K. Gupta

Drug release behavior of beads and microgranules of chitosan

Beads and microgranules carriers have important potential applications for the administration of therapeutic molecules. A novel approach for the preparation of chitosan beads and microgranules is presented. The present work is an investigation of the in vitro release kinetics of diclofenac sodium (DFS) from chitosan beads and microgranules. The in vitro release profiles of DFS from chitosan beads and microgranules are monitored using Shimadzu 1601 UV-VIS spectrophotometer. Drug release behavior of beads and microgranules has been compared. The release rate of DFS from the beads has been found to be slower in comparison to the microgranules. It may also be noted that the percent and amount of the drug release were much higher in acidic solution than in basic solution, probably due to the swelling properties of the matrix at acidic pH.

Preparation, characterization and release profiles of pH‐sensitive chitosan beads

Spherical crosslinked beads using chitosan, glycine and glutaraldehyde were prepared for controlled release formulations. Structural investigation of the beads was made with IR analysis. Morphological study of the beads was carried out by scanning electron microscopy. The swelling behaviour of the beads was monitored as a function of time in solutions of different pH. The release experiments were performed using thiamine hydrochloride (Thi-HCl) as a model drug. These preliminary results suggest the possibility of modifying the formulations to obtain the desired controlled release of drug in an oral sustained delivery system. © 2000 Society of Chemical Industry

pH dependent hydrolysis and drug release behavior of chitosan/poly(ethylene glycol) polymer network microspheres

Semi-interpenetrating polymer network (IPN) microspheres of chitosan and poly(ethylene glycol) PEG were prepared for controlled release of drugs. A new method for the chemical crosslinking of chitosan microspheres containing isoniazid (INH) as a model drug is proposed and evaluated. The method consists of the exposure of microspheres to the vapor of crosslinking agent that act in gaseous phase under mild conditions. The structural analysis of the microspheres was carried out by FTIR-analysis. The swelling behavior, hydrolytic degradation, structural changes of the microspheres and loading capacity (LC) of the microspheres for INH were investigated. The prepared microspheres have shown 93% drug loading capacity, which suggested that these semi-IPN microspheres are suitable for controlled release of drugs in an oral sustained delivery system.

Semi-interpenetrating polymer network beads of crosslinked chitosan–glycine for controlled release of chlorphenramine maleate

Spherical, semi-interpenetrating polymer network beads of chitosan and glycine, crosslinked with different concentrations of glutaraldehyde were prepared for controlled release of drugs. The structural and morphological studies of the beads were carried out with FTIR and SEM techniques. The swelling behavior of the beads at different time intervals was monitored in solutions of different pH. Structural changes of the beads in response to solution pH were put forward using the data obtained from IR/UV spectral analysis. The release experiments were performed in solutions of pH 2.0 and pH 7.4 at 37°C, using chlorphenramine maleate as a model drug. The results indicate that, chitosan might be useful as a vehicle for controlled release of drugs.

Studies on semi‐interpenetrating polymer network beads of chitosan–poly(ethylene glycol) for the controlled release of drugs

Semi-interpenetrating polymer network beads of chitosan and poly(ethylene glycol) were prepared and characterized for controlled release of drugs. A viscous solution of chitosan and poly(ethylene glycol) in 2% acetic acid was extruded as droplets with the help of a syringe and crosslinked using glutaraldehyde. The structural studies of the beads were performed by using a Fourier transform infrared spectrophotometer and scanning electron microscope. The swelling behavior, solubility, hydrolytic degradation, and loading capacity of the beads for isoniazid were investigated. The structural changes of the beads at pH 2.0 and 7.4 were put forward using the data obtained by infrared and ultraviolet spectroscopy. The prepared beads showed 82% drug-loading capacity, which suggested that these semi-interpenetrating polymer network beads are suitable for controlled release of drugs in an oral sustained delivery system.

STRUCTURAL CHANGES AND RELEASE CHARACTERISTICS OF CROSSLINKED CHITOSAN BEADS IN RESPONSE TO SOLUTION pH

The present investigation describes a novel method for preparing beads based on crosslinked chitosan with glutaraldehyde interpenetrating glycine polymer network. Four type of beads, viz., CHI1 (composed of chitosan, glycine and glutaraldehyde); CHI2 (composed of chitosan and glutaraldehyde); CHI3 (composed of chitosan and glycine) and CHI4 (only chitosan) were prepared and their release characteristics were studied using thyamine hydrochloride (Thy-HCl) as a model drug. Structural changes during swelling of CHI1 beads in solutions of different pH were studied using IR and UV spectroscopy.

Cytopathology of parasitic dermatitis in dogs

Out of 44 cases of dermatitis in dogs, 11 cases of parasitic origin were analyzed by cytopathology. Histopathologic examination of punch biopsies was also done for correlation with cytologic findings. Sarcoptic dermatitis was recorded in six cases, wherein, besides sarcoptic mites, neutrophils, macrophages, and plasma cells and keratinizing epithelial cells were also seen. Hematology revealed a relative neutrophilia and mild eosinophilia. Four cases of severe and generalized demodicosis complicated with bacteria and/or Malassezia sp. infection were also recorded. Histopathologically numerous Demodex sp. mites in varying stage of maturation were found damaging the hair follicles along with associated pathological changes and foreign body granulomas in one case. In addition, flea allergy dermatitis was also observed in one dog. In nutshell, cytology was found to be unequivocally effective in diagnosing parasitic dermatitis.

Validation of Romanowsky staining as a novel screening test for the detection of faecal cryptosporidial oocysts

Cryptosporidiosis is an emerging waterborne protozoan disease and one of the major causes of neonatal diarrhea in humans and animals. But the disease remains under diagnosed due to lack of availability of special stains in majority of laboratories at primary health centers. Therefore, it requires a rapid screening test for routine diagnosis in conventional laboratory set up. In this pursuit, the present study was planned. During this study, fecal samples from 100 representative animals randomly selected from 17 out breaks of bovine calf diarrhea, were stained with modified Ziehl Neelsen staining (mZN) and Leishman’s stain to demonstrate cryptosporidial oocysts and for routine fecal examination, respectively. By mZN staining, 25 cases confirmed the presence of cryptosporidial oocysts. However, examination of Leishman’s stained fecal smears revealed round hollow unstained bodies resembling cryptosporidia in 20 cases. Therefore, a comparative morphometric analysis was made between the two techniques to determine their relative efficacy in demonstrating cryptosporidia in the feces of affected animals. The analyses showed that the Leishman’s stain can be effective in making a presumptive diagnosis of cryptosporidiosis with a little experience. Confirmation of cryptosporidiosis was done by histopathological examination of intestinal sections of calves died during these out breaks. The findings appear to have great clinical value for routine laboratory screening of fecal samples for cryptosporidiosis as conventional Romanowsky stains are readily available and used for multipurpose examination in most of the laboratories at grass root level. Perusal of literature proved this to be the first attempt at easy diagnostics for cryptosporidiosis.

Pathological observations on clinical Anaplasma marginale infection in cattle

Gross and histopathological changes were recorded in a pregnant cattle died of clinical anaplasmosis, a tick transmitted economically important disease caused by Anaplasma marginale. Grossly emaciated carcass along with pale visible mucous membranes and pale serosal surface, splenomegaly and hepatomegaly was observed. Microscopically, in lungs variable extend of interstitial pneumonia, emphysema along with infiltration of mononuclear cells was seen. Spleen showed extensive increase in red pulp area with massive proliferation of lymphocytes. In liver marked thickening of capsule with fatty changes along with retention of bile was seen. Gall bladder showed congestion, glandular hyperplasia and thickening wall. Myocardium showed degeneration and necrosis.

Immunolocalization and Cellular Expression af Key Abc Transporter Proteins and Their Correlation with theGrades and Subtypes of Canine Mammary Tumour

Objective: To determine the immunolocalization and cellular expression of adenosine triphosphate-binding cassette (ABC) proteins viz. breast cancer resistance protein (BCRP) and multidrug resistance protein 1 (MDR1) in canine mammary tumour (CMT), as well as to correlate their expression with the histological subtypes and grades of CMT with a view towards therapeutic implications. Methods: Fifty-three cases of malignant CMT were included in the study. The histological sections taken from archived paraffin blocks were subjected to histopathology and imunohistochemistry for sub-typing, grading, immunolocalization and cellular expression of BCRP and MDR1 and their interrelation. Results: Both BCRP and MDR1 were mainly immulocalized in cellular membranes and to a lesser extent in the cytoplasm of the cancerous epithelial cells and stromal connective tissue. Carcinosarcomas followed by carcinomas and sarcomas revealed decreasing expression of both BCRP and MDR1 proteins. A positive and an inverse correlation between BCRP and MDR1 expression, respectively was observed with the increasing grade of CMT. Conclusion: The study implicates the role of ABC transporter proteins in possible chemotherapeutic drug resistance that may vary with the subtype and grade of CMT.