Showing papers in "Critical Reviews in Therapeutic Drug Carrier Systems in 1986"

Polyvalent polymeric drug carriers.

Abstract: A number of drug-carrier systems have been considered, so far, for time-controlled delivery, targeting, and decrease of toxicity of biologically active compounds. Many of these drug carriers are based on synthetic polymers. Prerequisites for polymeric drug carriers and the need for polyvalent systems capable of carrying different drugs are examined from the viewpoint of effective pharmaceutical uses. The cases of microcapsules, microspheres, nanoparticles, and emulsions based on polymers are recalled. Of particular interest are copolymers, such as amphiphilic block-copolymers and partially quaternized polytertiary amines, that can form hydrophobic microdomains in aqueous media. Discussions are focused on the capability of the corresponding microphases to solubilize, carry, and release lipophilic drugs. The present state of the art is illustrated by recent examples.

Protein-coated and polysaccharide-coated liposomes as drug carriers.

Abstract: Saccharides on the surface of cell membranes play an important role in cell-cell recognition, which is the most important process utilizable for targeting of drugs encapsulated in an artificial cell, liposome. To design a targetable drug carrier, hence, employing synthesized or natural glycolipids as the recognition site of the liposomal drug carrier is certainly one of useful approach. On the other hand, coating the outermost surface of liposomes with polysaccharide derivatives is also another way for liposomes to be utilized as a targetable drug carrier. In this review, from such a viewpoint, the importance and usefulness of saccharide moiety on the surface of liposomes will be discussed in conjunction with the targeting of drugs.

Synthetic immunomodulators and synthetic vaccines.

Abstract: Efforts have been made for several years to obtain well-defined, nontoxic adjuvants and antigens which could be used for human vaccination and immunostimulation. Among synthetic adjuvants, MDP represents one of the most studied family of compounds. This molecule is the minimal active structure of whole Mycobacteria and has been shown to be endowed with numerous biological activities. MDP is adjuvant active, increases nonspecific resistance against infectious challenges and, under certain conditions, increases resistance against tumor grafts. Moreover, MDP has other pharmacological properties such as pyrogenic and somnogenic activities. Several hundred MDP derivatives have been synthetized and some of the biological activities have been dissociated. One MDP derivative presently under clinical trials has been shown to be adjuvant active but is devoid of pyrogenicity. The mechanisms of activity of these MDP and derivative molecules will be discussed. More recently, synthetic antigens which are copies of natural epitopes, have been shown to induce protective antibodies against bacterial or viral pathogens. These synthetic antigens conjugated to synthetic carriers or to synthetic adjuvants such as MDP, may permit the preparation of totally synthetic vaccines.

Release of therapeutic agents from contact lenses.

Abstract: Drug release from contact lenses was studied by a technological approach. Different parameters such as introduction of drug into the lenses, release, hydration level, molecular weight of drugs, kinetics of release, and clinical tests were reviewed. Therapeutical benefits of this kind of dispensation was taken up. The actual inadequacies from the techniques used must be palliated by publication of new performance technologies that are studied today.

Polymeric microspheres as diagnostic tools for cell surface marker tracing.

Abstract: The adequate expression of cell-surface receptors and antigens is an important requirement for the functional ability of living cells. A lot of different methods for cell surface marker tracing have been described; however, most of these techniques have disadvantages limiting their wide-scale utilization in routine laboratory and clinical practice. The most recent technique for these purposes, approaching near the ideal one, is based on the use of synthetic microspheric particles made of polymers which are formed mainly by emulsion or radiation polymerization of a variety of monomers. The resulting spherical particles bear hydroxyl, carboxyl, amino, or other functional groups capable of covalent binding of proteins, dyes, or chemotherapeutic agents. Fluorescent, radioactive or haptenic labels may be introduced already during the polymerization, too. There are three main fields of application of such specific labeled microspheres in cell biology: (1) detection of cell surface markers; (2) studies of phagocytosis mediated via cell surface markers; and (3) cell separation according to cell surface markers. In this review general principles of preparation and applications of polymeric microspheres in cell biology are summarized.

Immunotoxins: current use and future prospects in bone marrow transplantation and cancer treatment.

Abstract: Immunotoxins are protein toxins which have been conjugated in whole or in part to antibodies in the hope of producing cell-type-specific toxic reagents with useful properties. Such reagents hold the promise for eliminating unwanted cells both in vivo and in vitro. In practice, to date, only in vitro usage has proven clinically and experimentally useful. The design of effective immunotoxins is based on utilizing cellular entry mechanisms or entry mechanisms inherent in the parent toxins to cross the plasma membrane barrier to the cytosol compartment where the toxins exert their effects. Knowledge in the area of receptor-mediated protein transport is expanding rapidly and new immunotoxins with increased efficiencies are anticipated.

Emulsion and activated carbon in cancer chemotherapy.

Abstract: Based on a lipid-absorbing ability of lymphatic capillaries, a fat emulsion containing anticancer agents was applied to selectively deliver more increasing amounts of anticancer agents into regional lymph nodes. The emulsions, in which the drug solution is contained as the innermost phase or as oily soluble drug, yield high drug concentrations in the lymphatic system. Clinical trial of the emulsion method was carried out preoperatively for 180 patients with stomach cancer. As a result, the emulsion enhanced the chemotherapeutic effect of the anticancer agent on lymph node metastasis. About a 20 m mu-sized activated charcoal, in which anticancer agents were absorbed, selectively delivered the anticancer agents to the lymphatic system. The activated charcoal was also excellent carrier material for the lymphatic system, and we have applied it to patients with lymphatic metastasis.