The aim of this review is to give an insight into the many potential applications of chitosan as a pharmaceutical drug carrier. The first part of this review concerns the principal uses of chitosan as an excipient in oral formulations (particularly as a direct tableting agent) and as a vehicle for parenteral drug delivery devices. The use of chitosan to manufacture sustained-release systems deliverable by other routes (nasal, ophthalmic, transdermal, and implantable devices) is discussed in the second part.

Chitosan: A Unique Polysaccharide for Drug Delivery

Poly(lactic acid) [PLA] and its co-polymers with glycolic acid [PLCG] have been known to be biodegradable and histocompatible for the past 20 years. Their physico-chemical and biological properties have been found suitable, in many instances, for sustaining drug release in vivo for days or months. Several dosage forms for parenteral administration have been investigated using these polymers and a microencapsulation technique is chosen frequently for its unique properties. There are a limited number of published papers concerning preparation and characterization of PLA or PLCG microcapsules, possibly because of commercial unavailability and difficulties in the synthesis of reproducible batches of these polymers. However, microcapsules can be made using different traditional and non-traditional techniques containing core materials ranging from biological proteins to synthetic drugs. An attempt is made here to review problems associated with the different microencapsulation techniques using PLA or PLCG. In vivo and in vitro drug release from these microcapsules is also reviewed.

Biodegradable poly(lactic acid) and poly(lactide-co-glycolide) microcapsules: problems associated with preparative techniques and release properties.

Nanoparticles--a historical perspective.

A photoactivatable drug delivery system is provided, in which a drug is combined eg by covalent bonding, incorporation in a matrix or encapsulation, with a photosensitive macromolecule In combination, the drug is inert The macromolecule is large enough to prevent migration of the combination within the body, so that the combination can be implanted at a location of maximum effectiveness The drug is released from the combination, in therapeutically active form, upon appropriate irradiation

Drug delivery systems

Characterization of Drug-Loaded Poly(d,l-lactide) Microspheres

Bovine serum albumin microspheres contatining 5-fluorouracil-6-3H were prepared by heating at 180° (or 150°, 100°) of 25% albumin solution in cottonseed oil emulsion. The shape of this microsphere was invariably spherical, and the average diameter was 0.66μ. After intravenous injection in mice, 5-fluorouracil-6-3H entrapped in albumin microspheres localized mainly in the liver, and the disappearance rate of radioactivity in microspheres from the tissue was very slow in comparison with that of free drugs. The microsphere might be delivered into reticuloendothelial system in the liver because ofits phagocytic activity, as well as the distribution following injection of albumin macroaggregates. Such preferential localization and sustained release of entrapped drugs suggested that albumin microspheres are useful as drug-carrier in chemotherapy.

https://www.jstage.jst.go.jp/article/cpb1958/27/1/27_1_204/_pdf

Drug-carrier Property of Albumin Microspheres in Chemotherapy. II. Preparation and Tissue Distribution in Mice of Microsphere-entrapped 5-Fluorouracil

Drug-carrier property of albumin microspheres in chemotherapy. V. Antitumor effect of microsphere-entrapped adriamycin on liver metastasis of AH 7974 cells in rats.

Drug-carrier property of albumin microspheres in chemotherapy. IV. Antitumor effect of single-shot or multiple-shot administration of microsphere-entrapped 5-fluorouracil on Ehrlich ascites or solid tumor in mice.

The drug extraction ability of water-in-oil-in-water emulsion was evaluated in vitro and in vivo. In vitro drug extraction into the emulsion was determined using a dialysis system and was significant compared to the control. Blood concentration of salicyclic acid, selected as a model drug, co-administered with the multiple emulsion to rabbits was significantly lower than in the control. The in vitro and in vivo experimental results suggest that the emulsion may be useful for the emergency treatment of drug overdose.

Detoxication capacity of a multiple (w/o/w) emulsion for the treatment of drug overdose: drug extraction into the emulsion in the gastro-intestinal tract of rabbits.

Yoshio Kato

Papers

Drug-carrier Property of Albumin Microspheres in Chemotherapy. II. Preparation and Tissue Distribution in Mice of Microsphere-entrapped 5-Fluorouracil

Drug-carrier property of albumin microspheres in chemotherapy. V. Antitumor effect of microsphere-entrapped adriamycin on liver metastasis of AH 7974 cells in rats.

Drug-carrier property of albumin microspheres in chemotherapy. IV. Antitumor effect of single-shot or multiple-shot administration of microsphere-entrapped 5-fluorouracil on Ehrlich ascites or solid tumor in mice.

Detoxication capacity of a multiple (w/o/w) emulsion for the treatment of drug overdose: drug extraction into the emulsion in the gastro-intestinal tract of rabbits.