Transdermal delivery, medications

As shown in Fig. 1, the speed of nicotine uptake in venous blood following several forms of nicotine delivery varies widely, from that of the very slow pattern of nicotine appearance in the blood (several hours to peak level) produced by current transdermal nicotine medications to the explosive rise produced by tobacco smoke inhalation. Nicotine gum, lozenge, tablet, and vapor inhaler can provide more rapid delivery of nicotine than the patch, but the speed and amount obtained are constrained by use patterns. Smokeless tobacco products deliver their nicotine more rapidly than nicotine gum and with less physical effort, but are still slower than cigarettes in their nicotine dehvery. 

Transdermal delivery of certain APIs is now common for the treatment of some medical conditions, and there are several excipients that are promoted as transdermal penetration enhancers. One of the earlier materials developed was laurocapram (Azone ). There is a detrimental interaction between laurocapram and mineral oil (liquid paraffin) whereby when both are included in the same formulation, the skin penetration-enhancing properties of laurocapram are lost. Such interactions have implications for extemporaneous mixing of different cream and ointment formulations in the pharmacy. 

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. 

Figure 8.6 Plasma concentration versus time profiles obtained following administration of different transdermal nitroglycerin systems for 24 hours (Modified from Transdermal Delivery Systems A Medical Rationale. Cleary, G.W. In Topical Drug Bioavailability, Bioequivalence, and Penetration. Shah, V.P. and Maibach, H.I. Eds. Plenum Press, New York, 1993, pp 17-68)...

TransPharma-Medical, an Israeli-based pharmaceutical company, is investigating the transdermal delivery of human parathyroid hormone fragment for the treatment of osteoporosis in addition to the delivery of human growth hormone [41], This technology utilizes a 1-cm2 patch that creates small channels or holes in the stratum... 

Cleary, G. W. 1993a. Transdermal delivery systems A medical rationale. In Topical drug bioavailability, bioequivalence, and penetration, edited by V. P. Shah, and H. I. Maibach. New York Plenum Press, pp. 17-68. 

Medical grade TPU are used mainly in transdermal patches, medical tubing, oxygen masks, catheters, drug delivery devices, IV connectors and cuffs. They are also used for bone repair... 

III. Group Silicone elastomers intended for medical use on skin, e.g., transdermal delivery system, patches, medical use [25-32] ... 

Transdermal drug-delivery systems offer several important adventages over more traditional approaches, in addition to the benefits of avoiding the hepatic first-pass effect. Transdermal drug delivery systems (TDDS) are usually in the form of patches incorporating pressure sensitive adhesives. There are two basic designs for transdermal patches matrix or reservoir type. Matrix-type patches include monolithic adhesive and polymer matrices, whereas reservoir-type patches include liquid and solid-state reservoirs [71-73]. For various types of transdermal delivery systems, medical grade adhesive silicones are used as [73,74] ... 

Another technology that we have advanced for systemic treatment is the transdermal therapeutic system (TTS) for release of drug through intact skin into the circulation. The transdermal delivery system represents a major breakthrough. Previously we really had only two approaches to giving medication systemically tablets, which go back to the Egyptians, and injectable dosage forms, invented about a century ago. The transdermal system is potentially far superior to both. 

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