PubMed Health⌕ Search

Biomedical subjects

G P Agrawal

Publications and source records attributed to G P Agrawal.

17 recordsLinked to original sources
PubMed2005

Calcium silicate based microspheres of repaglinide for gastroretentive floating drug delivery: preparation and in vitro characterization.

Gastroretentive dosage forms have potential for use as controlled-release drug delivery systems. Multiple unit systems avoid the 'all-or-none' gastric emptying nature of single-unit systems. A controlled release system designed to increase its residence time in the stomach without contact with the mucosa was achieved through the preparation of floating microspheres by the emulsion solvent diffusion technique consisting of (i) calcium silicate (FLR) as porous carrier; (ii) repaglinide, an oral hypoglycemic agent; and (iii) Eudragit S as polymer. The effect of various formulation and process variables on the internal and external particle morphology, micromeritic properties, in vitro floating behavior, physical state of the incorporated drug, drug loading and in vitro drug release were studied. The microparticles were found to be regular in shape and highly porous. The release rate was determined in simulated gastro-intestinal fluids at 37 degrees C. The formulation demonstrated favorable in vitro floating and release characteristics. The drug encapsulation efficiency was high. Incorporation of FLR in the microspheres proved to be an effective method to achieve the desired release behavior and buoyancy. The designed system, combining excellent buoyant ability and suitable drug release pattern, could possibly be advantageous in terms of increased bioavailability of repaglinide.

Algorithms↗
PubMed2005

Chitosan hydrochloride based microspheres of albendazole for colonic drug delivery.

Microspheres of chitosan hydrochloride (CH) were prepared in order to deliver albendazole specifically into the colon. Microspheres were prepared by an emulsion method using different ratios of drug and CH (1:1 to 1:5), agitation speeds (500 to 1500 rpm) and concentrations of glutaraldehyde in toluene as the cross-linking agent (0.25 to 1.0% w/v). The effect of polymer concentration, stirring rate and concentration of cross-linking agent on the particle size and drug loading was studied. With an increase in CH concentration, the average particle size was increased. Increased agitation speed reduced the size of the microspheres but higher agitation speed resulted in irregularly shaped microspheres. Increasing the concentration of cross-linking agent produced more regularly shaped microspheres of smaller size. The drug loading was highest at a drug: CH ratio of 1:3, stirring speed 1000 rpm and 0.75% w/v concentration of cross-linking agent. The effect of CH concentration on in vitro drug release from the microspheres was evaluated in simulated g.i.t fluids. A comparative in vitro drug release study of the optimized formulation was carried out in simulated colonic fluid, with and without 2% rat caecal content. The drug release in 24 h was 48.9% in colonic fluid without rat caecal content, and 76.5% in colonic fluid with rat caecal contents.

Albendazole↗
PubMed2004

Theory of incoherent optical solitons: beyond the mean-field approximation.

We present a general theory of partially coherent optical solitons in slow-responding nonlinear media that takes into account intensity fluctuations of the light sources generating such solitons. If intensity fluctuations of the source are negligible, the theory reduces to the previously reported mean-field theory of partially coherent solitons. However, when such fluctuations are significant, our theory shows that the properties of partially coherent solitons in saturable nonlinear media can be qualitatively different from those predicted by the mean-field theory.

Journal Article↗
PubMed2004

Hydrotropic solubilization of nimesulide for parenteral administration.

Nimesulide is a non-steroidal anti-inflammatory drug (NSAID) that exhibits analgesic, antipyretic and anti-inflammatory activities. It is practically insoluble in water. The effect of various hydrotropes such as nicotinamide, sodium ascorbate, sodium benzoate, sodium salicylate and piperazine on the solubility of nimesulide was investigated. The solubility enhancement of nimesulide by the hydrotropes was observed in decreasing order as piperazine > sodium ascorbate > sodium salicylate > sodium benzoate > nicotinamide. In order to elucidate the probable mechanism of solubilization, various solution properties of hydrotropes such as viscosity, specific gravity, surface tension, refractive index, specific conductance of hydrotropic solutions were studied at 25 +/- 2 degrees C on the basis of earlier studies. The hydrotropic solubilization of nimesulide at lower hydrotrope concentration may be attributed to weak ionic interactions while that at higher hydrotrope concentration may be due to molecular aggregation. Parenteral formulations using piperazine as a hydrotrope were developed and studied for physical and chemical stability.

Infusions, Parenteral↗
PubMed2004

Energy spectrum of a nonstationary ensemble of pulses.

We introduce a new definition of the energy spectrum of a nonstationary ensemble of pulses that reduces to the usual ones in the limit of statistically stationary ensembles of signals and of fully temporarily coherent ensembles.

Journal Article↗
PubMed2004

Preparation and characterization of reverse micelle based organogels of piroxicam.

The solubilization of piroxicam to increase transdermal permeation rate was attempted by incorporating the drug in reverse micelle systems consisting of lecithin/isopropyl myristate/water [RMS-1] and sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane/water [RMS-2]. The change in polarity of water present in the water pool formed by reverse micelles resulted in a solubilization of piroxicam. These systems were used for the formation of reverse micellar organogels RMO-1 and RMO-2 by means of either varying hydration ratio (Wo) or by addition of a macromolecule, e.g. gelatin, into the system or by taking both the parameters in consideration. These systems were evaluated for physical properties, toxicology, in vitro and in vivo transdermal permeation. Significant (p < 0.01) inhibition of carrageenan induced rat paw oedema was observed for products RMO-1 and RMO-2 and a marketed transdermal product after 3 h.

Administration, Topical↗
PubMed2000

Propagation-induced polarization changes in partially coherent optical beams.

Propagation of a partially coherent optical beam inside a linear, nondispersive, dielectric medium is studied, taking into account the vector nature of the electromagnetic field. Propagation-induced polarization changes are studied by using the Gaussian-Schell model for the cross-spectral-density tensor. The degree of polarization changes with propagation and also becomes nonuniform across the beam cross section. The extent of these changes depends on the coherence radius associated with the cross-correlation function. For optical beams with symmetric spectra, the bandwidth of the source spectra is found to play a relatively minor role.

Journal Article↗
PubMed1999

Asymmetric partially coherent solitons in saturable nonlinear media.

We investigate theoretically properties of partially coherent solitons in optical nonlinear media with slow saturable nonlinearity. We have found numerically that such a medium can support spatial solitons which are asymmetric in shape and are composed of only a finite number of modes associated with the self-induced waveguide. It is shown that these asymmetric spatial solitons can propagate many diffraction lengths without changes, but that collisions change their shape and may split them apart.

Journal Article↗
PubMed1990

Pathogenic fungi in soils of Jabalpur, India.

Results of a preliminary survey of pathogenic fungi in soils collected from forest, riverside and residential garbage soil in Jabalpur, India, are reported. A total of 45 soils samples were examined, of which 39 (87%) were positive for fungi, 66 species of fungi classified in 35 genera were isolated: Chrysosporium (78%), Fusarium (69%), Aspergillus (47%), Microsporum (38%), Gliocladium (16%), Acremonium (11%), Penicillium (11%), Humicola (9%), Scopulariopsis (7%), Paecilomyces (7%), Cladosporium (7%); Chaetomium, Colletotrichum, Cunninghamella, Microascus and Rhizopus (4% each); Absidia, Aphanocladium, Arthrobotrys, Botryotrichum, Candida, Cephaliophora, Cephalosporium, Curvularia, Histoplasma, Mucor, Shanorella, Syncephalastrum, Thermomyces, Trichophyton, Trichothecium and Verticillium (2% each); mycelia sterilia (6%). Acremonium persicinum, Cladosporium trichoides and Shanorella spirotricha are new to India. A new species of Humicola has also been isolated.

Fungi↗
PubMedDate not supplied

Floating-bioadhesive microspheres containing acetohydroxamic acid for clearance of Helicobacter pylori.

A new strategy based on gastric retention is proposed for the treatment of Helicobacter pylori. (H. pylori). A synergism between a floating and a bioadhesive system has been explored. Floating microspheres containing the antiurease drug acetohydroxamic acid (AHA) were prepared by a novel quasi-emulsion solvent diffusion method. The microballons were characterized for size distribution, morphology, drug content, drug release, and in vitro floating property. The microballons were coated with 2% w/v solution of polycarbophil by the air suspension coating method. The bioadhesive property of the microspheres was investigated by the detachment force measurement method. In vitro growth inhibition studies were performed in isolated H. pylori culture. The results suggest that AHA-loaded floating microspheres are superior as potent urease inhibitors whereas urease plays an important role in the colonization of H. pylori. We suggest that an oral dosage containing floating-bioadhesive microspheres may form a useful drug delivery system for the treatment of H. pylori.

Adhesives↗
PubMedDate not supplied

Surface-modified mesoporous ceramics as delivery vehicle for haemoglobin.

Aquasomes, a new drug delivery system comprised of surface-modified nanocrystalline ceramic carbohydrate composites, was developed to serve as haemoglobin carrier for oxygen delivery. The hydroxy-apatite ceramic core was prepared by coprecipitation and self-precipitation and coated with various sugars like cellobiose, maltose, sucrose, and trehalose. The effect of drying methods, i.e., air drying, vacuum drying, and lyophilization, on the degree of binding was studied by concanavalin-induced aggregation method. Haemoglobin was adsorbed over the sugar-coated ceramics, and percent loading was estimated by benzidine method. The adsorption of sugars on calcium hydro-apatite powder and haemoglobin adsorption on sugar-adsorbed ceramic followed both Freundlich and Langmuir isotherm. The haemoglobin aquasome formulations (equivalent to 7.5% Hb) were suspended in a phosphate buffer containing 7.5% w/v albumin and 0.01% w/v lecithin, and they were evaluated for oxygen-carrying capacity, which was found to be similar to fresh blood. The Hill coefficients were found to be fairly good for its use as oxygen carrier. The haemoglobin aquasome formulations did not induce haemolysis of red blood cells nor alter the blood coagulation time. The haemoglobin content of the formulation remained unchanged on storage for 30 days. The haemoglobin desorption was fairly low under shear conditions, indicating good stability of formulation in biological system. During in vivo study in rats the survivals were monitored as function of hematocrit in rats receiving isovolemic exchange transfusion. Arterial blood pressure and heart rate did not change significantly in animals transfused with aquasomal suspension on 50% exchange transfusion.

Adsorption↗
PubMedDate not supplied

Preparation and characterization of oxybenzone-loaded gelatin microspheres for enhancement of sunscreening efficacy.

The objective of our present study was to prepare and evaluate gelatin microspheres of oxybenzone to enhance its sunscreening efficacy. The gelatin microspheres of oxybenzone were prepared by emulsion method. Process parameters were analyzed to optimize the formulation. The in vitro drug release study was performed in pH 7.4 using cellulose acetate membrane. Microspheres prepared using oxybenzone:gelatin ratio of 1:6 showed slowest drug release and those prepared with oxybenzone:gelatin ratio of 1:2 showed fastest drug release. The gelatin microspheres of oxybenzone were incorporated in aloe vera gel. Sun exposure method using sodium nitroprusside solution was used for in vitro sunscreen efficacy testing. The formulation C5 containing oxybenzone-bearing gelatin microspheres in aloe vera gel showed best sunscreen efficacy. The formulations were evaluated for skin irritation test in human volunteers, sun protection factor, and minimum erythema dose in albino rats. These studies revealed that the incorporation of sunscreening agent-loaded microspheres into aloe vera gel greatly increased the efficacy of sunscreen formulation more than four times.

Animals↗