Patches, absorbent

Transdermal patches arc applied to the skin. The drug is mixed with the adhesive for the patch, and so it lies next to in readily absorb many chemicals and so uch as nitroglycerin (for heart disease),... 

Fibers of the conducting polymer polypvrrole are woven into radar camouflage cloth. Because it absorbs microwaves, rather than reflecting them back to their source, the cloth appears to be a patch of empty space on radar. 

An alternative to the oral route is the buccal mucoadhesive system. The Striant buccal system adheres to the inside of the mouth and the testosterone is absorbed through the oral mucosa and delivered to the systemic circulation. There is no first-pass effect, as the liver is bypassed by this route of administration. Patients apply a 30-mg tablet to the upper gum twice daily. The cost is similar to that of the patch or gel. Side effects unique to this dosage form include oral irritation, bitter taste, and gum edema. 

Other than possibly for the insensible perspiration they absorb, transdermal patches tend to operate as thermodynamically static systems, meaning as com-positionally fixed systems, from the moment they are applied until their removal. Marketed ethanol-driven estradiol and fentanyl patches are exceptions because they meter out ethanol and drive it into the stratum corneum to propel the absorption process. Compositional steadfastness is still the rule, however, and it is this feature that bestows the zero-order delivery attribute on the ordinary transdermal patch. Drug is present within the patches in reservoir amounts whether or not the reservoir compartment is easily distinguished, for there must be enough drug to sustain delivery over the full course of patch wear. 

Although most drugs are absorbed from the intestine by the blood capillary network in the villi, they can also be taken up by the lymphatic system (an integral and necessary part of the vascular system, the function of which is to collect extra tissue fluid and return it to the vascular compartment), particularly by M cells that reside in the Peyer s patch regions of the intestine. Peyer s patches have also been implicated in the regulation of the secretory immune response. Wachsmann et al. [277] reported that an antigenic material encapsulated within a liposome, when administered perorally, is taken up by these M cells and exhibited better saliva and serum IgA (primary and secondary)... 

Trospium chloride, a quaternary ammonium drug (Fig. 7.45), appears to be a substrate of P-gp, and it can be taken up by cells quicky [597]. The evidence for transmembrane diffusion appears substantial. The molecule is very soluble in water (>50 mg/mL), but not in lipids (9.2 pg/mL in mineral oil) the octanol-water log Kp is —1.22 [598]. The human intestinal absorption (HIA) is 11% the molecule is not metabolized. In cell intestinal patch uptake studies, trospium is absorbed from a... 

In this study, 4.4 mg of lead equivalent was applied to the skin under a covered wax/plastic patch on the forearms of human subjects of the applied dose, 1.3 mg of lead was not recovered from skin washings. The amount that actually remained in (or on) the skin and the mass balance of the fate of this lead was not determined it may have been absorbed or eliminated from the skin by exfoliation of epidermal cells. Thus, while this study provides evidence for dermal absorption of lead, it did not quantity the fraction of applied dose that was absorbed. The quantitative significance of the dermal absorption pathway as a contributor to lead body burden remains an uncertainty. The wax/plastic patch provided a means by which the lead compounds could permeate or adhere to the skin. The effect of concentration in aqueous solution may cause skin abrasion through enhanced acidity since the lead ion is acidic. Abraded skin is known to promote subsequent higher lead penetration. 

If the first volume of Capital is difficult to absorb, the reader of the second volume, where the reproduction schemes are located, faces an even greater challenge. Due to the unfinished form of the material, which Engels assembled from Marx s notes, it is generally agreed that it lacks coherence. Engels viewed the part of the material on the reproduction schema as excellent in content, but fearfully heavy in form, patched together from two treatments of the problems by two different models (quoted in Zarembka 2000 197). 

Transdermal and Topical Administration Transdermal administration is used to apply the drug on the skin surface. The drug is absorbed and transported by blood to receptors, which may be remote from the part of the skin where the transdermal patch is. The flrst pass metabohsm is circumvented. Topical administration is used to apply the drug for local effects. The typical areas for topical application are the skin, eyes, throat, nose, and vagina. 

In nicotine replacement therapy, the chewing gum releases nicotine, which is absorbed through the buccal mucosa every time a piece of chewing gum is chewed. The chewing gum is chewed for 30 minutes, only when one feels the urge to smoke. The transdermal patch provides a residual nicotine level throughout the application. A side-effect of nicotine chewing gum may be aphthous ulcers. 

Turpentine from any source is a skin irritant if allowed to remain in contact for a sufficient length of time hypersensitivity occurs in some persons. A study of nearly 85,000 patients between 1979 and 1988 from five different countries found that fewer than 1.8% had positive patch tests to 10% turpentine in oil." The liquid can be absorbed by the skin and mucous membranes, and intoxication by this route has been reported. ... 

As a transdermal patch (from which the drug is absorbed through the skin)... 

---