In 47 patients with disorders of the gastrointestinal tract, the bioavailability of digoxin tablets was assessed by measuring the area under the serum concentration-time curve (AUC) after the oral administration of single 0.5 mg doses. In 13 or 14 patients who had undergone a previous ileal resection, in 10 of 10 patients with sprue and in 14 of 14 patients with a variety of disorders of the gastrointestinal tract, digoxin absorption was normal despite marked steatorrhea in many. A patient with extensive jejunal and ileal resection, and inflammation of the remaining small bowel,was the sole exception. Impaired digoxin bioavailability was found in five of nine patients who had undergone jejunoileal bypass procedures (bypass patients. A strong correlation was noted between the length of jejunum remaining in continuity and the AUC (r = 0.86, p less than 0.01). Two of three bypass patients also showed decreased absorption of more rapidly dissolving tablets or an elixir. Digoxin bioavailability correlated significantly with and 2 hour serum xylose levels but not with urinary xylose excretion, fecal fat or the Schilling test result. The findings are consistent with the role of the upper small bowel as the predominant site of digoxin absorption as well as the reserve function of the ileum in the event of jejunal dysfunction or bypass.

Adult↗

PubMed1977

The effect of ascorbic acid on uric acid excretion with a commentary on the renal handling of ascorbic acid.

Under spontaneous conditions in man and dog, very little ascorbic acid is excreted in urine. Ascorbic acid clearance (C ascorbic acid) is promptly augmented when plasma ascorbic acid is increased by intravenous injection. No net tubular secretion of ascorbic acid is demonstrable in either man or dog when plasma ascorbic acid is elevated to levels as high as 12 mg/100 ml in man, and 28 mg/100 ml in the dog. Nevertheless, both in men and the Dalmatian dog, when the glomerular filtration rate (GFR) is decreased, excreted ascorbic acid in relation to the amount filtered is exaggerated so that C ascorbic acid:GFR approaches unity. It is possible that secreted ascorbic acid is masked under ordinary circumstances, with a more significant contribution of secreted ascorbic acid to total urinary ascorbic acid becoming apparent under conditions of low GFR. In man, when the plasma ascorbic acid level is raised to above 6 mg/100 ml, C urate:GFR rises from control value of 0.081 +/- 0.020, to 0.116 +/- 0.026. In both mongrel and Dalmatian dogs an effect of ascorbic acid on urate excretion is not conclusively shown. The uricosuric effect of ascorbic acid in man may be due to competition with uric acid for renal tubular reabsorptive transport. The difference in the metabolism of ascorbic acid in the dog as compared to man may help account for the inconsistent effect of ascorbic acid on uric acid excretion in the dog.

Aged↗

PubMed1977

Anemia and intestinal dysfunction in former residents of the Caribbean.

A group of subjects had common features of megaloblastic anemia due to vitamin B12 deficiency, normal or high serum folate, and evidence of intestinal malabsorption. They were all former residents of the Caribbean area now living in New York City. Despite similar symptoms and diagnostic studies, two subjects were found to have pernicious anemia and three to have tropical sprue. Achlorhydria, serum anti-intrinsic factor antibody, the severity of small intestinal abnormalities, and posttherapy Schilling tests were helpful differential factors. These subjects illustrate the problems that may be encountered in differentiating tropical sprue and pernicious anemia.

Adult↗

PubMed1976

Bioavailability of ascorbic acid in orange juice.

Several orange juice preparations were analyzed for biologically active and inactive ascorbic acid derivatives --L-ascorbic acid , dehydro-L-ascorbic acid, and inactive 2,3-diketo-L-gulonic acid. Fresh orange juice contained from 4 to 7 mg/100 ml of inactive ascorbic acid. In contrast, pasteurized orange juice contained from 15 to 30 mg/100 ml of inactive ascorbic acid (up to 400% more than fresh orange juice). Samples of fresh orange juice contained as much as 100% more active ascorbic acid than samples of pasteurized orange juice. There is great variability in prepared orange juice derivatives with a substantial decrease in bioavailability of active ascorbic acid.

Ascorbic Acid↗

PubMed1976

Folic acid absorption in regional enteritis.

The authors have investigated intestinal absorption of folic acid by jejunal perfusion with a triple lumen tube in five subjects with regional enteritis. The subjects' intestinal disabilities ranged from terminal ileitis to short bowel syndrome. Two had steatorrhea and two had low serum folate levels. Absorption of pteroylglutamic acid was normal in all five. This suggests that folic acid deficiency, common in this disorder, is largely caused by malnutrition, not malabsorption.

Adult↗

PubMed1975

Ascorbic acid deficiency in clinical disease including regional enteritis.

Explore the source record for details and available documents.

Administration, Oral↗

PubMed1975

Effect of parenteral acetazolamide on intestinal absorption of salt and water in man.

Acetazolamide was administered intravenously during jejunal perfusion of isotonic saline in six subjects. Bicarbonate was present in very low concentration intraluminally and there was net bicarbonate secretion during control and acetazolamide perfusions. Acetazolamide significantly inhibited sodium chloride, and water absorption. As this occurred in the absence of an effect on net bicarbonate secretion, it may have been due to an action other than carbonic anhydrase inhibition.

Acetazolamide↗

PubMed1974