This study investigated the effects of β-blockers and their combination with epinephrine on spinal nociceptive and motor blockade and compared them with propranolol. The spinal blocking effects of carteolol, oxprenolol, metoprolol, acebutolol, and sotalol were evaluated after intrathecal injection in rats. The spinal blocking effects of carteolol and oxprenolol in combination with epinephrine were further tested. Propranolol was used as a control. The results showed that at the same dose (0.6 μmol), both carteolol and oxprenolol were more potent than propranolol, and their duration of action was comparable to or longer than that of propranolol. At ED50 (50% effective dose), the potency was in the order of carteolol > oxprenolol > propranolol (P < 0.01). In addition, at ED25, ED50, and ED75 doses, carteolol induced a significantly longer time to full recovery than oxprenolol or propranolol. When 1:40,000 epinephrine was combined with a β-blocker (carteolol, oxprenolol, and propranolol) at ED50, both the blocking effect and its duration were significantly increased compared with the β-blocker alone (P < 0.05). We concluded that both carteolol and oxprenolol were superior to propranolol, whereas the other β-blockers did not show significant effects in terms of spinal blockade. Epinephrine enhanced the spinal blocking effect of carteolol, oxprenolol, and propranolol, suggesting that α-adrenoceptors may play a key role in enhancing the spinal anesthetic effect of β-blockers.

Dr Yu-Wen Chen is a Professor in the Department of Physical Therapy and Institute of Rehabilitation Science at the China Medical University, Taiwan. He obtained the degree of Bachelor of Physical Therapy (2000) and a PhD in Physiology (2006), both from the National Yang Ming Chiao Tung University, Taiwan. Since graduation, he was appointed as a Post-doctoral Research Fellow at the Chi-Mei Medical Center (Taiwan) prior to joining the faculty in 2007. He was promoted to full professorship in 2014. He has published more than 100 papers in reputed journals and has been serving as an editorial board member of repute.