Drug delivery system

Drug delivery refers to approaches, formulations, technologies, and systems for transporting a pharmaceutical compound in the body as needed to safely achieve its desired therapeutic effect. It may involve scientific site-targeting within the body, or it might involve facilitating systemic pharmacokinetics; in any case, it is typically concerned with both quantity and duration of drug presence. Drug delivery is often approached via a drug's chemical formulation, but it may also involve medical devices or drug-device combination products. Drug delivery is a concept heavily integrated with dosage form and route of administration, the latter sometimes even being considered part of the definition. Drug delivery technologies modify drug release profile, absorption, distribution and elimination for the benefit of improving product efficacy and safety, as well as patient convenience and compliance. Drug release is from: diffusion, degradation, swelling, and affinity-based mechanisms. Some of the common routes of administration include the enteral (gastrointestinal tract), parenteral (via injections), inhalation, transdermal, topical and oral routes. Many medications such as peptide and protein, antibody, vaccineand gene based drugs, in general may not be delivered using these routes because they might be susceptible to enzymatic degradation or can not be absorbed into the systemic circulation efficiently due to molecular size and charge issues to be therapeutically effective. For this reason many protein and peptide drugs have to be delivered by injection or a nanoneedle array. For example, many immunizations are based on the delivery of protein drugs and are often done by injection. Current efforts in the area of drug delivery include the development of targeted delivery in which the drug is only active in the target area of the body (for example, in canceroustissues), sustained release formulations in which the drug is released over a period of time in a controlled manner from a formulation, and methods to increase survival of peroral agents which must pass through the stomach's acidic environment. In order to achieve efficient targeted delivery, the designed system must avoid the host's defense mechanisms and circulate to its intended site of action. Types of sustained release formulations include liposomes, drug loaded biodegradable microspheres and drug polymer conjugates. Survival of agents as they pass through the stomach typically is an issue for agents which cannot be encased in a solid tablet; one research area has been around the utilization of lipid isolates from the acid-resistant archaea Sulfolobus islandicus, which confers on the order of 10% survival of liposome-encapsulated agents. Controlled drug delivery technology has progressed over the last six decades. This progression began in 1952 with the introduction of the first sustained release formulation. The 1st generation of drug delivery (1950–1980) focused on developing oral and transdermal sustained release systems and establishing controlled drug release mechanisms. The 2nd generation (1980–2010) was dedicated to the development of zero-order release systems, self-regulated drug delivery systems, long-term depot formulations, and nanotechnology-based delivery systems. The latter part of the 2nd generation was largely focused on studying nanoparticle formulations. The Journal of Controlled Release (JCR) has played a pivotal role in the 2nd generation of drug delivery technologies, and it will continue playing a leading role in the next generation. The best path towards a productive 3rd generation of drug delivery technology requires an honest, open dialog without any preconceived ideas of the past. The drug delivery field needs to take a bold approach to designing future drug delivery formulations primarily based on today's necessities, to produce the necessary innovations. The JCR provides a forum for sharing the new ideas that will shape the 3rd generation of drug delivery technology. The contribution of the JCR to the drug delivery field can be best understood by examining the history of controlled drug delivery technologies. Table 1 describes the three generations of drug delivery. The first controlled release formulation was introduced by Smith Kline & French in 1952 for 12-hour delivery of dextroamphetamine (Dexedrine). Since then, until the end of the 1970s, the basic understanding of controlled drug delivery was established, such as different drug release mechanisms including dissolution-, diffusion-, osmosis-, and ion exchange-based mechanisms. The technologies developed during the 1st generation were used to develop numerous twice-a-day and once-a-day oral delivery systems. The same drug release mechanisms were also used to develop once-a-day and once-a-week transdermal patches. The JCR was launched at the beginning of the 2nd generation of controlled drug delivery technologies. Table 1 During the last 30 years, numerous articles on various topics have been published. The topics cover all aspects of drug delivery science. Because of the complexity and interdependence of the topics, it is difficult to classify the published articles in certain categories, e.g., based on the drug release mechanisms, drug types, polymers, or drug delivery routes. Such classification may be useful in understanding the trend in drug delivery research over time, but the large number of articles with numerous variations in formulations and applications makes it very difficult. Since the ultimate goal of drug delivery research is to develop formulations that can be used in clinical applications to treat various diseases, the drug delivery research can be cataloged as shown in Fig. 1. The advances that will take place in drug delivery technologies during the next 30 years are difficult to predict. Regardless of the new technologies developed, however, the diseases to treat and the hurdles to overcome for improved drug delivery will not change significantly from our current needs. Improved drug delivery technologies will have to solve the problems listed in Table 1. The demand for developing modulated insulin delivery systems will continue to increase, as the number of patients with diabetes continues to rise. Targeted drug delivery to tumors, which has been the main research focus for more than a decade will not suddenly diminish. The ability to deliver a drug for long-term, i.e., 6 months or longer, for treating chronic diseases will be essential in improving the compliance of patients. Furthermore, innovative in vitro testing methods will have to be developed to accurately predict the in vivo pharmacokinetic of drugs and drug formulations in humans. By Garibli A. References: 1. https://en.wikipedia.org/wiki/Drug_delivery ?2. https://www.sciencedirect.com/science/article/pii/S0168365914002508 ?