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Lymphatic absorption

Figure 13 presents a schematic diagram for drug absorption from the peritoneal cavity. As mentioned above, particles (e.g., erythrocytes, bacteria, colloidal gold, and liposomes) which are not able to pass capillary membranes are removed from the peritoneal cavity via the lymphatic system (Fig. 13, I and II). Relatively low molecular weight compounds (e.g., drugs) are exclusively absorbed via splenic blood capillaries into the portal vein (Fig. 13, III). Figure 13 presents a schematic diagram for drug absorption from the peritoneal cavity. As mentioned above, particles (e.g., erythrocytes, bacteria, colloidal gold, and liposomes) which are not able to pass capillary membranes are removed from the peritoneal cavity via the lymphatic system (Fig. 13, I and II). Relatively low molecular weight compounds (e.g., drugs) are exclusively absorbed via splenic blood capillaries into the portal vein (Fig. 13, III).
Several studies have been performed in order to investigate the effect of liposomal size (Hirano and Hunt, 1985), lipid composition (Senior and Gregoriadis, 1982 Hirano et al., 1985), and lipid dose (Ellens et al., 1983, Kim et al., 1987) on the fate of liposomes after intraperitoneal administration. In the size range studied (0.048-0.72 Min), no size-dependent absorption could be expected (Hirano and Hunt, 1985). Particles larger than 22.5 pm are not expected to enter the lymphatic capillaries (Allen, 1956). After intraperitoneal administration of multivesicular liposomes (19 + 7 ym), Kim and Howell (1987a) and Kim et al. (1987) showed that liposomal entrapment of Ara-C prolongs the half-Ufe of the drug in the peritoneal... [Pg.302]

FIGURE 13 Schematic diagram for drug absorption fi om the peritoneal cavity. I and II represent the lymphatic system and III represents splenic blood capillaries. (Adapted from Hirano and Hunt, 1985.)... [Pg.302]

Jackson, A. J. (1981). Intramuscular absorption and regional lymphatic uptake of liposome-entrapped inulin. Drug Metab. Dispos., 9, 535-540. [Pg.323]

As a generalization, to be orally well absorbed a compound must be soluble in the contents of the gastrointestinal lumen [4]. Solubility in aqueous buffer is commonly used as a simpHfying surrogate for intestinal content solubility. There are rare exceptions to the principle that to be absorbed a compound must be soluble. SoHd particles, e.g. starch, can be absorbed. Absorption of very small quantities of even biologically very large compounds can occur via lymphoid tissue, e.g. orally active vaccines. Very hpophihc basic compounds, e.g. certain antimalarials, can be absorbed via the intestinal lymphatics and dehvered directly to the heart... [Pg.259]

The absorption of drugs from the rectal [32] cavity has been studied in some detail. Muranishi et al. [34] have shown that a significant increase in the absorption and lymphatic uptake of soluble and colloidal macromolecules can be achieved by pretreating the rectal mucosal membrane with lipid-nonionic surfactant mixed micelles. They found no evidence of serious damage of the mucosal membrane. Davis [30] suggested that the vaginal cavity could be an effective delivery site for certain pharmaceuticals, such as calcitonin, used for the treatment of postmenopausal osteoporosis. [Pg.538]

M. Murakami, Enhanced absorption and lymphatic transport of macromolecules via the rectal route, in Delivery Systems for Peptide Drugs (S. S. Davis, L. Ilium, and E. Tomlinson, eds.), Plenum Press, New York, 1986, p. 177. [Pg.581]

Wang, X. D., N. I. Krinsky, R. P. Marini et al. 1992. Intestinal uptake and lymphatic absorption of beta-carotene in ferrets A model for human beta-carotene metabolism. Am J Physiol 263(4Pt 1) G480-G486. [Pg.434]

Mucosa. The innermost layer of the wall is the mucosa, which consists of a mucous membrane, the lamina propria, and the muscularis mucosa. The mucous membrane provides important protective and absorptive functions for the digestive tract. The nature of the epithelial cells lining the tract varies from one region to the next. Rapidly dividing stem cells continually produce new cells to replace worn out epithelial cells. The average life span of these epithelial cells is only a few days. The lamina propria is a thin middle layer of connective tissue. This region contains the capillaries and small lymphatic vessels that take up the digested nutrient molecules. The muscularis mucosa is a thin layer of smooth muscle. Contraction of this muscle may alter the effective surface area for absorption in the lumen. [Pg.281]

Chylomicrons leave the absorptive cell by way of exocytosis. Because they are unable to cross the basement membrane of the blood capillaries, the chylomicrons enter the lacteals, which are part of the lymphatic system. The vessels of the lymphatic system converge to form the thoracic duct that drains into the venous system near the heart. Therefore, unlike products of carbohydrate and protein digestion that are transported directly to the liver by way of the hepatic portal vein, absorbed lipids are diluted in the blood... [Pg.302]

Utilize lymphatic Increase absorption of Food effects persist for... [Pg.549]

The role of lipids on absorption has been extensively reviewed by Porter and Charman [29, 30]. The influences are diverse and include effects on luminal drug solubility, altering the metabolic and barrier function of the intestinal wall, stimulating lymphatic transport and a reduction in gastric transit, thereby increasing the time available for dissolution. [Pg.556]

Hanberg, A., C.B. Nilsson, C. Trossvik, and H. Hakansson. 1998. Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the lymphatic absorption of a single oral dose of [3H]retinol and on the intestinal retinol esterification in the rat. Jour. Toxicol. Environ. Health 55A 331-344. [Pg.1061]

The rate of absorption from an SC injection site may be retarded by immobilization of the limb, local cooling to cause vasoconstriction, or application of a tourniquet proximal to the injection site to block the superficial venous drainage and lymphatic flow. In small amounts, adrenergic stimulants, such as epinephrine, will constrict the local blood vessels and, therefore, slow systemic absorption. Conversely, cholinergic stimulants (such as methacholine) will induce very rapid systemic absorption subcutaneously. Other agents may also alter their own rate of absorption by affecting local blood supply or capillary permeability. [Pg.452]

Absorption via Lymphatic Channels. Some lipophilic chemicals dissolved in lipids may be absorbed through the lymphatics. [Pg.456]

Many variations of intestinal perfusion methods have been used as absorption models over the years. In situ methods offer advantages over in vitro models. Although the animal has been anaesthetised and surgically manipulated, neural, endocrine, lymphatic, and mesenteric blood supplies are intact and therefore all the transport mechanisms present in a live animal should be functional. As a result absorption rates from these methods may be more realistic in magnitude than those determined from in vitro techniques. [Pg.46]

There are occasional anomalies to the rule that food reduces and delays peak plasma concentration. The anti-fungal drug, griseofulvin, has enhanced absorption if taken with a meal - possibly because it becomes emulsified by bile salts and passes more readily into the lymphatic drainage of the gut which bypasses the liver, entering the venous system directly. The immuno-suppressant cyclosporin, and calcium salts in general, show a similar increase in absorption when taken with a fatty meal. [Pg.150]

CN097 Satchithanandam, S., M. Reicks, R. J. Calvert, M. M. Cassidy, and D. Kritchevsky. Coconut oil and sesame oil affect lymphatic absorption of cholesterol and fatty acids in rats. J Nutr 1993 123(11) 1852-1858. [Pg.147]


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See also in sourсe #XX -- [ Pg.2 ]




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