PSMA6 and xerostomia: However, ongoing investigations have also revealed its ability to act directly on receptors, such as adrenergic (alpha-1), histaminergic, and muscarinic (M1 and M3), which have been associated with side effects of its use, such as xerostomia and sedation, which shows its great importance and variety of actions in different places, which also facilitates the understanding of the therapeutic repositioning by this drug [3,6].