The effect of in-line filtration on tobramycin delivery

The purpose of this study was to determine if the presence of an in-line 0.22 mu cellulose ester membrane filter would hamper the delivery of a common adult dose of tobramycin sulfate. Solutions of tobramycin sulfate 80 mg in 100 ml D5W were assayed after 30 minute infusions through unfiltered and filtered administration sets; solutions post-flush of filtered sets were also assayed. Assay was done by Emit-QST. The results indicated that there was no significant difference in the delivery of tobramycin sulfate, regardless of the presence of an in-line filter. Solutions post-flush contained about ten percent of the drug, reflecting the amount in solution that remained in the tubing. Since ten percent can alter pharmacokinetic monitoring for patient dosing, a consistent procedure for flushing filtered administration sets should be adopted to enhance accuracy of such determinations.