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Bioavailability of naproxen tablets and suppositories in steady state
Scandinavian Journal of Rheumatology. Supplement
|January 1, 1983
Summary
This study found that pre-dose naproxen serum concentrations accurately predict overall drug exposure (AUC) in rheumatoid arthritis patients. This supports using fixed blood sampling times in clinical trials for naproxen.
Area of Science:
- Pharmacokinetics
- Rheumatology
- Drug Metabolism
Background:
- Rheumatoid arthritis (RA) management often involves non-steroidal anti-inflammatory drugs (NSAIDs) like naproxen.
- Understanding naproxen pharmacokinetics is crucial for optimizing treatment efficacy and safety in RA patients.
- Evaluating different dosage forms, such as tablets and suppositories, is important for patient convenience and therapeutic equivalence.
Purpose of the Study:
- To determine the pharmacokinetic profile of naproxen in rheumatoid arthritis patients.
- To assess the correlation between pre-dose serum naproxen concentrations and overall drug exposure (Area Under the Curve - AUC).
- To compare the bioavailability and efficacy of naproxen administered as tablets versus suppositories.
Main Methods:
- Serum naproxen concentrations were measured in RA patients after 10 days of treatment to achieve steady-state conditions.
- Naproxen levels were quantified using mass fragmentography.
- Blood samples were collected at fixed time points, including immediately before dose intake, to correlate with AUC.
Main Results:
- Pre-dose serum naproxen concentrations showed a strong correlation with AUC for both 12-hourly and once-daily dosing regimens (r = 0.85 and r = 0.83, respectively).
- The mean steady-state concentration was 45.0 +/- 1.7 mg/l, and the mean half-life was 15.2 +/- 1.4 hours with 12-hourly dosing.
- Naproxen suppositories demonstrated a relative bioavailability of 103% +/- 4% compared to tablets, indicating comparable drug absorption.
Conclusions:
- Fixed time-point blood sampling, particularly pre-dose concentrations, is a reliable method for assessing naproxen exposure in clinical trials.
- Naproxen tablets and suppositories exhibit comparable bioavailability and likely similar efficacy in RA patients.
- The established pharmacokinetic parameters provide valuable data for naproxen dosing optimization in rheumatoid arthritis therapy.