Introduction
Hyoscine is a non-selective muscarinic acetylcholine receptor antagonist that binds to a group of muscarinic receptors (M1-M5) that modulates the release of acetylcholine or dopamine indirectly. M1-like muscarinic receptors (M1, M3, M5) and M2-like muscarinic receptors (M2, M4) activate and inhibit G-protein-mediated second messenger transduction, respectively.1,2 Hyoscine blockade of the M2 muscarinic auto-receptor in the axon terminal is thought to raise acetylcholine levels in the substantia nigra (SN) and ventral tegmental area (VTA) midbrain areas, increasing striatal dopaminergic levels in the mesopontine nuclei.3,4 Positive psychotic symptoms like hyperactivity and stereotypy may result from such activity.5,6 Inhibition of M4 subtype receptors, on the other hand, has been linked to memory and attention problems.1
We report a case of hyoscine-induced psychosis in a 9-year-old female. The psychosis began when the medicine was taken and faded once it was stopped. After a few days of being off the medicine, the child was perfectly fine.