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Uremic sera contain inhibitors that block digitoxin-valproic acid interaction
1Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, 77030, USA. amitava.dasgupta@uth.tmc.edu
The American Journal of the Medical Sciences
|October 27, 2001
Summary
Valproic acid displaces digitoxin from serum albumin in healthy individuals. However, in uremic sera, inhibitors block this drug interaction, affecting digitoxin levels.
Area of Science:
- Pharmacology
- Clinical Chemistry
- Drug Interactions
Background:
- Digitoxin and valproic acid bind strongly to serum albumin.
- Simultaneous administration leads to competition for binding sites.
Purpose of the Study:
- Investigate the interaction between digitoxin and valproic acid in normal and uremic sera.
- Determine the effect of valproic acid on digitoxin protein binding.
Main Methods:
- Utilized fluorescence polarization immunoassays to measure total and free digitoxin and valproic acid.
- Employed a modified protocol for enhanced sensitivity in measuring free digitoxin.
- Incubated serum samples with varying concentrations of valproic acid and measured free digitoxin.
Main Results:
- Valproic acid significantly increased free digitoxin in normal sera.
- A slight decrease in free digitoxin was observed in uremic sera.
- Indoxyl sulfate identified as an inhibitor of digitoxin-valproic acid interaction in uremic serum; hippuric acid showed no effect.
- No significant interaction observed between digoxin and valproic acid.
Conclusions:
- Valproic acid displaces digitoxin from protein binding sites in normal serum.
- Uremic sera contain inhibitors that impede the digitoxin-valproic acid interaction.