Showing papers in "Critical Reviews in Therapeutic Drug Carrier Systems in 1996"

Transfersomes, liposomes and other lipid suspensions on the skin: permeation enhancement, vesicle penetration, and transdermal drug delivery.

Abstract: Agents with MW > 50%) and reproducibly various agents (200 < or = MW < or = 10(6); lipophilic/hydrophilic) into the body. Transfersomes were successfully used in animals and humans, also for the transcutaneous peptide and protein delivery. The theoretical rational for this is described together with the corresponding experimental models and practical examples.

Saponins as vaccine adjuvants.

Abstract: Naturally occurring triterpene glycosides (saponins) from Quillaja saponaria have considerable adjuvant activity. Adjuvant functions include stimulation of high levels of antibody to T-dependent and T-independent antigens, induction of mouse IgG1, IgG2b, and IgG2a isotypes, and induction of cytotoxic T lymphocyte responses. This article reviews responses due to specific saponins of saponin preparations, effect of formulation, structure/function studies, and use in different preclinical and clinical vaccine applications.

Systemic delivery of peptides and proteins across absorptive mucosae.

Abstract: As therapeutic peptides and proteins become readily available through rapid advances in recombinant technology, and because rapid presystemic elimination renders them ineffective when administered orally, pharmaceutical scientists are faced with the challenge of delivering these macromolecules systemically; therefore, alternative routes of delivery need to be investigated Transmucosal delivery through absorptive mucosae represents one of these alternatives This route has the advantage of being noninvasive and of bypassing hepatogastrointestinal clearance The absorptive mucosae that have been investigated for delivery of peptides and proteins include buccal, nasal, pulmonary, rectal, and vaginal Nasal delivery has been studied extensively and has been the most successful--nasal sprays for buserelin, desmopressin, oxytocin, and calcitonin are already available commercially In general, enzyme inhibitors and permeation enhancers need to be coadministered for successful delivery of these biopharmaceuticals Classes of enhancers used for transmucosal delivery include bile salts, dihydrofusidates, cyclodextrins, surfactants, and chelating agents Each of these agents exerts its enhancing effects by a different mechanism, and each has been associated with adverse effects This article discusses the physiology of each of the mucosae used, the fundamentals of transmucosal delivery, and recent progress in systemic delivery of therapeutic peptides and proteins across each of the mucosae; in an effort to highlight principles of transmucosal delivery, it also discusses the transmucosal delivery of enkephalin, calcitonin, and insulin as case studies

Current Applications of Polysaccharides in Colon Targeting

Abstract: Polysaccharides have over the years been used widely in pharmaceutical, chemical, and biochemical drug delivery. This family of natural polymers has an appeal to the area of drug delivery as it is comprised of polymers with a large number of derivatizable groups, a wide range of molecular weights, varying chemical compositions, and for the most part, a low toxicity and biodegradability, yet a high stability. The main scope of this review is to relate the polysaccharides available now to the rapidly growing field of colonic drug delivery. Polysaccharides have been applied to the area as controlled release coatings, matrices, macromolecular carriers, and biodegradable carriers. Bacterial sources of polysaccharidases as well as a detailed treatise of the enzymatic flora of the colonic region are discussed, followed by a presentation of the polysaccharides available for the purpose of colon-specific drug delivery. A final overview of the various approaches to obtain colon-specific delivery by using polysaccharides and a summary of available in vitro and in vivo testing methods will lead to the conclusion that polysaccharides at this point appear to be very promising compounds for use in obtaining colon-specific drug delivery systems.

Drug delivery to lymphatic tissue.

Abstract: Efficient diagnosis and therapy of diseases affecting lymph nodes rely on the availability of drugs that are retained by lymph nodes. Intralymphatically or interstitially administered macromolecular carriers accumulate efficiently in draining lymph nodes. However, because of the high variability of lymphatic networks and drainage routes, systemic administration of lymphotropic carriers would be preferable and currently represents a major focus in lymphotropic drug design. This review focuses on advances in the development of intravenous drug carriers and briefly discusses agents used for local delivery.

The Role of Scanning Probe Microscopy in Drug Delivery Research

Abstract: The success of a drug delivery system is often dependent on the surface properties of the device. These surface properties will determine the complex dynamic interfacial events that occur when the system is introduced into the aqueous environment of a patient. Development of the scanning probe microscopes has provided a number of very powerful new surface analytical techniques that are making a significant contribution to the characterization of drug delivery systems and the interfacial processes that occur when such systems are exposed to aqueous living environments. In this review, we describe the design and attributes of these instruments and discuss the impact of the techniques on a wide range of drug delivery research. The scanning probe microscopes are providing new insights into important problems concerning drug delivery, including the molecular structure of polymeric biomaterial surfaces, the conformation of target biomolecules, the influence of morphology on biodegradation, the adsorption of proteins to synthetic surfaces, and the structure and interactions of colloidal particles. As the whole field of scanning probe microscopy continues to advance, drug delivery research is set to benefit; in the final section of the review, the future potential derived from the ability to characterize new surface properties under aqueous conditions is discussed.