Drug delivery methods

Relenza ) in 1999. The polar nature of Relenza precluded significant oral absorption, and therefore an infraoral inhalation drug delivery method was developed that delivered the drug to the primary site of infection. 

This review of PCL and its copolymers is largely drawn from the nonpatent literature and focuses primarily on aspects relevant to drug delivery. Methods of polymerization are considered at some length because of the impact on polymer structure and morphology, which in turn determine the permeability and biodegradability of the product. 

Lead optimization of new chemical entities (NCEs) based on pharmacokinetic behavior plays a major role in modern drug discovery. Despite advancement of drug delivery methods, the oral route remains the most frequent route of administration for approved new drugs. Therefore, during lead optimization it is essential to identify NCEs with sufficient oral absorption predicted using a variety of in vitro and in vivo assays. It is well recognized that in order for a NCE to achieve reasonable oral absorption, it will need to have adequate aqueous solubility, as well as intestinal permeability [1], Recent advancements in chemistry, such as parallel and combinatorial synthesis, have resulted in a multifold increase in the number of compounds that are available for evaluation in new drug discovery. Furthermore, a variety of improved structural chemistry... 

Park, K., and Robinson, J.R., Bioadhesive polymers as platforms for oral controlled drug delivery method to study bioadhesion, Int. J. Pharm., 19 107-127 (1984). 

The most common drug delivery method for treating ocular disorders is topical administration, due to its convenience and safety. However, the anterior segment of the eye also has various protective mechanisms for maintaining visual functions. After instillation of an ophthalmic drug, most of it is rapidly eliminated from the precorneal area due to drainage by the nasolacrimal duct and dilution by the tear turnover (approximately 1 pL/min) [17,18]. In addition, there is a finite limit to the size of the dose that can be applied and tolerated by... 

Provides consideration of a variety of emerging dermal, nasal, and ocular drug delivery methods... 

A therapeutic substance can be administered to a patient via a number of pathways. Oral delivery (by the mouth) was among the very first drug delivery methods used in the pharmaceutical industry [26]. Drugs may also be transferred to the alimentary channel via sublingual (under the tongue) or rectal (to the rectum) administration. 

Pan Y, Li YJ, Zhao HY, Zheng JM, Xu H, Wei G, Hao JS, Cui FD (2002) Bioadhesive polysaccharide in protein delivery system chitosan nanoparticles improve the intestinal absorption of insulin in vivo. Int J Pharm 249(1-2) 139-147 Park K, Robinson JR (1984) Bioadhesive polymers as platforms for oral-controlled drug delivery method to study bioadhesion. Int J Pharm 19 107-127 Patel H, Ryman BE (1981) Systemic and oral administration of liposomes. In Knight CG(ed) Liposomes From Physical Structure To Therapeutic Applications, Elsevier, Amsterdam, pp 409-441... 

Macromolecular Drug Delivery Methods and Protocols, edited by Mattias Belting 2009 479. Plant Signal Transduction Methods and... 

The nanomaterials thus manufactured in different industries—particularly drugs and pharmaceuticals— might pose risks to human health and other organisms due to their composition, reactivity, and unique size. Nanotechnology research and development, particularly in medical research, work at the micro- and nanoscale levels to develop new drug delivery methods, therapeutics, and pharmaceuticals. In such areas of research it is equally important to consider the potential interactions of nanomaterials with the environment and the associated risks. This involves studying the effects of natural nanoparticles in the air and soil, life cycle aspects of manufactured nanomaterials, and their fate and transport. Risk assessment also includes studies... 

The first commercially available DPI system appeared on the market in 1949, developed and marketed by Abbott under the name Aerohaler. Like all pulmonary drug-delivery methods that existed before now, it delivered small molecule compounds (brochodilators or inhaled corticosteroids) to the airway (not necessarily to the deep lung) for the treatment of asthma or chronic obstructive pulmonary disease. Table 6 lists some of the early DPI systems and their basic characteristics. 

This chapter is divided into three sections. In Section 4.2, the two most relevant physicochemical properties for drug delivery, solubility and stability, are discussed. In addition to providing a basic understanding of the importance of solubility and stability to drug delivery, methods to enhance solubility and physical and chemical stability are described. Section 4.3 focuses on the processes required for the proper drug formulation. Since most drugs are administered in the solid state, the formulation process for tablets is described in detail. Finally, Section 4.4 discusses some of the basic drug delivery methods, with an emphasis on the physicochemical properties that impact those methods. 

Continued revenues after expiry of patent. A new drug delivery method can continue to generate revenues for the manufacturer years after expiry of the patent for the original active ingredient. This may sometimes exceed the earnings from the original product. 

As in all instantaneous absorption models, the entire absorbed dose of drug is taken to enter the systemic circulation instandy at time zero (< = 0). This provides an excellent approximation of the rapid drug delivery direcdy into the systemic circulation provided by a bolus IV injection, which truly occurs over a very short period of time (typically several seconds). However, this assumption does not actually require a strict interpretation of the word instantaneous. Even if an absorption process takes a substantial period of time (minutes or hours), it can still be approximated as instantaneous as long as absorption occurs quickly relative to other ADME processes. Thus, other routes of drug delivery besides a bolus IV injection can be approximated by instantaneous absorption if the time it takes for the absorption process to be essentially complete is very small compared to the half-life of elimination. The equations throughout most of this section are written specifically for a bolus IV injection, but modifications that can be employed to apply the equations to other drug delivery methods are described in Section 10.7.5. 

Marks J D (2004). Selection of internalizing antibodies for drug delivery. Methods Mol. Biol. 248 201-208. 

Alternative Drug Delivery Methods for Peptides and Proteins... 

As evident from the previous discussion, a major barrier to the use of peptides as clinically useful drugs has to do with their poor delivery properties, because proteolytic enzymes present at most routes of administration are able to quickly metabolize most peptides. Peptides and proteins are, for the most part, hydrophilic in nature and, for this reason, do not readily penetrate lipophilic biomembranes. As well, they have short biological half-lives because of rapid metabolism and clearance, all of which deters from their efficient use in drug therapy. It is for these reasons that alternative drug delivery methods for peptides and proteins are an area of particular interest to the pharmaceutical industry. 

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