Tobramycin concentration

Monitoring In patients with normal renal function, serum tobramycin concentrations are approximately 1 mcg/mL 1 hour after dose administration. Monitoring of serum concentrations in patients with renal dysfunction or patients treated with concomitant parenteral tobramycin may reduce the risk of toxicity. 

Elidemir O, Maciejewski SR, Oermann CM. Falsely elevated serum tobramycin concentrations in cystic fibrosis patients treated with concurrent intravenous and inhaled tobramycin. Pediatr Pulmonol 2000 29(l) 43-5. 

Sample material Serum or plasma. Serum and plasma samples of patients who receive penicillin or penicillin analogues besides the aminoglycoside cannot be stored for any prolonged period. In such cases the tobramycin concentration will drop. 

Specificity The drugs tabulated below produce a 15% increase in tobramycin concentration if added to a sample containing 4 mg/1 tobramycin, in a concen- ... 

The following drugs lead to a 25% increase in tobramycin concentration if they are added in the stated concentrations to a sample having a tobramycin concentration of 4 mg/1. 

Eisenberg J, Pepe M, Williams-Warren J, Vasiliev M, Montgomery AB, Smith AL, Ramsey RW. A comparison of peak sputum tobramycin concentration in patients with cystic fibrosis using jet and ultrasonic nebulizer systems. Chest 111 955-962, 1997. 

On the basis of these data, no further therapy will likely be required until after the next dialysis treatment since one generally desires to have tobramycin concentrations fall below 2 mg/L before administering another dose. 

Because of its narrow therapeutic index, tobramycin concentrations are frequently monitored. The thera-... 

Figure 9.4 Scatter plot of pooled tobramycin concentration—time profiles relative to the most recent dose administered. Solid line is the inverse square kernel smooth to the data using a 0.3 sampling proportion, which suggests that concentrations declined biphasically after dosing.

Figure 9.19 Scatter plots of observed tobramycin concentrations ( ) overlaid with predicted concentrations (solid line) in four patients randomly selected from each of the renal function groups. Patient 60, severe renal impairment patient 101, moderate renal impairment patient 112, mild renal impairment patient 53, normal renal function. Each patient s CrCL is plotted as a dashed line. The model predicted concentrations were based on Eq. (9.17) using the final estimates reported in Table 9.18 (FOCE-I) after removal of two outlier observations and four influential patients.

Richman, J. Zolezio, H. Tang-Liu, D. Comparison of ofloxacin, gentamicin, and tobramycin concentrations in tears and in vitro MICs for 90% of test organisms. Antimicrob.Agents Chemother., 1990,34, 1602-1604... 

To simulate what might happen in the gut, tobramycin 50 mg/mL was mixed with sucralfate 500 mg in 40 mL of water at pH 3.5 and allowed to stand for 90 minutes at 25 C. Analysis of the solution showed that the tobramycin concentration fell rapidly and progressively over 90 minutes to about 1%. When the pH of the mixture was then raised to 6.5 to 7 for 90 minutes, there was no change in the concentration of tobramycin, suggesting that the interaction was irreversible. The reason for this change is not known, but the suggestion is that sucralfate forms insoluble chelates with tobramycin. ... 

Inhibitory Zone Diameter for Tobramycin concentration (disc) 10 yg is mm. 

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