Definition
- Multicyclic compounds that inhibit the reuptake of neurotransmitters or block their metabolism, resulting in an increase concentration of monamines in the synapse.
- Tricyclic antidepressants (TCAs): amitriptyline (Elavil), nortriptyline, doxepin, imipramine (Tofranil), desipramine, trimipramine, protriptyline, clomipramine (Anafranil)
- Selective serotonin reuptake inhibitors (SSRIs): fluoxetine (Prozac), sertraline (Zoloft), fluvoxamine (Luvox), citalopram (Celexa), paroxetine (Paxil)
- Other agents:
- Amoxapine (Moxadil), maprotiline, trazodone (Desyrel), bupropion (Wellbutrin)
- Venlafaxine (Effexor), mirtazapine (Remeron), nefazodone (Serzone), duloxetine (Cymbalta)
- Normal range: see Table 16.8; not established for all drugs in this class
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TABLE 16 " “8Normal Therapeutic Levels for Antidepressants*View LargeTABLE 16 " “8Normal Therapeutic Levels for Antidepressants* Drug/Drug Combination Normal Level (ng/mL) Potentially Toxic Level (ng/mL) Amitriptyline + nortriptyline 95 " “250 >500 Nortriptyline 50 " “150 >500 Imipramine + desipramine 150 " “300 >500 Desipramine 100 " “300 >500 Doxepin + nordoxepin 100 " “300 >400 Protriptyline 70 " “240 >400 Bupropion 50 " “100 Trazodone 800 " “1,600 Fluoxetine 50 " “480, with 20 " “60 mg/d Norfluoxetine 50 " “450, with 20 " “60 mg/d Clomipramine + norclomipramine 220 " “500 >900 " *Not established for all drugs in this class. " When used as an antidepressant, therapeutic range not well established when prescribed for obsessive " “compulsive disorder.
Use
- Treatment of mood disorders and depression
Limitations
- Immunoassay screening of serum/plasma/urine for TCAs does not detect other antidepressants (e.g., SSRIs).
- Target analytes: imipramine, nortriptyline.
- Cutoff concentrations:
- 10 " “50 ng/mL ELISA
- 300 or 500 ng/mL EIA qualitative
- 150 ng/mL EIA semiquantitative
- Variable cross-reactivity with other TCAs, metabolites: consult the manufacturers package insert.
- Will not detect SSRIs and newer antidepressants.
- No SSRI-specific immunoassays are currently available.
- General drug screens comprising alkaline liquid " “liquid extraction or solid-phase extraction followed by GC/MS or gas chromatography analysis detect TCAs, SSRIs, trazodone, bupropion, venlafaxine, mirtazapine, and amoxapine with limit of detection ranging from 20 to 250 ng/mL.