Related Experiment Videos
[The biological availability of digitoxin]
Fortschritte Der Medizin
|October 13, 1977
Summary
Digitoxin bioavailability varies by formulation. Tablets showed faster absorption and a shorter half-life (t1/2), suggesting significant pre-absorption metabolism, while dragées exhibited delayed absorption and a longer t1/2, indicating higher bioavailability.
Area of Science:
- Pharmacokinetics
- Drug Metabolism
- Bioavailability Studies
Context:
- Digitoxin, a cardiac glycoside, requires careful dosing due to its narrow therapeutic index.
- Understanding formulation-dependent bioavailability is crucial for optimizing digitoxin therapy.
Purpose:
- To compare the bioavailability and pharmacokinetic profiles of digitoxin administered via tablets and dragées.
- To investigate the influence of formulation on digitoxin absorption, elimination, and potential pre-absorption metabolism.
Summary:
- A single 0.5 mg dose of digitoxin was administered to 6 healthy volunteers in intravenous, tablet, and dragée formulations.
- Tablets demonstrated rapid absorption and a shorter mean half-life (7.4 days) compared to dragées (9.7 days) and intravenous administration (9.5 days).
- Higher urinary excretion of glycosides was observed with tablets, suggesting a significant extrahepatic first-pass effect and degradation before absorption, which explains the shorter half-life.
Impact:
- The study highlights significant formulation-dependent differences in digitoxin bioavailability and metabolism.
- Findings suggest that digitoxin tablets undergo substantial pre-absorption degradation, impacting their pharmacokinetic profile.
- This research provides essential data for selecting appropriate digitoxin formulations to ensure therapeutic efficacy and safety.