A previous article that appeared on these same pages listed the drugs currently being studied in the field of alternatives to common catecholamine vasoconstrictors. In this context, one of the most recently introduced products is dexmedetomidine, an alpha-agonist, i.e., a molecule acting on alpha-2 adrenergic receptors with a higher specificity than adrenaline itself. This, in fact, acts on multiple receptors; the link with beta-2 receptors, for example, mediates the excitatory action on the heart muscle. This leads to a partial contraindication to be used in patients with certain heart diseases.
Therefore, in order to focus on the new molecule, this paper aims to evaluate the indications provided by the study by Yasuda and colleagues, which is recently reported on Odontology and related, as already explained in the title, to the effects induced by the combination of the vasoconstrictor in dental anesthesia drugs, such as mepivacaine.
The study carried out on a mouse model evaluated different pharmacological aspects: regional and hemodynamic blood flow, tissue distribution, and anaesthetic action. The objective is to establish, in advance, whether the vasoconstrictor in dental anesthesia can be used in the case of the cardiopathic patient.
Vasoconstrictor in dental anesthesia
Tissue pharmacokinetics have been evaluated with the help of autoradiography. 20 µl of the test solution (mepivacaine associated with dexmedetomidine at a concentration of 12.5 µg/ml) were injected into the palatal mucosa, adjacent to the first upper molar. Bone and mucosal samples were taken at 2, 20, 40, and 60 minutes. The clinical data, i.e., the anaesthetic effect, was evaluated through the study of somatosensory evoked potentials.
Maximum blood radioactivity was recorded 5 minutes after administration of mepivacaine alone, while the addition of the vasoconstrictor moved the detection to 50 minutes after injection.
Compared to the control (mepivacaine group), the addition of the molecule significantly decreases the amplitude from peak to peak, when evaluated from the appearance of the first positive wave, by up to 60 minutes after injection.
In the third group treated with only dexmedetomidine, there were no decreases in the test of evoked potentials, and this showed that the significant difference in the test group was not attributable to the analgesic action that the molecule would have at the level of the central nervous system.
Ultimately, the general evaluated hemodynamic variables consist of blood pressure and heart rate; in this case, no significant changes were detected.
In conclusion, even within the limits of the animal model, the study has preliminarily shown how dexmedetomidine, co-administered locally to mepivacaine, is able to increase its anaesthetic action and prolong its tissue permanence without interfering with the general hemodynamic picture.