This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Mizogami, M. Articles by Takakura, K. Search for Related Content PubMed PubMed Citation Articles by Mizogami, M. Articles by Takakura, K. Related Collections Pharmacology

---

ANESTHETIC PHARMACOLOGY

Local Anesthetics Adsorbed onto Infusion Balloon

Maki Mizogami, MD PhD^*, Hironori Tsuchiya, PhD, and Ko Takakura, MD PhD^*

Departments of *Anesthesiology and Dental Basic Education, Asahi University School of Dentistry, Mizuho, Gifu, Japan

Address correspondence and reprint requests to Maki Mizogami, MD, PhD, Department of Anesthesiology, Asahi University School of Dentistry, 1851-1 Hozumi, Mizuho, Gifu 501-0296, Japan. Address e-mail to makikai{at}dent.asahi-u.ac.jp

We compared the adsorption of different local anesthetics onto infusion balloons and studied one of the possible mechanisms for adsorption. After injection of lidocaine, bupivacaine, ropivacaine, and mepivacaine solutions (1 mM each; pH 7.4) into balloons of 100-mL volume, their concentrations in effluents flowing out at 4 mL/h were determined over time by high-performance liquid chromatography. All were adsorbed in a structure-dependent manner, and the concentration decreased by 6%–14% within 5 min. Bupivacaine was most strongly adsorbed, followed by lidocaine, ropivacaine, and mepivacaine. QX-314, a quaternary ammonium derivative of lidocaine, was only weakly adsorbed compared with the parent compound lidocaine. The extent of adsorption of local anesthetics was related to their hydrophobicity (evaluated by reversed-phase chromatography) and was much more at pH 7.4 than at pH 6.0. A hydrophobic interaction with balloon materials appears to be responsible for the adsorption of local anesthetics. When infusion balloons are used for the continuous administration of local anesthetics, attention should be paid to the possibility that their actual concentrations in effluents are smaller than those present when they are initially prepared.

IMPLICATIONS: Lidocaine, bupivacaine, ropivacaine, and mepivacaine decreased in the effluents flowing out of infusion balloons, indicating that local anesthetics are often adsorbed onto the balloons and that their actual infused concentrations may be smaller than predicted.