Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In recent years it has become possible by means of a radioimmunoassay to measure Digoxin concentration in the serum of digitalized patients. With this method it could be shown that the resorption of Digoxin is decreased by partial resection of the samll intestines, by malabsorption syndromes, after ingestion of Neomycin, Colestyramine and antacids. In renal insufficiency, however, the elimination half-life period of Digoxin is increased conspiciously (from about 35 hours up to about 120 hours). This results in a raised serum concentration of cardiac glycosides unless the dosage is decreased considerably. The incidence of Digitalis intoxication in Digitalis treated patients has been reported to rank as high as 20%. There is, however, no strict correlation between the serum glycoside level and the clinical symptoms, because the glykoside concentration in the serum does not represent the pharmacologically active concentration at the receptor. Experimental investigations of cardiac glycoside binding to the receptor for cardiac glycosides in human heart cell membranes revealed, that receptor bound Digoxin for instance is diminished in serious renal insufficiency and it depends on the serum concentration of potassium, calcium and magnesium. In hypoxia, after myocardial infarction and in myxedema the sensitivity for cardiac glycosides is increased. The opposite is true in hyperthyreoidism, fever and in children. All of these factors have to be kept in mind and paid attention to in the clinical evaluation of the measured Digoxin concentration in the serum.
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PMID:[Significance of serum digoxin concentration and its influencing factors]. 6 Nov 53

The absorption of oral digoxin preparations has been a topic of much concern during the last 5 years. The completeness of digoxin absorption is proportional to the area under the serum concentration time curve and to the urinary excretion of digoxin after single doses. During chronic therapy the completeness of absorption is proportional to these values and also to the steady state serum concentration. Determination of absolute bioavailability of a given digoxin preparation requires a comparative study using intravenous digoxin as a standard. Oral digoxin solutions are incompletely absorbed, but have biological availability greater than or equal to that of tablets. The absorption of digoxin tablets depends upon their dissolution rate which in turn is related to drug particle size. Digoxin tablets with small drug particles have rapid rates of dissolution and can be absorbed as completely as oral solutions. The bioavailability of digoxin from tablets can be influenced by changes in gastro-intestinal motility, malabsorption syndromes, and by co-administration of food or other drugs. New regulations now insure that all marketed digoxin tablet preparations have satisfactory bioavailability. Problems with biological availability at present are unlikely to account for unexpected clinical results during digoxin therapy.
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PMID:Bioavailability of drugs: the digoxin dilemma. 79 91

Seven subjects who underwent jejunoileal bypass surgery for massive obesity participated in a study to examine the relative bioavailability of digoxin before and one to two months after surgery. They were given a loading dose of 1 mg digoxin in divided oral doses followed by oral maintenance doses of 0.5 mg daily. There were no significant differences in the area under the serum concentration time curve, steady state serum levels or 24 hour steady state excretion of digoxin before and after surgery. We conclude that the bioavailability of digoxin from the Lanoxin tablets employed is not impaired in these patients, although urinary d-xylose and 24 hour fecal fat excretion indicated moderate to severe malabsorption after surgery.
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PMID:The effect of jejunoileal bypass on the pharmacokinetics of digoxin in man. 83 89

The relative steady-state bioavailability of two oral digoxin dosage forms was studied in 17 subjects with malabsorption syndromes. Male subjects received the following treatments in randomized crossover fashion for 14 days: three 0.125-mg digoxin tablets or three 0.1-mg digoxin capsules once daily. Female subjects received digoxin on the same schedule but at two-thirds the dose. Serum and urine samples were collected and analyzed for digoxin by radioimmunoassay, and treatments were compared by evaluating pharmacokinetic parameters. The mean area under the serum concentration versus time curve for tablets (28.1 h.nmol/L [21.9 h.ng/mL]) was smaller (p less than 0.03) than that for capsules (31.1 h.nmol/L [24.3 h.ng/mL]), and the mean maximum serum digoxin concentration for tablets (2.9 nmol/L [2.3 ng/mL]) was lower (p less than 0.02) than that for capsules (4.0 nmol/L [3.1 ng/mL]). There was no difference in cumulative urinary excretion of digoxin between the two treatments. In contrast to previous reports, we observed that digoxin from Lanoxin Tablets appears to be well absorbed in subjects with malabsorption. Nevertheless, these subjects absorbed digoxin from capsules better than from tablets, with the greatest differences occurring in subjects without a colon and in those subjects with the lowest serum carotene concentrations.
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PMID:Absorption of digoxin from tablets and capsules in subjects with malabsorption syndromes. 281 51

Digoxin is a commonly prescribed medication for a variety of cardiovascular abnormalities. The therapeutic index of digoxin is considered narrow and drug is absorbed predominantly from the duodenum and upper jejunum. When the small intestine is intact, the absorption can vary; therefore, in the case of a small bowel resection or bypass, this erratic absorption may be accentuated. There is some controversy concerning the effect of small bowel resection or bypass on the absorption of digoxin. Some investigators have shown that small bowel resection or bypass decreases the absorption of oral digoxin, whereas others report no change in absorption. When the study methodologies were evaluated, certain common factors that support each view were found. In most studies reporting malabsorption, a solid dosage form of digoxin was used. Studies reporting no change in absorption investigated a solution dosage form.
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PMID:Perspectives on digoxin absorption from small bowel resections. 682 64

Digoxin absorption is found to be decreased in patients with malabsorption syndromes on the basis of mucosal defects. Since intestinal mucosa can be damaged by cytostatic drugs, it was the purpose of these studies to investigate the influence of various cytostatic drugs on digoxin and digitoxin plasma levels and urinary excretion. In 9 patients with malignant lymphoma, who received 0.8 mg beta-acetyldigoxin (n = 6) or 0.5 mg digitoxin (n = 3) before and 24 h after combined therapy with cyclophosphamide, vincristine, procarbazine, and prednisone (CVPP) or cyclophosphamide, vincristine and prednisone (CVP), plasma glycoside concentrations were measured 0 to 8 h after digoxin and 0--168 h after digitoxin application and the areas under the plasma concentration-time curves were calculated. In 12 patients on 0.3 mg beta-acetyldigoxin and in 10 patients on 0.1 mg digitoxin, daily plasma glycoside concentrations and daily renal excretion were measured before and after CVPP, CVP or cyclophosphamide, vincristine, cytarabine and prednisone (CVAP) treatment schemes. The diminished steady-state plasma digoxin concentrations and daily renal glycoside excretion during the 24-168 h period after the cytostatic dose demonstrate a reversible impairment of digoxin absorption. In contrast cytostatic drug therapy does not lead to reduction in steady-state digitoxin plasma levels and daily renal glycoside excretion. The delayed time to peak after a single dose of digoxin or digitoxin during cytostatic drug therapy shows that rate of absorption of both glycosides is reduced. Our results indicate the need for very exact monitoring of digoxin dosage during cytostatic therapy. The use of digitoxin for these patients is an alternative in maintaining adequate digitalization.
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PMID:Inhibition of digoxin absorption but not of digitoxin during cytostatic drug therapy. 688 30