The Holy Grail of local anesthesia is the ability to strike a nerve block of long duration that eliminates the sensation of pain without affecting motor function. Researchers at Children’s Hospital Boston have discovered an anesthetic method that seems to do just that. The formula? Lidocaine + surfactants.
In local anesthesia, in contrast to the total, it is necessary that the drug blocks pain locally without interfering with other motor activities. An example of this is delivery, which the mother needs a local anesthetic to block pain without interfering with the ability to push the fetus. In this work we tested the efficacy of this treatment in humans, as it did in rats, might be useful in a variety of medical applications.
The discovery was published in the online early edition of Proceedings of the National Academy of Sciences is beginning to find an agent to prolong the effects of anesthesia. They focused on surfactants, a subclass of so-called “enhancers on the permeability of the chemicals” that allow drugs more easily spread through tissue.
In tests of three kinds of surfactants, along with anesthetics QX-314 and QX-222 (both derivatives of lidocaine), found that this approach did not prolong sensory block in the sciatic nerve of rats, up to 7 hours or more depending on surfactant. However, the treatment did not prolong the motor impairment and, in some cases, motor block was absent or very short. In rats, this meant they were able to tolerate a hot plate on their feet for long periods (pain) but they were still able to balance and take weight on his legs (motor).
Here it is not a new drug but a new approach, the question now is to decipher the mechanism whereby these surfactants work and look at their possible side effects.
The researchers speculate that the surfactant makes anesthetics are able to easily penetrate the sensory nerves, which have little or nothing of a thick layer called myelin, whereas motor neurons, which contain abundant myelin, the active drug is trapped in it, without ever entering the motor nerve.
The next steps in the laboratory will explore the effects of enhancers on the permeability in both animal and examine its security as high-dose combination of drugs could be toxic to nerves. The final plan is to test the new approach in larger animals before they reach humans.
