMed1997

Determination of ornidazole in pharmaceutical dosage forms based on reduction at an activated glassy carbon electrode.

The electrochemical reduction of ornidazole was studied at a glassy carbon electrode activated by applying a new pretreatment. The dependence of intensities of currents and potentials on pH, concentration, scan rate, nature of the solvent (aqueous media, mixed aqueous-organic systems) and surfactant was investigated. Linear calibration plots were obtained over the concentration ranges 4x10(-6)-6x10(-4) and 6x10(-6)-6x10(-4) mol l(-1) in 0.2 M H(2)SO(4) and acetate buffer (pH 4.7), respectively. The method was applied to the determination of ornidazole in different drug formulations.

Journal Article↗
PubMed2001

Determination of sildenafil citrate and related substances in the commercial products and tablet dosage form using HPLC.

This study aimed at developing and validating an HPLC method for the assay of sildenafil citrate and its related substances that might coexist in the drug commercial products and in tablets' formulation as impurities that originate from synthesis processes or degradation. A chromatographic system comprising a microBondapak C(18) (10 microm) column, a mobile phase of ammonium acetate (pH 7.0, 0.2 M)-acetonitrile (1:1, v/v), a flow rate of 1 ml/min and a UV detector set at 240 nm has shown good chromatographic separation for sildenfil and the other related substances. The degree of linearity of the calibration curves, the percent recoveries of sildenafil and related substances, the limit of detection, LOD, and limit of quantitation, LOQ for the HPLC method have been determined. The HPLC method under study was found to be specific, precise, accurate, reproducible indicating stability and robust.

Chromatography, High Pressure Liquid↗
PubMed2001

HPTLC determination of nimesulide from pharmaceutical dosage forms.

A simple, rapid, reproducible and stability indicating high performance thin-layer chromatographic method for the analysis of Nimesulide both the bulk drug and from pharmaceutical formulations is reported. The mobile phase selected consists of Cyclohexane-Ethylacetate [60:40, v/v]. It gave compact spots both for Nimesulide and its degraded products at Rf values 0.44 and 0.712, respectively. Densitometric analysis of nimesulide was carried out at 295 nm. The calibration curve of Nimesulide in methanol was linear in the range of 100-900 ng. The mean value of correlation coefficient, slope and intercept were 0.9989+/-0.0011, 504.655+/-0.0013 and 85331.56+/-0.0253, respectively. The limits of detection and quantitation were 60 and 100 ng, respectively. The drug content was within the limits (+/-5% of the labelled content of the formulations). The recovery of Nimesulide was about 99.5%.

Anti-Inflammatory Agents, Non-Steroidal↗