• Tadayoshi Kurita, Kotaro Takata, Masahiro Uraoka, Koji Morita, and Shigehito Sato.
• Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, Japan. tadkur@hama-med.ac.jp
• Anesth. Analg. 2007 Sep 1;105(3):656-60.

BackgroundWe previously reported that landiolol, an ultra-short-acting beta1-adrenoceptor antagonist, does not alter the electroencephalographic effect of isoflurane. Here, we investigated the influence of landiolol on the minimum alveolar anesthetic concentration (MAC) of isoflurane required to prevent movement in response to a noxious stimulus in 50% of subjects.MethodsTen swine (29.0 +/- 3.4 kg) were anesthetized by inhalation of isoflurane. MAC was determined using the dewclaw clamp technique, in which movement in response to clamping is recorded. After determination of MAC in the baseline period, an infusion of landiolol (0.125 mg x kg(-1) x min(-1) for 1 min, then 0.04 mg x kg(-1) x min(-1)) was started. After a 20-min stabilization period, MAC was again assessed (0.04 mg x kg(-1) x min(-1) landiolol). The infusion of landiolol was then increased from 0.04 to 0.2 mg x kg(-1) x min(-1), and after a 20-min stabilization period, MAC was again assessed (0.2 mg x kg(-1) x min(-1) landiolol). Finally, the infusion of landiolol was stopped, and after a 20-min stabilization period, MAC was assessed for a fourth time (Baseline 2).ResultsLandiolol clearly attenuated the increases in heart rate and mean arterial blood pressure that occurred in response to the dewclaw clamp, but did not alter the MAC of isoflurane.ConclusionsLandiolol does not alter the antinociceptive effect of isoflurane. This result, combined with that from our previous work, also suggests that landiolol does not influence the anesthetic potency of inhaled anesthetics.

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