Absorption in humans

No studies were located regarding absorption in humans and animals after inhalation exposure to methyl parathion. However, it can be concluded that pulmonary absorption occurred in humans as evidenced by... 

The data presented above suggest that methyl parathion would be absorbed by humans following ingestion of food and drinking water contaminated with methyl parathion. However, no data are available on the rate and extent of absorption in humans. 

Although the extent of absorption was not measured, the above evidence suggests that absorption in humans occurs rapidly following dermal exposure to commercial pesticide formulations of methyl parathion. 

Artursson P and Karlsson J. Correlation between oral drug absorption in humans and apparent drug permeability coefficients in human intestinal epithelial (Caco-2) cells. Biochem Biophys Res Commun 1991 175 880-5. 

Caco-2 cells and ezetimibe, a potent inhibitor of chloresterol absorption in humans, it was reported that (1) carotenoid transport was inhibited by ezetimibe up to 50% and the extent of that inhibition diminished with increasing polarity of the carotenoid molecule, (2) the inhibitory effects of ezetimibe and the antibody against SR-BI on P-carotene transport were additive, and (3) ezetimibe may interact physically with cholesterol transporters as previously suggested - and also down-regulate the gene expression of three surface receptors, SR-BI, NPCILI, and ABCAl. 

E. P., McEarland,. W., Schaper, K.-J. Quantitative estimation of drug absorption in humans for passively transported compounds on the basis of their physico-chemical parameters. 

A volume-related term (expressed by polarizability) and electrostatics (expressed by partial atomic charge) made minor contributions to intestinal absorption in humans. Lipophilicity, expressed by logP or logD values, shows no correlation with the human absorphon data. Recently, similar results were obtained for 154 passively transported drugs on the basis of surface thermodynamics descriptors [39] ... 

Camire (2002) showed that texturization does not seem to have a great effect on mineral retention and bioavailability. Others have reported increased retention of ascorbic acid in rice- and maize-based snacks (Hazell and Johnson, 1989 Plunkett and Ainsworth, 2007), increased iron diffusibility and absorption of iron-complexed protein (Poltronieri et al, 2000 Watzke, 1998), and no difference in iron and zinc absorption in human subjects fed textured bran-flour (Fairweather-Tait et al, 1989). 

Eairweather-Tait, S. J., Porhvood, D. E., Symss, L. L., Eagles, J., and Minski, M. J. (1989). Iron and zinc absorption in human subjects from a mixed meal of extruded and nonextruded wheat bran and flour. Am. ]. Clin. Nutr. 49, 151-155. 

No studies were located regarding absorption in humans or animals after inhalation exposure to diisopropyl methylphosphonate. 

Absorption. No studies were located regarding the mechanism of absorption in humans or animals after inhalation, oral, or dermal exposure to diisopropyl methylphosphonate. Both facilitated transport and diffusion through the lipophilic portions of the membrane could be involved in absorption processes. No data were found regarding lipid solubility or partition coefficients. 

No studies were located for reducing absorption in humans or animals exposed to diisopropyl methylphosphonate. Standard methods such as cathartics or activated carbon could be used. However, exposure would have to be identified within 4-6 hours since diisopropyl methylphosphonate is rapidly absorbed from the gastrointestinal tract (Ellenhom and Barceloux 1988). 

It is far more difficult to establish the mechanism(s) of drug absorption in humans. Most investigators analyze drug absorption data in humans (from blood or urine data) by assuming first-order absorption kinetics. For the most part this assumption seems quite... 

Since many essential nutrients (e.g., monosaccharides, amino acids, and vitamins) are water-soluble, they have low oil/water partition coefficients, which would suggest poor absorption from the GIT. However, to ensure adequate uptake of these materials from food, the intestine has developed specialized absorption mechanisms that depend on membrane participation and require the compound to have a specific chemical structure. Since these processes are discussed in Chapter 4, we will not dwell on them here. This carrier transport mechanism is illustrated in Fig. 9C. Absorption by a specialized carrier mechanism (from the rat intestine) has been shown to exist for several agents used in cancer chemotherapy (5-fluorouracil and 5-bromouracil) [37,38], which may be considered false nutrients in that their chemical structures are very similar to essential nutrients for which the intestine has a specialized transport mechanism. It would be instructive to examine some studies concerned with riboflavin and ascorbic acid absorption in humans, as these illustrate how one may treat urine data to explore the mechanism of absorption. If a compound is... 

GH Sokol, DJ Greenblatt, BL Lloyd, A Gecrgotas, MD Allen, JS Harmatz, TW Smith, RI Shader. Effect of abdominal radiation therapy on drug absorption in humans. J Clin Pharmacol 18 388-396, 1978. 

Table 2 Correlation of Dissolution Rates with Biological Measurements for Tolbutamide and Tetracycline Absorption in Humans... 

Predicting Oral Drug Absorption in Humans Lawrence X. Yu, Larry Gatlin, and Gordon L. Amidon... 

The use of vesicle cell membranes, isolated cells, and cell monolayers and intestinal tissue studies has provided valuable correlations with in situ and in vivo drug absorption in animals as well as correlations with drug absorption in clinical studies. Most prominent among the literature sources establishing correlations between in vitro tissue and cellular systems with drug absorption in humans are the work of Dowty and Dietsch [73], Lennernas et al. [74], and Stewart et al. [75],... 

Steinbaugh, MD Taylor. Comparison of intestinal permeabilities in multiple in vitro and in situ models Relationship to absorption in humans. Pharm Res 12 693-699, 1995. 

DM Oh, PJ Sinko, GL Amidon. Predicting oral drug absorption in humans A macroscopic mass balance approach for passive and carrier-mediated compounds. In DZ D Argenio, ed. Advanced Methods of Pharmacokinetic and Pharmacodynamic Systems Analysis. New York Plenum Press, 1990, pp 3-11. 

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