Levobupivacaine is a drug that has analgesic, motor blocking, and sensory blocking effects on the human body, whose properties are dictated by its chemical characteristics, such as pK, which has a value of 8.1. The pK of a drug can be informative information that indicates its ionisation under physiological conditions. For example, drugs with a high pK, such as that of levobupivacaine, tend to be their ionised form under physiological state, meaning that they would not easily cross the hydrophobic plasma membrane of cells. This, however, is counteracted by the high lipid solubility of levobupivacaine, which increases the ease with which it can diffuse through the phospholipid bilayer. Additionally, high-protein binding quality (97%) is characteristic of levobupivacaine, which strengthens its binding to cell surface proteins, thereby lengthening the binding, and thus action time.
The S(-)-enantiomer of levobupivacaine is a high-potency, long-acting anaesthetic with a relatively slow onset of action. Indeed, it has been found in certain studies that, as a surgical anaesthetic, it has a sensory ad motor blocking activity for over 90% of adult patients who received appropriate doses for their bodily composition, and duration of the surgery, with an onset time of 15 minutes.
More specifically, levobupivacaine achieves its effects by acting on the neuronal voltage-sensitive sodium channels, where it prevents the transmission of nerve impulses. The normal function of these sodium channels is halted temporarily, as the drug interferes with their opening, thereby inhibiting the conduction of action potentials in nerves involved in sympathetic, sensory, and motor activity. This interruption results in decreased muscle control, and overall analgesic effects which allow for levobupivacaine to act as a local anaesthetic.
Levobupivacaine varies slightly in its effects depending on the characteristics of the neuron in question. For example, in myelinated neurons, the nodes of Ranvier are targeted and more easily blocked than unmyelinated neurons, and small nerves are more easily blocked than large nerves.
When compared to the racemic bupivacaine mixture, levobupivacaine generally has been shown to have similar effects. As an anaesthetic, it is similar in nerve-blocking potency compared to its R(+)-enantiomer and racemic mixture, although its effects are affected by the route of administration and the concentration, however, they were ultimately similar among the three. Some animal studies indicate that among the three, levobupivacaine shows an increased duration of anaesthesia and/or greater potency, and there is evidence that in humans it is as potent as bupivacaine.