By L. Jose. University of Florida. 2017.
Preparation of drug delivery coatings on stents has several challenges discount epivir-hbv 150 mg line, including some of those mentioned above order epivir-hbv 150 mg with amex. Stents have very low surface area, typically in the range of 1–2 cm2, 124 Anderson et al. The release of the drug from the coating must be coordinated with the intended biological targets, which may be upregulated anywhere from minutes to weeks after the stent implantation procedure. The coating must survive several physical challenges. The coating must also not interfere with the primary function of the stent, which is to physically support the walls of the blood vessel. There are several ways to prepare drug delivery coatings and to control the release of a drug from the stent surface. The method SurModics has employed is to form coatings using combinations of nonbiodegradable polymers and drug, with the objective of achieving a homoge- neous mixture on the surface of the stent. The release of the drug is controlled by the loading of the drug and the composition of the polymer components, both of which influence the rate at which the drug diffuses out of the coating. Additional control of the release can be achieved by applying barrier coatings onto the surface of the drug-containing polymer layer. As an example of the work done at SurModics with drug delivery coatings, we will describe examples involving several model drug compounds. Due to proprietary constraints, these drugs will not be named. Polymer coatings containing drug were prepared by depositing films on stainless steel disks or laser-cut, stainless steel, balloon-expandable stents. Coating solutions were prepared using a blend of two polymers, polyethylenevinylacetate and polybutylmethacry- late (PEVA and PBMA), and drug. The concentrations of components (polymers and drug) were varied to obtain different loading levels of drug, different ratios of drug to polymer, and different ratios of the polymer components.
In so-called cellulite purchase 150mg epivir-hbv mastercard, there is no phlogosis of the cells epivir-hbv 100 mg sale, but perhaps an alteration of interstitial tissues. Why has such an empirical misuse been applied for so long in medicine and everyday life? There was a time when cellulite was conceived as a mere increase of fat in subcuta- neous tissues associated with an altered lymphatic and venous ﬂow and lymphatic stasis. Furthermore, there was a deeply rooted notion that cellulite was closely related with the speciﬁc stasis subsequent to hypotonia or venous and lymphatic disease and, therefore, it was assumed that a previous varicose disease should exist for cellulite to appear. Most often the interstitial alterations of cellulite dis- ease appear ﬁrst and the varicose or lymphatic pathology manifests itself only later. In any case, the characteristic peau d’orange appearance of cellulite is either caused by an increase in the fat or interstitial liquid content, or to the alteration and retraction of connective tissue layers occurring at different times and in different manners. Venous–lymphatic stasis is the outward expression of malfunctioning in the endocrine- metabolic regulation of the interstitium. From our point of view, however, this deﬁnition does not include all the stages of the disease as far as their evolution in time is concerned and, worse, it does not consider all its etiological and physiopathological variants. There are clearly three stages of development: edema, ﬁbrosis, and sclerosis, but the initial edema is not always the ﬁrst pathological manifestation since an alteration of the interstitial matrix, the connective structure, or the adipose tissue often precedes its appearance. In some particular cases, such as lipedema and lipolymphedema, the edema— characterized by the presence of free water instead of lymph—results from an alteration of the interstitial or adipocytic metabolic mechanisms. PATHOPHYSIOLOGY OF CELLULITE & 43 In Dercum’s syndrome, for example, an alteration of interstitial structures due to phlogosis of the nervous axon was suggested, associated with bacteria from the intestine. German authors [especially Letzel (1)] have found such bacteria in ‘‘cellulite’’ tissues or, at least, the presence of lesions caused by these bacteria.