Depression is commonly encountered in the general population, affecting over 15% of people at some point during their lives. Consequently, the prevalence of patients taking mood-altering pharmaceuticals is significant. These medications include selective serotonin reuptake inhibitors (SSRI), serotonin-norepinephrine reuptake inhibitors (SNRI), tricyclic antidepressants (TCA), norepinephrine-dopamine reuptake inhibitors (NDRI), monoamine oxidase inhibitors (MAOI), and atypical antidepressants (Table 28-1). Each of these classes of medications present unique implications for the anesthetic management of the patient and thus it is essential to understand the mechanism of action, side effect profile, and drug interactions of each.
TABLE 28-1Common Antidepressants ||Download (.pdf) TABLE 28-1 Common Antidepressants
|Selective serotonin reuptake inhibitors ||Citalopram, escitalopram, fluvoxamine, fluoxetine, paroxetine, sertraline |
|Serontonin-norepinephrine reuptake inhibitors ||Venlafaxine, duloxetine, milnacipran |
|Tricyclic antidepressants ||Amitriptyline, amoxapine, clomipramine, desipramine, doxepin, imipramine, maprotiline, nortriptyline, proptriptyline, trimimpramine |
|Norepineprhine-dopamine reuptake inhibitors ||Bupriopion |
|Monoamine oxidase inhibitors ||Deprenyl, phenelzine, selegiline, tranylcypromine |
|Atypicals ||Amisulpride, viloxazine, trazadone, nefazodone, mirtazapine |
|Herbal ||Gingko biloba, ginseng, St. John’s wort |
Major depressive disorder (MDD) is classified by the DSM-IV as depressed mood or loss of interest/pleasure in life activities for at least 2 weeks, including at least two of the following symptoms:
Depressed mood most of the day
Diminished interest or pleasure in all or most activities
Significant unintentional weight loss or weight gain
Insomnia or sleeping too much
Agitation or psychomotor retardation noticed by others
Fatigue or loss of energy
Feelings of worthlessness or excessive guilt
Diminished ability to think or concentrate, or indecisiveness
Recurrent thoughts of death
It is important, however, for the anesthesiologist to distinguish major depressive disorder from secondary causes of depressed mood, especially hypothyroidism, substance abuse, dementia, Parkinson’s disease, and inflammatory conditions.
SELECTIVE SEROTONIN REUPTAKE INHIBITORS
Selective serotonin reuptake inhibitors (SSRIs) are thought to be the most effective antidepressants with the safest pharmacological profile and thus are the most frequently encountered antidepressant by anesthesiologists. SSRIs work by preventing the reuptake of serotonin from neuronal clefts, thus potentiating the propagation of serotonergic impulses. They selectively work on serotonin and thus avoid altering the norepinephrine or acetylcholine pathways. Yet, despite their ubiquitous use, SSRIs still have several potential adverse effects, such as nausea, headache, loss of libido, erectile dysfunction, suicidal ideation, and most notably for the anesthesiologist serotonin syndrome.
It is also important to recognize that, within this class, escitalopram can precipitate hyponatremia and fluoxetine is a potent inhibitor of cytochrome P-450 2D6. The inhibition of the hepatic cytochrome P-450 system causes an unpredictable increase in concentrations of certain hepatically metabolized drugs, including beta-blockers, TCAs, codeine, donepezil, haloperidol, risperidone, and tramadol. Also, notably SSRIs do not affect the seizure threshold.
Serotonin syndrome is a potentially life-threatening event associated with an increased level of serotonin in the blood, usually secondary to concomitant administration ...