Effect of Complex Formation on Drug Absorption III: Concentration- and Drug-dependent effect of a Nonionic Surfactant

1966 ◽  
Vol 55 (4) ◽  
pp. 394-398 ◽  
Author(s):  
Gerhard Levy ◽  
Karen E. Miller ◽  
Richard H. Reuning
Keyword(s):  
Complex Formation ◽  
Nonionic Surfactant ◽  
Drug Absorption ◽  
Dependent Effect ◽  
Drug Dependent

Effect of Complex Formation on Drug Absorption VIII

1968 ◽  
Vol 57 (8) ◽  
pp. 1342-1346 ◽  
Author(s):  
Richard H. Reuning ◽  
Gerhard Levy
Keyword(s):  
Complex Formation ◽  
Drug Absorption

Effect of Complex Formation on Drug Absorption I

1964 ◽  
Vol 53 (12) ◽  
pp. 1471-1475 ◽  
Author(s):  
Gerhard Levy ◽  
Richard H. Reuning
Keyword(s):  
Complex Formation ◽  
Drug Absorption

Effect of Complex Formation on Drug Absorption V

1968 ◽  
Vol 57 (1) ◽  
pp. 101-104 ◽  
Author(s):  
Gerhard Levy ◽  
Judith A. Anello
Keyword(s):  
Complex Formation ◽  
Drug Absorption

The effect of ferrous sulfate and pH on L-dopa absorption

1990 ◽  
Vol 68 (5) ◽  
pp. 603-607 ◽  
Author(s):  
Roderick R. A. Campbell ◽  
Brian Hasinoff ◽  
Gary Chernenko ◽  
James Barrowman ◽  
Norman R. C. Campbell
Keyword(s):  
Gastrointestinal Tract ◽  
Complex Formation ◽  
Rat Model ◽  
Drug Absorption ◽  
Ferrous Sulfate ◽  
Iron Binding ◽  
Percent Reduction ◽  
Experimental Animals ◽  
Jejunal Segment

Ferrous sulfate decreases L-dopa bioavailability in humans probably as a result of binding of L-dopa by iron in the gastrointestinal tract. This study was conducted to determine if iron by binding L-dopa decreases L-dopa absorption and to investigate the effect of different pH buffers on intestinal absorption of L-dopa in the presence and absence of ferrous sulfate. A rat model developed to examine drug absorption was used. Control animals had buffered [14C]L-dopa solutions injected into two in vivo closed segments of intestine; a 5-cm duodenal and a 5-cm proximal jejunal segment. These studies were conducted using solutions buffered at pH 5.5, 6.5, 7.5, and 8.5. An identical procedure was followed for experimental animals except ferrous sulfate was injected with the buffered L-dopa solutions. Ferrous sulfate resulted in a reduction in L-dopa absorption in the buffers at all pHs in both the duodenum and jejunum. The average reduction in L-dopa absorption in the presence of iron was 22.6% in the duodenum and 23.9% in the jejunum. There was a tendency for ferrous sulfate to cause a greater reduction in L-dopa absorption as the buffer pH increased. There was also a decrease in L-dopa absorption in the higher pH buffers in the absence of iron. Despite this latter result, in the jejunum there was an increase in the percent reduction in L-dopa absorption associated with ferrous sulfate as pH increased. Although this tendency was not as consistent in the duodenum as the jejunum, the combined results are compatible with the chemical model of increased L-dopa–iron binding as pH increases.Key words: L-dopa, ferrous sulfate, complex formation, chelation, drug absorption.

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