Glutaraldehyde cross-linked chitosan microspheres as a long acting biodegradable drug delivery vehicle: studies on the in vitro release of mitoxantrone and in vivo degradation of microspheres in rat muscle

Evaluation of process parameters involved in chitosan microsphere preparation by the o/w/o multiple emulsion method

Chitosans are interesting biopolymers largely studied for applications in the medical and pharmaceutical fields. In this work, an o/w/o multiple emulsion technique was used for the preparation of hydrophobic drug loaded microspheres. Moreover, the influence of critical variables (concentration of acetic acid in the polymer solution and drug-polymer ratio) on microsphere morphology and drug content was evaluated. Two chitosans of different molecular weights and deacetylation degree were employed; ketoprofen, a non-steroidal anti- inflammatory drug, was chosen as the hydrophobic model drug. The multiple emulsion method produced well-formed microspheres with good yields. Acetic acid concentration in the polymeric solutions influenced particle size and drug content of the microspheres. The highest drug encapsulation efficiencies were obtained for the lowest theoretical drug/chitosan ratio.

Antitumour activity of mitoxantrone-loaded chitosan microspheres against Ehrlich ascites carcinoma

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.

Glutaraldehyde as a fixative in bioprostheses and drug delivery matrices

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.