Comparative assessment of trough and peak levels and AUC24 for amikacin in nontuberculous mycobacterial infection

Background: Amikacin, an aminoglycoside antibiotic, is widely used for the treatment of nontuberculous mycobacterial (NTM) infections. To date, therapeutic drug monitoring (TDM) of amikacin has primarily relied on the measurement of peak and trough levels as indicators rather than the 24-hr area under the concentration-time curve (AUC24).

Methods: NTM patients referred for amikacin TDM from March 2021 to May 2023 were assessed for the AUC24 values based on administered dose. We investigated re-admission rates, all-cause mortality and AFB smear results to evaluate clinical outcome based on the actual AUC24 values. Ototoxicity and nephrotoxicity were also investigated as adverse effects in correlation with TDM parameters.

Results: Among 65 patients, the mean and median values of AUC24 were 234 and 249 mg·hr/L, respectively. In a group of patients with AUC24 values less than 250 mg·hr/L, 42.4 % of patients were re-admitted for pulmonary symptoms. On the contrary, another group with AUC24 values equal to or more than 250 mg·hr/L, had lower re-admission rates (25.0 %). They also showed lower all-cause mortality rates and more improvement on acid-fast bacilli smear results. Moderate to poor correlation between AUC24 values and peak/trough levels were observed. Ototoxicity and nephrotoxicity were revealed to be associated with drug exposure duration rather than AUC24 values.

Conclusion: In this study, we performed comparative assessment of trough/peak level, traditional clinical marker for amikacin TDM, and AUC24 value. Although AUC24 values showed poor to moderate correlation to trough/peak levels, higher AUC24 correlated with favorable clinical outcomes without additional risk of toxicity.