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Stability of theophylline elimination rate
Clinical Pharmacology and Therapeutics
|April 1, 1987
Summary
Theophylline elimination rates show minimal variation within individual patients over time, contrary to some clinical assumptions. This study confirms theophylline
Area of Science:
- Pharmacokinetics
- Clinical Pharmacology
- Drug Metabolism
Background:
- Theophylline dosing recommendations often assume low intrapatient variability in elimination rates.
- Previous reports suggest significant intrapatient variability, challenging current assumptions.
- This variability impacts bioavailability studies of slow-release theophylline formulations.
Purpose of the Study:
- To systematically investigate the intrapatient variability of theophylline elimination rate over extended periods.
- To assess the constancy of theophylline elimination under controlled conditions.
- To provide data for refining theophylline dosing and bioavailability study methodologies.
Main Methods:
- Controlled study of theophylline elimination rate in 10 patients.
- Extended time interval monitoring of elimination rate constants.
- Statistical analysis of initial and subsequent elimination rate values.
Main Results:
- Initial elimination rate constants varied between 0.062 and 0.136 hours-1.
- Observed changes in elimination rate ranged from -5.9% to 9.4% over 2 to 11 months.
- A high correlation (0.96) was found between initial and subsequent elimination rate values.
Conclusions:
- The elimination rate of theophylline demonstrates minimal intrapatient variability over time when studied under controlled conditions.
- Findings support the assumption of relative constancy for theophylline elimination in clinical practice and bioavailability studies.
- This research provides evidence against significant intrapatient variability impacting theophylline pharmacokinetics.
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