Digoxin intestinal absorption

It decreases digoxin renal excretion It decreases digoxin plasma protein binding It decreases digoxin intestinal absorption It decreases digoxin sensitivity at its site of action... 

Intestinal absorption of digoxin is less complete compared to digitoxin. In order to improve absorption, acetylated- and methylated-digoxin derivates were developed. Digitoxin is metabolised in hepatic microsomal enzymes and can be cleared independently from renal function. The therapeutical serum level of digoxin is 0.5-2.0 ng/ml and 10-35 ng/ml of digitoxin. Steady state plateau of therapeutic plasma concentrations is reached after 4-5 half-life-times using standard daily doses [5]. 

Relationship between rat intestinal absorption clearance and lipid solubility. The results shown with the squares represent the relationship between intestinal absorption clearance (ka) observed from the in situ jejunum loop in the presence ( ) and absence ( ) of cyclosporin A in rats and octanol-buffer (pH 7.0) partition coefficients (log D) determined in this study. The numbers refer to 1, atenolol 2, nadolol 3, acetamide 4, celiprolol 5, acebutolol 6, doxorubicin 7, timolol 8, sulfathiazole 9, quinidine 10, sulfamethoxazole 11, digoxin 12, cyclosporin A 13, vinblastine 14, b-estradiol 15, verapamil. Modified from A.Tsuji and I. Tamai. Pham. Res., 13 963—977 (1996). 

DIGOXIN ST JOHN S WORT Plasma concentrations of digoxin seem to be 1 by St John s wort St John s wort seems to 1 P-gp-mediated intestinal absorption of digoxin Watch for a 1 response to digoxin... 

DIGOXIN ITRACONAZOLE Itraconazole may cause t plasma levels of digoxin cases reported of digoxin toxicity Itraconazole inhibits P-gp-mediated renal clearance and t intestinal absorption of digoxin Monitor digoxin levels watch for digoxin toxicity... 

Itraconazole inhibits P-gp-mediated renal clearance and t intestinal absorption of digoxin... 

Not fully understood. Spironolactone inhibits the excretion of digoxin by the kidney (by 13%) but does not affect its biliary clearance. Animal studies have suggested that spironolactone may induce P-glycoprotein expression, resulting in reduced intestinal absorption of substrates such as digoxin. Spironolactone probably also causes a reduction in the volume of distribution of digoxin. 

P-glycoprotein (P-gp) works as a transporter at the intestinal mucosa pumping drugs out into the lumen. Absorption of P-gp substrates, such as digoxin, cyclosporine, etc., can be increased by inhibitors of P-gp and reduced by inducers. 

Diarrheal conditions may decrease drug absorption as a result of reduced intestinal residence time. The absorption of several drugs was decreased in response to lactose- and saline-induced diarrhea [145]. Digoxin absorption from tablets was impaired in one subject who developed chronic diarrhea as a result of x-ray treatment [146]. Abdominal radiation or the underlying disease has been shown to reduce digoxin and clorazepate absorption [147]. A dosage form that provides rapid drug dissolution (e.g., solution) may partially resolve this problem. 

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