**5.2 Phenobarbital**

Phenobarbital belongs to the family of barbiturates. These are characterized by providing the central nervous system with a depressant effect depending on the administered dose [44]. Its anticonvulsant mechanism is based on increasing the inhibitory activity of GABA, binding to the GABA receptor, and facilitating even more inhibitory neurotransmission. This inhibition reduces ATP levels, which causes the opening of Ca2+ channels associated with the NMDA receptor, coupled with the fact that a prolonged opening of these Ca2+ would lead to excitotoxic neuronal death [45]. The anticonvulsant dose ranges between 10 and 40 μg/ ml. The administration of these doses and higher ones generates toxicity that is generally due to the increase in Ca2+ entry into the neuron [46]. Mitochondria are an intracellular target of barbiturates since they depolarize the mitochondrial membrane by inhibiting complex one of the electron transports chains and, furthermore, they could have an uncoupling effect on oxidative phosphorylation [47]. Its absorption of phenobarbital is gastric, which generates a decrease in peristaltic tone. Although it is metabolized in the liver and discharged through the kidneys and urine, it has a great fat solubility that crosses cell membranes, producing several alterations [48].
