Match each patient's clinical presentation of a psychotropic medication adverse effect to the primary pharmacodynamic or pathophysiologic mechanism responsible for the finding.
- A patient on maintenance therapy for bipolar I disorder presents with excessive thirst and frequent urination; urine osmolality is 150 mOsm/kg and does not increase following a water deprivation test.Interference with adenylyl cyclase signaling at the renal vasopressin V2 receptor, impairing aquaporin-2 channel insertion.
- A young male given an intramuscular injection for acute agitation suddenly develops a painful, sustained upward deviation of the eyes and extreme cervical muscle contraction.Acute, high-affinity blockade of dopamine D2 receptors in the nigrostriatal pathway, disrupting the striatal dopamine-acetylcholine balance.
- A patient treated for refractory schizophrenia develops severe, socially embarrassing drooling (sialorrhea) concurrent with paradoxical complaints of blurred vision and severe constipation.Paradoxical muscarinic M4 receptor agonism in salivary glands combined with systemic M1 and M3 receptor antagonism.
- A patient receiving an augmenting agent for depression with insomnia exhibits significant daytime somnolence and a 6-kg weight gain in a month, while explicitly denying any sexual dysfunction.Potent combined central histamine H1 receptor blockade and serotonin 5-HT2C receptor antagonism.
- A patient recently transitioned to a new long-acting injectable antipsychotic develops bilateral breast discharge, secondary amenorrhea, and early osteopenia.Loss of tonic dopaminergic inhibition within the tuberoinfundibular pathway, resulting in unchecked anterior pituitary lactotroph secretion.
Answer
The correct matches require linking the clinical phenotype of the adverse effect to its exact molecular neuropharmacologic mechanism, such as linking clozapine's sialorrhea to M4 agonism, and lithium's polyuria to V2 receptor adenylyl cyclase interference.
Each pair correctly links a highly specific clinical adverse effect to its precise molecular mechanism. Lithium causes nephrogenic diabetes insipidus via V2 receptor interference. High-potency typicals cause dystonia via nigrostriatal D2 blockade. Clozapine causes sialorrhea via M4 agonism despite other anticholinergic effects. Mirtazapine causes weight gain and sedation via H1 and 5-HT2C antagonism. Risperidone causes hyperprolactinemia via tuberoinfundibular D2 blockade.
Step-by-Step Solution
Key Concept
Pharmacodynamic mechanisms of psychotropic medication adverse effects
Estimated Time:2m 0s