Gastrointestinal system absorption

Casein refers to a family of proteins, namely, ttgi-, 0. 2-, p-, and k-caseins (Table 5.1). Digestion of a- and p-caseins leads to production of peptides that may bind to opioid receptors that exist in the nervous, endocrine, immime, or gastrointestinal system (Kampa et ah, 1996 Meisel, 2004). These compoimds may modulate absorption processes in the gut and can potentially affect gastrointestinal fimction through transit... 

Diquat and paraquat are quaternary ammonium compounds largely used as contact herbicides and crop desiccants. When systemic absorption occurs, paraquat and diquat are rapidly distributed into the body. Paraquat primarily accumulates in the lungs and kidneys, while the highest diquat concentrations have been found in the gastrointestinal tract, liver, and kidneys (WHO, 1984). Urine is the principal route of excretion for both diquat and paraquat, which are primarily eliminated as unmodified compounds. Occupationally exposed workers can be monitored by measuring paraquat and diquat concentrations in urine samples (Table 6). Blood concentrations are useful to monitor acute poisoning cases. 

Zweibaum A, M Laburthe, E Grasset, D Louvard. (1991). Use of cultured cell lines in studies of intestinal cell differentiation and function. In M Field, CA Frizzell, eds. Handbook of Physiology, Section 6, The Gastrointestinal System, Vol. IV, Intestinal Absorption and Secretion. Bethesda, MD Am Physiol Society, pp 223-255. 

The gastrointestinal system of zebrafish presents clear differences from the human system. The zebrafish does not possess a stomach, the intestine is continuous with the pharynx through a short esophagus, and no sphincters are present [61]. However, zebrafish have most of the cell types observed in the small intestine -absorptive, endocrine, goblet, and interstitial cells of Cajal, although Paneth cells are absent. Gut contractions are under the control of the enteric nervous systems, which respond to different pharmaceuticals in similar way as the mammalian counterpart. For example, zebrafish embryos can be used as predictor of emetic response to pharmaceuticals, one of the most commonly reported clinical adverse effects to be considered in the development of new dmgs [61]. 

A combination of neomycin and nonabsorbable erythromycin base given orally prior to colorectal surgery can markedly reduce the incidence of postoperative wound infection. Orally administered neomycin is sometimes used to suppress the facultative flora of the gut in patients with hepatic encephalopathy. It is unclear how this improves coma, but one theory is that it reduces systemic absorption of the bacterial metabo-htes that allegedly cause hepatic encephalopathy. Although more than 95% of an oral dose of neomycin is excreted unchanged in the stool of normal subjects, the bioavaUabUity of neomycin may be much higher in patients with an abnormal gastrointestinal mucosa. 

Gastrointestinal system Carbenoxolone Cimetidine Amiloride, spironolactone Antacids Inhibition of ulcer healing. Reduced absorption if taken simultaneously. 

The diterpene salvinorin A from Salvia divinorum (Epling and Jativa-M), in doses of 200-500 pg produces effects which are subjectively identical to those experienced when the whole herb is ingested. Salvinorin A is effectively deactivated by the gastrointestinal system, so alternative routes of absorption must be used to maintain its activity. Traditionally the herb is consumed either by chewing the fresh leaves or by drinking the juices of freshly crushed leaves. The effects of the herb when consumed this way depend on absorption of salvinorin A through the oral mucosa before the herb is swallowed. 

This presentation describes the effects of salvinorin A in humans, its deactivation by the gastrointestinal system and the essential role of the oral mucosa as an absorption site for salvinorin A from orally ingested leaves. 

The systemic availability of an inhaled glucocorticoid represents the additive and complex combination of pulmonary and gastrointestinal drug absorption. Absorption is influenced by many factors, including delivery device, the use of a spacer, the particle size of the inhaled drug, and the absorption and metabolism of the swallowed drug (1). 

Adverse Effects. Nystatin is generally well tolerated when applied locally. Systemic absorption through mucous membranes may cause some gastrointestinal disturbances (nausea, vomiting, diarrhea), but these side effects are generally mild and transient. Topical use of butenafine, naftifine, and tolnaftate is likewise safe, although local burning and irritation of the skin may occur in some individuals. 

Gastrointestinal Tract Absorption. The structure and function of this tract is varied and complex. The structure of the pesticide may be altered within the G.I. tract due to changes in pH in the stomach and intestine, or due to enzymatic action within the gut before it is absorbed into the lacteals and eventually into the hepatic portal system or lymphatic system. 

It is possible that systemic absorption of airborne aluminum occurs via the lungs, gastrointestinal tract after mucociliary clearance from the respiratory tract (ICRP 1994), or via the olfactory tract. Gitelman et al. (1995) found a better correlation between respirable aluminum air concentrations and urinary... 

The term absorption refers to the rate and extent to which an administered dose of a drug is taken into the body. In the case of oral administration, interest lies with the rate and extent of systemic absorption from the gastrointestinal tract following administration. If a drug is taken into the intestinal cells, it is deemed to have been absorbed, regardless of the extent to which it is metabolized. In contrast, the term bioavailability refers to the proportion of an administered dose that reaches the systemic circulation unchanged. 

Epling and Jativa-M) containing the neoclerodane diterpene divinorin A or salvinorin A (Fig. 12.1). It was the first documented non-alkaloidal diterpene hallucinogen. It is inactivated by the gastrointestinal system if orally ingested, and the effect is produced after absorption through the oral mucous. 9... 

Although systemic absorption of the prednisolone from the enema probably does occur, especially when the colon is particularly inflamed, corticosteroids usually have less systemic effects when given this way. Furthermore, by giving an enema, the drug is being delivered directly to its site of action - remember that in ulcerative colitis the disease is confined to the lower gastrointestinal tract. 

Data on the absorption, distribution, metabolism, and excretion of hydrogen chloride are sparse. There are reports of severe nonlactic metabolic acidosis developing rapidly after ingestion of hydrochloric acid (suggesting systemic absorption from the gastrointestinal tract), but this effect has not been reported after dermal exposure to concentrated hydrochloric acid or after inhalation of hydrogen chloride vapor or aerosol. No studies were found on upper respiratory... 

Disposition in the Body. Systemic absorption has been reported following topical application of solutions of naphazoline. It is not used systemically but is readily absorbed from the gastrointestinal tract. 

The most striking effect of systemic absorption of cocaine is central nervous system stimulation. Signs and symptoms can include excitement, restlessness, rapid and irregular pulse, dilated pupils, headache, gastrointestinal upset, delirium, and convulsions. Death usually results from respiratory feilure. Moderate doses of cocaine can also raise body temperature. Systemic absorption through mucous membranes is rapid and has been compared in speed with that of intravenous administration. 

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