[CAS NO. 27262-48-2]  Levobupivacaine HCl

Levobupivacaine is an amide-type local anaesthetic. Levobupivacaine acts via blockade of voltage-sensitive ion channels in neuronal membranes, preventing transmission of nerve impulses. Localised and reversible anaesthesia is produced by interference with the opening of the sodium channel, which inhibits conduction of the action potential in nerves involved in sensory and motor activity and sympathetic activity. Levobupivacaine displaces H-BTX from sodium channels of rat brain synaptosomes with IC50 of 2.9 μM and Hill coefficients of 1.2. When cell membrane is held at -80 mV, -70 mV, -60 mV or -100 mV, Levobupivacaine shows tonic inhibition of sodium channel in GH3 cells with IC50s of 132.1, 37.6, 21.6 and 264 μM, respectively. Levobupivacaine depresses action potential of isolated axon in vitro. Levobupivacaine (1mM) depresses action potential amplitude and maximal rate of rise of action potential (dV/dt) in the crayfish giant axons with value of 88 and 81 respectively, after perfusion for 15 min. Levobupivacaine also displays activity on cardiac ion channels. In isolated ventricular myocytes, the apparent affinity for inactivated state of the sodium channel is 4.8 μM for Levobupivacaine, with a calculated KD of 39μM. On inhibition of cardiac delayed rectifier potassium channels (hKv1.5), the steady-state block for Levobupivacaine (20 μM) is 31%, with a calculated KD of 27.3 μM. Levobupivacaine may also inhibit cardiac calcium channels. 10 μM Levobupivacaine produces a 50% decrease in contractile force of guinea-pig papillary muscles.