Browsing by Author "Jameela, SR"

Now showing 1 - 6 of 6
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    Antitumour activity of mitoxantrone-loaded chitosan microspheres against Ehrlich ascites carcinoma
    (JOURNAL OF PHARMACY AND PHARMACOLOGY, 1996) Jameela, SR; Latha, PG; Subramoniam, A; Jayakrishnan, A
    Glutaraldehyde cross-linked chitosan microspheres containing the antineoplastic agent mitoxantrone were prepared and the antitumour activity was evaluated against Ehrlich ascites carcinoma in mice by intraperitoneal injections. The tumour inhibitory effect was followed by monitoring animal survival time and change in body weight for a period of 60 days. While the mean survival time of animals which received 2 mg and 1 mg of free mitoxantrone intraperitoneally was 2.1 and 4.6 days, respectively, animals which received 2 mg mitoxantrone via microspheres showed a mean survival time of 50 days. Five out of 8 animals treated using microspheres lived beyond 60 days. The percentage ratio mean survival time of the treated group divided by the mean survival time of the untreated group for animals treated using mitoxantrone-loaded chitosan microspheres containing 2 mg of the drug was 290 compared with 12.2 for those which received 2 mg of the free drug. The antitumour effect of mitoxantrone-loaded microspheres against Ehrlich ascites carcinoma was much higher than that of doxorubicin-loaded microspheres reported by previous workers. Our data demonstrate the potential of mitoxantrone-loaded chitosan microspheres for sustained drug delivery to minimize drug toxicity and maximize therapeutic efficacy.
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    Glutaraldehyde as a fixative in bioprostheses and drug delivery matrices
    (BIOMATERIALS, 1996)
    The use of glutaraldehyde as a fixative in bioprostheses and drug delivery matrices is reviewed. The chemistry of glutaraldehyde cross-linking and its effect on the biological performance of a number of bioprostheses such as tissue heart valves, vascular grafts, pericardial patches, tendon grafts and drug delivery matrices are examined.
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    Poly(epsilon-caprolactone) microspheres as a vaccine carrier
    (CURRENT SCIENCE, 1996) Jameela, SR; Suma, N; Misra, A; Raghuvanshi, R
    Poly(epsilon-caprolactone) (PCL), a biocompatible and biodegradable polymer hitherto thought unsuitable for protein delivery because of its poor permeability to macromolecules, is shown to be sufficiently permeable to proteins to function as a vaccine carrier, Using a model antigen such as bovine serum albumin (BSA), we demonstrate that a single injection of BSA-loaded PCL microspheres generates an immune response comparable in magnitude and time kinetics to that of a conventional three-injection schedule of the antigen in a rat model, Unlike polyesters such as poly(lactic acid) (PLA) and poly(glycolic acid) (PGA), PCL degrades slowly and therefore does not generate an acid environment adversely affecting the antigenicity of vaccines and may prove to be promising as a vaccine carrier.
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    Preparation and evaluation of photocrosslinkable chitosan as a drug delivery matrix
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2002) Jameela, SR; Lakshmi, S; James, NR; Jayakrishnan, A
    Epichlorohydrin (1-chloro-2,3-epoxypropane) was reacted with sodium azide in the presence of a phase transfer catalyst to obtain 1-cliloro-2-hydroxy-3-azidopropane, which was further coupled onto chitosan to prepare. a photocrosslinkable derivative of the biopolymer. Elemental analysis and infrared (IR) spectroscopy confirmed the incorporation of azide groups onto chitosan. Films were cast from an aqueous acetic acid solution of azidated chitosan containing a model drug, such as theophylline. Irradiation of the film with ultraviolet (UV) light led to crosslinking of the drug incorporated film. IR spectra indicated complete surface crosslinking within 2 h of irradiation. Release of theophylline from uncrosslinked and crosslinked films was examined in simulated gastric and intestinal fluids without enzymes at 37 degreesC. The release of the drug from the crosslinked films was slower than the release from uncrosslinked films. Although the system is far from being optimized to obtain sustained release of a pharmacologically active agent for long periods, the data obtained indicate the possibility of developing photocrosslinkable matrices of biopolymers, such as chitosan, for sustained drug delivery with many advantages over chemical crosslinking. (C) 2002 Wiley Periodicals, Inc.
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    Progesterone-loaded chitosan microspheres: a long acting biodegradable controlled delivery system
    (JOURNAL OF CONTROLLED RELEASE, 1998)
    Smooth, highly spherical, crosslinked chitosan microspheres in the size range of 45-300 mu m loaded with progesterone were prepared by glutaraldehyde crosslinking of an aqueous acetic acid dispersion of chitosan containing progesterone in a non-aqueous dispersion medium consisting of liquid paraffin and petroleum ether stabilized using sorbitan sesquioleate. Ln vitro release of the drug into phosphate buffer at 37 degrees C was determined as a function of crosslinking density of the microspheres and particle size. The extent of drug release had a remarkable dependence on the crosslinking density of the microspheres, the highly crosslinked spheres releasing only around 35% of the incorporated steroid in 40 days compared to 70% from spheres lightly crosslinked. Determination of the in vivo bioavailability of the steroid from microsphere formulation by intramuscular injection in rabbits showed that a plasma concentration of 1 to 2 ng/ml was maintained up to 5 months without a high 'burst effect'. Data obtained suggest that the crosslinked chitosan microspheres would be an interesting system for long term delivery of steroids, (C) 1998 Elsevier Science B.V.
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    Protein release from poly(epsilon-caprolactone) microspheres prepared by melt encapsulation and solvent evaporation techniques: A comparative study
    (JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION, 1997)
    Poly(epsilon-caprolactone) (PCL) microspheres containing c. 3% bovine serum albumin (BSA) were prepared by melt encapsulation and solvent evaporation techniques. PCL, because of its low T-m, enabled the melt encapsulation of BSA at 75 degrees C thereby avoiding potentially toxic organic solvents such as dichloromethane (DCM). Unlike the solvent evaporation method, melt encapsulation led to 100% incorporation efficiency which is a key factor in the microencapsulation of water-soluble drugs. Examination of the stability of the encapsulated protein by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that protein integrity was unaffected by both methods of encapsulation. In vitro release of the protein into phosphate buffer examined at 37 degrees C from microspheres prepared by both techniques showed that the release rate from melt-encapsulated microspheres was somewhat slower compared to the release from solvent-evaporated spheres. Both released around 20% of the incorporated protein in 2 weeks amounting to approximately 6.5 mu g mg(-1) of microspheres. Although the diffusivity of macromolecules in PCL is rather low, it is shown that PCL microspheres are capable of delivering sufficient quantity of proteins by diffusion for prolonged periods to function as a carrier for many vaccines. Unlike poly(lactic acid) (PLA) and poly(glycolic acid) (PGA) polymers which generate extreme acid environments during their degradation, the delayed degradation characteristics of PCL do not generate an acid environment during protein release and, therefore, may be advantageous for sustained delivery of proteins and polypeptides.