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Circadian variation in serum amikacin levels
L Elting1, G P Bodey, B Rosenbaum
1Department of Medical Specialties, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Journal of Clinical Pharmacology
|September 1, 1990
Summary
Monitoring amikacin (a powerful antibiotic) levels is crucial for neutropenic patients. Early morning blood draws provide higher, more reliable amikacin concentrations for effective therapeutic drug monitoring.
Area of Science:
- Pharmacology
- Nephrology
- Infectious Diseases
Background:
- Variable serum amikacin concentrations can occur even at steady-state, complicating therapeutic drug monitoring.
- Neutropenic patients receiving continuous infusion amikacin therapy require precise monitoring to ensure efficacy and safety.
Purpose of the Study:
- To determine the optimal timing for monitoring serum amikacin levels in neutropenic patients undergoing continuous infusion therapy.
- To investigate diurnal variations in amikacin serum concentrations and their relationship to renal function.
Main Methods:
- Prospective study involving 50 neutropenic patients receiving continuous infusion amikacin.
- Serial blood sampling for amikacin level determination at different times of day (early morning and evening).
- Correlation analysis between amikacin levels, renal function, and time of day.
Main Results:
- Serum amikacin levels were significantly higher in early morning samples compared to evening samples within the same patient.
- Observed diurnal variations in amikacin levels parallel known patterns of renal function, suggesting kidney clearance as the primary driver.
- These findings highlight the importance of consistent timing for therapeutic drug monitoring.
Conclusions:
- Recommend early morning blood collection for routine monitoring of amikacin serum levels to ensure consistent and comparable peak concentration measurements.
- Advise late evening sampling when dosage adjustments are contemplated to maintain continuous therapeutic serum concentrations.
- Emphasize the role of diurnal variations in renal clearance in explaining amikacin level fluctuations.