Transdermal delivery system

The nitrates are available in various forms (eg, sublingual, transmucosal, translingual spray, and inhalation). Some adverse reactions are a result of the metiiod of administration. For example, sublingual nitroglycerin may cause a local burning or tingling in the oral cavity. However, die patient must be aware that an absence of this effect does not indicate a decrease in the drug s potency. Contact dermatitis may occur from use of die transdermal delivery system. 

Transdermal Delivery—Attributes of Transdermal Delivery Systems... 

We tend to think of them being much the same, but the functioning of semisolid dermatological products stands in stark contrast with that of transdermal delivery systems. To begin with, most topical applications... 

The development pharmaceutics section of the application should address the clinical need for a transdermal delivery system and the appropriateness of the active ingredient for this type of product based on... 

Dissolution testing has become an important component of the assessment of the quality of solid oral dosage forms and oral suspensions. The basic procedures for these oral dosage forms have been extended to transdermal delivery systems as well. The release rate for modified-release oral dosage forms adds a level of sophistication to the concept of dissolution testing, setting acceptance criteria at multiple time points. 

Various dissolution test systems have been developed and several of them now enjoy compendial status in pharmacopeias, for example the reciprocating cylinder (United States Pharmacopeia Apparatus 3), the flow-through apparatus [European Pharmacopoeia (Pharm. Eur.) 2.9.3], or the apparatus for transdermal delivery systems, such as the paddle over disc. Hydrodynamic properties of these and other apparatus have been described only sparingly. The paucity of quantitative data related to hydrodynamics of pharmacopeial dissolution testers is lamentable, since well-controllable hydrodynamics are essential to both biopharmaceutical simulations and quality control. Here, we focus the discussion on the paddle and the basket apparatus, since these are the most important and widely used for oral solid dosage forms. A brief treatise on the hydrodynamics of the flow-through apparatus completes this section. 

S. T. K. Narishetty and R. Panchagnula. Transdermal delivery system for zidovudine In vitro, ex vivo and in vivo evaluation. Biopharm. Drug Dispos. 25 9-20 (2004). 

Continuous sequential regimen - It can be applied as a sequential regimen in combination with an estradiol-only transdermal delivery system. 

While uncontrolled topical delivery of proteins and peptides for local application such as open wound healing is easily achieved, it is much more challenging to use transdermal delivery systems to deliver protein across intact skin. In theory, transdermal delivery could provide constant drug release for days, avoids first-pass metabolism, and could allow drug effects to be rapidly terminated by simply removing... 

The MAO-B inhibitor, l-deprenyl, has been approved by the FDA for use in Parkinson s disease. At the lower dose range, it does not interact with tyramine. As mentioned earlier, there is preliminary evidence of antidepressant efficacy for a transdermal delivery system for selegiline. This formulation does not interact with tyramine to produce a hypertensive crisis (181). 

Andersson TL, Stehle B, Davidsson B, Hoglund P. Bioavailability of estradiol from two matrix transdermal delivery systems Menorest and Climara. Maturitas 2000 34(l) 57-64. 

Approved packaging is normally selected after completing package performance qualification testing as well as product compatibility and stability studies. Since in most cases (exceptions transdermal delivery systems, diagnostic tests, and medical devices) packaging is not intimately involved in the manufacturing process of the product itself, it differs from other factors, such as raw materials. 

A transdermal is one such drug. What does the term transdermal mean Trans means through and dermal means skin, therefore a transdermal drug is one absorbed through the skin. The United States Pharmacopeia CUSP) 24 [1], offers the following definition/discussion of a transdermal delivery system ... 

OBJECTIVE To validate the manufacturing process for transdermal delivery systems by... 

CONCLUSIONS The process for manufacturing transdermal delivery systems has been... 

Transdermal iontophoresis involves the application of an electric field across the skin to facilitate (primarily) ionic transport across the membrane. Iontophoresis, it is important to point out, is differentiated from electroporation [14], another electrical approach to enhance transdermal transport, by the low fields employed. Whereas iontophoresis has achieved commercialization, there is (to our knowledge) no active development in progress of a transdermal delivery system employing electroporation. 

Koo PJ. Postoperative pain management with a patient-controlled transdermal delivery system for fentanyl. Am J Health Syst Pharm. 2 00 5 62 1171-1176. 

A. Wiegand, K. Bauer, R. Bonn, et al. Pharmacodynamic and pharmacokinetic evaluation of a new transdermal delivery system with a time-dependent release of glyceryl trinitrate. J. Clin. Pharmacol. 32 77—84, 1992. 

Cutaneous biotransformation is mostly associated with the stratum basale layer where there can be phase I and phase II metabolism. However, the skin is not very efficient, compared to the liver. The epidermal layer accounts for the major portion of biochemical transformations in skin, although the total skin activity is low (2-6% that of the liver). Where activity is based on epidermis alone, that layer is as active as the liver or, in the case of certain toxicants, several times more active. For some chemicals, metabolism can influence absorption, and transdermal delivery systems of drugs utilize this activity. For example prodrug such as lipid esters are applied topically, and cutaneous esterases liberate the free drug. These basal cells and extracellular esterases have been shown to be involved in detoxification of several pesticides and bioactivation of carcinogens such as benzo(a)pyrene. For rapidly penetrating substances, metabolism by the skin is not presently considered to be of major significance, but skin may have an important first-pass metabolic function, especially for compounds that are absorbed slowly. 

Kanikkannan, N. 2002. Iontophoresis-based transdermal delivery systems. BioDrugs 16 339-347. 

Transdermal Delivery Systems. Transdermal delivery of drugs over extended periods of time for systemic therapy has received significant attention. The importance and future prospects of this field are further reflected in the section on Transdermal and Transmucosal Delivery Systems (Chapters 17-23). Intact human skin, once thought to be an impermeable barrier, was realized as a potential portal of entry for systemic drug therapy only recently. 

Such design criteria have been successfully utilized in commercially available membrane-reservoir type of transdermal delivery systems for scopolamine, nitroglycerin, and more recently, estradiol (40,41). 

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