Gastrointestinal tract absorbed

Chlordecone is readily absorbed (>90%) from the gastrointestinal tract. Absorbed chlordecone rapidly (within 24-48 h) establishes an equilibrium of distribution among most tissues. Absorption of chlordecone may also occur through skin, especially in patients with dermatitis or skin rash. Compared to... 

Toxicity. Fluoroborates are excreted mostly in the urine (22). Sodium fluoroborate is absorbed almost completely into the human bloodstream and over a 14-d experiment all of the NaBF ingested was found in the urine. Although the fluoride ion is covalently bound to boron, the rate of absorption of the physiologically inert BF from the gastrointestinal tract of rats exceeds that of the physiologically active simple fluorides (23). 

Only a small (ca 3%) fraction of ingested or inhaled manganese is absorbed, which occurs primarily by the intestines (209). Once absorbed, manganese is regulated by the Hver, where it is excreted into the bile and passes back into the intestine, where some reabsorption may occur (210). Manganese is elirninated almost exclusively (>95%) by the bile in the gastrointestinal tract. 

Normally, dietary tyramine is broken down in the gastrointestinal tract by MAO and is not absorbed. In the presence of MAOI, however, all of its potent sympathomimetic actions are seen. Other side effects of MAOI include excessive CNS stimulation, orthostatic hypotension, weight gain, and in rare cases hepatotoxicity. Because the monoamine oxidase inhibitors exhibit greater toxicity, yet no greater therapeutic response than other, newer agents, clinical use has been markedly curtailed. The primary use for MAOIs is in the treatment of atypical depressions, eg, those associated with increased appetite, phobic anxiety, hypersomnolence, and fatigues, but not melancholia (2). 

The relative toxicities of thallium compounds depend on their solubHities and valence states. Soluble univalent thallium compounds, eg, thaHous sulfate, acetate, and carbonate, are especiaHy toxic. They are rapidly and completely absorbed from the gastrointestinal tract, skin peritoneal cavity, and sites of subcutaneous and intramuscular injection. Tb allium is also rapidly absorbed from the mucous membranes of the respiratory tract, mouth, and lungs foHowing inhalation of soluble thallium salts. Insoluble compounds, eg, thaHous sulfide and iodide, are poorly absorbed by any route and are less toxic. 

Swallowing. If it is sufficiently irritant or caustic, a swallowed material may cause local effects on the mouth, pharynx, esophagus, and stomach. Additionally, carcinogenic materials may induce tumor formation in the alimentary tract. Also, the gastrointestinal tract is an important route by which toxic materials are absorbed. The sites of absorption and factors regulating absorption have been reviewed (42,43). 

The modes of action for niclosamide are interference with respiration and blockade of glucose uptake. It uncouples oxidative phosphorylation in both mammalian and taenioid mitochondria (22,23), inhibiting the anaerobic incorporation of inorganic phosphate into adenosine triphosphate (ATP). Tapeworms are very sensitive to niclosamide because they depend on the anaerobic metaboHsm of carbohydrates as their major source of energy. Niclosamide has selective toxicity for the parasites as compared with the host because Httle niclosamide is absorbed from the gastrointestinal tract. Adverse effects are uncommon, except for occasional gastrointestinal upset. 

The dmg is readily absorbed from the gastrointestinal tract and may persist in human tissues for two months after adrninistration. Quinacrine is given as a single dose for the treatment of tapeworms it is manufactured by Winthrop-Breon of New York, New York. 

Toxicity. The toxicity of barium compounds depends on solubility (47—49). The free ion is readily absorbed from the lung and gastrointestinal tract. The mammalian intestinal mucosa is highly permeable to Ba " ions and is involved in the rapid flow of soluble barium salts into the blood. Barium is also deposited in the muscles where it remains for the first 30 h and then is slowly removed from the site (50). Very Httle is retained by the fiver, kidneys, or spleen and practically none by the brain, heart, and hair. 

Water-insoluble barium salts are poorly absorbed. In fact, barium sulfate is used as a contrast material for x-ray examination of the gastrointestinal tract based on its limited solubility andlow toxicity (52). Barium sulfate fed to mice at various levels up to 8 ppm dietary Ba ( 1.14 mg/kg-d as Ba " ) for three generations had no significant effects on growth, mortality, morbidity, or reproductive performance (53). 

Bile Acid Sequestrants. The bile acid binding resins, colestipol [26658424] and cholestyramine, ate also effective in controlling semm cholesterol levels (150). Cholestyramine, a polymer having mol wt > ICf, is an anion-exchange resin. It is not absorbed in the gastrointestinal tract, is not affected by digestive enzymes, and is taken orally after being suspended in water (151). 

The primary routes of entry for animal exposure to chromium compounds are inhalation, ingestion, and, for hexavalent compounds, skin penetration. This last route is more important in industrial exposures. Most hexavalent chromium compounds are readily absorbed, are more soluble than trivalent chromium in the pH range 5 to 7, and react with cell membranes. Although hexavalent compounds are more toxic than those of Cr(III), an overexposure to compounds of either oxidation state may lead to inflammation and irritation of the eyes, skin, and the mucous membranes associated with the respiratory and gastrointestinal tracts. Skin ulcers and perforations of nasal septa have been observed in some industrial workers after prolonged exposure to certain hexavalent chromium compounds (108—110), ie, to chromic acid mist or sodium and potassium dichromate. 

Drugs that are too highly hydrophilic are often absorbed rather poorly from the gastrointestinal tract. It is sometimes possible to circumvent this difficulty by preparing esters of such compounds so as to change their water lipid partition characteristics in order to enhance absorption. Once absorbed, the esters are cleaved by the numerous esterase enzymes in the bloodstream, releasing free drug. 

PTU is also well absorbed from the gastrointestinal tract. Peak serum concentrations are in the range of 3 f.Lg/ml at 1 h after drug ingestion after an oral dose of... 

SUCCINIM IDES The succinimides are easily absorbed in the gastrointestinal tract and are effective in controlling... 

Opioids are easily absorbed subcutaneously and intramuscularly, as well as from the gastrointestinal tract, nasal mucosa (e.g., when heroin is used as snuff), and lung (e.g., when opium is smoked). About 90% of the excretion of morphine occurs during the first 24 hours, but traces are detectable in urine for more than 48 hours. Heroin (diacetyhnorphine) is hydrolyzed to monoacetylmorphine, which is then hydrolyzed to morphine. Morphine and monoacetylmorphine are responsible for the pharmacologic effects of heroin. Heroin produces effects more rapidly than morphine because it is more lipid soluble and therefore crosses the blood-brain barrier faster. In the urine, heroin is detected as free morphine and morphine glucuronide (Gutstein and Akil 2001 Jaffe et al. 2004). 

Mescaline is considerably less potent than LSD equipotent amounts are 5 mg and 1 pg, respectively. Peyote is readily absorbed from the gastrointestinal tract. Mescaline is mainly concentrated in the liver, spleen, and kidney. Up to 60% is excreted unchanged in the urine mescaline metabolites are devoid of any psychoactive effect. 

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