Excipient drug delivery system

One useful drug delivery system is derived from polymers that contain acid-labile linkages in their backbones because hydrolysis rates of such polymers can be readily manipulated by means of acidic or basic excipients physically incorporated into the matrix (2). Further, under certain conditions the hydrolysis of such polymers can be... 

Cytotoxicity Studies Cell culture models have been employed to determine the cytotoxicity of new chemical entities, drug delivery systems, and excipients. Various techniques are available to assess cytotoxicity and cell... 

Drug development work also includes formulation, stability studies, and selection of drug delivery systems, as discussed in Section 5.6. Once the API has been prepared, excipients are added ... 

Pharmaceuticals, for the purpose of this book, means chemical compounds that are used in pharmaceutical production. This can comprise the active ingredient, which is also called active pharmaceutical ingredient (API) or drug substance or drug product and the inert pharmaceutical ingredients (excipients) that are used to formulate a drug product in the form of tablets, capsules, ointments, creams, lotions, parenterals, inhalers, and a variety of drug delivery systems. 

Excellent accessibility to the buccal mucosa makes application of the dosage form painless. It ean be preeisely loeated, and is easily removed without diseomfort at the end. The oral cavity consists of a pair of buccal mucosae. Hence, a drug delivery system can be applied at various sites, on the same mucosa or on the left or right buccal mucosa on different applications. This is particularly advantageous if the delivery system contains a drug or excipient whieh mildly and reversibly damages or irritates the mucosa. 

There are few occasions where a drug is delivered alone in a pure form into the body, but it is usually combined with other materials (called excipients) to form drug delivery systems ( medicines , formulations or dosage forms ). These promote accurate dosing, therapeutic effectiveness, stability and patient acceptability. By far the most common route for delivering drugs into the body is by the oral route, swallowing a tablet or capsule. 

Excipients manufacture The manufacture of novel excipients may be provided in an application or supporting DMF. Typically these excipients are noncompendial and are used in specialized dosage forms and drug delivery systems. CDER chemists are responsible for the scientific reviews and evaluation of the records and data associated with the manufacture of these novel excipients. The review will include starting materials, key intermediates, reagents, and solvents. cGMP inspections by the Field usually will be performed on request from CDER. 

More recently, we have seen the development of drug delivery systems as a specialized sector in the pharmaceutical industry. This whole concept is based on the interaction of excipients with the API and manufacturing process, and sometimes with other excipients, to produce a formulation of a medicinal product that meets a particular performance specification. 

Many interactions will directly influence the efficacy of the product, and thus potentially the health and/or treatment of the patient. However, it must be reemphasized that excipient interactions are not always detrimental. Sometimes they can be used to our advantage, particularly in the areas of product manufacture and drug delivery systems (see below). 

Another example of an excipient-excipient interaction that can be used to our advantage is the one between xanthan gum and locust bean gum (carob gum or cer-atonia) in the presence of water. This interaction forms the basis of the identification test for Xanthan Gum NF. The interaction creates a much more viscous gel system than can be created using either component alone. This has been used in the formulation of controlled release oral solid dosage forms in the TimeRx drug delivery system (11). 

We include certain excipients in a formulation specifically because they interact with the physiological fluids and the bodily functions in a certain way. For example, as discussed above, we include disintegrants in immediate release tablet and capsule formulations, because we know that when they encounter the aqueous environment of the stomach, they will cause the tablet or capsule to disintegrate and thereby aid dissolution of the API. Another example is the general case of hydrophilic colloid matrices used as prolonged release drug delivery systems. We know that when these materials contact the aqueous environment of the GIT they swell and create a diffusion barrier that slows the rate of dissolution of the dissolved drug. 

Intimately related to these factors is the design of the device, formulation, and the interface with the patient. Much of the discussion below will focus on the implications of excipients on formulation challenges for inhaled aerosol products. This chapter summarizes excipients for pulmonary formulations from several perspectives (i) excipient selection based on principles of delivery, (ii) physicochemical requirements for excipients, and (iii) specific challenges for formulations faced with aerosol drug delivery systems, including (a) biological aspects, (b) microbiological aspects, (c) analytical issues, and (d) future prospects. 

Figure 1 Increasingly complex drug-delivery systems erode definitive differentiation between drug and excipient. ...

Excipient Development for Pharmaceutical, Biotechnology, and Drug Delivery Systems... 

We certainly hope that this book will encourage regulatory authorities to develop new regulatory processes for independent review and use of excipients. The availability of independent review will encourage innovation and development of commercially viable new excipients. Ultimately, all this should help quickly develop lifesaving drug delivery systems benefiting humans. 

Factors affecting the delivery include the physical form of the drug, the entry into the body, the design and the formula of the product. This may depend on the physicochemical properties of the excipients, the control of the drug-excipient interaction at the absorption site. Thus, polysaccharides may play an essential role for effectiveness and reliability of the different drug delivery systems. 

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