Drug delivery systems form development

Since the development of the Spansule brand (Smith Kline Beech am) of coated beads and granules in the late 1960s, various dmg product technologies have been developed and patented to achieve extended durations of therapeutic effects. Each of these does so by various mechanisms of control of dmg release from adrninistered dosage forms. Each method has its advantages and disadvantages, a discussion of which is available in the pharmaceutical hterature (see Drug delivery systems) (21). 

As discussed earlier, noncollagenous proteins, particularly albumin and to a lesser extent gelatin, in the form of microspheres and nanoparticles continue to be exploited as drug delivery systems. Oppen-heim (71) and Speiser (72) reviewed the technology developed to produce ultrafine particles, often referred to as nanoparticles. 

An erodible insert developed as a potential ocular drug-delivery system is marketed as a prescription drug for the lubricant properties of the polymer base. Lacrisert is a sterile ophthalmic insert used in the treatment of moderate to severe dry eye syndrome and is usually recommended for patients unable to obtain symptomatic relief with artificial tear solutions. The insert is composed of 5 mg of hydroxypropylcellulose in a rod-shaped form about 1.27 mm diameter by about 3.5 mm long. No preservative is used, since it is essentially anhydrous. The quite rigid cellulose rod is placed in the lower conjunctival sac and first imbibes water from the tears and after several hours forms a... 

Historically, the oral route of administration has been used the most for both conventional and novel drug-delivery systems. There are many obvious reasons for this, not the least of which would include acceptance by the patient and ease of administration. The types of sustained- and controlled-release systems employed for oral administration include virtually every currently known theoretical mechanism for such application. This is because there is more flexibility in dosage design, since constraints, such as sterility and potential damage at the site of administration, axe minimized. Because of this, it is convenient to discuss the different types of dosage forms by using those developed for oral administration as initial examples. 

Drug-delivery systems are essentially specialized dosage forms developed to overcome the limitations of conventional dosage forms, such as simple tablets, capsules, injectable solutions, etc. Some of the reasons behind the development of oral DDSs are listed below ... 

Compared to classical drug delivery systems such as liposomes or peptides, nanotubes have a higher efficiency [41] and this can be used for the further development of delivery systems. Stability and diversity of nanotube forms provide long time circulation and biocompatibility that result in more efficient transport of substances. 

Solid oral dosage forms containing new chemical entities (NCEs) are commonly formulated into tablets or capsules as their first market image formulation. Subsequent drug product line extension development on these NCEs may evaluate more specialized drug delivery systems. Dissolution testing of standard oral tablets or capsules will commonly utilize the paddle or basket apparatus. In this chapter we focus primarily on the development and subsequent validation of dissolution testing methods that use these two devices. 

The rational development of a drug delivery system can be timely and costly. Formulation development and optimization requires a step-wise approach by Lrst screening and evaluating various formulationsin vitro before one initiates formulations/dosage forms tesfringvo. 

For a very long time, scientists generally underestimated the importance of excipients in pharmaceutical dosage forms. Excipients were cheap ingredients viewed solely as inert supports for medicaments. Today, with modern pharmaceutical excipients on the shelf, development of various novel drug delivery systems, and production with high-speed tablet/capsule machines, excipients are rather more than the sugar in the pill.9,10... 

Carbopol resins also have been used in controlled-release dosage forms. Especially, the resins Noven AA-1 USP and Carbopol 934P NF are being extensively developed in bioadhesive drug delivery systems for topical, bucal or nasal, ocular, and rectal applications (e.g., Fentanyl ). Noven CA-1 USP and CA-2 USP are used as oral laxative and antidiarrheal products in swallowable and chewable tablets. 

A supercritical C02-based technique was applied to produce a biocompatible polymer in form of microspheres. With the SAS process carried out in a batch mode, micronic particles of polymer were obtained with a narrow particle size distribution. Co-precipitation of pharmaceuticals for the production of controlled drug delivery systems has been proposed as a preliminary result, since further analyses are under development. The experimental apparatus is easy-to-use and the purification of the precipitated solid from the solvent can be achieved by suitably increasing the time for solvent removing. 

Although conventional eye drops still represent about 90% of all marketed ophthalmic dosage forms, there have been significant efforts towards the development of new drug delivery systems. 

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