Comparison of Drug Delivery Systems

Comparison of Drug Delivery Systems1. INTRODUCTION1.1. Current berth of Drug Delivery SystemsDuring the past two decades, Drug development technology in Pharmaceutical Industry with innovations in formulation development have sure a lot of attention. Drug economy as an opportunity to extend merchandise life cycles has indeed proved its place in the market with meaningful advantages of therapeutic gains as well as commercial success. In India drug development technology is still in nascent stage with academia and look for institutes collaboration as main stay of the development of allegory products. The main motto of Indian companies, in the development of newer pharmaceutical formulations by using NCE in order to achieve by providing cost effective, therapeutically effective with short term and long term options. While development in the verbal travel plan is still the main focus, pulmonary, cutaneous, transdermal and other multiple routes are gaining increased attention1.T he application of neo technology in the field of drugs administered via oral, parenteral, pulmonary and intra-ocular finds a newer, reveal than the conventional dosage forms is an important era in the drug delivery. The health scenario in India demands Novel Drug Delivery Systems (NDDS) for more than 20 diseases and conditions for which rationale for such system is established. More than half of these conditions are prevalent in India and other developing and under-developing countries only and offer a expectant challenge and opportunity for the Indian Pharmaceutical Industry2.A number of drug delivery platform technologies currently exist that may be adapted to various drug molecules to yield A-one medicines. Such medicines while offering obvious benefits to patients will also generate a more stable and patent protected revenue stream3.Although the drug delivery concept is not new, a great progress has recently been done in the treatment of variety of diseases. Targeting deliv ery of the drugs to the lesions and controlling the kick rate at the site of action is the most important aspect of Drug Delivery System. Research is being carried out throughout the world at a great place, devising strategies for drug delivery to overcome biological barriers and the physiochemical properties of the modern drugs. Above all the prominence of drug delivery systems can be understood by the variety that out of the $250 billion worldwide value of pharmaceuticals, 10% is attributed to it4.In this context controlled drug delivery along with targeted drug delivery forms the essence of modern and future drug delivery systems.1.2. Controlled Drug Delivery SystemsAs the name implies, CDDS serves two functions. First it involves transport of the drug to particular part of the body and the sulfur function is that of the controlled release.The main advantages of Controlled drug delivery systems areMaintenance of optimum therapeutic drug concentration in the blood with minimum f luctuations.Predictable and uniform delivery for extended duration.Enhancement of activation duration for short half life drugs.Minimizes the side effects.Reduce the frequent dosing.Reduce the wastage of drug.Better patient compliance.1.2.1. verbal Controlled drug Delivery SystemsOral controlled release technology was evolved with matrix technology. Several research papers in the 1950s and 1960s reported as transparent matrix tablets or monolithic granules. In 1952, a new formulation spansule a timed- release formulation was introduced by Smith Kline French which launched a far-flung search for other applications in the design of dosage forms. Advances in oral controlled release technology are attributed to the development of novel biocompatible polymers and machineries that allow preparation of novel design dosage forms in a reproducible manner5. For controlled release systems, the oral route has by far received most attention and success because of the position that gastro-i ntestinal physiology offers more flexibility in dosage form design than other routes6. Apart from that owing to patient acceptance, convenience of administration, cost-effective manufacturing, and generally long product shelf-life is a continuous emphasis to develop oral formulations will persist. Some of the marketed oral controlled release products were listed in table no.1.1.Table No. 1.1. Marketed oral controlled release products71.2.2. Particulate Oral Drug Delivery SystemIn any drug delivery system the use of carriers to convey a certain treat of the drug is important as drug itself. Various carrier systems in application till date are macromolecular drug carriers, micellar systems, liposomes, red cells and microparticulates. These were apply to carry a wide variety of pharmaceutical agents in a number of different therapeutic situations. Among these chiefly microparticulate carriers has been accounted for an important potential application in the administration of therapeut ic molecules such as sustained drug delivery in cancer and infectious disease or for the administration of gut reactive drugs8.Moreover, due to their size microparticulates are not usually administered through intravenous routes but via alternate routes. Thus, inclusion of drugs in microparticulate carriers clearly holds significant promise for the value in the therapy of several disease categories.They serve many purposes9 such asProtecting the incorporated components from degradationControlling drug releaseIncreasing adjuvancyTargeting to the particularized sites.Due to the unique physiological conditions in the GI tract, the particulate systems are required to meet the following criteria before they can be used as effective oral delivery vehicles10.Firstly they should be resistant to undergo degradation in GI tract.The encapsulated drug in the particles need to be clothed with high efficiency in GI tract to be therapeutically effective. Currently it is believed that, less than 1% of the particles can be absorbed after oral administration.1.3. Biodegradable polymers and MucoadhesionMucoadhesive polymersMucoadhesive polymers11 have properties to get adhered to the mucus membrane and hence capable of prolonging the contact time of the drug with a body tissue. The use of mucoadhesive polymers can importantly improve the performance of many drugs. This improvement ranges from better treatment of local pathologies to improved bioavailability and controlled release to enhance patient compliance.Ideal characteristics of mucoadhesive polymers12It should be able to bear both oil and water soluble drugs for the purpose of controlled drug delivery.It should possess an optimum molecular weight to the mucoadhesive.It should demonstrate local enzyme inhibition and penetration sweetening properties.It should show specificity for attachment to an area or cellular site.It should show specificity and stimulate endocytosis.It should be inert and compatible with the enviro nment.It should be easy and inexpensive to fabricate.It should have wide mechanical strength.It should possess a wide margin of safety both locally and systemically.Microspheres can be defined as solid, approximately spherical particles ranging in size from 1 to 1000 m. They are made of polymeric, waxy or other protective materials, i.e. biodegradable synthetic polymers and modified natural products such as starches, gums, proteins, fats and waxes. Microspheres are small and have large surface to volume ratio. At the lower end of their size range they have colloidal properties. The interfacial properties of microspheres are extremely important, often dictating their activity.Microparticles are of two typesMicrocapsules The entrapped substance is completely surrounded by a distinct capsule wall.Microspheres The entrapped substance is dispersed throughout the microsphere matrix are shown in the Fig 1.1.Fig 1.1. Differentiation between microcapsules and microspheresMicrosphere carrier systems made from the naturally occurring biodegradable polymers have attracted considerable attention for several years in sustained drug delivery. However, due to short residence time at the site of absorption, the success of these microspheres is limited. By providing the drug delivery system a means of intimate contact with the absorbing membrane, these delivery systems would be advantageous which can be achieved by coupling mucoadhesion characteristics to microspheres and developing mucoadhesive microspheres13,14.