Psychopharmacology – Mechanisms & Drug Profiles

Vocabulary flashcards summarizing mechanisms of action, receptor profiles and key clinical points for autonomic agents, antipsychotics, and antidepressants covered in the lecture notes.

A2-Adrenergic Receptor Agonist

Drug class that stimulates presynaptic α2-receptors to reduce autonomic symptoms of rapid opioid, alcohol, benzodiazepine and nicotine withdrawal.

Clonidine

α2-Adrenergic agonist used to lessen autonomic withdrawal symptoms from opioids, alcohol, benzodiazepines and nicotine.

Guanfacine

α2-Adrenergic agonist sharing clonidine’s withdrawal-suppressing properties.

Yohimbine

α2-Adrenergic receptor antagonist employed in treating idiopathic or medication-induced erectile dysfunction.

Prazosin

α1-Adrenergic receptor agent used to suppress PTSD-related nightmares; precise mechanism for nightmare control is unknown.

β-Adrenergic Receptor Antagonists

Blockers helpful for lithium-induced or other medication-induced (TCA, valproate) postural tremor.

Barbiturates

Sedatives that act on the GABA-benzodiazepine-chloride ion channel complex to enhance inhibitory neurotransmission.

Memantine

NMDA receptor blocker that tempers excessive glutamatergic activity implicated in Alzheimer’s disease.

Agomelatine

Melatonin MT1/MT2 agonist and serotonin antagonist with antidepressant properties.

Typical (First-Generation) Antipsychotics

D2 receptor antagonists in the mesolimbic pathway; also block M1 (anticholinergic), H1 (histaminic) and α1 (adrenergic) receptors, producing multiple side effects.

M1-Cholinergic Blockade (FGAs)

Leads to dry mouth, blurred vision, constipation and cognitive blunting.

H1-Histamine Blockade (FGAs)

Causes weight gain and drowsiness.

α1-Adrenergic Blockade (FGAs)

Produces cardiovascular effects such as orthostatic hypotension.

Atypical (Second-Generation) Antipsychotics

Serotonin-dopamine antagonists (5-HT2A and D2) with broader receptor actions and lower EPS risk than FGAs.

Clozapine

Antagonist at D1, D4, α1, 5-HT1A and M1-M5 plus H1 receptors; effective for treatment-resistant schizophrenia.

Olanzapine

Antagonist at D2 and 5-HT2 receptors along with 5-HT6, D1, H1, α1 and α2 blockade.

Quetiapine

5-HT2 and D2 antagonist also blocking α1, α2 and H1 receptors; sedation prominent.

Risperidone

Antagonist at 5-HT2A, D2, α1, α2 and H1 receptors; conversion to active metabolite depends on CYP2D6, which is inhibited by paroxetine and fluoxetine.

Lurasidone

High affinity antagonist for 5-HT7 and 5-HT2A; moderate affinity for 5-HT1A and α2 receptors.

Aripiprazole

Partial D2 agonist, potent 5-HT2A antagonist and α1 antagonist; also approved for several child and adolescent indications.

Brexpiprazole

More potent 5-HT1A partial agonist than 5-HT2A antagonist, yet less potent than its D2 binding; offers balanced dopamine-serotonin modulation.

Caripiprazine

D2/D3 partial agonist with D3-preferring affinity; greater D2 antagonism compared to aripiprazole.

Selective Serotonin Reuptake Inhibitors (SSRIs)

Antidepressants that inhibit SERT, raising synaptic serotonin.

Fluoxetine

SSRI with 5-HT2C antagonism enhancing prefrontal dopamine/norepinephrine; long-lived metabolite minimizes withdrawal.

Sertraline

Activating SSRI with 5-HT2C actions, dopamine transporter inhibition and sigma-1 receptor binding.

Paroxetine

SSRI possessing muscarinic anticholinergic and NET inhibition; highest risk of discontinuation syndrome due to rapid plasma decline.

Fluvoxamine

SSRI with the most potent sigma-receptor binding and greatest drug-interaction potential among SSRIs.

Citalopram

R- and S-enantiomer mixture; R enantiomer confers mild antihistaminic action; notable for pronounced QT-interval prolongation.

Escitalopram

Pure active S-enantiomer of citalopram; best tolerated SSRI with minimal CYP-mediated interactions and reduced antihistaminic effects.

Vilazodone

SPARI combining SERT inhibition with 5-HT1A partial agonism to stimulate striatal dopamine release.

Serotonin Partial Agonist/Reuptake Inhibitor (SPARI)

Drug class that both inhibits serotonin reuptake and partially agonizes 5-HT1A receptors (e.g., vilazodone).

Discontinuation Syndrome (SSRIs)

Withdrawal-like symptoms appearing when short-half-life SSRIs (notably paroxetine) are stopped abruptly.

QT-Interval Prolongation (SSRI)

Cardiac conduction effect most pronounced with citalopram among SSRIs.

CYP2D6 Inhibition

Metabolic blockade by paroxetine or fluoxetine that can hinder risperidone’s activation to its active metabolite.

Lithium-Induced Tremor

Postural tremor ameliorated by β-adrenergic receptor antagonists.

NMDA Receptor Overexcitation

Glutamate-mediated process implicated in Alzheimer’s disease; targeted by memantine.