High-pressure liquid chromatography analysis and single-dose disposition of tobramycin in human volunteers

Abstract

A sensitive and specific fluorometric high-pressure liquid chromatography technique was developed to measure both tobramycin and an internal standard (gentamicin C2). The assay utilizes direct extraction of the o-phthalaldehyde derivatives from serum and urine. Coefficients of variation were 7.9% (serum) and 6.0% (urine) at a tobramycin concentration of 1.0 ,tg/ml. The lower limit of assay sensitivity was 0.2 ,ug/ml. Results obtained from high-pressure liquid chromatography were in excellent agreement with those from radioimmunoassay for both serum (r = 0.97) and urine (r = 0.91). No other aminoglycoside antibiotics and no other antibiotics that were tested caused interfering peaks. Tobramycin (1 mg/kg intravenous bolus) was administered to three healthy volunteers. Tobramycin concentrations were detectable for 10 h in serum and for 240 h in urine after a 1-mg/kg intravenous dose. A two-compartment pharmacokinetic model was required to describe the tobramycin disposition. Urinary recovery of tobramycin over a 10-day period accounted for 95.8, 94.3, and 83.1% of the administered dose. High-pressure liquid chromatography methodology is sufficiently sensitive to determine single-dose, two-compartment tobramycin pharmacokinetics from urinary excretion data, thus verifying the prolonged excretion of tobramycin after a single dose. The analytical methodology and pharmacokinetic techniques described may be useful in studying other aminoglycosides. limits the applicability of these methods for routine clinical use (1, 2). Others have employed derivatization of aminoglycosides in serum and quantitation by measuring the peak height or peak area of the desired derivative (6,7,10

Animal model distinguishing in vitro from in vivo carbenicillin-aminoglycoside interactions

“…In the control animal, the in vivo serum half-lives of these three aminoglycosides were 30. 4 carbenicillin (28.6 h). The in vivo effects of carbenicillin on the halflife of tobramycin alone were also assessed in dogs 4, 5, and 6.…”

Simple and sensitive method for quantification of low tobramycin concentrations in human plasma using HPLC–MS/MS

“…Therefore, traditionally, analysis of aminoglycosides has been performed using pre-column derivatization with ultraviolet or fluorescent detection [7][8][9][10][11][12][13][14] or post-column derivatization with fluorescent detection [7,15]. However, derivatization methods require complicated sample preparation procedures and incomplete or unstable derivatization may be a source of error in the method.…”

“…Published chromatographic methods for the quantification of tobramycin in human plasma report a LLQ suitable for regular therapeutic drug monitoring: 0.1 [18], 0.15 [22], 0.2 [12,13], 0.3 [14], 0.5 [9], 0.6 [23], 0.9 [11], 1.0 [10], and 2 mg/l [15]. In this article we present a simple, rapid and, above all, sensitive method (LLQ 0.05 mg/l) for the quantification of tobramycin in plasma using HPLC-MS/MS.…”

Aminoglycoside antibiotics — two decades of their hplc bioanalysis

“…Tobramycin is used in the treatment of serious gramnegative infections (Haughey et al, 1980). It has a narrow therapeutic range and can cause severe nephroand ototoxicity at serum concentrations exceeding 12 mg/mL (Kabra et al, 1983; Table 1).…”