Psychopharmacologic Agents

• The prevalence of psychiatric disorders such as depression and anxiety has significantly increased in the US.

• Statistics: 9.6 million adults in the US are documented as suffering from severe mental illness.

• Guidelines: Most psych medications should be continued through the perioperative period.

Selective Serotonin Reuptake Inhibitors (SSRIs)

• EX Drugs: Fluoxetine, Paroxetine, Sertraline, Fluvoxamine, Citalopram, Escitalopram

• Mechanism of Action (MOA): Bind and inhibit the serotonin transporter protein (SERT), blocking the reuptake of serotonin from the synaptic cleft back into the presynaptic neuron, which inhibits serotonergic transmission.

  • These are first line tx in depression and should be continued through periop period

• Side Effects:

  • Insomnia, nausea, diarrhea, headache, dizziness, sexual dysfunction.

  • Elderly patients may experience hyponatremia.

  • Antiplatelet effects may increase bleeding risks.

  • CYP450 inhibitors

  • QT Interval Prolongation: Citalopram and Escitalopram

  • Serotonin Syndrome:

    • A condition marked by toxic levels of synaptic and extracellular serotonin causing autonomic excitability, neuromuscular excitability, and mental status changes.

    • Symptoms: Life-threatening hyperpyrexia, rigidity, risk of rhabdomyolysis, multi-organ failure, and disseminated intravascular coagulation.

    • Common Causes: Often caused by drug combinations or interactions.

Serotonin Norepinephrine Reuptake Inhibitors (SNRIs)

• EX Drugs: Venlafaxine, Desvenlafaxine, Duloxetine, Levomilnacipran

• Mechanism: Inhibit both norepinephrine transporter (NET) and SERT.

• Usage: Commonly employed as first or second-line treatments for anxiety, depression, and chronic pain.

• Side Effects:

  • Increased sweating, tachycardia, urinary retention, and dose-dependent hypertension. “SHIVERS”

  • Withdrawal symptoms with abrupt cessation.

Tricyclic Antidepressants (TCAs)

• EX Drugs: Amitriptyline, Doxepin, Clomipramine, Nortriptyline, Imipramine, Desipramine

• Usage: Second line or alternative treatments for depression and as analgesic adjuncts (pain relief typically observed in 7-14 days)

• Common Side Effects: Anticholinergic effects (dry mouth, urinary retention, constipation, blurred vision, confusion).

• Risks:

  • May cause cardiac conduction delays, potentially leading to dysrhythmias.

  • Prolonged QT interval necessitates ECG screening, especially in patients with heart disease.

  • Avoid Amitriptyline in pts with hx heart disease (arrhythmias, HF, conduction disorders) an open angle glaucoma

    • Causes increased HR and orthostatic hypotension?

  • Increases MAC requirements of volatile anesthetics due to increased catecholamines.

    • Exaggerated responses to ephedrine for the first 4-6 weeks of TCA administration. After initial increase in catecholamines, receptor down regulation and depleted catecholamine stores result in lesser response

    • Direct acting PHENYLEPHRINE is the preferred vasopressor if needed.

Monoamine Oxidase Inhibitors (MAOIs)

• EX Drugs: Phenelzine, Moclobemide, Isocarboxazid, Selegiline, Tranylcypromine

• Second-line treatment for severe depression, not used as often due to side effects (hypotension, insomnia) and potential lethal overdosing

• Mechanism: Inhibit either MAO-A or MAO-B;

  • MAO-A ENZYMES: metabolize serotonin, NE, and Epi

  • MAO-B ENZYMES: metabolize phenylethylamine

  • **MAOIs form an irreversible complex with MAO enzyme which causes an increase in neurotransmitter release (Norepinephrine, epinephrine, serotonin, dopamine)

• Risks:

  • By itself, causes orthostatic hypotension

  • Hypertensive crisis may occur WITH tyramine containing foods or indirect acting vasopressors (ephedrine)

    • Use directing acting vasopressors (Phenylephrine); 1/3 total dose

  • serotonin syndrome due to drug interactions with OTC dextromethorphan, Ecstasy, SSRIs, Meperidine, atypical antipsychotics

• Anesthesia considerations:

  • No longer recommended to discontinue MAOIs but the anesthesia plan should be altered.

  • Avoid the use of Meperidine

  • Regional anesthesia is acceptable, but Ephedrine should not be used if patient experiences hypotension

  • Direct acting vasopressors should be used (Phenylephrine)

Lithium

• Drug of choice for maintenance of bipolar disorder–

  • Often given with anticonvulsants or other antipsychotic medications

  • Narrow therapeutic window

• Side effects: tremors, thirst, confusion, weight gain, polyuria, & edema

• Avoid NSAIDs, ACE inhibitors, Diuretics (which can ↑ lithium levels)

• Prolongs the duration of neuromuscular blocking agents, reducing MAC requirements (as causes more sedation)

• **still continue periop

Antipsychotics/Neuroleptics

• Medications used to treat schizophrenia and other serious mental illnesses

• Dopamine receptor antagonists (first generation) EX: Haloperidol, Loxapine, Pimozide, Chlorpromazine, Thioridazine, Perphenazine, Fluphenazine

  • antiemetic properties (Haloperidol)

  • risk of prolonged QT interval, tardive dyskinesia, sexual dysfunction, neuroleptic malignant syndrome

• Serotonin-Dopamine receptor antagonists (second generation- atypical antipsychotics) EX: Abilify, Zyprexa, Seroquel, Risperdal

• More commonly used

• Should be continued throughout the perioperative period.